BGuthrie Photos: DC -- Natl Air and Space Museum -- Gallery 213: (a) Time and Navigation

DC -- Natl Air and Space Museum -- Gallery 213: (a) Time and Navigation:

Bruce Guthrie Photos Home Page: [Click here] to go to Bruce Guthrie Photos home page.

Recognize anyone? If you recognize specific folks (or other stuff) and I haven't labeled them, please identify them for the world. Click the little pencil icon

underneath the file name (just above the picture). Spammers need not apply.

Slide Show: Want to see the pictures as a slide show? [Slideshow]

Copyrights: All pictures were taken by amateur photographer Bruce Guthrie (me!) who retains copyright on them. Free for non-commercial use with attribution. See the [Creative Commons] definition of what this means. "Photos (c) Bruce Guthrie" is fine for attribution. (Commercial use folks including AI scrapers can of course contact me.) Feel free to use in publications and pages with attribution but you don't have permission to sell the photos themselves. A free copy of any printed publication using any photographs is requested. Descriptive text, if any, is from a mixture of sources, quite frequently from signs at the location or from official web sites; copyrights, if any, are retained by their original owners.

Help? The Medium (Email) links are for screen viewing and emailing. You'll want bigger sizes for printing. [Click here for additional help]

[1] GAL213_130512_0003_STITCH.JPG

Medium (Email) (Bigger?)

[2] GAL213_130512_0022.JPG Medium (Email) (Bigger?)	[3] GAL213_130512_0028.JPG Medium (Email) (Bigger?)	[4] GAL213_130512_0037.JPG Medium (Email) (Bigger?)
[5] GAL213_130512_0042.JPG Medium (Email) (Bigger?)	[6] GAL213_130512_0047.JPG Medium (Email) (Bigger?)	[7] GAL213_130512_0060.JPG Medium (Email) (Bigger?)
[8] GAL213_130512_0066.JPG Medium (Email) (Bigger?)	[9] GAL213_130512_0073.JPG Medium (Email) (Bigger?)	[10] GAL213_130512_0079.JPG Medium (Email) (Bigger?)
[11] GAL213_130512_0090.JPG Medium (Email) (Bigger?)	[12] GAL213_130512_0104.JPG Medium (Email) (Bigger?)	[13] GAL213_130512_0110.JPG Medium (Email) (Bigger?)
[14] GAL213_130512_0113.JPG Medium (Email) (Bigger?)	[15] GAL213_130512_0118.JPG Medium (Email) (Bigger?)	[16] GAL213_130512_0127.JPG Medium (Email) (Bigger?)
[17] GAL213_130512_0131.JPG Medium (Email) (Bigger?)	[18] GAL213_130512_0136.JPG Medium (Email) (Bigger?)	[19] GAL213_130512_0143.JPG Medium (Email) (Bigger?)
[20] GAL213_130512_0148.JPG Medium (Email) (Bigger?)	[21] GAL213_130512_0154.JPG Medium (Email) (Bigger?)	[22] GAL213_130512_0158.JPG Medium (Email) (Bigger?)
[23] GAL213_130512_0163.JPG Medium (Email) (Bigger?)	[24] GAL213_130512_0174.JPG Medium (Email) (Bigger?)	[25] GAL213_130512_0184.JPG Medium (Email) (Bigger?)
[26] GAL213_130512_0188.JPG Medium (Email) (Bigger?)	[27] GAL213_130512_0197.JPG Medium (Email) (Bigger?)	[28] GAL213_130512_0201.JPG Medium (Email) (Bigger?)
[29] GAL213_130512_0206.JPG Medium (Email) (Bigger?)	[30] GAL213_130512_0211.JPG Medium (Email) (Bigger?)	[31] GAL213_130512_0222.JPG Medium (Email) (Bigger?)
[32] GAL213_130512_0229.JPG Medium (Email) (Bigger?)	[33] GAL213_130512_0235.JPG Medium (Email) (Bigger?)	[34] GAL213_130512_0243.JPG Medium (Email) (Bigger?)
[35] GAL213_130512_0257.JPG Medium (Email) (Bigger?)	[36] GAL213_130512_0259.JPG Medium (Email) (Bigger?)	[37] GAL213_130512_0270.JPG Medium (Email) (Bigger?)
[38] GAL213_130512_0275.JPG Medium (Email) (Bigger?)	[39] GAL213_130512_0285.JPG Medium (Email) (Bigger?)	[40] GAL213_130512_0289.JPG Medium (Email) (Bigger?)
[41] GAL213_130512_0300.JPG Medium (Email) (Bigger?)	[42] GAL213_130512_0307.JPG Medium (Email) (Bigger?)	[43] GAL213_130512_0312.JPG Medium (Email) (Bigger?)
[44] GAL213_130512_0319.JPG Medium (Email) (Bigger?)	[45] GAL213_130512_0320.JPG Medium (Email) (Bigger?)	[46] GAL213_130512_0325.JPG Medium (Email) (Bigger?)
[47] GAL213_130512_0330.JPG Medium (Email) (Bigger?)	[48] GAL213_130512_0342.JPG Medium (Email) (Bigger?)	[49] GAL213_130512_0348.JPG Medium (Email) (Bigger?)
[50] GAL213_130512_0360.JPG Medium (Email) (Bigger?)	[51] GAL213_130512_0365.JPG Medium (Email) (Bigger?)	[52] GAL213_130512_0370.JPG Medium (Email) (Bigger?)
[53] GAL213_130512_0377.JPG Medium (Email) (Bigger?)	[54] GAL213_130512_0382.JPG Medium (Email) (Bigger?)	[55] GAL213_130512_0394.JPG Medium (Email) (Bigger?)
[56] GAL213_130512_0406.JPG Medium (Email) (Bigger?)	[57] GAL213_130512_0412.JPG Medium (Email) (Bigger?)	[58] GAL213_130512_0417.JPG Medium (Email) (Bigger?)
[59] GAL213_130512_0423.JPG Medium (Email) (Bigger?)	[60] GAL213_130512_0430.JPG Medium (Email) (Bigger?)	[61] GAL213_130512_0437.JPG Medium (Email) (Bigger?)
[62] GAL213_130512_0443.JPG Medium (Email) (Bigger?)	[63] GAL213_130512_0452.JPG Medium (Email) (Bigger?)	[64] GAL213_130512_0457.JPG Medium (Email) (Bigger?)
[65] GAL213_130512_0462.JPG Medium (Email) (Bigger?)	[66] GAL213_130512_0468.JPG Medium (Email) (Bigger?)	[67] GAL213_130512_0472.JPG Medium (Email) (Bigger?)
[68] GAL213_130512_0478.JPG Medium (Email) (Bigger?)	[69] GAL213_130512_0483.JPG Medium (Email) (Bigger?)	[70] GAL213_130512_0487.JPG Medium (Email) (Bigger?)
[71] GAL213_130512_0491.JPG Medium (Email) (Bigger?)	[72] GAL213_130512_0495.JPG Medium (Email) (Bigger?)	[73] GAL213_130512_0501.JPG Medium (Email) (Bigger?)
[74] GAL213_130512_0505.JPG Medium (Email) (Bigger?)	[75] GAL213_130512_0513.JPG Medium (Email) (Bigger?)	[76] GAL213_130512_0518.JPG Medium (Email) (Bigger?)
[77] GAL213_130512_0525.JPG Medium (Email) (Bigger?)	[78] GAL213_130512_0534.JPG Medium (Email) (Bigger?)	[79] GAL213_130512_0540.JPG Medium (Email) (Bigger?)
[80] GAL213_130512_0546.JPG Medium (Email) (Bigger?)	[81] GAL213_130512_0549.JPG Medium (Email) (Bigger?)	[82] GAL213_130512_0554.JPG Medium (Email) (Bigger?)
[83] GAL213_130512_0569.JPG Medium (Email) (Bigger?)	[84] GAL213_130512_0579.JPG Medium (Email) (Bigger?)	[85] GAL213_130512_0585.JPG Medium (Email) (Bigger?)
[86] GAL213_130512_0596.JPG Medium (Email) (Bigger?)	[87] GAL213_130512_0606.JPG Medium (Email) (Bigger?)	[88] GAL213_130512_0614.JPG Medium (Email) (Bigger?)
[89] GAL213_130512_0620.JPG Medium (Email) (Bigger?)	[90] GAL213_130512_0625.JPG Medium (Email) (Bigger?)	[91] GAL213_130512_0635.JPG Medium (Email) (Bigger?)
[92] GAL213_130512_0653.JPG Medium (Email) (Bigger?)	[93] GAL213_130512_0657.JPG Medium (Email) (Bigger?)	[94] GAL213_130512_0671.JPG Medium (Email) (Bigger?)
[95] GAL213_130512_0676.JPG Medium (Email) (Bigger?)	[96] GAL213_130512_0680.JPG Medium (Email) (Bigger?)	[97] GAL213_130512_0687.JPG Medium (Email) (Bigger?)
[98] GAL213_130512_0692.JPG Medium (Email) (Bigger?)	[99] GAL213_130512_0699.JPG Medium (Email) (Bigger?)	[100] GAL213_130512_0704.JPG Medium (Email) (Bigger?)
[101] GAL213_130512_0708.JPG Medium (Email) (Bigger?)	[102] GAL213_130512_0713.JPG Medium (Email) (Bigger?)	[103] GAL213_130512_0717.JPG Medium (Email) (Bigger?)
[104] GAL213_130512_0723.JPG Medium (Email) (Bigger?)	[105] GAL213_130512_0728.JPG Medium (Email) (Bigger?)	[106] GAL213_130512_0733.JPG Medium (Email) (Bigger?)
[107] GAL213_130512_0738.JPG Medium (Email) (Bigger?)	[108] GAL213_130512_0743.JPG Medium (Email) (Bigger?)	[109] GAL213_130512_0749.JPG Medium (Email) (Bigger?)
[110] GAL213_130512_0753.JPG Medium (Email) (Bigger?)	[111] GAL213_130512_0757.JPG Medium (Email) (Bigger?)	[112] GAL213_130512_0763.JPG Medium (Email) (Bigger?)
[113] GAL213_130512_0772.JPG Medium (Email) (Bigger?)	[114] GAL213_130512_0778.JPG Medium (Email) (Bigger?)	[115] GAL213_130512_0784.JPG Medium (Email) (Bigger?)
[116] GAL213_130512_0807.JPG Medium (Email) (Bigger?)	[117] GAL213_130512_0813.JPG Medium (Email) (Bigger?)	[118] GAL213_130512_0819.JPG Medium (Email) (Bigger?)
[119] GAL213_130512_0826.JPG Medium (Email) (Bigger?)	[120] GAL213_130512_0832.JPG Medium (Email) (Bigger?)	[121] GAL213_130512_0838.JPG Medium (Email) (Bigger?)
[122] GAL213_130512_0845.JPG Medium (Email) (Bigger?)	[123] GAL213_130512_0851.JPG Medium (Email) (Bigger?)	[124] GAL213_130512_0857.JPG Medium (Email) (Bigger?)
[125] GAL213_130512_0863.JPG Medium (Email) (Bigger?)	[126] GAL213_130512_0871.JPG Medium (Email) (Bigger?)	[127] GAL213_130512_0880.JPG Medium (Email) (Bigger?)
[128] GAL213_130512_0885.JPG Medium (Email) (Bigger?)	[129] GAL213_130512_0891.JPG Medium (Email) (Bigger?)	[130] GAL213_130512_0897.JPG Medium (Email) (Bigger?)
[131] GAL213_130512_0900.JPG Medium (Email) (Bigger?)	[132] GAL213_130512_0914.JPG Medium (Email) (Bigger?)	[133] GAL213_130512_0920.JPG Medium (Email) (Bigger?)
[134] GAL213_130512_0923.JPG Medium (Email) (Bigger?)	[135] GAL213_130512_0928.JPG Medium (Email) (Bigger?)	[136] GAL213_130512_0932.JPG Medium (Email) (Bigger?)
[137] GAL213_130512_0941.JPG Medium (Email) (Bigger?)	[138] GAL213_130512_0946.JPG Medium (Email) (Bigger?)	[139] GAL213_130512_0951.JPG Medium (Email) (Bigger?)
[140] GAL213_130512_0956.JPG Medium (Email) (Bigger?)	[141] GAL213_130512_0964.JPG Medium (Email) (Bigger?)	[142] GAL213_130512_0969.JPG Medium (Email) (Bigger?)
[143] GAL213_130512_0972.JPG Medium (Email) (Bigger?)	[144] GAL213_130512_0975.JPG Medium (Email) (Bigger?)	[145] GAL213_130512_0978.JPG Medium (Email) (Bigger?)
[146] GAL213_130512_0984.JPG Medium (Email) (Bigger?)	[147] GAL213_130512_0989.JPG Medium (Email) (Bigger?)	[148] GAL213_130512_0992.JPG Medium (Email) (Bigger?)
[149] GAL213_130512_1001.JPG Medium (Email) (Bigger?)	[150] GAL213_130512_1006.JPG Medium (Email) (Bigger?)	[151] GAL213_130512_1015.JPG Medium (Email) (Bigger?)
[152] GAL213_130512_1021.JPG Medium (Email) (Bigger?)	[153] GAL213_130512_1026.JPG Medium (Email) (Bigger?)	[154] GAL213_130512_1037.JPG Medium (Email) (Bigger?)
[155] GAL213_130512_1042.JPG Medium (Email) (Bigger?)	[156] GAL213_130512_1047.JPG Medium (Email) (Bigger?)	[157] GAL213_130512_1058.JPG Medium (Email) (Bigger?)
[158] GAL213_130512_1065.JPG Medium (Email) (Bigger?)	[159] GAL213_130512_1071.JPG Medium (Email) (Bigger?)	[160] GAL213_130512_1076.JPG Medium (Email) (Bigger?)
[161] GAL213_130512_1081.JPG Medium (Email) (Bigger?)	[162] GAL213_130512_1086.JPG Medium (Email) (Bigger?)	[163] GAL213_130512_1093.JPG Medium (Email) (Bigger?)
[164] GAL213_130512_1099.JPG Medium (Email) (Bigger?)	[165] GAL213_130512_1108.JPG Medium (Email) (Bigger?)	[166] GAL213_130512_1111.JPG Medium (Email) (Bigger?)
[167] GAL213_130512_1114.JPG Medium (Email) (Bigger?)	[168] GAL213_130512_1120.JPG Medium (Email) (Bigger?)	[169] GAL213_130512_1125.JPG Medium (Email) (Bigger?)
[170] GAL213_130512_1134.JPG Medium (Email) (Bigger?)	[171] GAL213_130512_1139.JPG Medium (Email) (Bigger?)	[172] GAL213_130512_1143.JPG Medium (Email) (Bigger?)
[173] GAL213_130512_1147.JPG Medium (Email) (Bigger?)	[174] GAL213_130512_1151.JPG Medium (Email) (Bigger?)	[175] GAL213_130512_1165.JPG Medium (Email) (Bigger?)
[176] GAL213_130512_1172.JPG Medium (Email) (Bigger?)	[177] GAL213_130512_1176.JPG Medium (Email) (Bigger?)	[178] GAL213_130512_1186.JPG Medium (Email) (Bigger?)
[179] GAL213_130512_1192.JPG Medium (Email) (Bigger?)	[180] GAL213_130512_1197.JPG Medium (Email) (Bigger?)	[181] GAL213_130512_1201.JPG Medium (Email) (Bigger?)
[182] GAL213_130512_1206.JPG Medium (Email) (Bigger?)	[183] GAL213_130512_1212.JPG Medium (Email) (Bigger?)	[184] GAL213_130512_1216.JPG Medium (Email) (Bigger?)
[185] GAL213_130512_1222.JPG Medium (Email) (Bigger?)	[186] GAL213_130512_1230.JPG Medium (Email) (Bigger?)	[187] GAL213_130512_1236.JPG Medium (Email) (Bigger?)
[188] GAL213_130512_1242.JPG Medium (Email) (Bigger?)	[189] GAL213_130512_1246.JPG Medium (Email) (Bigger?)	[190] GAL213_130512_1255.JPG Medium (Email) (Bigger?)
[191] GAL213_130512_1263.JPG Medium (Email) (Bigger?)	[192] GAL213_130512_1267.JPG Medium (Email) (Bigger?)	[193] GAL213_130512_1273.JPG Medium (Email) (Bigger?)
[194] GAL213_130512_1282.JPG Medium (Email) (Bigger?)	[195] GAL213_130512_1287.JPG Medium (Email) (Bigger?)	[196] GAL213_130512_1294.JPG Medium (Email) (Bigger?)
[197] GAL213_130512_1299.JPG Medium (Email) (Bigger?)	[198] GAL213_130512_1303.JPG Medium (Email) (Bigger?)	[199] GAL213_130512_1309.JPG Medium (Email) (Bigger?)
[200] GAL213_130512_1318.JPG Medium (Email) (Bigger?)	[201] GAL213_130512_1324.JPG Medium (Email) (Bigger?)	[202] GAL213_130512_1328.JPG Medium (Email) (Bigger?) $Dividing Engine Dividing engine, made by Jesse Ramsden, London, 1775. This machine permitted the automatic and highly accurate division of a circle into degrees and fractions of degrees of arc. Invented by Englishman Jesse Ramsden in the 1770s, the machine ultimately led to mass production of precision octants and sextants and gave British manufacturers dominance in the field of marine instruments for decades. Ramsden's invention was so valuable to the nation's maritime interests that he received a share of the Longitude Prize.$
[203] GAL213_130512_1342.JPG Medium (Email) (Bigger?)	[204] GAL213_130512_1354.JPG Medium (Email) (Bigger?)	[205] GAL213_130512_1356.JPG Medium (Email) (Bigger?)
[206] GAL213_130512_1366.JPG Medium (Email) (Bigger?)

Specific picture descriptions: Photos above with "i" icons next to the bracketed sequence numbers (e.g. "[1] ") are described as follows:
1. GAL213_130512_0028.JPG: Welcome to Time and Navigation: How did you find your way here today? Did you use a map? Or look for familiar landmarks? Or rely on GPS? As you visit this exhibition and see how people have navigated over the centuries, think about how you find your way from here to there.
2. GAL213_130512_0037.JPG: Time and Navigation: The Untold Story of Getting from Here to There If you want to know where you are, you need an accurate clock. This surprising connection between time and space has been crucial for centuries. About 250 years ago, sailors first used accurate clocks to navigate the oceans. Today we locate ourselves on the globe with synchronized clocks in orbiting satellites. Among the many challenges facing navigation from then to now, one stands out: keeping accurate time. This exhibition explores how revolutions in timekeeping over three centuries have influenced how we find our way.
3. GAL213_130512_0042.JPG: Navigating at Sea Instruments to find and keep time revolutionized the way mariners crossed the oceans. In 1700, Europe's mariners and mapmakers knew only about half the Earth's surface with any detail. Rival nations were exploring the seas in search of greater wealth, power, and prestige. But uncharted seas were dangerous. To make ocean travel safer and faster, people had to develop better maps, better navigation tools and techniques, and better clocks.
4. GAL213_130512_0060.JPG: Navigating Without a Clock Mariners achieved remarkable feats of exploration using only the simplest tools. Before accurate ship clocks were common, European navigators paid careful attention to time derived from the Sun, Moon, and stars. Aware of the risks, seafarers relied on their tools, know-how, and sometimes even luck when they ventured out on the world's uncharted, dangerous oceans.
5. GAL213_130512_0066.JPG: "The art of navigation demonstrates how by the shortest good way, by the aptest direction, and in the shortest time, a sufficient ship between any two places... be conducted." -- John Dee in 1570 Dead Reckoning Simple navigation methods and instruments served European mariners for centuries. Starting at a known or assumed position, a navigator used simple but reliable tools to track three things: • The ship's compass heading. • The ship's speed. • The time spent on each heading and at each speed. With this information, the navigator could calculate the route and distance the ship had covered and mark a sea chart, if he had one. This method was called dead reckoning. It was used by Columbus and most other mariners of the Age of Exploration.
6. GAL213_130512_0073.JPG: "If you want to learn to pray, go to sea." -- - Portuguese proverb Challenging the High Seas Methods to navigate open seas differ from culture to culture. People accomplished amazing feats of navigation across open oceans well before modern Europeans took to uncharted seas. Vikings and Polynesians, for example, built sturdy boats and found their way without maps across vast distances by closely observing their environment. Viking Voyages In the harsh, stormy waters of the North Atlantic between A.D. 750 and 1000, waves of peoples from Scandinavia -- collectively known as the Vikings -- sailed west to settle Britain, Iceland, Greenland, and even North America. They hopped from island to island and also observed the presence of birds near land and their migration patterns. Polynesian Voyages Over thousands of years, Polynesians migrated across vast distances and spread their culture across the Pacific. But they left no written record. Modern voyagers have recreated their routes, canoes, and methods. They suggest early Polynesian navigators sailed from island to island by observing Sun and stars, wind and waves, and the behavior of birds and fish.
7. GAL213_130512_0104.JPG: Frontispiece, The Mariners Mirrour, 1588 This illustration is the frontispiece to The Mariner's Mirrour, one of the most famous collections of sea charts from the 16th century. First printed in Holland, it was translated into English and published in 1588. English sailors used it for about 100 years. The illustration shows many of the instruments used by early navigators.
8. GAL213_130512_0110.JPG: Dead Reckoning Lead Line: Measures water depth and brings up a sample of the bottom. Compass: Determines direction -- north, south, east, or west, and points in between. Sandglass: Measures intervals of time for ship speed and periods of duty. Dividers: Measure the distance between two points on a chart to mark the ship's position.
9. GAL213_130512_0113.JPG: Using the Sun and Stars: Cross Staff: Measures the Sun's angle above the horizon at midday. Horary Quadrant: Finds the time of day by measuring the Sun's altitude. Nocturnal: Finds local time at night by observation of stars near the North Pole. Mariner's Astrolabe: Measures the angle of the Sun or a star above the horizontal line of reference.
10. GAL213_130512_0127.JPG: The Longitude Problem Seafaring's greatest danger was getting lost. By 1700, finding latitude at sea was routine and fairly accurate. But finding longitude was mostly guesswork. Astronomers thought the answer to finding longitude lay in observing the skies. Others thought the solution was a good seaworthy clock, but no such clock existed. After an outpouring of ideas and generations of work, both a good clock and a good sextant for observations were invented. These instruments revolutionized position-finding at sea.
11. GAL213_130512_0131.JPG: Dead Reckoning at Sea A navigator can take measurements of the ship speed and direction and the effects of wind and current. He can estimate the ship's location fairly accurately–at least over short distances.
12. GAL213_130512_0136.JPG: Longitude Lines of longitude are imaginary lines circling the globe through poles. Also called meridians, they are designated in degrees east of west of a starting reference line from 0� at the prime meridian to 180� on the opposite side of the globe.
13. GAL213_130512_0143.JPG: Cash for Creativity European governments offered huge prizes to inspire a solution to the longitude problem. Finding longitude at sea became urgent when European states competed for overseas empires and maritime trade. Starting in the late 1500s, Europe's major seafaring nations -- Spain, the Netherlands, Portugal, the Venetian Republic, England, and France -- offered vast sums of money to anyone who could solve the longitude problem. These prizes stimulated an inventive outpouring from both the greatest scientific minds and the humblest tinkerers.
14. GAL213_130512_0148.JPG: Solving the Longitude Problem: Sea Clocks and Watches: Finding longitude greatly improved once a portable clock was invented that could keep accurate time at sea -- the chronometer. Prizes offered by Spain in 1598 and the Dutch Republic two years later stimulated the best scientific minds of the day to build better clocks for finding position at sea. The challenge was enormous. At that time, no clock -- on land or sea -- could keep better time than within about 15 minutes a day. But after nearly two centuries, with the invention of the chronometer, accuracy at sea improved to about 1/5th of a second a day.
15. GAL213_130512_0154.JPG: "One [method of finding longitude] is by a Watch to keep time exactly. But, by reason of the motion of the Ship, the Variation of Heat and Cold, Wet and Dry, and the Difference of Gravity at different Latitudes, such a watch hath not yet been made." -- - Sir Isaac Newton, 1714
16. GAL213_130512_0158.JPG: Early Sea Clock Experiments: Galileo Galilei: Italian Galileo Galilei competed for two longitude prizes. To Spain, he offered a solution based on the moons of Jupiter, which he had discovered with a telescope of his own design in 1610. To the Dutch in 1642, he proposed both his astronomical solution and an accurate sea clock -- the first clock ever to have a pendulum. Galileo died before making the clock, but his son built a model in 1649. Christiaan Huygens: In pursuit of a sea clock, Christiaan Huygens, a mathematician from the Netherlands, changed timekeeping forever. He patented the first working pendulum clock in 1656 and later devised a watch regulator called a balance spring. These inventions became standard components for keeping good time. Pendulum clocks immediately became the best timekeepers for use on land. But several sea trials demonstrated to Huygens that the pendulum clock would never work accurately on a heaving ship's deck.
17. GAL213_130512_0163.JPG: Dutch Pendulum Clock, about 1680 One of the earliest pendulum clocks
18. GAL213_130512_0174.JPG: Galileo's Pendulum Clock Design Replica This is a replica of Galileo's design for a pendulum clock. In 1642, for a Dutch longitude prize, Galileo proposed both an astronomical solution and an accurate sea clock -- the first clock ever to have a pendulum. Galileo died before making the clock, but his son built a model in 1649.
19. GAL213_130512_0188.JPG: Navigation Gone Wrong A British Fleet Runs Aground While returning from Gibraltar in 1707, a squadron of British Royal Navy ships went badly astray off the coast of England, with disastrous results. What Happened The weather had been overcast and stormy for days. On October 22, Admiral Cloudesley Shovell consulted with all his navigators to determine the fleet's position. Most believed they were sailing on the latitude of Ushant near France. Shovell set a course for home, based on their advice. The Consequences They were wrong. Later that night, Shovell's flagship, the Association, slammed into the rocks off the Scilly Isles and sank within minutes. Three other ships and over 1,000 men, including the admiral, were lost to the sea. Lessons Learned The tragedy, the worst maritime disaster in British history to that time, provoked demands for safer navigation. Parliament passed the Longitude Act of 1714, which created a panel of experts to oversee rewards for solving the problem of finding longitude at sea.
20. GAL213_130512_0197.JPG: John Harrison's Sea Clocks: A stunning technical breakthrough came when English carpenter and clockmaker John Harrison built five experimental sea clocks between 1735 and 1772. With them, he demonstrated the feasibility of accurate timekeeping at sea. His best clock tested at sea -- a large, portable, silver-cased watch -- kept time with an accuracy of about 1/5th of a second per day. Shortly before he died, Harrison received nearly the full �20,000 that England had offered to anyone who could solve the longitude problem -- but not until King George III himself intervened. Harrison sent his last sea clock to the king's private observatory in 1772, where George III witnessed its performance and deemed it prize-worthy.
21. GAL213_130512_0201.JPG: Making the sea clock practical To design and build a standardized seagoing timekeeper took decades. John Harrison's timekeepers were ingenious but difficult to reproduce accurately and affordably. Still, they guided the work of later watchmakers, whose modifications would standardize the portable timepieces that came to be known as marine chronometers. Ferdinand Berthoud, a Swiss clockmaker serving the king of France, produced many marine clocks, including a weight-driven version that inspired the first American sea-going clock. This is Berthoud's marine clock No. 24 from 1782. While John Harrison was working in England, French clockmaker Pierre Le Roy was also inventing elements of the modern marine timekeeper. This is an illustration from 1766 depicts the improved escapement in Le Roy's marine clock.
22. GAL213_130512_0206.JPG: "In this age of science... it is indeed most astonishing that any ship should be permitted to set out on a voyage without a chronometer." -- Captain Basil Hall, 1825
23. GAL213_130512_0211.JPG: Chronometer Movements
24. GAL213_130512_0222.JPG: What Makes a Marine Chronometer So Precise? Marine chronometers are key-wound, spring-driven timekeepers that are more precise than most others mainly because of several special features: MAINSPRING ARRANGEMENT – Combines the spring with a fusee to equalize the force of the spring as it unwinds. SPRING DETENT ESCAPEMENT – Transfers power from the spring to keep the balance swinging regularly, while interfering with it as little as possible. BALANCE WHEEL – Regulates the pace of the chronometer with a special combination of two metals that expand and contract at different rates to compensate for temperature changes. PROTECTIVE BOX WITH GIMBAL – Holds the chronometer level with the horizon to prevent position changes that can alter its ability to keep precise time.
25. GAL213_130512_0235.JPG: Using a Marine Chronometer Marine chronometers are precise, specialized clocks for finding longitude at sea. They serve as portable time standards.
26. GAL213_130512_0243.JPG: The United States Goes to Sea Oceans and waterways shaped the country from the very beginning. As a young nation, the United States was eager to join the world's maritime powers. Its commercial reach spread around the globe in the 19th century, and American ships sailed every ocean. They carried immigrants to new homes, exotic goods from Asia, and prospectors to the California gold fields. American seaports flourished. Shipping grew faster, safer, and more reliable.
27. GAL213_130512_0257.JPG: America's earliest contributions to navigation. Intent upon contributing to the art and science of navigation, civilian and naval innovators worked to lessen the dangers of seafaring by seeking better ways to find time and place. A Navigation Encyclopedia The New American Practical Navigator has served American sailors since 1802. Popularly known as Bowditch's for its first compiler, Nathaniel Bowditch, it remains a useful handbook of astronomical tables, meteorological information, and navigational instructions. Navigation By Line of Position While nearing land on his way to Scotland in 1837, Captain Thomas Sumner of Boston had an insight that made an enduring contribution to navigation. Cloudy weather permitted only one sighting on the Sun. With that limited information, Sumner made three different calculations based on estimates of his latitude. Plotted on a chart, the results lay along a straight line. He realized that any ship seeing the Sun at the same altitude in the sky must be located somewhere on that line. This was confirmed by sailing along that course until a lighthouse was sighted on the coast. Sumner published his method for determining what was later called a "line of position" in 1843, and it became standard practice.
28. GAL213_130512_0259.JPG: America's First Sea-Going Chronomenter This timekeeper was the first American-made marine timekeeper taken to sea. William Cranch Bond, a 23-year-old Boston clockmaker, crafted it during the War of 1812. It went to sea only once, on a voyage to Sumatra (now in Indonesia) aboard the U.S. Navy vessel Cyrus in 1818. Chronometers would not be common aboard American ships until about 1830. Bond's chronometer differed from spring-powered English models. Unable to buy British spring steel in wartime, Bond used a French design powered by a falling weight.
29. GAL213_130512_0270.JPG: Meet The Clockmaker William Cranch Bond William Bond and Son, begun in 1793, became one of America's best-known chronometer dealers. Its instruments were vital tools for New England's maritime enterprise. The company's success enabled the founder's son, William Cranch Bond, to pursue his passion for astronomy. He became the first director of the Harvard College Observatory in 1839. He conducted longitude expeditions and started a service for telegraphing time signals to New England.
30. GAL213_130512_0275.JPG: The U.S. Exploring Expedition The United States dispatched an ambitious mission to uncharted oceans. In 1838, six U.S. Navy vessels set out on a great voyage of exploration. Aboard were several hundred seamen and scientists under the command of Lt. Charles Wilkes. Authorized by Congress, the U.S. Exploring Expedition (also known as the Ex. Ex. or the Wilkes Expedition) would explore and map the Pacific, Antarctica, and the northwest coast of the United States. A tremendous feat of navigation, the expedition broadened knowledge of uncharted areas of the world and helped expand American commerce, industry, and scientific knowledge. It cemented the nation's status as a new world economic leader.
31. GAL213_130512_0285.JPG: The Expedition''s "Scientifics" The expedition included a formidable group of botanists, naturalists, artists, taxidermists, and other scientists to collect and catalog plant, animal, and cultural artifacts throughout the newly charted territories. Referred to as the "Scientifics," they included naturalist Titian Ramsay Peale and geologist James Dwight Dana. The scientific corps published 19 volumes on their findings. Wilkes himself contributed two volumes on meteorology and hydrology.
32. GAL213_130512_0289.JPG: Instruments and Methods Charles Wilkes spent a small fortune acquiring navigation equipment. He outfitted the expedition with 28 marine chronometers, 12 sextants, a library for each vessel, and many other astronomical and meteorological instruments. The chronometers Wilkes purchased came from the finest English makers. The actual instruments used on the expedition were returned to the U.S. Navy and dispersed. ". . . Meteorological observations in every shape + form. Transit observations of Star Passing the meridian for determining the rates of Chros [chronometers]. Observations of moon culminating stars, for the purpose of deducing Longitude, all these and more were daily being taken or made, the most important by Capt. Wilkes in person + the remainder under his direction + superintendence." -- Lt. Micajah G. L. Claiborne, remarking about navigation observations during the Wilkes Expedition
33. GAL213_130512_0300.JPG: Marine Chronometers
34. GAL213_130512_0342.JPG: Meet The Mapmaker Charles Wilkes Charismatic but haughty, Captain Charles Wilkes became an experienced naval officer known for his expertise and accuracy in mapping and charting. He was passionate about navigation technology. Before leading the U.S. Exploring Expedition, he headed the Navy's Department of Charts and Instruments (now the U.S. Naval Observatory), where he worked tirelessly on synchronizing marine chronometers. Despite the expedition's success, Wilkes's heavy-handed treatment of his crew resulted in his court-martial and a reprimand.
35. GAL213_130512_0348.JPG: Ship Model of USS Porpoise One of six ships of the U.S. Exploring Expedition, the Porpoise sailed around the world between 1838 and 1842. The ship's crew scouted Antarctica, surveyed the Pacific Ocean, and mapped the Columbia River.
36. GAL213_130512_0360.JPG: How to Use a Sextant Use on of these sextants to measure the angle between the horizon and the bright star on the wall in front of you. 1. On the left side of the sextant, find the eye tube, index arm, and scale. 2. Look through the eye tube and move the index arm. See how the right side of the image moves while the left remains directed at the horizon. 3. Slowly move the index arm until the star comes into view. Adjust the arm so the star lines up with the horizon. 4. Keeping the arm in the same position, read the scale. This shows the altitude of the star in degrees.
37. GAL213_130512_0365.JPG: Can you navigate the Flying Cloud? Imagine being the navigator on the clipper ship Flying Cloud in 1854. Your goal is to sail 25,750 kilometers (16,000 miles) around South America to San Francisco as fast as possible. For this experience, you'll be simulating many of the steps required to determine position. This method later became standard practice for finding position at sea.
38. GAL213_130512_0370.JPG: Gold! Flying Cloud races from New York to San Francisco is just 89 days! The 1848 discovery of gold in California inspired efforts to speed the trip to San Francisco from East Coast ports, a sea trip around the tip of South America that averaged about six months. American shipbuilders began to craft slim vessels built for speed -- the clipper ships. In 1851, Boston-built Flying Cloud sailed from New York to San Francisco in an astonishing 89 days, 21 hours. Three years later, the same vessel set a new record -- 89 days, 8 hours -- that stood for 135 years. Flying Cloud's Navigator was a Woman: Josiah Perkins Creesy, Jr. commanded the ship, and, uncommon for the time, his wife Eleanor navigated. As a child in Massachusetts, she had learned navigation skills from her seafaring father. New Science Shaves Months from Voyage: Mrs. Creesy was among the first to follow new sailing directions, based on winds and currents, published by Matthew Maury at the U.S. Navy's Depot of Charts and Instruuments (later the U.S. Naval Observatory).
39. GAL213_130512_0394.JPG: NC-4 by Ted Wilbur The U.S. Navy's Curtiss NC-4 flying boat made the first crossing of the Atlantic by air in 1919. Note the uncomfortable, exposed position of flight commander and navigator Albert Read in the nose. Read's discomfort was only one of many navigational shortcomings of the 15-day, multiple-stop voyage. Out of three airplanes, only the NC-4 completed the entire flight.
40. GAL213_130512_0412.JPG: A Harrowing Ordeal: The first attempt to fly to Hawaii from the mainland United States, in 1925, resulted in a fight for survival and an amazing feat of navigation and seamanship. The U.S. Navy PN-9 making the flight burned far more fuel than expected. After missing a supply ship, Cmdr. John Rodgers and his crew had to make a forced landing nearly 500 kilometers (310 miles) from Honolulu. Without a working transmitter radio to call for help, the five men had to improvise. They ripped fabric from a wing to make a sail, and Rodgers "sailed" his plane toward Hawaii. Ten days later, a submarine that had given them up for lost spotted them just off the coast of Kauai.
41. GAL213_130512_0417.JPG: The Challenges of Air Navigation The hazards of aviation created a demand for specialized navigation and timing technology. Early aviators on long flights sometimes faced great danger because they could not figure out exactly where they were. "Fixing" position over water, in the dark, or in poor weather was difficult. The consequences of getting lost could be dire. The celestial navigation tools sailors used at sea didn't work as well in the air. Aviators needed new equipment and techniques.
42. GAL213_130512_0457.JPG: Why Did Nations Take the Risk? Many nations took on the challenge of navigating across the ocean by air. Between the world wars, the United States and many European countries competed for national prestige by setting new transoceanic records, establishing overseas airline service, connecting colonial possessions, and demonstrating military power. In peacetime, these achievements showed how far aviation had come in only a few years. But as war broke out again, the ability to cross oceans by air meant that no nation was safe from attack.
43. GAL213_130512_0462.JPG: The Era of Transoceanic Flight Begins: Flying boats spearheaded aerial exploration and overseas transport in the 1920s and '30s and opened the era of regular transoceanic flights. Although landplanes and airships had the range to cross oceans, explorers, airlines, and military aircrews often preferred flying boats. With runways few and far between in most countries, flying boats could land in almost any sheltered stretch of water. They also made in-flight emergencies over the open ocean much more survivable. Still, navigating across an ocean in any type of aircraft was difficult and often perilous.
44. GAL213_130512_0468.JPG: Dornier Do R4 Superwal I-RIDE, 1/20 Scale European explorers and record setters, such as Roald Amundsen and Wolfgang von Gronau, pioneered oceanic flight in the 1920s and '30s in Germany's Dornier Wal ("whale"). This model represents a four-engine Superwal operated by the Italian SANA airline in the Mediterranean. It set a dozen records in 1928.
45. GAL213_130512_0478.JPG: Naval Aircraft Factory PN-9, 1/16 Scale Cmdr. John Rodgers and his crew attempted to fly from the mainland United States to the Hawaiian Islands in 1925 in the PN-9 depicted by this model.
46. GAL213_130512_0483.JPG: Why was navigating in the air more difficult than navigating at sea? Weather Haze obscured the horizon line needed for sextant sightings. Clouds could keep navigators from sighting the Sun and stars or determining wind drift. Instability The natural roll of the airplane and air turbulence made taking accurate sightings and readings challenging.
47. GAL213_130512_0487.JPG: Speed Airplanes moved many times faster than ships, so air navigators had to work faster to fix their position. Even minor miscalculations could result in much greater errors. Cockpit Environment Cramped open cockpits, low temperatures, and wind speeds over 160 kilometers (100 miles) per hour made air navigation unpleasant. Heavy gloves (or frozen fingers) made sighting with a sextant, determining drift, and making calculations nearly impossible.
48. GAL213_130512_0491.JPG: Navigating in the Air Aviators needed faster, more accurate, and more reliable navigation than sailors. The introduction of air travel brought new challenges for navigators. Finding position in the air was more difficult than at sea, and becoming lost often meant death. Innovators worked to adapt nautical tools and techniques for aerial use and to make them easier to use. World War II spurred great advances in air navigation to meet the urgent needs of nations at war.
49. GAL213_130512_0501.JPG: "Flying the Beam" Radio navigation became the most important air navigation technology. [Before World War II, radio navigation could only provide a course or a bearing to a station. The invention of timekeeping technologies, such as the crystal oscillator, led to a new era of systems that could fix position accurately and were easier to use. Each system of radio navigation uses time in a slightly different way and each requires its own type of navigational charting.] By World War II, a web of air navigation radio stations and beacons connected by "airways" began to cover the globe. When war broke out, new military equipment revolutionized air navigation. This allowed less experienced users to achieve the same results as highly trained celestial navigators and eventually decreased the need for professional navigators. "Today's electronically guided airman is still a human. He does not think he is a superman. If he does, he doesn't stay with us very long." -- Charles F. Blair, Jr., trans-polar aviator, 1953
50. GAL213_130512_0505.JPG: Radio Navigation Radio navigation relies on the transmission and reception of electromagnetic signals to determine position or course. "Flying the Beam" "Flying the beam" in the 1930s and 1940s meant using radio range stations to navigate. Pilots hoped to hear a steady tone on the radio that meant they were on course. If they drifted off course to either side, they would hear different sounds -- a Morse code "A" or "N".
51. GAL213_130512_0513.JPG: Radio Navigation for the Air Age: Before World War II, radio navigation could only provide a course or a bearing to a station. The invention of timekeeping technologies, such as the crystal oscillator, led to a new era of systems that could fix position accurately and were easier to use. Each system of radio navigation uses time in a slightly different way and each requires its own type of navigational charting.
52. GAL213_130512_0518.JPG: Radio Compass
53. GAL213_130512_0534.JPG: Radio Range Antennas create four "beams" that aviators locate by listening to audio signals. When the signals overlap into a constant tone, the aviator is "flying the beam."
54. GAL213_130512_0540.JPG: Radio Compass Aircraft equipment locates signals from a ground station. Typically, a needle points toward a station, giving a bearing relative to the direction the aircraft is headed.
55. GAL213_130512_0569.JPG: Navigation Radar Aircraft equipment receives microwave signals to create an image of ground features from signal time delays.
56. GAL213_130512_0579.JPG: VOR (Very-high frequency Omni Range) Aircraft equipment interprets a bearing from time delay in signals transmitted by a ground-based station.
57. GAL213_130512_0596.JPG: LORAN-C (LOng RAnge Navigation) Aircraft equipment interprets time delays from pairs of ground stations.
58. GAL213_130512_0606.JPG: LORAN-C Receiver, 1981
59. GAL213_130512_0614.JPG: GPS (Global Positioning System) Aircraft equipment interprets time signals received from a network of satellites.
60. GAL213_130512_0620.JPG: Garmin GPS 155 Receiver, 1995
61. GAL213_130512_0625.JPG: Learning to Navigate in the Air: Before World War II, unreliable navigation was a major obstacle to making aviation safe. Engineers greatly improved aircraft performance between the world wars, but they gave little thought to the challenges of navigation. A handful of dedicated inventors worked hard to overcome this problem.
62. GAL213_130512_0635.JPG: Racing the Reaper: Charles Lindbergh's New York to Paris flight was one of many oceanic flight attempts in 1927. Some that were even more challenging than Lindbergh's were successful, but some aviators disappeared, never to be heard from again.
63. GAL213_130512_0653.JPG: "Precise navigation of long-range aircraft requires careful coordination of all three methods of navigation: * Celestial for position fixes, * Dead Reckoning for flight between the fixes, and * Radio Direction Finding for getting into the airport on the nose and for radio bearings when the sky is not visible." -- Harry Connor, navigator on Howard Hughes' 1938 around-the-world flight.
64. GAL213_130512_0657.JPG: Open and Exposed: On most early bombers and flying boats, such as this 1920s U.S. Navy Douglas PD-1, the navigator made sightings from the nose, where his view would not be obstructed by the biplane's wings and struts. He had no protection from the elements. The force of the wind made his sextant difficult to handle.
65. GAL213_130512_0671.JPG: Improving the Workspace: In 1927, the Army Air Corps Fokker C-2 Bird of Paradise became the first airplane to fly from the U.S. mainland to Hawaii. Navigator Albert Hegenberger had the new luxury of facing rear and behind a semi-protective windscreen while making his celestial sightings. Pilot Lt. Lester Maitland (right) stands with navigator Lt. Hegenberger (left) in front of the Fokker C-2 Bird of Paradise before their historic flight to Hawaii in 1927. In many ways, this flight was a far greater test of aeronautical capability than Lindbergh's flight to Paris was a month earlier.
66. GAL213_130512_0676.JPG: GPS Transforms US Military Operations Time and positioning go beyond navigation. GPS has become an indispensible military asset and transformed space into a platform for war. Public awareness of GPS grew during the 1990–91 Persian Gulf War, which showcased its effectiveness to synchronize operations, provide navigation information, pinpoint targets, and locate personnel. GPS now is the core navigation system for U.S. military aircraft, vessels, vehicles, and personnel. It has changed the nature of weapons targeting, command and control, guidance of unmanned systems, and supply delivery on the battlefield.
67. GAL213_130512_0680.JPG: The GBU-39 Small Diameter Bomb Since World War II, the U.S. military has sought to reduce the number of bombs needed to destroy a target through improved accuracy. This saves lives on the ground and reduces the risks to aircrews and aircraft. First-generation GPS-guided bombs were essentially conventional bombs with steerable fins. The Small Diameter Bomb represents a new generation of weapons that greatly reduce the explosive power needed and minimize the effects of so-called "collateral damage" to noncombatants and their property. Its smaller size allows aircraft to carry more weapons and strike up to four times as many targets on a single mission. Its lower weight permits the use of pop-out wings that can give it a glide range of more than 60 miles. It was first used in combat in Iraq during 2006.
68. GAL213_130512_0687.JPG: Time, Accuracy, and GPS GPS requires precise clocks to provide astounding positional accuracy. Atomic clocks in GPS satellites keep time to within three nanoseconds -- three-billionths of a second. Position accuracy depends on the receiver. Most handheld GPS receivers are accurate to about 10 to 20 meters (33 to 66 feet). Synchronizing GPS All GPS satellites must transmit their data signals at the exact same time, so precise synchronization is essential. Their signals are monitored constantly and adjusted as needed. The GPS Operations Center at Schriever Air Force Base in Colorado Springs, Colorado, controls the constellation of satellites that provides navigation data to military and civilian users worldwide. GPS Accuracy Both military and civilian users can obtain higher accuracy by using a second GPS unit at a fixed nearby location -- a method called Differential GPS. In this way, positions can be determined with an accuracy better than 1 centimeter (less than half an inch). For military users, additional encrypted signals can provide high accuracy.
69. GAL213_130512_0692.JPG: How Does the NIST-7 Atomic Clock Work? The NIST-7 provided a standard frequency rather than the time of day. To define the length of a second, the instrument measured with exquisite precision the frequency of microwaves absorbed by Cesium 133 atoms. The NIST-7 can be broken down into: Source of Cesium Atoms – in many energy states. Laser A – Puts atoms into the lowest energy state. Microwave Cavity – Microwaves at just the right frequency cause atoms to change to a higher, excited energy state. Frequency Divider – Converts the very high microwave frequency (about 9 billion cycles per second) to lower frequencies that are easier to use for counting. Servomechanism – Changes the frequency of the microwaves in the cavity to put the greatest number of atoms into the excited state, which results in the largest light signal on the detector. Laser B – Causes atoms in the excited state to emit light. Detector – Detects the emitted light.
70. GAL213_130512_0708.JPG: What makes an Atomic Clock Tick? The name "atomic clock" simply refers to the use of atoms within the clock. An atomic clock works by measuring the frequency at which certain parts of the atom "tick".
71. GAL213_130512_0713.JPG: Who Needs Relativity? The atomic clocks in the GPS system are so accurate that they take into account Albert Einstein's understanding of time, space, and relativity. Because GPS satellites experience less gravity and move at high velocity, their clocks operate at a different rate than those on Earth. Since all the clocks in the system must be synchronized, a net correction of 38 millionths of a second per day must be added to the satellite clocks' time signals.
72. GAL213_130512_0723.JPG: Evolving Solutions for Satellite Navigation: Civilian Satellite Time The U.S. Department of Commerce established a precise time service based on satellite signals in 1974. The National Bureau of Standards provided the time. The electric power industry found the time service useful for synchronizing AC generators to move electricity from one part of the power grid to another. The signals were transmitted by Geostationary Operational Environmental Satellites (GOES) of the National Oceanic and Atmospheric Administration (NOAA) until the end of 2004.
73. GAL213_130512_0728.JPG: GPS: A Unified System for the Military In 1973, the Defense Department combined its competing satellite navigation systems. The new joint program under the Air Force was called the NAVSTAR Global Positioning System, or GPS. It introduced synchronized time from space, provided by onboard atomic clocks. The system was intended for a range of military applications, including locating ships and targeting weapons. GPS designers envisioned that civilians would use the system as well.
74. GAL213_130512_0733.JPG: Developing Components for GPS GPS required the development, testing, and refinement of receivers, atomic clocks, and other components. Developing GPS components began in 1973, when the Joint Program Office was established under the Air Force to run and maintain the system. As designs evolved, positioning and navigation accuracy improved. GPS Begins: GPS resulted from a combination of parallel efforts in the 1960s. Defense Department planners decided to combine the best technologies from these various programs -- the Navy's Transit and TIMATION, the Air Force's 621B, and the Army's SECOR -- into one. At a meeting over Labor Day weekend in 1973, they created the Defense Navigation Satellite System. It was later renamed the NAVSTAR Global Positioning System, now generally known as GPS. The GPS Satellite Constellation: Rockwell International (now a division of Boeing) was contracted to build GPS satellites beginning in 1974. By 1986, 18 had been launched into orbit, making the system usable for many applications. The full suite of 24 satellites needed for global coverage was in orbit by early 1995. Beginning in the 1990s, Lockheed Martin built new generations of GPS satellites. More than 30 GPS satellites were operational after 2010. GPS satellites are positioned in precise, circular orbits 18,000 kilometers (11,000 miles) above the Earth. They orbit once every 12 hours.
75. GAL213_130512_0738.JPG: How Does GPS Work? 1. Tracking stations use radio signals to determine orbits of GPS satellites. 2. Command center transmits orbital data, time corrections, and location of other satellites in the GPS constellation. 3. GPS satellites simultaneously transmit synchronized time and orbital data to Earth. 4. GPS receivers compute location using orbital data and the difference in arrival times of the signals of at least 4 satellites.
76. GAL213_130512_0749.JPG: Transit Satellite This is a backup Transit 5-A satellite from the 1970s. Other versions of Transit carried different antennas and internal components. Developed in the 1960s by the U.S. Navy, the Transit system grew to six satellites, gave worldwide coverage every 90 minutes, and provided position accuracy to within 200 meters (660 feet). Transit service was made available to commercial shipping in 1967 and operated until 1996.
77. GAL213_130512_0757.JPG: The Winnie Mae The Winnie Mae, a special Lockheed Model 5C Vega flown by famed aviator Wiley Post, completed two around-the-world record flights and a series of special high-altitude substratospheric research flights. It was named for the daughter of its original owner, F. C. Hall, who hired Post to pilot the plane. With the consent of his employer, Post entered the Winnie Mae in the National Air Races and piloted the plane to the first of its records, now inscribed on the side of its fuselage: "Los Angeles to Chicago 9 hrs. 9 mn. 4 sec. Aug. 27, 1930." On June 23, 1931, Post began an around-the-world flight to try to bring prestige to the United States by shattering the previous 21-day record set by the German airship Graf Zepplin. Post lacked training in most navigational techniques and selected Harold Gatty as his navigator. The Tasmanian-born Gatty was the chief instructor for the Weems System of Navigation and regarded by many as the most capable air navigator in the nation. Gatty utilized the tools and techniques of the Weems System for the flight, including his prototype drift meter, which became highly successful in later forms. Gatty occupied the main cabin, and Post had a hatch installed in the cabin ceiling behind the wing spar, so Gatty could make his celestial observations. On July 15, 1933, Post left New York. Closely following his former route but making only 11 stops, he circled the world in 7 days, 18 hours, and 49 minutes. Post knew no more about navigation in 1933 than in 1931, so his decision to go solo without a navigator was far riskier. Fortunately, both the radio compass and autopilot worked flawlessly, and he completed the flight with minimal trouble. Post next modified the Winnie Mae for long-distance, high-altitude operation. He recognized the need to develop some means of enabling the pilot to operate in a cabin atmosphere of greater density than the outside atmospheric environment. Because of its design, the Winnie Mae could not be equipped with a pressure cabin. Post therefore asked the B. F. Goodrich Company to assist him in developing a full-pressure suit for the pilot. Post hoped that by equipping the plane with an engine supercharger and jettisonable landing gear, and himself with a pressure suit, he could cruise for long distances at high altitude in the jetstream. On March 15, 1935, Post flew from Burbank, California, to Cleveland, Ohio, a distance of 2,035 miles, in 7 hours, 19 minutes. At times, the Winnie Mae attained a ground speed of 340 miles per hour, indicating that the airplane was indeed operating in the jetstream. Wiley Post died shortly afterward in the crash of a hybrid Lockheed Orion-Sirius floatplane near Point Barrow, Alaska, on August 15, 1935. His companion, humorist Will Rogers, also perished in the accident. The Smithsonian Institution acquired the Winnie Mae from Mrs. Post in 1936. During its high-altitude flight research, the Winnie Mae made use of a special tubular steel landing gear developed by Lockheed engineers Clarence L. "Kelly" Johnson and James Gerschler. It was released after takeoff by the pilot using a cockpit lever, thus reducing the total drag of the plane and eliminating its weight. The Winnie Mae would then continue on its flight and land on a special metal-covered spruce landing skid glued to the fuselage. During these flights, Post wore the world's first practical pressure suit, an important step on the road to human space travel. The suit was the third type developed by Post and Russell S. Colley of the B. F. Goodrich Company. It consisted of three layers: long underwear. an inner black rubber air-pressure bladder, and an outer contoured cloth suit. A pressure helmet was then bolted onto the suit. It had a removable faceplate Post could seal when he reached an altitude of 17,000 feet. The helmet had an oxygen system and could accommodate earphones and a throat microphone. The suit could withstand an internal pressure of 7 pounds per square inch. Bandolera-type cords prevented the helmet from rising as the suit was pressurized. A liquid oxygen container, consisting of a double-walled vacuum bottle, utilized the natural "boil off" tendencies of supercold liquid oxygen to furnish gaseous oxygen for suit pressurization and breathing purposes. This early full-pressure suit is the direct ancestor of full-pressure suits used on the X-15 research airplane and manned space voyages. The Winnie Mae, its jettisonable landing gear, and Post's pressure suit are in the collection of the National Air and Space Museum.
78. GAL213_130512_0763.JPG: Mariner 10 Launched in 1973, Mariner 10 used the gravity of Venus to propel it to Mercury with minimal use of fuel. To reach Mercury, Mariner 10 first passed by Venus, threading through a narrow 400-kilometer (250-mile) "window" of space a few thousand kilometers above the surface. That level of accuracy had not been possible with the navigation systems available for the Pioneer 4 mission in 1959. After a gravitational assist from Venus, Mariner 10 entered an orbit around the Sun that allowed it to pass by Mercury three times in 1974 and 1975.
79. GAL213_130512_0772.JPG: Volkswagen Touareg Stanley Meet Stanley, a 2005 Volkswagen Touareg modified to navigate without remote control and without a human driver in the seat. Stanley won the 2005 Grand Challenge, a robot race sponsored by the Defense Advanced Research Projects Agency (DARPA), by successfully navigating 212 kilometers (132 miles) across desert terrain. The exact course had been kept secret until two hours before the race. Stanley is just one example of how navigation research may someday shape the way we drive. Stanley decided how to navigate mapped terrain and unmapped obstacles in real time using onboard computers. It integrated a course map expressed in about 3,000 points of latitude and longitude, stored memory of past experiences, and new data about the road ahead gathered from rooftop laser sensors, video cameras, radar, and GPS antennas.
80. GAL213_130512_0778.JPG: Navigation for Everyone Global time and navigation services are revolutionizing daily life. Innovators have combined precise navigation, positioning, and timing information with digital maps and other data to form essential utilities all over the worlds. These new applications are changing the definitions of navigation and raising new questions. How is navigation technology changing your life?
81. GAL213_130512_0784.JPG: Global Transportation Links: At the beginning of the 21st century, the world is connected as never before by webs of transportation links made possible by global navigation tools.
82. GAL213_130512_0807.JPG: Looking Ahead How will time and navigation services continue to change? Global navigation services play an increasingly large role in many aspects of daily life. Opportunities for innovation abound. So do challenges and questions. How can navigation tools remain available? Can we become too dependent on the technology? Who will decide what gets developed? What comes next for time and navigation?
83. GAL213_130512_0813.JPG: NextGen A revolution in air traffic control promises safer and more efficient air travel. In 2003, U.S. aviation agencies joined those of other nations in a program to modernize how global air traffic is managed. Based on satellite positioning, the Next Generation Air Traffic System, or NextGen, is replacing the existing network of ground-based navigation beacons and radar.
84. GAL213_130512_0819.JPG: Future Clocks Innovations in timing technology could improve navigation even further. To make and run the most accurate clocks today, you need a laboratory. There, atomic clocks can be as big and power-hungry as necessary. But could someone build a tiny, wristwatch-size atomic clock that stays as accurate as its larger clock cousins, yet consumes little power and costs less to build? Researchers are working on just such clocks to back up the atomic clocks in GPS satellites. One day they could be part of every GPS receiver or provide timing for communications of all sorts.
85. GAL213_130512_0832.JPG: International Systems As in the past, nations with global ambitions continue to seek global navigation capabilities. The GPS system operated by the United States is not the only satellite navigation system. In the 1990s and 2000s, many nations began developing or improving their own systems. Who's in Charge of Satellite Navigation Systems? Different nations develop and deploy independent navigation capabilities. Multiple constellations of satellites can improve positioning, navigation, and timing for everyone. Planning is required so systems do not interfere with each other. International Systems GPS -- Operated by the U.S. Department of Defense and coordinated with the U.S. Department of Transportation and other civilian government agencies. GLONASS -- Initially developed by the Soviet Union during the Cold War and now operated as a global system by Russia's Federal Space Agency. Galileo -- Under development as a civilian-operated global system by a consortium of European nations. Operations are coordinated by an agency under the auspices of the European Commission. Beidou -- The Beidou Navigation Satellite System (BDS) was planned and developed by the government of China. Global coverage with about 35 satellites was planned for 2020. IRNSS -- The Indian Space Research Organisation (ISRO) began developing the Indian Regional Navigational Satellite System (IRNSS) in 2006 to provide positioning services around India. QZSS -- The Japanese government planned to develop the Quasi-Zenith Satellite System (QZSS) to provide data links and positioning services for Japan.
86. GAL213_130512_0838.JPG: Satellite Systems in Jeopardy? Threats can imperil satellite navigation systems. Satellites provide essential navigation services, but threats exist to their operation. Radio interference from both natural and human sources presents serious problems for the system's myriad users. Engineers and scientists continue to develop solutions to ensure the continued operation of global navigation services. Solar Interference Solar activity can interfere with satellite signals. Solar storms occasionally interrupt clear reception of signals from space. Those who design satellite systems must plan for these disruptions and be aware of how solar activity varies with the 11-year sunspot cycle. System Maintenance The successful operation of a satellite navigation system requires around-the-clock monitoring of the satellites' health and the periodic replacement of older satellites. The process is labor-intensive and expensive and requires multiple backups to ensure continuous operation. Man-made Radio Interference GPS and other satellite positioning systems were designed to use quiet parts of the spectrum. However, these channels face the danger of being overwhelmed by communications signals from other nearby frequencies. Engineers must test the possibility of interference from multiple systems. Intentional Jamming Although their use is illegal in the United States, portable GPS jammers are traded clandestinely and used by those who wish not to be tracked or otherwise located by GPS. These devices cause nearby navigation systems to malfunction, potentially threatening public safety. System Under Attack The increasing reliance on navigation satellites for military and commercial activities makes them a tempting target for an enemy. While it is difficult to disable the satellites themselves, these and other GPS components must be protected from interference or attack.
87. GAL213_130512_0845.JPG: Magellan GPS Test Components - "Breadboard" The Magellan Systems Corporation produced some of the earliest hand-held GPS units for civilian use. In 1986 its engineers began experimenting with electronic mockups of a unit. This is the earliest "breadboard" used to test circuitry and components at Magellan.
88. GAL213_130512_0851.JPG: Geodetic Surveying: Geodetic surveys provide data based on the shape of the planet and common reference systems for geographic coordinates. Precision navigation would not function properly without these global references. Accurate mapping and navigation must take into account the irregular shape of the Earth.
89. GAL213_130512_0857.JPG: Navigation Gone Wrong Soviets Shoot Down an Airliner While flying from Anchorage, Alaska to Seoul, South Korea on September 1, 1983, a Korean Air Lines jumbo jetliner strayed into Soviet airspace. The error proved tragic. What Happened Mostly out of range of land-based radio beacons and air traffic radar stations, the crew of KAL Flight 007 had to depend on inertial navigation. But flying without an assigned navigator, the pilot and copilot failed to notice that the plane's autopilot was not following the waypoints programmed into the inertial navigation system. The Consequences The Boeing 747 strayed more than 180 kilometers (110 miles) off course and into Soviet airspace. It was seen as a potential threat, and fighter planes were ordered to shoot it down. All 269 people on board perished. The incident greatly increased East-West tensions. President Ronald Reagan used the incident to draw a contrast with the secretive Soviet Union by emphasizing that GPS was to be freely available to civilian users around the world. Lessons Learned The tragedy highlighted a continuing issue with over-reliance on automated navigation systems. The flight crew trusted a specific system so much that they ignored other indications of error. The use of GPS in recent years has helped reduce navigational errors, but accidents due to complacency still occur.
90. GAL213_130512_0863.JPG: The World at Your Fingertips Civilians begin to use satellite navigation. Manufacturers of GPS receivers for military users -- Texas Instruments, Rockwell Collins, Magnavox, and Interstate Electronics -- were the first to offer them to civilians, especially scientists and surveyors. Receivers gradually grew smaller, more portable, and more user-friendly. Around the year 2000, demand exploded as new devices and more accurate signals gradually became available.
91. GAL213_130512_0871.JPG: Meet The Inventor Charles Stark Draper A professor and aeronautical engineer at the Massachusetts Institute of Technology (MIT), Charles Stark Draper played a major role in advancing the art of inertial navigation. Largely through his efforts, inertial navigation became essential for aircraft, missiles, submarines, and the Apollo spacecraft. The Navy's fleet ballistic missiles and the Air Force's intercontinental ballistic missiles depended on his systems. They also later became standard on military and commercial aircraft. "For the greatest practical effectiveness [a] navigational system must be able to function as a self-contained unit without dependence or information. . . . The ideal arrangement is a ‘black box.'" -- - Charles Stark Draper
92. GAL213_130512_0880.JPG: How Did the USS Alabama Navigate? CENTRAL NAVIGATION COMPUTER (CNC) – The positioning information provided by the CNC supports the submarine's inertial navigation system. This included: TRANSIT and LORAN-C RECEIVERS for position FREQUENCY STANDARD Atomic clock for timing SONAR for position SHIP'S INERTIAL NAVIGATION SYSTEM – Provides latitude, longitude, heading, speed and ship's altitude. This included: MARDAN COMPUTER and Typewriter STABLE PLATFORM Including Accelerometers and Gyroscopes
93. GAL213_130512_0891.JPG: Inertial Navigation An inertial navigation system uses motion and rotation sensors along with a computer to figure out the position, orientation, and speed of movement of a vehicle without using any outside visual references or signals which don't reach underwater.
94. GAL213_130512_0897.JPG: Navigating the USS Alabama: The navigation equipment displayed here is from the fleet ballistic submarine Alabama. It was commissioned in 1985, carries up to 24 Trident ballistic missiles armed with nuclear warheads, and is still active in the fleet. The Alabama was built with three navigation systems: the ship's inertial navigation system (SINS), a LORAN-C receiver, and a Transit satellite receiver system for correcting the inertial system. It has since been fitted with a GPS receiver and the Trident II navigation system.
95. GAL213_130512_0900.JPG: Submarines used radio signals to correct their inertial navigation systems. Submarines carry an inertial navigation system, which measures the boat's motion and constantly updates position. Because it does not rely on radio signals or celestial sightings, it allows the boat to navigate while remaining hidden under the surface. To maintain accuracy, the submarine must periodically update its position using outside navigational radio signals. From the 1960s to the 1990s, Transit satellites and LORAN shore stations provided those signals. GPS has now replaced both.
96. GAL213_130512_0920.JPG: Evolving Solutions for Satellite Navigation: Satellite Navigation Before GPS, several satellite systems were developed to provide time and navigation services. During the Cold War, the U.S. military sought a global navigation system that would be more accurate than the Navy's Transit system and be available at all times. Several groups of government and military researchers independently designed different systems to address this need.
97. GAL213_130512_0923.JPG: How did Transit Work? Shifts in radio frequency were used to find position. The Transit system, initially designed to provide precise positioning for the Polaris submarine fleet, depended on noting changes in Doppler frequency shift. During the 15 minutes it took a Transit satellite to pass from horizon to horizon, navigators on a ship or submarine measured the Doppler shift in the satellite's radio transmissions to produce a fix of their position.
98. GAL213_130512_0928.JPG: Transit: The First Satellite Navigation System Beeping radio signals from Sputnik inspired the idea of using satellites to navigate. The idea for the first space-based navigation system was born at the Johns Hopkins University's Applied Physics Laboratory (APL) in 1957, as scientists listened to the radio signals from Sputnik, the world's first satellite. By 1964, the Navy was using radio signals from its own satellites to navigate submarines and surface ships, a system they named Transit.
99. GAL213_130512_0932.JPG: Inventing Satellite Navigation During the Cold War, the U.S. military sought more reliable global time and navigation systems. The possibilities of traveling in space inspired plans to navigate from space. Innovators tried different approaches to see whether radio transmissions from orbiting satellites could be used to determine positions on Earth. They found that time from precise clocks on satellites, transmitted by radio signals, could in fact determine location. The military combined several systems into one and created the Global Positioning System -- GPS.
100. GAL213_130512_0941.JPG: Meet The Navigator James A. Lovell, Jr. James Lovell navigated to the Moon and back twice. He served as command module pilot on Apollo 8, the first mission to the Moon, and as spacecraft commander on Apollo 13, the aborted lunar landing mission. All three astronauts helped navigate the Apollo 8 spacecraft, but Lovell was responsible for getting it to the Moon and back. Among the tools Lovell used was a sextant, much like those once used by mariners at sea.
101. GAL213_130512_0946.JPG: Navigation Gone Wrong Mariner 1 is Destroyed The first American spacecraft sent to explore another planet, Mariner 1 was launched on July 22, 1962. But it never reached Venus. It never even reached space. WHAT HAPPENED Unbeknownst to its operators, the launch computer that controlled the Atlas rocket carrying Mariner 1 contained a tiny programming error. A single character had been left out of the guidance equations. THE CONSEQUENCES About four minutes into its flight, the Atlas rocket carrying Mariner 1 began behaving erratically. The rocket had to be destroyed, and with it Mariner 1. LESSONS LEARNED The disaster revealed a critical need to thoroughly debug software before launch. NASA also learned that software can be engineered so that small errors do not impact safety. Thanks to NASA's corrective actions, several Apollo lunar modules safely landed on the Moon despite minor software "bugs."
102. GAL213_130512_0951.JPG: A Helping Hand from Gravity To reach destinations beyond the Moon, space navigators learned to take advantage of gravity. A spacecraft can use the gravity of one celestial body to propel it toward another. While the trajectory is longer than a more direct route, a "gravity assist" saves fuel. But it requires complex calculations, precise navigation, and atomic clocks for timing. Many planetary missions would be impractical without gravity assist because of the extra fuel and larger rockets they would otherwise need.
103. GAL213_130512_0964.JPG: People Travel to the Moon The Apollo 8 mission marked the first time people navigated away from Earth. In December 1968, Apollo 8 left Earth orbit and traveled a vast distance to a precise orbit around the Moon. To accomplish this feat, the astronauts used an onboard system that incorporated inertial, radio, and celestial navigation.
104. GAL213_130512_0969.JPG: Pioneer 4 Pioneer 4 was the first U.S. spacecraft to escape Earth's gravity and reach the vicinity of the Moon. It was launched in 1959, two months after the Soviet probe Luna 1 passed within a few thousand kilometers of the Moon. Using timing accurate to one thousandth of a second, mission planners hoped Pioneer 4 would pass within 32,000 kilometers (20,000 miles) of the Moon. But the spacecraft had no ability to change its course once its booster rocket cut off, and it did not come closer than three times that distance.
105. GAL213_130512_0972.JPG: Reaching for the Moon Early missions to the Moon missed their target because precision paths were difficult to achieve. The United States and the Soviet Union each tried to reach the Moon with robotic spacecraft in 1959. They sent spacecraft to orbit the Moon, pass nearby, or crash land on the surface. After some initial failures, advances in navigation and propulsion technology eventually led to success.
106. GAL213_130512_0975.JPG: The Ranger Program: Ranger spacecraft were designed to reach the surface of the Moon. Launches began in 1961. Rangers were navigated by radio from Goldstone, California, and made mid-course corrections using onboard thrusters. The first Ranger missions failed, although Ranger 4 managed to impact the lunar surface. Rangers 7, 8, and 9 also struck the Moon after returning detailed images of the lunar surface.
107. GAL213_130512_0978.JPG: Guidance, Navigation, and Control Guidance: Aiming a spacecraft by controlling the direction of its rocket thrust at launch or any other time the rocket changes speed or direction Navigation: Getting from one place to another while in space. This often involves long periods of coasting and short bursts from small rockets to change course. Control: Orienting a spacecraft in its three axes of rotation (changing the direction it "faces"). This may be done to aim an antenna, correct course, or dock with another craft.
108. GAL213_130512_0984.JPG: Ranger 1 Satellite 1/24 Scale Model The goal of the first two Ranger missions was to place Ranger 1 and its twin Ranger 2 in elliptical orbits around the Earth. Both spacecraft reentered the atmosphere instead of reaching their intended orbits. Rangers 3, 4, and 5 each carried a television camera to return images of the Moon right up to the point of impact. They also carried a seismometer that was designed to operate after impact. Of the three, only Ranger 4 landed on the Moon, and none of the three probes returned data.
109. GAL213_130512_0992.JPG: Top Secret: LORAN: In World War II, navigators began switching from mechanical time to frequency-based time systems. In 1940, British scientists and engineers developed GEE -- a practical medium-range (up to several hundred miles) system of radio navigation based on measuring the time-delay between sets of radio signals. The United States built on this effort and created a longer-range system called LORAN (LOng-RAnge Navigation) to provide oceanic coverage for ships and aircraft. Although initially no more accurate than celestial navigation, LORAN had a big advantage: it worked when the sky was clouded over. And during the day, when sextant Sun "shots" could only provide a line of position, LORAN gave a precise fix. GEE and LORAN were essential tools for American and British forces in World War II.
110. GAL213_130512_1006.JPG: Quartz Clock The quartz clock keeps better time than the best mechanical clocks. It contains a specially cut quartz crystal that vibrates at a particular frequency when voltage is applied. The vibrations can be sustained in an electrical circuit and will generate a signal of constant frequency that can be used to keep time.
111. GAL213_130512_1015.JPG: U.S. Naval Observatory Quartz Clock The introduction of quartz clocks at the U.S. Naval Observatory in Washington, D.C., in 1935 marked a major improvement in timekeeping. This clock was used at the observatory to provide radio time signals to ships and aircraft.
112. GAL213_130512_1021.JPG: Radio Time for Aviation Aviators learned to use radio signals to set their watches to the second. While ships could carry reliable chronometers to time celestial observations, aviators needed smaller, lighter, and more accessible time pieces. Such clocks could be made, but at the cost of precision and accuracy. One solution was the use of radio broadcasts of time signals that allowed air navigators to accurately set their watches to the second. "All [the Group Navigator] did during the main briefings was to call out the signal by which we all synchronized our watches. 'Set your watches at oh-four-hundred-zero-seven hours. Five, four, three, two, one, HACK!" -- Lt. Col. Harry Crosby, US Army Air Forces
113. GAL213_130512_1026.JPG: Radio Time Signals Navigators used radio time signals to accurately set their second-setting watches. Stations around the world broadcast these time signals hourly.
114. GAL213_130512_1037.JPG: Longines-Wittnauer Weems Second-Setting Watch Standard Model Before 1927, watches used with sextants for celestial sightings could only be set to the minute. A watch error of 30 seconds caused a navigational error of up to 12 kilometers (7 miles). In 1927, P. V. H. Weems devised a watch with an adjustable second hand that could be set using radio time signals. These examples were his personal navigation watches.
115. GAL213_130512_1047.JPG: Sidereal Time Sidereal time, or "star time," is based on Earth's rotation relative to the stars, rather than to the Sun. The sidereal day is almost 4 minutes shorter than our 24-hour day. When navigating by the stars, an observer will see the same constellation at the same place in the sky about four minutes earlier than the night before.
116. GAL213_130512_1058.JPG: Teaching Lindbergh Navigation: America's new hero needed instruction in navigation. He found a teacher in P. V. H. Weems. Charles Lindbergh began planning even riskier oceanic flights after he returned from Paris. He knew his seat-of-the-pants approach to navigation was no longer enough. So, Lindbergh sought out the best navigation instructor he could find: U.S. Navy officer Lt. Cmdr. Philip Van Horn Weems. [P. V. H. Weems tutored Charles Lindbergh and other air navigation pioneers in new techniques of celestial navigation. Weems had been inspired while serving in support for the NC-4's Atlantic crossing in 1919. Often angering his traditional-thinking superiors, he pursued new methods of air navigation.] Weems spent two weeks in 1928 instructing Lindbergh in his more practical system of celestial navigation. Lindbergh stayed in touch with Weems afterward and helped promote his new air navigation business. [Weems improved the processes and equipment for fixing position. He also established programs and schools to educate many of the most influential aviators of the 1930s. His greatest legacy was influencing the air navigation programs of U.S. airlines and the military. His techniques became the standard for long-range navigation for three decades. P. V. H. Weems first demonstrated his new methods of celestial air navigation in a Navy mail plane off the coast of California in 1927. Weems' chief navigation instructor in the early 1930s was Harold Gatty, who was widely regarded as the nation's most capable air navigator. He taught navigation to Charles Lindbergh's wife and co-pilot, Anne Morrow Lindbergh, and convinced the Army Air Corps and Pan American Airways to adopt the Weems System of Navigation.] Lindbergh Lost: Besides being uncertain of his position at times on his transatlantic flight, Charles Lindbergh found himself lost several times on his Caribbean and Latin American tour. In each case, faulty equipment let him down. He realized he had to find better ways of fixing position if he was going to continue to make long-range flights and promote safe long-distance air travel.
117. GAL213_130512_1065.JPG: Simple Tools for a Difficult Crossing: Lindbergh navigated the Spirit of St. Louis on his transatlantic flight with an earth inductor compass, a drift sight, a speed timer (a stopwatch for the drift sight), and an eight-day clock. Despite weather deviations and extreme fatigue, Lindbergh reached the coast of Ireland within 5 kilometers (3 miles) of his intended great circle course. But he knew that chance, not skill or equipment, had allowed such accuracy -- winds during his flight had caused no significant drift.
118. GAL213_130512_1071.JPG: Pioneer Drift Meter Lindbergh carried a Navy drift meter like this one to measure wind drift. He never used it because it was too difficult to mount and operate outside the window while flying and still manage to control the aircraft safely.
119. GAL213_130512_1076.JPG: Pioneer Earth Inductor Compass The earth inductor compass was popular in the United States for long distance flights in the period 1924-1934. Charles Lindbergh relied on this type of compass on his New York to Paris flight to maintain course until it malfunctioned. It's primary attraction was that it was far more stable than liquid-filled "whiskey" magnetic compasses and featured a controller that could dial in a heading that could be followed with a left/right indicator similar to that used for VOR navigation decades later. This made is far easier to hold a heading over long periods, particularly when fatigued. It used a wind-driven generator to create an induction field that created variable current as it interacted with the Earth's magnetic field. Less reliable than a liquid compass, it fell out of favor by the mid-1930s, replaced by gyroscopic heading indicators. Albert Hegenberger oversaw its development in the early 1920s for the U.S. Army Air Service.
120. GAL213_130512_1081.JPG: Waltham Eight-Day Clock Lindbergh brought this clock with him on his transatlantic flight in the Spirit of St. Louis. His simple dead reckoning approach to navigation did not require an accurate clock. "Eight-day" refers to how long the clock would run on a full winding.
121. GAL213_130512_1086.JPG: Great Circle The shortest distance between two points on a globe is not always a straight line -- it's an arc called a great circle. This complicates long-distance navigation. Rather than stay on a constant heading, pilots must regularly adjust their course to stay on the arc. The great circle effect is most dramatic near the Poles.
122. GAL213_130512_1093.JPG: Meet the Teacher Philip Van Horn Weems P. V. H. Weems, a U.S. naval officer, tutored Charles Lindbergh and other air navigation pioneers in new techniques of celestial navigation. Weems had been inspired while serving in support for the NC-4's Atlantic crossing in 1919. Often angering his traditional-thinking superiors, he pursued new methods of air navigation. Weems improved the processes and equipment for fixing position. He also established programs and schools to educate many of the most influential aviators of the 1930s. His greatest legacy was influencing the air navigation programs of U.S. airlines and the military. His techniques became the standard for long-range navigation for three decades.
123. GAL213_130512_1099.JPG: Bureau of Standards Model 2 Bubble Sextant Weems used this sextant in training Charles Lindbergh and Lincoln Ellsworth. The National Bureau of Standards designed it for the Navy in 1924, and Bausch & Lomb manufactured it.
124. GAL213_130512_1108.JPG: Pioneer Mark 3 Model 1 Aircraft Octant Charles Lindbergh made daytime celestial observations with this octant while Anne flew the Tingmissartoq from the rear seat. The bubble level was problematic and leaked during their flight.
125. GAL213_130512_1111.JPG: Bendix Radio Direction Finder Earhart used an antenna similar to this later model in her attempt to locate Howland Island. The loop worked by manually turning the crank on the controller until a "null" or point of low-signal strength was found.
126. GAL213_130512_1114.JPG: Navigation Gone Wrong Amelia Earhart Disappears During an around-the-world flight attempt in 1937, Amelia Earhart and her expert navigator, Fred Noonan, vanished in the South Pacific. What Happened The Lockheed Model 10E's limited range forced them to use tiny and remote Howland Island as a refueling stop. Missing it would guarantee disaster. They overflew the Gilbert Islands, their best means of fixing position, in the dark. Their eastbound route led them into headwinds that cost them fuel. Clouds hampered their navigational sightings. Neither knew Morse code, critical for the ship-based radio direction finder system the Navy used to support their flight. The plane was poorly outfitted for navigation and long-range communication, and neither was well trained on the radio equipment they did have. "[Fred] Noonan is the only one of Commander Weems' students who has ever been lost at sea." -- "Baltimore Sun," 1937 The Consequences Their flight required an effective blend of dead-reckoning, celestial navigation, and radio direction finding, but poor planning, inexperience, and circumstance compromised all three. They never reached Howland Island and likely perished in the ocean. Lessons Learned The exact errors that caused Earhart and Noonan to miss Howland Island may never be known, but their disappearance served as warning to other aviators not to take navigation lightly.
127. GAL213_130512_1120.JPG: Most often remembered as the year Charles Lindbergh flew alone across the Atlantic, 1927 also witnessed other record flights that presented far greater challenges. But the limitations of navigation technology often proved deadly. Even the relatively simple navigational task of crossing the North Atlantic claimed many lives. These disasters marked a turning point in navigational systems.
128. GAL213_130512_1125.JPG: Cartoon, Slipstream Magazine, October 1927 Government-supported record attempts using sturdy flying boats had the best chance of success. Privately financed flights with land planes flown by amateurs often ended in disaster, as this 1927 political cartoon illustrates.
129. GAL213_130512_1134.JPG: "If the Colonel [Lindbergh] doesn't know how to navigate, who knows anything about anything?" -- New York Times, May 4, 1928 Lindbergh's Calculated Risk Charles Lindbergh's 1927 transatlantic flight highlighted the limitations of early air navigation technology. Though not the first person to cross the Atlantic by air (over 100 had preceded him), Lindbergh demonstrated that transatlantic flight would soon be practical. Because he lacked any means for fixing position, his flight also illustrated that, until better navigational tools and techniques were developed, this type of flying could be a gamble. Indeed, many who attempted it perished.
130. GAL213_130512_1143.JPG: Navigation and the World at War World War II drove the United States to develop new navigational technologies on an unprecedented scale. Celestial navigation was not well suited for use in all-weather military operations or by the tens of thousands of inexperienced young navigators entering military service. To remedy this, Great Britain and the United States created complex radio navigation systems that used advances in timing technologies and electronic computing. These systems revolutionized navigation.
131. GAL213_130512_1147.JPG: Mark IV Aircraft Float Light The float light was a smoke-producing flare designed to be dropped by an aircraft over open water for drift sighting during the day or night. This type would have been used from the late 1930s through World War II.
132. GAL213_130512_1151.JPG: Why Was LORAN Such a Milestone? With LORAN, navigators went from using mechanical-based time measured in seconds to using radio frequency-based time measured in microseconds (millionths of a second). Mechanical clocks and watches that referenced a standardized time became less important to navigation, because electronic systems such as LORAN could accurately calculate a relative position with their own internal time. This achievement was only possible through massive national investments in developing and combining the technologies of radio transmission and timing. LORAN's heart was its timing unit -- a crystal oscillator that allowed a receiver on an aircraft, ship, or submarine to measure the difference between "master" and "slave" radio pulses. Early LORAN equipment was sensitive, and operators had to monitor it carefully, especially in areas with salt air and high humidity, which rapidly corroded components.
133. GAL213_130512_1165.JPG: Hyperbolic System In a hyperbolic system such as LORAN, a receiver on an aircraft or ship picks up radio signals broadcast by one or more pairs of radio stations spaced hundreds of miles apart. The system works by measuring the time delays between signals from the two stations. By tuning in different pairs, the navigator could plot lines of position in the form of hyperbolas (arcs) that intersect to give a precise location.
134. GAL213_130512_1172.JPG: LORAN Coverage -- August 1945: By the end of World War II, LORAN chains consisting of 72 operable stations provided navigation over 30 percent of the globe, mostly in the northern hemisphere. More than 70,000 receivers for aircraft, ships, and submarines had been built. By the height of the Cold War, coverage had extended to 70 percent of the Earth's surface. The ionosphere and terrain limited daytime coverage, so LORAN was far more effective at night.
135. GAL213_130512_1176.JPG: Type 62A GEE Mark II Indicator Unit The British Royal Air Force and the U.S. Eighth Air Force relied extensively on the GEE hyperbolic system in their bombing campaigns over Europe, where it was essential in the overcast skies. Late in the war, GEE combined with a system of radar beacons (known as GEE-H) allowed the bomber crews to attack their targets without seeing them. AN/APN-4 LORAN Set The APN-4 was the first LORAN set for aircraft to enter service. It had a separate receiver and display unit. The navigator had a leather hood to put over the oscilloscope's cathode ray tube so he could clearly see it in daylight. LORAN was most valuable when the skies couldn't be seen for celestial navigation and when coastlines couldn't be picked up by radar. It did require a skilled operator.
136. GAL213_130512_1186.JPG: Meet The Clockmaker Alfred Loomis A multimillionaire Wall Street banking tycoon, Alfred Loomis lacked a formal scientific education, yet he became one of the most important American scientists of World War II. Loomis's fascination with timekeeping precision led to the invention of LORAN, the first successful long-range, electronic area navigation system. He played a crucial role in creating the Massachusetts Institute of Technology's Radiation Laboratory, where radar and LORAN were developed. This unlikely scientist had a huge impact on the shift in navigation technology from mechanical timekeeping to radio frequency. "Since the stations themselves would be about a thousand miles apart, there was a problem of synchronization. [Loomis] proposed solving [it] using his specialty -- in this case highly accurate quartz clocks -- at each station." –- Scientist Edward Bowen, describing Loomis's "light bulb" moment of creating the LORAN system, October 1940
137. GAL213_130512_1192.JPG: R Radio Network for Space Navigation: Timing is crucial for communicating with a spacecraft traveling across the solar system. Such a spacecraft navigates using precisely timed radio signals sent back and forth to Earth. Navigators on Earth track its location and speed and transmit course adjustments. These techniques allow navigators to guide a probe to a planetary rendezvous or a pinpoint landing.
138. GAL213_130512_1197.JPG: Navigation in Space 1. Deep Space Network (DSN) sends signals to a spacecraft, which returns these signals to the stations on Earth. The spacecraft may also track the position of its destination against a star field. 2. Using precise time information from these signals, navigators calculate the spacecrafts location and velocity with respect to the Earth, and ultimately with respect to its destination. They compare the spacecraft's current course with its desired target and calculate a course correction. 3. DSN stations transmit course correction commands, which the spacecraft executes.
139. GAL213_130512_1201.JPG: The Deep Space Network: A global network of tracking stations was created to navigate spacecraft beyond the Moon's orbit. In the late 1950s, NASA built a global network of tracking stations now known as the Deep Space Network. The network tracks spacecraft, navigates them to their objectives, and receives communications from them. A spacecraft's faint signal transmitted at low power across millions of kilometers has been likened to a whisper from space. To listen and respond accurately, timing is everything.
140. GAL213_130512_1206.JPG: Deep Space When referring to the Deep Space Network, deep space starts just past the Moon's orbit and includes the solar system and beyond. To an astronomer, deep space might mean what's beyond our galaxy.
141. GAL213_130512_1212.JPG: Navigating in Space To journey across the vast expanses of space, navigators drew on age-old methods and invented new ones. Space navigators drew upon techniques used on the sea and in the air. They also had to invent a new science of space navigation, using star sightings, precise timing, and radio communications. The great distances spacecraft had to travel called for even greater precision in timing and positioning than ever before.
142. GAL213_130512_1230.JPG: SPACE NAVIGATION: A Timeline of Improvements Increasingly accurate clocks and improved navigation methods have allowed navigators to calculate spacecraft positions with greater accuracy. By 2012, missions could be tracked with 100,000 times the accuracy possible in the early 1960s.
143. GAL213_130512_1236.JPG: Visiting Other Worlds: Advanced timekeeping and navigational methods have made possible extended missions to other worlds. More accurate time standards have enabled navigators to send spacecraft to specific locations and allowed scientists to conduct lengthy and sophisticated explorations.
144. GAL213_130512_1242.JPG: Targeting Mars: Mission planners can now guide spacecraft to more precise landings on Mars than ever before. Better navigation techniques allow a spacecraft not only to fly by or land on a planet, Moon, or asteroid, but also to enter a precise orbit or land at a specific place that interests scientists. Two missions to place rovers on the surface of Mars provide examples. Navigators on Earth used radio signals to guide the Mars Exploration Rovers to the Red Planet in 2004. Mapping and time standards were precise enough to narrow the landing site to an ellipse-shaped area 150 by 20 kilometers (93 by 12� miles). This image shows the landing area chosen for the Mars Science Laboratory rover Curiosity. Improved landing control allowed scientists to target the Mars Science Laboratory rover Curiosity even closer to interesting geological features. The target area within Gale Crater was about 20 kilometers (12� miles) across and was refined as the spacecraft approached Mars. Curiosity landed in August 2012.
145. GAL213_130512_1246.JPG: Hemispherical Resonator Gyroscope Spacecraft traversing the solar system carry inertial navigation devices to supplement Earth-based radio navigation. Most use a simple but accurate gyro that measures motion by the change in vibration of a cup-shaped device -- similar to how a wine glass "hums" when you rub a wet finger around its rim.
146. GAL213_130512_1267.JPG: "Until that mission, the 100th had never been badly hit. All told, the Double Strike lost 60 planes, 600 men. "Although the two task forces lost heavily, I had the feeling that we all felt good about the daring and effective attack. We were grim but we felt somehow special that we were being talked about in pubs all over England." -- Lt. Harry Crosby, squadron navigator, 418th Bomb Squadron, Eighth Air Force
147. GAL213_130512_1273.JPG: Beechcraft AT-7 Navigator, 1/16 Scale No amount of classroom work or simulator practice could prepare navigator cadets for the difficulties of performing in real airplanes. The Army Air Forces procured hundreds of aircraft designed for navigation training, mostly AT-7s. Cadets often trained for up to 100 hours in AT-7s. They found that navigating while maneuvering was difficult.
148. GAL213_130512_1282.JPG: "How did those pilots navigate? How could they find an aircraft carrier in the middle of the ocean and make a landing? At least an Air Corps' field stayed put." -- Lt. Col. Harry Crosby, US Army Air Forces
149. GAL213_130512_1287.JPG: Meet The Navigator The WAVES The WAVES (Women Accepted for Volunteer Emergency Service) provided support personnel to the Navy and Marine Corps during World War II. Their service allowed more men to be deployed to combat theaters. One of their most prominent roles was providing navigation instruction to pilot candidates and navigators. This included classroom instruction, operating Link Celestial Navigation Trainers, and assisting on training flights. A select few WAVES flew as navigators on Naval Air Transport Service Flights in the United States and the Caribbean.
150. GAL213_130512_1294.JPG: PVH Weems The Unheralded Teacher for Aviation's Celebrities In addition to Charles Lindbergh, Weems tutored and advised many famous navigators and pilots from the late 1920s to the early 1950s.
151. GAL213_130512_1299.JPG: Winnie Mae Equipment Diagram When it debuted in 1927, the Lockheed Vega made other single-engine planes obsolete. It quickly became the preferred choice for many record setters. Post added to his Vega a long-range fuel tank, a hatch on top for celestial sightings, and side ports for drift sightings.
152. GAL213_130512_1303.JPG: "For Extraordinary Achievement... "Mr. Gatty, as navigator, made an airplane flight around the world... not only eclipsing in time all previous world flights but also by his intrepid courage, remarkable endurance, and matchless skill materially advancing the science of aerial navigation." -- Citation for Harold Gatty's Distinguished Flying Cross
153. GAL213_130512_1328.JPG: Dividing Engine Dividing engine, made by Jesse Ramsden, London, 1775. This machine permitted the automatic and highly accurate division of a circle into degrees and fractions of degrees of arc. Invented by Englishman Jesse Ramsden in the 1770s, the machine ultimately led to mass production of precision octants and sextants and gave British manufacturers dominance in the field of marine instruments for decades. Ramsden's invention was so valuable to the nation's maritime interests that he received a share of the Longitude Prize.
154. GAL213_130512_1354.JPG: Observing the Moon: Astronomers had long known that the Moon changes its position against the background of the sky and stars fairly quickly. It moves the distance of its own diameter in about hour, a distance called a "lunar." This steady motion could be used to measure time. To figure out local time, an observer noted how close the Moon's edge was to a particular star. He then looked up in a book of tables the predicted time of that event. The difference between the two times could be used to figure out longitude.
155. GAL213_130512_1356.JPG: Solving the Longitude Problem Observing the Sky Navigation improved with the help of new astronomical information and new instruments. Leading English astronomers were certain the solution to finding longitude lay in better celestial observations. They convinced King Charles to establish an observatory at Greenwich in 1675. Two centuries later, a line through his observatory would become Earth's "Prime Meridian." The octant and sextant were invented to make use of the observatory's new star catalogs, published beginning in 1725. These portable angle-measuring tools served two purposes: improving latitude observations and finding longitude.
156. GAL213_130512_1366.JPG: Celestial Navigation at Sea To locate themselves on the open ocean, navigators can determine their position by observing the Sun, Moon, stars, or planets. Some of these techniques involved using the North Star, the Lunar Distance Method, and finding local noon with a sextant.
Multi Column: Number of columns of thumbnails to appear per page (normally defaults to 3): [1 col] [2] [3] [4] [5] [6] [7] [8] [9] [10]
AAA "Gem": AAA considers this location to be a "must see" point of interest. To see pictures of other areas that AAA considers to be Gems, click here.
Description of Subject Matter: Time and Navigation: The Untold Story of Getting from Here to There
April 12, 2013 – March 27, 2022
If you want to know where you are, you need an accurate clock. This surprising connection between time and space has been crucial for centuries. About 250 years ago, sailors first used accurate clocks to navigate the oceans. Today we locate ourselves on the globe with synchronized clocks in orbiting satellites. Among the many challenges facing navigation from then to now, one stands out: keeping accurate time. Featuring 144 objects, this exhibition explores how revolutions in timekeeping over three centuries have influenced how we find our way. The exhibition is organized into the following five sections:
* Navigating at Sea is an immersive environment that suggests a walk through a 19th-century sailing vessel.
* Navigating in the Air relates how air navigators struggled with greater speeds, worse weather, and more cramped conditions than their sea-going predecessors.
* Navigating in Space traces how teams of talented engineers invented the new science of space navigation using star sightings, precise timing, and radio communications.
* Inventing Satellite Navigation describes how traveling in space inspired plans to navigate from space.
* Navigation for Everyone tells the stories of real people—a fireman, a farmer, and a student—who use modern navigation technology in their everyday lives and addresses what might come next.
Presented in collaboration with the National Museum of American History.
Bigger photos? To save server space, the full-sized versions of these images have either not been loaded to the server or have been removed from the server. (Only some pages are loaded with full-sized images and those usually get removed after three months.) I still have them though. If you want me to email them to you, please send an email to guthrie.bruce@gmail.com and I can email them to you, or, depending on the number of images, just repost the page again will the full-sized images.
Directly Related Pages: Other pages with content (DC -- Natl Air and Space Museum -- Gallery 213: (a) Time and Navigation) directly related to this one: [Display ALL photos on one page]:
- 2011_DC_SIAIR_Gall213A: DC -- Natl Air and Space Museum -- Gallery 213: (a) Time and Navigation (1 photo from 2011)
Same Subject: Click on this link to see coverage of items having the same subject: [(Smithsonian) Air and Space Museum (Everything)] [(Smithsonian) Air and Space Museum (Non-Events)] [Museums (History)]
2013 photos: Equipment this year: I mostly used my Fuji XS-1 camera but, depending on the event, I also used a Nikon D7000 and Nikon D600. Trips this year: three Civil War Trust conferences (Memphis, TN, Jackson, MS [to which I added a week to to visit sites in Mississippi, Louisiana, and Tennessee], and Richmond, VA), and my 8th consecutive San Diego Comic-Con trip (including sites in Nevada and California). Ego Strokes: Aviva Kempner used my photo of her as her author photo in Larry Ruttman's "American Jews & America's Game: Voices of a Growing Legacy in Baseball" book. Number of photos taken this year: just over 570,000.
Connection Not Secure messages? Those warnings you get from your browser about this site not having secure connections worry some people. This means this site does not have SSL installed (the link is http:, not https:). That's bad if you're entering credit card numbers, passwords, or other personal information. But this site doesn't collect any personal information so SSL is not necessary. Life's good!
Limiting Text: You can turn off all of this text by clicking this link: [Thumbnails Only]
Photo Contact: [Email Bruce Guthrie].