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| | Project Vanguard - Wikipedia, the free encyclopedia |
 | | The 1.4 kg spherical Vanguard satellites (designated "Test Vehicles" prior to launch) were built at the NRL, and contained as their payload seven mercury cell batteries in a hermetically sealed container, two tracking radio transmitters, a temperature sensitive crystal, and six clusters of solar cells on the surface of the sphere. |
 | | TV-4 achieved a stable orbit with an apogee of 3,969 km (2466 miles) and a perigee of 650 km (404 miles) ; it was estimated that it would remain in orbit for 240 years, and Vanguard 1 remains the oldest human-made satellite still in orbit at this time. |
 | | Vanguard met 100 percent of its scientific objectives, providing a wealth of information on the size and shape of the Earth, air density, temperature ranges, and micrometeorite impact. |
| en.wikipedia.org /wiki/Project_Vanguard (1246 words) |
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