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Transit 1A



Transit 1A was the first attempted launch of the Navy navigation satellite series. The mission failed when the third stage did not ignite. The primary objective of Transit 1A was to test the feasibility of a more accurate system of world-wide maritime and aerial navigation under all weather conditions by launching an instrumented satellite into a near-circular 640 km (400 mi.) Earth orbit inclined at 49.8 degrees.

Mission Profile

Transit 1A launched on 17 September 1959 at 14:33 UT from the Atlantic Missile Range in Cape Canaveral, Florida. The first stage cutoff at 162.3 seconds after liftoff, and stage separation occurred at 166.5 seconds, as planned. The second stage cutoff at 274.3 seconds and separated at 275.8 seconds. Flight to this point was nominal, but the third stage failed to ignite. The stage reached an altitude of 640 km (400 mi.) after 25 minutes, but did not achieve orbit and fell back to the Earth. The mission determined in a preliminary way the feasibility of making refraction corrections and determining orbit by means of Doppler signals.

Spacecraft and Subsystems

The Transit 1A satellite was a 91 cm (36 in.) diameter sphere composed of two layers of fiberglass with a honeycomb structure in between. Total mass was 119 kg. The antenna was a broadband logarithmic spiral stripe of silver painted on the outside surface of the shell. The payload held four transmitters (54, 162, 216, and 324 MHz), two command receivers, and two ultra-stable oscillators in temperature-resistant flasks. An infrared scanner was included to measure the satellite's rotation. Power to the 54 and 324 MHz transmitters was supplied by two silver-zinc batteries. Solar cells continuously charged two nickel-cadmium batteries to power the other components.

Launch Vehicle

The launch vehicle was a Thor-Able with three stages. The first stage was a modified U.S.A.F. IRBM burning kerosene (RP-1) and liquid oxygen. The second stage was a modified Vanguard liquid propellant (Unsymmetrical dimethyl hydrazine - UDMH, and white inhibited fuming nitric acid - WIFNA) engine. The third stage was a solid propellant (nitrocellulose, nitroglycerine, ammonium perchlorate) motor based on the Vanguard design. The full rocket was 27.4 m (90 ft.) high, 2.44 m (96 in.) in diameter at the base, and had a liftoff mass of 47,600 kg (105,000 lbs. wt.)

Facts in Brief

Launch Date: 1959-09-17
Launch Vehicle: Thor-Able
Launch Site: Cape Canaveral, United States
Mass: 119.0 kg

Funding Agency

  • Department of Defense-Department of the Air Force (United States)


  • Navigation/Global Positioning

Additional Information

Questions or comments about this spacecraft can be directed to: Dr. David R. Williams.

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