An engineering test satellite. Based on its orbital position data derived from is transmissions, the shape of the earth was refined.
Total Mass: 1 kg.
Ad Hoc Committee on Special Capabilities rejects Army/Von Brauns's Project Orbiter (Redstone) and USAF Atlas proposals; selects Navy/Vanguard for first US satellite.
Prime contract for Project Vanguard awarded the Martin Co.
Vanguard Test Vehicle (TV-1), a modified Martin Viking first-stage and Vanguard solid-propellant third-stage Grand Central Rocket as second-stage, launched with instrumented nose cone to an altitude of 121 miles and met all test objectives.
Project Vanguard world-wide tracking system (minitrack) became operational.
President Eisenhower in a White House press release congratulated the Soviet scientists on SPUTNIK I. He gave a brief history of the development of the U.S.-IGY satellite program and pointed to the separation of Project Vanguard from work on ballistic missiles.
IGY Vanguard prototype (TV-2) with simulated second and third stage successfully met test objectives, by reaching 109-mile altitude and 4,250 mph.
First US orbital attempt. IGY Vanguard (TV-3), the first with three live stages, failed to launch a test satellite.
Trial firing of IGY Vanguard (TV-3Bu) satellite.
Transmitted pear-shaped earth data. Life expectancy of perhaps a 1,000 years.
VANGUARD I still in orbit and transmitting on its second anniversary after traveling 131,318,211 miles. NASA reported that VANGUARD I orbit was being altered by solar pressure.
Vanguard I completed third year in orbit and was still transmitting. Vanguard I provided much useful data on orbits, including the slight pear-shape of the Earth and the effect of solar pressure. Vanguard also provided the second stage for the Able, Delta, and Able-Star, as well as the third stage of Scout, pioneering solid-propellant stages used in Polaris and Minuteman.