- 01 August 1955 Vanguard selected to launch first US satellite. Spacecraft: Vanguard 1. Launch Vehicle: Vanguard. More details
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.
- 07 October 1955 Vanguard contract awarded. Spacecraft: Vanguard 1. Launch Vehicle: Vanguard. More details
Prime contract for Project Vanguard awarded the Martin Co.
- 11 April 1957 Vanguard payload tested on sounding rocket. Launch Vehicle: Vanguard. More details
U.S.-IGY scientific satellite equipment, including a radio transmitter and instruments for measuring temperature, pressure, cosmic rays, and meteoric dust encounters, was tested above earth for the first time, as a rocket containing this equipment was fired by the Navy to a 126-mile altitude.
- 01 May 1957 Vanguard suborbital test. Spacecraft: Vanguard 1. Launch Vehicle: Vanguard. More details
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.
- 01 October 1957 Vanguard tracking system operational. Spacecraft: Vanguard 1. Launch Vehicle: Vanguard. More details
Project Vanguard world-wide tracking system (minitrack) became operational.
- 09 October 1957 Vanguard supported by Eisenhower. Spacecraft: Vanguard 1. Launch Vehicle: Vanguard. More details
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.
- 23 October 1957 Vanguard suborbital test. Spacecraft: Vanguard 1. Launch Vehicle: Vanguard. More details
IGY Vanguard prototype (TV-2) with simulated second and third stage successfully met test objectives, by reaching 109-mile altitude and 4,250 mph.
- 06 December 1957 Vanguard 1A Spacecraft: Vanguard 1. Mass: 1 kg. Launch Site: Cape Canaveral . Launch Vehicle: Vanguard. More details
First US orbital attempt. IGY Vanguard (TV-3), the first with three live stages, failed to launch a test satellite.
- 05 February 1958 Vanguard 1B Spacecraft: Vanguard 1. Mass: 1 kg. Launch Site: Cape Canaveral . Launch Vehicle: Vanguard. More details
Trial firing of IGY Vanguard (TV-3Bu) satellite.
- 17 March 1958 Vanguard 1 Spacecraft: Vanguard 1. Mass: 1 kg. Launch Site: Cape Canaveral . Launch Vehicle: Vanguard. More details
Transmitted pear-shaped earth data. Life expectancy of perhaps a 1,000 years.
- 29 April 1958 Vanguard 2A Spacecraft: Vanguard 1. Mass: 1 kg. Launch Site: Cape Canaveral . Launch Vehicle: Vanguard. More details
- 28 May 1958 Vanguard 2B Spacecraft: Vanguard 2. Mass: 10 kg. Launch Site: Cape Canaveral . Launch Vehicle: Vanguard. More details
- 26 June 1958 Vanguard 2C Spacecraft: Vanguard 2. Mass: 10 kg. Launch Site: Cape Canaveral . Launch Vehicle: Vanguard. More details
- 26 September 1958 Vanguard 2D Spacecraft: Vanguard 2. Mass: 10 kg. Launch Site: Cape Canaveral . Launch Vehicle: Vanguard. More details
- 17 February 1959 Vanguard 2 Spacecraft: Vanguard 2. Mass: 10 kg. Launch Site: Cape Canaveral . Launch Vehicle: Vanguard. More details
Operated for 18 days; satellite wobble degraded data.
- 14 April 1959 Vanguard 3A Spacecraft: Vanguard 3. Mass: 10 kg. Launch Site: Cape Canaveral . Launch Vehicle: Vanguard. More details
- 14 April 1959 30-inch Sphere Spacecraft: Vanguard 3. Launch Site: Cape Canaveral . Launch Vehicle: Vanguard. More details
- 22 June 1959 Vanguard 3B Spacecraft: Vanguard 3. Mass: 10 kg. Launch Site: Cape Canaveral . Launch Vehicle: Vanguard. More details
- 18 September 1959 Vanguard 3 Spacecraft: Vanguard 3. Mass: 23 kg. Launch Site: Cape Canaveral . Launch Vehicle: Vanguard. More details
Radiation, micrometeoroid data. Third stage failed to separate from payload. Partial Failure.
- 17 March 1960 Vanguard second anniversary. Spacecraft: Vanguard 1. Launch Vehicle: Vanguard. More details
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.
- 17 March 1961 Vanguard third anniversary. Spacecraft: Vanguard 1. Launch Vehicle: Vanguard. More details
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.