Vanguard SLV-1

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Vanguard SLV-1: A Short, Easy-to-Understand Overview

Vanguard SLV-1 (Vanguard Space Launch Vehicle-1) was the second flight of the American Vanguard rocket. It was part of the International Geophysical Year (IGY) program and aimed to learn how to place satellites into Earth orbit and study the space environment using a small satellite.

Background
- The IGY Vanguard program planned to launch satellites during 1957–1958 to explore Earth and space science.
- Vanguard SLV-1 carried the Vanguard 2B satellite, which carried ultraviolet detectors and equipment to study the magnetosphere.

Launch vehicle
- Date and place: May 27, 1958, from Cape Canaveral (Launch Complex 18A), Florida.
- The rocket was a three-stage Vanguard vehicle.
- First stage: General Electric X-405 engine using kerosene (RP-1) and liquid oxygen.
- Second stage: Aerojet General AJ-10 engine using a storable propellant (UDMH) and oxidizer.
- Third stage: Solid-propellant motor built by Grand Central Rocket Company.
- The vehicle stood about 21.9 meters tall and was designed to carry roughly 11.3 kg to a 555 km Earth orbit.
- The payload was Vanguard 2B, a 9.75 kg, 50.8 cm diameter magnesium sphere with onboard detectors and telemetry.

Spacecraft
- Vanguard 2B carried Lyman-alpha ultraviolet detectors and a magnetosphere-related instrument.
- The satellite was designed to deploy from the third stage into an Earth orbit and transmit data back to Earth.

Mission and outcome
- The launch proceeded normally until about 261.5 seconds after liftoff.
- The second stage did not shut down properly due to an oxidizer- depletion problem, causing an attitude reference error.
- The third stage was then deployed on a steep, high-arc trajectory, and the mission failed to reach orbit.
- The rocket reached a peak altitude around 3,500 km and traveled about 12,000 km downrange, landing off the coast of what is now South Africa.
- The failure was traced to instability in the second-stage engine; subsequent Vanguard flights were adjusted to prevent a repeat of this issue.

Impact
- Vanguard SLV-1 highlighted early challenges in orbital rocket design but provided valuable data that helped improve later Vanguard missions and the United States’ orbital-launch capabilities.

See also
- Vanguard rocket
- Project Vanguard
- Spaceflight launches and related technologies