ATS-2

ATS-2 was a communications satellite launched by NASA on April 6, 1967, on an Atlas-Agena D rocket from Cape Canaveral.

Objectives

The ATS-2 had the following objectives: test new concepts in spacecraft design, propulsion and stabilization; capture high quality images of cloud cover; collect data measurements in an aerospace environment; and test improved communication systems.

Features

The satellite had a cylindrical shape with a diameter and a height of. After including the motor cover, the satellite was about tall. The surface of the satellite was covered by solar panels, and it utilized gravity-gradient stabilization for control.

Experiments

The following 12 experiments were conducted:

Radio astronomy
Magnetospheric electric fields
Electron magnetic spectrometer deflection
Particle telescope
Omnidirectional proton and electron detectors
Very low frequency (VLF) receiver
Earth's albedo
Microwave communication transponder
Gravity-Gradient Stabilization
Advanced Vidicon Camera System
Thermal coating degradation
Solar cell degradation

Mission

The launch of ATS-2 went entirely according to plan up to the first Agena burn. When the second burn was initiated, the Agena engine failed to restart and thus the satellite could not be placed in the correct orbit. Postflight investigation found that the oxidizer isolation valve had failed to close after the first burn. This valve was supposed to prevent propellant from escaping the tanks and filling the turbopump during the coasting phase, but since it remained open, the pump developed vapor lock and thus it became impossible to pump oxidizer in. A small amount of impulse was generated by the gas generator igniter cartridge. The low periapsis of the orbit caused the satellite to tumble more than the stabilization system could compensate, which complicated its mission. The satellite still produced some usable data from the experiments, most notably those regarding cosmic rays and particles. It reentered the atmosphere on September 2, 1969.