From 18 Miles High
What goes up must come down – the right way, especially in Jupiter’s powerful gravity. To assure a proper descent, an all-out simulation of the Galileo probe’s separation mechanisms’ operation and parachute deployment was conducted the morning of July 17 at the U.S. Army’s test range at White Sands, N.M. In this test, an exact duplicate of the probe, made of the same materials, was carried 18 miles up by a huge helium balloon and then released.
Everything worked. The main parachute deployed more slowly than expected, but that didn’t interfere with the separation sequence of the forward heatshield and the orange-and-white-checkered descent module. Offsetting the significance of the deployment anomaly is the fact that it’s possible to adjust the descent sequence somewhat. Still, to play it safe, Group scientists are working to predict the effect if the same thing should happen during the mission and to determine whether additional testing may be desirable.
Here in El Segundo, Group engineers and technicians have installed probe subsystem units and integrated five of the flight probe’s six science instruments. The sixth, the neutral mass spectrometer, will arrive soon from NASA’s Goddard Space Flight Center. The probe’s instruments will study Jupiter’s atmosphere, clouds, and energy.
The integrated instruments are engineering models; they will be exchanged for flight models early next year. The reason? Some of the actual instruments would be damaged by necessary test procedures. For example, the helium abundance detector has two diaphragms that are designed to be sequentially ruptured by increasing pressure when the probe descends into the thick, turbulent atmosphere of the solar system’s largest planet. Obviously, the diaphragms must be intact at launch.
SCG has designed and developed the probe portion of the two-part Project Galileo mission for NASA’s Ames Research Center. The Jet Propulsion Laboratory is building the orbiter and is responsible for overall management of the joint JPL/NASA Ames project. Galileo’s launch on the space shuttle is currently planned for May 1986.