January 23, 1996




Release No.:  96-002W


Early Wallops' Test Pays-Off with Galileo Probe  


When scientists announced Monday the early results from NASA's Galileo probe that plunged into Jupiter's 
atmosphere on Dec. 7, 1995, engineers at the NASA Goddard Space Flight Center's Wallops Flight Facility, 
Wallops Island, VA, saw  the long-range results on a test they helped conduct of a similar probe in 1971.

The Planetary Atmosphere Experiments Test (PAET) was one step in providing the technical base 
necessary  for advanced planetary exploration to other planets. The fore-runner of the Galileo probe was 
launched on a suborbital flight on a Scout rocket from Wallops Island on June 20, 1971.

Joe Duke, chief of the Wallops Operations Division, said, "The connection between the PAET and the 
Galileo probe is a prime example of the long-term results and benefits of the very basic science and 
technology research conducted at Wallops."  Duke also was the range coordinator of the PAET mission

The primary mission objective of the PAET was to demonstrate in the Earth's atmosphere the capability of 
selected experiments to determine the structure and composition of an unknown planetary atmosphere from 
a probe vehicle entering  the atmosphere at high speed. 

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The PAET probe, which measured 36 inches in diameter, 25 inches long and weighed 137 pounds, 
reentered the Earth's atmosphere at 15,000 mph and impacted in the Atlantic Ocean 600 miles from 
Wallops Island.  The PAET spacecraft was designed and built by NASA Ames Research Center, Mountain 
View, CA, which also manages the Galileo probe project.

Preliminary analysis of early data returned by the Galileo probe mission into Jupiter's atmosphere has 
provided a series of startling discoveries for project scientists.

Information on the extent of water and clouds and on the chemical composition of the Jovian atmosphere is 
particularly revealing.  Probe instruments found the entry region of Jupiter to be drier than anticipated and 
they did not detect the three-tiered cloud structure that most researchers had postulated.  The amount of 
helium measured was about one-half of what was expected.

The Galileo probe made the most difficult planetary atmospheric entry ever attempted.  It survived entry 
speeds of more than 106,000 mph, temperatures twice those on the surface of the Sun and deceleration force 
up to 230 times the strength of gravity on Earth.

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