HAC’s Probe spacecraft for NASA’s Galileo mission to Jupiter was the subject of a three-day design review hosted by Space and Communications Group’s NASA Systems Division.
The Probe is one of two Galileo mission spacecraft due to be launched from the Space Shuttle in January 1982 on a 3 ½-year, 500-million mile journey to the largest planet in the solar system. The mission is intended to provide scientists with detailed information about Jupiter and will provide the first close-up view of the planet’s atmosphere.
NASA Systems Division, under a $35 million contract with NASA, is developing the Probe and the telemetry relay communications receiver and antenna that will be aboard the second spacecraft, the Orbiter.
NASA Ames Research Center is managing the Galileo Program and the Jet Propulsion Laboratory has overall project management responsibility and is developing the Orbiter.
Representatives from NASA Headquarters in Washington, DC, NASA Ames, Hughes, JPL, and General Electric attended the review.
The Probe, which is made up of the descent module and the deceleration module, weighs 550 pounds, is 49 inches in diameter, and is 34 inches long.
SCG is developing the descent module of the Probe and has subcontracted the development of the deceleration module to General Electric’s Re-Entry Systems Division in Philadelphia. The deceleration module is a heat shield that will protect the descent module until it enters the planet’s atmosphere.
The descent module is designed to descend through Jupiter’s atmosphere to the planet, transmitting the findings of the scientific instruments it carries to the Orbiter, which will relay the information to Earth.
The Orbiter will circle the planet for 20 months, taking pictures and analyzing the atmosphere from its vantage point 622,000 miles away from the planet.
The descent module will carry all the electronics and scientific instruments for the mission.
The Probe will separate from the Orbiter 150 days away from Jupiter. Instruments will be turned on five hours before the Probe reaches the planet.
The descent module will ride inside the deceleration module during those 150 days until they reach Jupiter’s atmosphere. The descent module will then be pulled out of its protective “capsule” by a parachute. The parachute will help slow the descent module’s pass through the atmosphere, which will allow for a longer sampling time, according to Uldis Lapins, HAC Program manager.
Radio transmissions back to Earth from the Galileo spacecraft will begin once the probe has entered the atmosphere. Six instruments will be aboard the descent module. The instruments and their objectives are:
- an atmosphere structure instrument to chart the probe’s deceleration history and then give temperature and pressure profiles of the atmosphere.
- a nephelometer will show the vertical extent and structure of the clouds.
- a helium abundance detector will show the ratio of helium to hydrogen in the atmosphere.
- a net flux radiometer will measure the planet’s energy balance, which is the relationship between energy from the Sun reaching the planet and the energy coming from the planet.
- a lightning and radio emission detector will measure the amount of radio frequency noise.
- a neutral mass spectrometer will chart the atmosphere’s chemical compounds and physical state.
On their way to Jupiter, the Galileo spacecraft will come within a few thousand kilometers of Mars.