Illustration of Galileo at Jupiter

The Galileo spacecraft, which had been awaiting launch from NASA's Kennedy Space Center in Florida, has been returned to the Jet Propulsion Laboratory, Pasadena, Calif., where it will be outfitted for the new trajectory it will fly to Jupiter.

The spacecraft arrived at JPL Saturday, Feb. 21, 1987 after one-week trip across the southern U.S. aboard special NASA trailers. Some of the spacecraft's scientific instruments have already been returned to the institutions where they were constructed. Eventually, all the instru- ments will be returned for refurbishment and installation on the spacecraft, which is being prepared for possible launch in October 1989.

At JPL, new hardware will be added to the space- craft and new software will be loaded into the memories of its onboard computers. Galileo is in JPL's spacecraft assembly facility where new hardware designs will be developed and new spacecraft hardware and software will be tested. The spacecraft will remain at JPL until about six months before it is to be launched.

The Galileo mission calls for two years of intensive studies of Jupiter and its four largest moons while the spacecraft orbits the giant planet. The Galileo orbiter will also send probe into Jupiter's atmosphere. The probe has also been returned to JPL.

Before the Space Shuttle Challenger accident in January 1986, Galileo was scheduled to be launched on 30-month trip to Jupiter in May 1986 from the shuttle and Centaur G-prime upper-stage booster. The Centaur G-prime program for the shuttle was cancelled in June 1986, necessitating new upper stage to boost Galileo on its interplanetary course after the spacecraft is placed in Earth- orbit by the shuttle.

The Inertial Upper-Stage (IUS) to be used in lieu of the Centaur G-prime does not provide the energy needed to send Galileo directly to Jupiter. To compensate, mission planners have devised new trajectory that will send the spacecraft around Venus once and Earth twice. The so-called Venus-Earth-Earth Gravity Assist (VEEGA) trajectory augments the spacecraft's energy with boosts from the gravities of Venus and Earth. With the planned launch on the VEEGA trajectory in late 1989, Galileo will reach Jupiter in 1996.

Galileo was designed to travel through the cold space between Earth and Jupiter, so some hardware changes, including the addition of sunshades, must be made to protect the spacecraft's instruments and electronics from the heat it will encounter in the vicinity of Venus.

Galileo's 4.8-meter (15.7-foot) diameter, gold- filament antenna will remain furled like closed umbrella during the spacecraft's passage through the inner solar system. Smaller antennas that can withstand the hot temperatures will provide Galileo with communications capability until the larger antenna can be unfurled after the spacecraft passes the Earth and is on its way to Jupiter.

Hardware and software changes and testing of the spacecraft will continue through autumn 1988.

Project Galileo is managed by JPL for NASA's Office of Space Science and Applications.

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