Inching Ahead : Oft-Delayed Jupiter Spacecraft Project Takes Tiny Step on Eventual Trip of 2.4 Billion Miles

One key scientist has died and several others have retired while waiting for the often-delayed Galileo spacecraft to blast off for Jupiter, but success moved a little closer Tuesday when a probe that will dash through the Jovian atmosphere was packaged for a trip across town.

It was a small step perhaps. But for the men and women who have grown gray and weary while waiting for their mission to get off the ground, any progress is to be cherished.

Built by the Space and Communications Group of Hughes Aircraft Co., the small probe is to be trucked today from El Segundo to the Jet Propulsion Laboratory near Pasadena. The probe will be carried to Jupiter aboard JPL’s Galileo spacecraft.

Sometime between Oct. 12 and Nov. 21, Galileo is scheduled to be carried to low Earth orbit by the space shuttle. Originally, the craft was to use powerful liquid fueled rockets to blast itself from Earth orbit to Jupiter, but heightened safety concerns over cargo carried aboard the shuttle compelled the National Aeronautics and Space Administration to switch to less powerful--but safer--solid rockets.

A Tortured Route

That means Galileo will have to follow a tortured route, flying first to Venus and using the gravity of Venus to pick up speed and fling it back toward Earth. Then it will fly past Earth twice, using the Earth’s gravity to boost its speed more, finally sending it on toward the distant planet.

The trip will be more than 2.4 billion miles, and the craft will not reach Jupiter until December of 1995. But for a lot of scientists who have feared many times over the last few years that the entire project was going to be scrapped, 1995 is better than nothing.

Technical and scheduling problems had already delayed the project a couple of years even before the space shuttle Challenger exploded, delaying it even further.

The wisdom of proceeding with the mission has been questioned by NASA executives “at least once every year,” said Joel Sperans, chief of the space exploration project for NASA’s Ames Research Center. “We’ve had a lot of challenges, but they are behind us. I’m confident we will make it now.”

Hasn’t Been Easy

But for many who have devoted considerable portions of their careers to the project, it has not been easy.

“There has been a lot of wear and tear on the bodies as well as the hardware,” said Benny Chin, program manager for Ames.

Robert Boese, principal investigator for one of the probe’s six instruments, died in December of 1986. Other scientists have retired, and many others just drifted away to other agencies after growing weary over the seemingly endless delays.

“It’s been a very long program,” said John Radecki, program manager at Hughes.

During the lengthy delays, the mission has been “reprogrammed” six times. But if successful, the $1.36-billion mission will give scientists their first look at an asteroid, and it will tell much about the giant, gaseous planet known as Jupiter.

Two Main Parts

Galileo consists primarily of two parts: Ames Research Center’s atmospheric probe, which will plunge into the Jovian atmosphere at 107,000 miles an hour, and JPL’s mother ship, which will orbit the planet for about 20 months, sending back data for that entire period.

“It’s a scientifically rich mission,” said Richard Spehalski of JPL, who is the overall project manager.

About 150 days before Galileo reaches the planet, the 4-foot-diameter atmospheric probe will separate from the main spacecraft. As the probe rips through the planet’s atmosphere at that speed, it will slow down so quickly that “deceleration” forces will be equal to 350 times that of the gravitational pull of Earth. That will have the effect of making the 745-pound probe weigh as much as a DC-10 jetliner.

For 75 minutes, the probe will plunge into Jupiter’s atmosphere. Sometime after passing through the first layers of clouds, the probe will be crushed by the dense atmosphere.

But before that happens, it will have sent back enormous amounts of data, scientists hope.

To Make 10 Orbits

Meanwhile, the “mother ship” will continue to study the planet and its four moons, making 10 orbits of the giant planet and sending back about 50,000 pictures.

There is, however, at least one other significant hurdle to overcome. Like all deep space probes, Galileo will use radioisotopes to generate the electricity it will need to run its instruments. And since it requires White House approval to launch any spacecraft with radioactive materials aboard, the mission must now undergo intensive review by several federal agencies before the President’s approval for launch can even be requested.

Spehalski, the project director, said he expects that approval to be granted in September--the month before the scheduled launch.