PASADENA, Calif., Nov. 4 (UPI) -- NASA is preparing for a final battery of observations with its Galileo space probe, which is scheduled to cap a seven-year science mission Tuesday with its closest approach ever to Jupiter and an unprecedented pass by its odd inner moon, Amalthea.
After the Amalthea flyby, Galileo will begin its 35th and final orbit around the solar system's largest planet. Last January, mission scientists used the spacecraft's close encounter with the Jovian moon Io to set it on a course that will take it directly into the planet's crushing atmosphere on Sept. 21, 2003, where it will be incinerated. The maneuver is planned to avoid the possibility of contaminating any potential indigenous life forms on the ocean-bearing moon, Europa.
"We're all focused on making this the most successful encounter that we can," said Galileo project manager Eilene Theilig, with NASA's Jet Propulsion Laboratory, in an interview with United Press International.
Although Galileo's official demise will not occur until next September, this latest pass by Jupiter and Amalthea could turn the spacecraft into an instant relic. Its latest pass by Jupiter will be the equivalent of about one-fifth the distance between Earth and the moon, close enough to expose Galileo to a massive dose of radiation. Operating in the Jovian system since 1995, the indefatigable probe already has been exposed to four times as much radiation as it was designed to withstand.
"It's a risky maneuver," acknowledged JPL spokesman Guy Webster. "That's why we do it last."
Even if Galileo's instruments do not survive, the spacecraft will remain on course for destruction by Jupiter's atmosphere.
"Knowing the risks of the Amalthea encounter, we used the last passage of Io to put the spacecraft on path to take it to impact requiring no future course corrections from us," Theilig told UPI. "We wanted to make sure that while we could still control the spacecraft we did that."
Galileo's science team has set a course for the probe to pass about 160 kilometers (99 miles) above Amalthea's cratered surface -- a little more than half the length of the egg-shaped moon. The close flyby, scheduled to take place at 1:19 a.m. Eastern Time Nov. 5, is of particular interest because so little is known about Jupiter's inner moons.
Tiny Amalthea appears to give off more heat than it takes in from the sun. Scientists also are eager to learn the moon's mass and density -- measurements that will yield important clues about how Amalthea formed. Learning about planetary systems and dynamics is important in the search for planets -- and possibly life -- in other solar systems.
"There's a large effort on to identify planets around other stars and understanding how our own system formed is applicable to those studies," Theilig said.
The flyby also will give scientists information about Jupiter's inner magnetosphere and its thin dusty rings, believed to have been formed from particles blasted off Amalthea and the planet's other inner moons.
If the probe survives the encounter, the science data collected during the pass is expected to be radioed to Earth over the next two months. Galileo's flight team is scheduled to disband in January and return to oversee the probe's cremation eight months later.
