It's global warming of Jupiter that's causing this tragedy. Those comets never would have hit it a few years back had Galileo not added to it's gravitational pull.
Posted on 09/21/2003 6:32:11 AM PDT by TomB
Ground controllers for one of NASA's most successful planetary probes will bid a fond farewell Sunday to Galileo, a spacecraft that spent the better part of eight years studying Jupiter and its moons. The Galileo probe will create its own funeral pyre as it burns up in the Jovian atmosphere, a fiery end to its 14 years of space travel.
"It's a little sad to be present at the demise of a great spacecraft," said Claudia Alexander, Galileo's project manager, who will await confirmation that the craft indeed hits Jupiter Sunday in a darkened control room with others at NASA's Jet Propulsion Laboratory (JPL). NASA officials decided to destroy the spacecraft rather than risk the chance of it crashing into and contaminating one of Jupiter's moons.
Alexander told SPACE.com that Galileo will only penetrate into the topmost region of Jupiter's atmosphere. Because the spacecraft lacks any protection against reentry, it will break apart into pieces that are easily vaporized due to friction. There is hope by some JPL researchers that Galileo will be able to relay data back to Earth during its death dive, but Alexander is skeptical.
"We hope, with our fingers crossed, to receive data from as far down as possible," she said. But because Galileo will be entering a high radiation area on its way down to Jupiter, and the fact that the craft has already absorbed much more radiation than it was designed for, could affect its ability to effectively send data, she added.
By mission's end, Galileo had discovered 21 new moons around Jupiter and caught the flashy destruction of comet Shoemaker-Levy 9, which slammed into the gas giant in 1994.
Some 1500 people are expected to pay their respects to Galileo during the end of mission celebration at JPL. "You know there will be a few moist eyes when it finally disappears, but mostly it's a feeling of great satisfaction," said Torrence Johnson, project scientist for Galileo since the mission began. "We went there and exceeded even our highest expectations and it's set the stage for future missions."
A rocky road to Jupiter
First conceived in the mid-1970s, the Galileo mission took its name from famed astronomer Galileo Galilei, who made the first telescope observations of Jupiter in 1610. The planet's largest moons, Io, Callisto, Europa and Ganymede, are known as the Galilean satellites in honor of Galileo's observations of their motions about Jupiter.
"You've got something here that everyone can appreciate as a miniature Solar System," said Johnson told SPACE.com. Studies of the Jovian system, he added, allow researchers to better understand the evolution of the Solar System and the properties of extrasolar planets.
Galileo's launch was delayed when the space shuttle Challenger exploded just after launch in January of 1986. The spacecraft was slated for deployment during a shuttle mission that year, but investigators delayed its launch -- and all others -- until they determined that faulty solid rocket booster O-rings caused the Challenger accident. Eventually, the spacecraft launched on Oct. 18, 1989 from the space shuttle Atlantis.
"Not only did Galileo's launch get pushed back three years, the length of its cruise time nearly tripled," Alexander said.
Following the Challenger accident, the Centaur booster expected to push Galileo to Jupiter was considered too dangerous to ride along in a space shuttle and was replaced with a less powerful rocket. To compensate, Galileo engineers to come up with VEEGA -- short for Venus Earth Earth Gravity Assist -- to swing its way toward Jupiter over six years, passing the asteroids Ida and Gaspra on the way.
But that wasn't the end of Galileo's travel woes. En route to Jupiter, Galileo's high-gain antenna refused to open, cutting off the craft's prime communication link with Earth. Without the device, JPL researchers resorted to using a slower antenna until in-flight repairs could be made.
"We were pretty desperate on that," explained JPL engineer Greg Lavanas in a telephone interview. "We just couldn't get it to work and we tried all sorts of things, and with the low-gain antenna, data came in so slow you could almost count the bits as they came in."
JPL scientists ultimately abandoned the high-gain antenna entirely, choosing instead to improve Galileo's software and data-compression ability to send more data through the low-gain antenna. By storing collected data on a tape recorder until it could be sent, Galileo's science mission was saved.
"I've always said the computer was dumber than your average VCR to program," Alexander said.
The Jovian drop
One of the high points of Galileo was the success of its atmospheric probe, a combination reentry vehicle and weather balloon designed to relay observations of Jupiter's atmosphere.
Galileo released the probe while still five months away from Jupiter and both arrived about the same time in December 1995. Over the course of 58-minutes, the probe fell 124 miles (204 kilometers) into Jupiter and transmitted data to the Galileo spacecraft.
"The probe was groundbreaking, just incredible," said Timothy Dowling, director of the Comparative Planetology Laboratory (CPL) at the University of Louisville. "Before Galileo, we had absolutely no direct measurements of a gas giant's atmosphere."
The probe's biggest surprise for researchers was the unexpected rarity of water it detected. Observations by Pioneer in 1973, the two Voyager spacecraft in 1979 and the Hubble Space Telescope led scientists to believe the atmosphere held vast amounts of water. "We learned that it's pretty hot and dry," Alexander said.
Watery moon
Although Jupiter's atmosphere appeared devoid of much water, the planet's moons seem flush with the stuff in one form or another. Galileo's studies of Europa reinforced the belief by researchers that the moon carries a liquid, subsurface ocean.
"It's a major step forward for finding potential habitable zones in our Solar System, nearby stellar systems and perhaps even more," Johnson said. "Europa's oceans would contain about twice the amount of water than all the oceans of Earth."
Galileo swung within 124 miles (about 204 kilometers) of Europa, photographing winding cracks across the moon's surface. The tidal forces of Jupiter's gravity that cause the constant turmoil of Io's volcanoes may pull on Europa too forming seafloor volcanoes that keep subsurface water liquid.
"I think Europa is one of the most exciting objects in the Solar System," said Ronald Greeley, planetary geologist at Arizona State University in Tempe. Greeley chairs the Europa Focus Group at NASA's Astrobiology Institute. Thanks to Galileo, researchers are now armed with images of Europa at resolutions of 10 meters per pixel, much finer than images by Voyager, he added.
What's more, Alexander said, is that the age of Europa's surface got younger as Galileo made more and more observations on subsequent passes. "For me, it was always significant that these icy moons aren't just frozen solid, and devoid of activity or anything interesting."
A moon bigger than a planet and the hottest lava around
While images of Europa, and the potential of liquid water beneath its icy crust, remain some of the more popular aspects of Galileo, the mission also made major discoveries concerning Jupiter's other large moons; namely Callisto, Ganymede and Io.
Galileo's observations showed Callisto and Ganymede as icy worlds akin to Europa, with Ganymede - bigger than Mercury - boasting its own magnetosphere, two findings that were not picked up in Voyager observations. But catching up with the small but angry Io, Jupiter's volcanic moon, seemed a challenge that some mission scientists gave up once Galileo arrived at the Jovian planetary system.
"The Io data we had pretty much kissed goodbye," Lavanas said. Galileo's original flight plan only called for a single pass by Io upon arrival at Jupiter, he added.
As the spacecraft approached Jupiter, three things were expected to occur at the same time. Galileo would conduct maneuvers to enter Jupiter orbit, receive and relay data from the atmospheric probe and collect data on Io as it swept past the little moon. But the lack of a high gain antenna meant Galileo would have to store atmospheric data on the tape recorder instead of Io observations, then relay them back with the low-gain antenna.
"We never intended to go back," Galileo's Io specialist Rosaly Lopes told SPACE.com. Lopes is the science coordinator for the Near-Infrared Mapping Spectrometer (NIMS) that made thermal scans of the Galilean Satellites.
Galileo was able to return to Io after it completed its primary mission in 1997; not once but four times beginning in 2000. While researchers had to contend with radiation-damaged instruments and finicky camera, the craft's instruments recorded active volcanoes and lava flowing with temperatures of 1800 Kelvin (1526.85 degrees Celsius), hotter than anyplace on Earth.
"It's a very inhospitable place," Lopes said. "But at the same time, it's a volcanologist's dream."
A return visit
Despite the impending doom of Galileo, the Jupiter mission may be survived by at least one successor.
Researchers at JPL have proposed the Jupiter Icy Moons Orbiter (JIMO) mission to study a handful of the larger Jovian moons thought to harbor water, or even some small form of life, beneath their frozen exteriors. Under the proposal, the JIMO would visit Ganymede, Callisto and Europa.
NASA's Office of Space Science is also weighing a proposal for the Jupiter Polar Orbiter with Probes (JPOP) mission under the New Frontiers program. JPOP calls for a dedicated spacecraft to conduct a detailed survey of Jupiter's polar region from orbit and release planetary probes to penetrate deep into the planet. The next New Frontiers mission, be it to Jupiter or no, is slated for launch in 2009.
In the meantime, JPL will host hundreds of Galileo engineers and scientists from mission's past and present, who will be present for the spacecraft's funeral party on Sunday. Like most of her Galileo colleagues, Lopes plans to attend and looks forward to the spacecraft's plunge into Jupiter.
"It's kind of a nice ending, rather than just leaving it to die in the cold of outer space," Lopes said. "It's so much more dramatic."
WILL THIS LEAD TO INTERGALACTIC WAR???
DASCHLE "DEEPLY SADDENED".
Watch the end of civilization, planned for sometime this afternoon, here.
The guys who built it, that's who.
The probe is past it's useful life, and it is nearly out of manuvering propellant. So, in order to protect Europa, which has an outside chance of life, from contamination, they are purposely crashing it into Jupiter.
What? Are you upset they didn't contact you and get your opinion? The probe is almost dead, the journey is over.
It's global warming of Jupiter that's causing this tragedy. Those comets never would have hit it a few years back had Galileo not added to it's gravitational pull.
If you would have read my post you would have seen that since they can't maneuver the probe, there was a chance it could crash into Europa, and they don't want to contaminate that moon.
Anyway, most of the electronics are fried from the radiation anyway, it's at the end of its life. If "something unusual happens" six months from now, it won't be able to do anything anyway.
How do you think I felt when Magellan took the plunge. I worked on that spacecraft and helped to fly it from JPL. However, I knew that the plunge needed to take place. This protects Europa. IMHO, it is the correct path to take.
(cue violin music........) ;-)
So what are you working on now Michael?
BTW, good to "see" you again.
I think both are important. Each has its own strengths. :-)
THAT'S THE POINT! It still has a bit of fuel left, so they will guide it while they still can.
I can't even keep spiders out of my house, I'm not all that concerned about the ecosystem of Europa.
Which explains very well why they didn't ask your opinion.
OOOOH! Black helicopter stuff. Excellent!
I'll be sure to ping you to all the wing-nut tin-foil threads as a representative of the "gubmint".
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