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Galileo, Consumed by Jupiter
We ran stories about Galileo's impending incineration earlier this month and last November when the plan was decided.
Here is a typical passage from Journey Beyond Selene, about the worst glitch in Galileo's mission, and the beginnings of how it would be worked around. Failures and the engineers who salvage them are the recurring tragic, triumphant story of our missions into space. Reproduced without permission:
With such triply redundant hardware built into their spacecraft, mission planners could feel confident that they had designed a communications system that was almost completely resistant to failure, and for the first eighteen months after Galileo's 1989 launch, there was no reason to assume anything would fail. Finally, on April 11, 1991, when the ship's trajectory had spiraled out as far as the edge of the asteroid belt between Mars and Jupiter, JPL planners decided it was at last probably safe to unlock the high-gain antenna and spread its ribs. It was only then that they'd learn if triply redundant was redundant enough.
Though the deployment of the high-gain system was not a complicated exercise, it was a critical one, and for that reason the chieftans of the Galileo project made sure they were there to watch it happen. On hand at the flight director's console that afternoon were mission director Neal Ausman, deputy mission director Matt Landanow, and project manager Bill O'Neil. O'Neil and Ausman were far and away the higher ranking of the three men, but Landanow, they all knew, was far and away the most knowledgeable. As chief engineer during the Galileo design phase, he had familiarized himself with every strut, nut and rivet of the ship, and could practically describe their placement and purpose from memory alone. If anything went wrong this afternoon, Landanow would likely be the first person to recognize it -- and the first person to come up with a way to fix it.
For the first forty minutes or so after the deployment command went up, O'Neil, Ausman and Landanow had little to do. Like so many other JPL controllers before them, they knew they would have to tolerate the nonnegotiable limits of light speed, waiting twenty minutes as their signal traveled from Pasadena to the spacecraft and then another twenty minutes as it traveled back again. For that entire time their screens told them nothing, flickering merely with the self-evident information that their command had indeed been sent. Finally, after just over the anticipated forty minutes had elapsed, a column of numbers began to blink on the glass. Landanow gave the figures a quick scan and immediately noticed something amiss. He read them again -- a bit more closely -- and this time started to feel downright queasy. The antenna, from all indications, was pulling what the engineers called stall current. The motor was drawing power, the deployment gears were engaged, but the ribs of the umbrella appeared to be going nowhere at all.
"We're stuck," Landanow said flatly.
"How can you tell?" O'Neil asked.
"The current is saturated, something is jammed," Landanow said. "In any event, the antenna's not budging."
Ausman gave the numbers on the screen a read of his own, confirmed what Landanow was saying, and immediately called out to his flight controllers, instructing them to send a second deployment command up to the ship. The engineers complied, and forty minutes later another stall signal came down. A third command yielded a third signal, and a fourth a fourth. With each new report Landanow winced. If he knew this ship -- and he surely did -- he could all but guarantee that whatever was hanging up the antenna was not much: a single too-tight fitting, perhaps, a single protruding bolt, one that was situated in just such a way that it managed to jam all eighteen ribs. If it were somehow possible to transport the Galileo spacecraft to a hangar in Pasadena, Landanow knew he could probably roll over a stepladder, climb up to the antenna, and spring it free with his hands alone. But Galileo was not in a hangar in Pasadena; it was tens of millions of miles away, at the edge of the asteroid belt between Mars and Jupiter, and more elaborate measures would be necessary.
FYI, NASA TV has a live webcast here. UATV is another place to watch as they are rebroadcasting the NASA channel...
Don't forget Pioneer 10!
Pioneer 11 is also somewhere though scientist do not know if 11 is still transmitting signal. After 4 million years(!) it will reach constellation of Aquila.
Here's a little snack for the troll ... if you heard it on the radio, it probably wasn't a reputable source. See http://www.badastronomy.com/bad/misc/jupiter_galil eo.html
Since Jamie rather thoughtlessly posted a direct link to the JPL real stream and now none of us can see it; please visit NASA's website listing all the alternate feeds for NASA TV and use one of these instead.
- "Hear that?! The percolations are imminent! Cease your ingress!"
The quest to get usable data out of Galileo has driven some of the world's most advanced communication and signal processing algorithms over the past few years. AS a result they were able to achieve a better than ten fold increase in data rate from 10 bps to a maximum of 120 bps, a pretty spectacular achievement that saved the mission. You can read the technical details here
Toronto-area transit rider? Rate your ride.
Hi, no offense, but this is the most laughable thing I have ever heard.
a) The main fissionable form of plutonium is Pu-239, not Pu-238.
b) Even if this was Pu-239 on board, forty pounds thereof is a borderline critical mass. You would need tampers to make it a good bomb.
c) Even if this was Pu-239 on board and there was enough of it for a critical mass, it is not arranged in a critical geometry that will produce good fission under a Jovian pressure crush.
d) Even if this was Pu-239 in a critical mass in a critical geometry, Galileo lacks the tritium primer required to kickstart a fusion reaction from a fission reaction.
e) Even if Galileo had a working thermonuclear weapon on board, a thermonuclear detonation on Jupiter would not blow up Jupiter, because there isn't enough of an oxygen fraction in the Jovian atmosphere to set the hydrogen afire. Think about it. Jupiter has collided with large asteroids and comets before now. These collisions give off heat considerably in excess of any nuclear detonation. The huge pressures at Jupiter's interior produce heat considerably in excess of any nuclear detonation. If Jupiter could have turned into a star (it cannot) it would have done so by now.
f) Learn more about physics.
H4x0r Economist - k33ping d3m0cr4cy l33t 51Nc3 1987
nope, two streams are in windows media format. Though I'm not sure if that's better or worse.
SAILING MISHAP
Short version: There is absolutely nothing to worry about. Read on for the long version.
That is because throwing 48 pounds of Pu-238 (which is useless as weapons grade material, Pu-239 is much better for sustaining fission chain reactions) into Jupiter is like tossing a salt shaker into the ocean. Jupiter already has massive radition belts generated by its interactions with the solar wind. It has surely ingested more than 48 pounds of the various isotopes of Uranium from the thousands or millions of meteorite strikes Jupiter has sustained. And the total energy that could be released by complete fission of all of that plutonium into stable elements would insignificant next to the gravitational-potential energy released by the steady contraction of Jupiter's gas clouds that results from the planet's massive gravitational pull. Because of this contraction, Jupiter already releases significantly more energy back into space that it absorbs from the sun.
Finally, with a total mass that is about 0.0001 times that of the Sun, Jupiter is too small to support fusion reactions in its core by about two (2) orders of magnitude. The smallest stars are about 0.08 times the Sun's mass.
The maneuvering fuel is nearly gone, and the spacecraft components have sustained many tens of times their design tolerances of radiation. Taken together, it's entirely possible that Galileo would soon become uncontrollable and crash somewhere like Eurpoa, where we may one day send probes to search for life. Because Galileo was not sterilized before launch, it would contaminate wherever it ended up, and could cast doubt of any future test results from expeditions there.
(As a testimony to the hardiness of life, microbes on a camera lens or something were brought to and back from the moon, it wasn't until later that they realized someone sneezed on the lens or some nonsense and the damn bugs survived the whole round trip).
While it would be nostalgic to have left Galileo in orbital purgatory around Jupiter, it's not possible to do this with any assurance that it won't later be a hazard. It is fitting, in a way, that Galileo will become part of Jupiter, the target of so much of its (and his) focus. If only NASA would bring the success of this mission into the public spotlight as a way to raise awareness as to its more successful programs.
Coming soon to Saturn - Cassini, July 4, 2004. (Alas, the last of the "great explorer" probes.)
Bush Lies On the Record.
Jupiter is not "larger" than Earth, it's a whole hell of a lot larger than Earth. According to Google:
mass of Jupiter / mass of Earth = 317.816611
So Jupiter has 317 times the mass of Earth. That's why the orbit is faster.
Mod down posts with a "Free Mac Mini/iPod" sig, they're spam!
The amount of radiation in Galileo's plutonium decay generator is insignificant compared to the radiation the Jovian moons get from Jupiter's magnetosphere and background levels of cosmic rays - it'd be a bit like a needle made of hay in a haystack.
Any bacteria on the craft would probably be killed by the radiation as well, but it isn't really worth taking that chance (life is amazingly tenacious).
But more thanjust the "safety" aspect, there are real reasons why Galileo had to go down - JPL wanted ot use the starfinder camera to observe some rocks near Amalthea that may have been magnetically lifted off the surface of the moon, and they wanted to use it's final minutes to observe parts of the exosphere.
Bzzt. You fail physics. 1) the probe will likely be vaporized into a 1000-km trail of dust by the impact with the atmosphere at 48 km/s. It won't slow down intact and then sink into the core of Jupiter. 2) The temperature reaches the melting point of metal a few thousand kms down into Jupiter. Even if the probe was intact by the time it sank that far, it would melt/dissolve long before it reached the core. 3) The RTG's contain Pu-238, which as has been stated repeatedly, is not suitable as a nuclear explosive. 4) Even if there was an explosion, it is so incredibly miniscule compared to the mass/size of Jupiter that it simply would not matter. 5) Jupiter CANNOT sustain nuclear fusion - it simply lacks the mass. The pressure in the core is far too low to overcome Coulomb repulsion between protons so that they can fuse. The minimum mass of a star that can sustain fusion is approximately 75 Jupiter masses. That is very, very well-understood physics (look up the astronomical tem "brown dwarf").
Human genome = 3 billion base pairs = 6 GBit. Windows + Office = 20 Gbit. Which is more impressive?
Nonsense. Apparently you missed all the other quotes on this thread, or didn't believe them. Just in case it'll help, here is the math. Note that Jupiter is not even close to half of the mass required for sustained fusion.
It's amazing that the atmosphere probe, which entered at 47 km/sec, managed a controlled deceleration and survived.
Brackets contain world's first nanosig, highly magnified:[.]
Did you notice the comma? It's not "Galileo consumed by Jupiter", which is past tense. It's "Galileo, consumed by Jupiter" which has no tense.
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....