The solar root just emailed back , we dont have write permission to chmod jupiter.
Declan
I believe that it is true to say that normally sub-critical masses can be rendered critical by compressing them in a very specific way - (not that this is likely to happen as the probe burns up in the Jovian atmosphere).
FWIW, I wrote a web page debunking this. Since some of the arguments are not my area of expertise (and just because I like constructive criticism), I invite comments.
Will Galileo Make Jupiter a Star? Also, check out the graphic I made on the main web page of the site. 
This isn’t quite right, BA. The hydrogen bombs I know of have a single fissile core surrounded by high explosive, which is used to trigger the fusion of lithium deuterate. There’s a nice diagram and description here. Other than that, real nice work.
Aww, hell, I knew I’d get something wrong. Shoulda just waited for the Bad Astronomer to communicate so beautifully what I was trying to say.
I would disagree in calling an RTG a reactor, though it may boil down to semantics. In a reactor, you are regulating the reaction process. In an RTG, you just let the radioisotope decay merrily away, and use the heat to generate electricity through a thermocouple.
By the way, QED, thanks for that link. I was using a very old model of how to get a hydrogen fusion process, and was wrong initially. I have corrected that page, and rearranged things a bit to make it tidier. Sigh; debunking something on this scale is difficult. I guess that’s one reason I’ve put it off so long.
I guess it’s important for P.R. purposes to narrowly define “nuclear reactor” so that NASA can say with a straight face that it’s not launching nuclear reactors. I don’t have any great problem with that. Saves a lot of unnecessary scare mongering, like that which prompted this thread.
But objectively, what you’ve got is a vessel or apparatus in which a controlled nuclear reaction takes place. Hence, nuclear reactor.
The presence or absence of external regulators that maintain a desired level of criticality will govern how useful the device may be for a particular application, but don’t change the fundamental nature of the beast.
It comes down to the meaning of “controlled”, or rather, “uncontrolled”. NASA argues that “uncontrolled” refers to the reactor, and means “not having external regulating mechanisms”. But the usual way of interpreting “uncontrolled” is that it refers the reaction, not the reactor. Uncontrolled reaction = bomb.
On the radio this morning;
Very loosely quoted-
“NASA is crashing the Galileo into Jupiter so that it doesnt crash into Europa and contaminate its environment with Earth microbes which may be in/on the space craft. Reason being that if NASA wants to send a future probe up to Europa it wont find Earth microbes accidentily.”
This leads to other questions. Is it possible for any microbes to still be alive on the spacecraft?
Do we have living organisms on this planet that can survive in space for as long as the Galileo has been up there?
And could they survive a crash landing onto another planet?
The chances of anything being alive or surviving a crash landing are undoubtably slim. But considering the possibility of our exploring Europa is greater than Jupiter, contamination of the moon would forever confuse the issue of life’s origins if any is found, and Europa looks like one of the more promising locations to find lilfe, a Jupiter suicide plunge seems like the better option, no?
Besides, it must be a lot easier to steer a tiny spacecraft into a massive Jupiter than a tiny moon. Jupiter would be a lot harder ro miss.
Yes, calling the members “Dopers” is MUCH more trustworthy. 
I don’t think it’s as clear-cut as that. I don’t think acceleration affects microscopic organisms as badly as macroscopic ones. If there was something alive on the probe before crashing into Europa, chances are there’d still be some left after. There’s not enough atmosphere to heat the thing up much prior to the crash, and insufficient oxidisers to burn it up after the crash. All your microbe needs is a little bit of cushioning to survive.
The major question is whether any microbes survived the trip from earth.
The short answer is probably that nobody knows for sure; bacterial spores can be extremely durable, especially if (say) they had happened to become encapsulated in some material or other, such as epoxy.
However… the chances of any random bacteria that happens to survive the trip subsequently finding the necessary materials for survival and reproduction (or rather the chances of the kind of bacteria suited to survival on Europa having been accidentally stowed away) would be quite slim.
Heck, the chances of Galileo eventually colliding with Europa would be pretty slim.
The “planetary protection” squad at NASA is nothing if not paranoid.
However, terrestrial bacteria in spore form were recovered from a camera in the Surveyor 3 (an unmanned spacecraft that landed on the Moon) by Apollo 12 astronauts. They were successfully revived on Earth. This is after three years of exposure to vacuum, radiation, etc.
Besides the general scientific implausability of this happening it sounds suspiciously like the plot of an Arthur C. Clarke novel (2010 and the susbsequent sequels). Where Jupiter was turned into a sun by the monolith(s) to provide the (fictional) inhabitants of Europa with a source of energy.
How about the end of the world?
“the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up.”
Being right in the middle of it should make for a spectacular show!
How about the end of the world?
“the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up.”
Being right in the middle of it should make for a spectacular show!
But short?
Kind of hard to appreciate the show when your entire body is vaporized beteeen the time the light reaches your eyes and the neuron impulses would otherwise reach your brain. Some show.
(Looks Outside)
Okay, I guess we really had nothing to worry about…