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Stardust to Return January 15
accessdeniednsp writes "Seven years ago, the Stardust probe was sent to intercept Comet Wild 2, gather dust particles, and return to Earth. Stardust is scheduled to touch down in a Utah desert on January 15. From the article: 'Our mission is called Stardust, in part because we believe some of the particles in the comet will, in fact, be older than the sun,' said Don Brownlee of the University of Washington, the principal investigator of the mission."
But if there was SOMEWAY for something to be alive in the dust, couldn't it put people in danger? Like, a new life thats sorta like a virus, or bacteria but can live in space. Couldn't bringing all this stuff back to Earth be a tad bit dangerous?
Yay, I have a sig.
Composition of cometary objects isn't as important as their mass, in terms of protecting Earth from impacts.
Really, the sheer kinetic energy inherent in hyperbolic objects is so large as to make the thought of deflecting them silly.
For example, a cometary object 1km square would weigh a billion metric tons, and carry ~48 quadrillion Btus (or 1.41117626 * 10^13 kilowatt hours, a number so large it's silly), which would power the entire US for around six months if converted to electricity.
Basically, all we can do is hope. There's no imaginable engine that could be built on earth and sent to a comet in time to change it's orbit enough to avoid earth.
Thanks, that's a well appreciated clarification.
Interesting, I guess I called it a "failure" because I'm looking at it from the engineering side (I'm a NASA engineer - looking through my paradigm "success" means the spacecraft itself worked as designed).
But overall, the engineering is just a tool to complete the mission, which is science (and clearly there is a lot of good science coming out of Genesis). Sometimes we need to be reminded....
Worst...sig...ever!
Umm, the idea isn't to stop the comet; it's to nudge it off course by a few thousand miles. To do that, all you have to do is change it's velocity by say 1 m/s a few months before impact. That would only take 5e11 joules or 140,000 KWh for your comet. That's an amount of energy comparable to what a single gasoline tanker truck can hold.
Or you could stop thinking engines and start thinking bombs/projectiles.
Exactly what I was thinking. Seems like a few broad, flat, even remotely massive projectiles travelling a few tens of thousands of km/s ought to be able to knock a comet suitably off course, given enough advance notice. Carry up something big and heavy and cheap in the space shuttle and send it off. Or, heck, if circumstances are dire enough, throw chunks of space shuttle or ISS at it.
If we start planning now, it ought to be relatively easy to get some kind of fairly flexible asteroid deterrent up there. The trick is making it something that isn't also conspicuously similar to an orbital weapon. Dreaming up countermeasures is no good if the other world powers won't let it sit in orbit for fear we might turn it against them.
I'm no physicist, but couldn't an anti-comet bullet be turned into, say, an anti-city bullet by throwing it around a single AU orbit and back into a terrestrial target? Would there be any way to track such an incoming object without advance notice?
Now I've lead myself down a rabbit-trail, but couldn't a superpower with a space program conceivable launch a purported comet impactor and surreptitiously swing it around against a city? Would there be any way to prove after the fact what had happened?
In an age of nuclear weapons, it seems silly to drop rocks from orbit, but still. One wonders.
When it comes to launching things into space, these terms are mutually exclusive.
Laws are horrible moral guides, moral guides make even worse laws.