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NASA's Deep Impact
NivenMK1 writes "The Seattle Times has an interesting article on NASA's plan to nail the comet Tempel 1 with a chunk of copper the size of a bathtub on July 4 this year. This copper 'bullet' is intended to strike the comet at approximately 23,000 mph and hit with a force equivalent to 4.7 tons of TNT.
Scientists hope to discover what exactly the comet is made of and what changes have occurred to the outer layers with reference to the core."
You want to analyse the comet, which you can do by looking at the emission lines of the cloud forming after the impact, ect.
An explosive is normally composed of chemically very reactive components, that can react with each other and the material of the comet, making it very hard to discern what WAS there and what was created by the blast.
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The article doesn't state if this velocity is relative to Cape Cod or relative to the comet. It makes a big difference.
Look at the numbers:
The impact power of the copper rod is 4+ tonnes of TNT. IF you wanted to double the blast, you would have to send more than 4 tonnes of explosives.
at 30km/s+, the kinetic energy of the material is bigger than the chemical energy of explosives.
The added energy just doesnt matter anymore because it would be difficult to time the blast, plus the softness of the explosives would reduce the impact penetration.
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
Nasa is conducting the experiment precicely BECAUSE nobody know what will happen next. If we knew with certainty what was going to happen, THEN there wouldn't be a very good reason for carrying on with the experiment.
Last year they spent $200 billion blowing up comet Baghdad and we're all still waiting to see how that cliffhanger's going to end! This time it's cheaper and it doens't involve killing anybody.
I've loved astronomy on a casual basis since childhood and I think it's important to mankind. I'm not one of those people who thinks we should abandon NASA spending because there are still underprivilidged marmasets living in a swamp somewhere or whatever.
But isn't this kind of, uh... wrong? Possibily destroying a comet? It seems so destructive to possibly break apart something that's been circling our sun for millions of years.
I understand that comets are more like "dirty snowballs" than things of infinite beauty, and I can definitely understand the scientific reasons for this mission because they're going to get all kinds of data that they couldn't get otherwise.
This seems kind of wrong to me, though.
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I don't think the emission lines would actually provide much of a problem, it would be pretty easy to filter out the gaseous emissions of the explosives... I think the greater problem would be the unpredictability of the momentum problem if you added a chemical explosion. With a solid projectile, you can expect to learn a lot about the comet simply by what happens to the path of the intercepting projectile- ie shooting the snowball example. But, if you shoot a snowball with an RPG, or an iceball with an RPG, it's a lot harder to look at the resulting dispersion and tell what the target was made of after the fact.
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she won't let you fly, but she might let you sing
And I quote:
"If we knew what we were doing it wouldn't be research."
- Albert Einstein
Spending 311 million dollars without knowing what happens next doesnt seem a very nice idea.
I am sure there is military research aspect in this project too. The ability to hit a comet with a bathtub-sized hunk of metal is probably good practice for hitting an adversary's satellite with a bar of soap-sized hunk of metal.
I highly doubt this is purely civilian science in action.
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