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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."
July 4 this year?! What a coincidence - it's the date the project I'm working on now should be finished to.
...where the bullet misses its target and curves back round to origin.
Don't miss guys - and watch out for Hubble!
AT&ROFLMAO
....But hitting a rock on Independance day sounds like a bad idea, what if it's an Alien's rock?
We can't just keep going around the Solar system bashing things up that's not ours!
Why copper?
Is it because Tempel 1 is known to not contain any copper itself, so it makes the spectral signature easier to read?
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.
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
The article doesn't state if this velocity is relative to Cape Cod or relative to the comet. It makes a big difference.
Our comets are now under attack. Please join the Society for the Preservation of Comets, before it's too late.
Hopefully together we can make a difference. It's time to stop these bigoted scientists from damaging comets with bathtub size copper slugs, just "to see what will happen."
Without comets, there would be no space snowballs. This must stop.
Take the cheese to sickbay, the doctor should see it as soon as possible - B'Elanna Torres, "Learning Curve"
...NASA is lying. The comet is actually heading straight for Earth and the best plan they have is to launch a copper bathtub filled with Bruce Willis.
Unfortunately, the MPAA sent a cease and desist order to NASA informing them that this would be infringing on the IP of one of their client's copyrighted movies.
Hence, plan B involves throwing a bathtub at the comet instead. Go NASA!
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?
The lump of copper is 820 pounds, and will be equivalent to 5 tons of TNT. If you sent an 820-pound lump of TNT, you would get an explosion of about 5.4 tons of TNT. An extra .4 tons-TNT increase, in exchange for a vastly more dangerous mission and chemical contamination is not a good trade.
At these speeds, the kinetic energy is so great that chemical explosives are nearly pointless.
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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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And millions of years from now the aliens invezstigating the comet will scratch their heads thinking 'why is there a piece of copper the size of a bathtub on this comet'. Far greater amusement factor.
This project has been around since 2001; probably a dup /. article somewhere... Anyway, here is the NASA website, which gives more details on the mission.
http://deepimpact.jpl.nasa.gov/
ph34r teh p0w3r 0f th3 c0w
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
Yes.
Is it fascism yet?
Given NASA's budget, copper made more sense. Finding themselves unable to afford chemical or nuclear explosives, NASA employees have spent the last four years collecting stray pennies - checking under seat cushions in taxis, keeping a watchful eye on the sidewalks and streets near their offices, and so on and so forth. Also, twice a year they held bake sales in the Vistor's Center where purchases had to be paid for entirely in pennies. Since they also lacked the budget to purchase a safe, or even a large piggy bank, one enterprising employee scrounged an old bathtub from a nearby dump, and placed it in the hall outside the Deep Impact lab for people to toss the pennies into. (Which is why the project is using the new "size of a bathtub" metric instead of the international "Volkswagon" unit of measurement.)
A marriage is always made up of two people who are prepared to swear that only the other one snores.
Another reason they are doing a kinetic impact is because they want to judge the structure of the comet. Right now, scientists don't really know if the comet's consistency is that of a fluffy snowball or a hard chunk of ice. If you used explosives, you would have melting of the ice, whatever its consistency, and would get less information about the construction of the comet. Once possibility is that the comet might be loosely packed enough that the impactor goes in one side and flies out the other....
Also, I'm surprised the article submitter didn't include a link to the mission website.....
And I quote:
"If we knew what we were doing it wouldn't be research."
- Albert Einstein
How acurately can they predict the comets path (whenever I here about near earth passes they are always given in wide ranges as to how near they actually came).
You hear about near-Earth passes, as you call them, because they're always the first time we've noticed said object getting close to the Earth. This comet (and many others, plus asteroids, etc) has a pretty well-known orbit around the Sun. We have plenty of observations and can accurately predict where it's going to be at any given point in time (barring things like orbital changes due to outgassing, disintegration, etc).
There's another object in the sky that we can do this with: the Moon. It's VERY close to Earth, yet we can be pretty safe in saying it ain't about to hit us. Lots of observations == confidence in a body's motion.
The "scary" ones you hear about are new objects we've never seen before, and all of sudden they look like they're coming "close". Once we get enough observations of them, we can calculate their orbits, and you pretty much never hear about them again.
Endless arguments over trivial contradictions in books written by ignorant savages to explain thunder in the dark.
How do we know that this hasn't already happened and that there isn't already a bathtub sized chunk of copper on it.
It'll be easy to tell them apart. Aliens are generally either tall and thin or short and squat, so their bathtubs would be quite a different shape.
I once spoke to someone who works on the Deep Impact project, and he said that, after the Mars Polar Odyssey crashed, their motto became "Deep Impact: We're Supposed to Crash."
I have gas, but my car uses petrol.
Leave it to Americans to come up with a plan along the lines of: "Wonder what that's made of... lets blow it up!"
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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