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Cometary Fireworks Go Off Without Hitch
PingXao writes "The JPL Deep Impact mission has successfully slammed a sattelite into Tempel 1 at 23,000 mph. (37,000 kph). The autonomous navigation system was primed for up to 3 course corrections in the final 2 hours of flight but only had to execute two of them. The second was so small - expending less than a pound of propellant - that impact would have occurred without it. Initially thought to be shaped like a pickle, it came to resemble more of a banana shape as comet Tempel I drew closer. Impact was estimated to have released 19 Gigajoules of energy, or the equivalent of 4.5 tons of TNT."
1 tonne of TNT = 4.184 x 10^9 joule = 4.184 Gigajoules/tonne
:-)
19/4.184 ~ 4.5 tonnes TNT
TNT has a lot of energy
Also a pretty cool, official NASA Quicktime movie from the impactor's camera - kind of wobbly and jerky, but nifty nevertheless.
;-)
I think it contains what are by far the best, and closest pictures of a comet nucleus - and I've no idea if it's from 'final' data yet. I gather there's a lot left to download from the flyby probe, but was it a Huygens-Cassini style relay setup or was impactor data received directly on Earth? If it's the latter, I suppose there isn't much chance of retrieving any more of the close-up data, as the delicate hardware stuck to the impactor's copper mass must have made quite a splat...
Tedious Bloggy Stuff - hooray?
btw: The pictures are just breathtaking... on them it really looks like 4.5kt (which is a testemony of the amazing light collection power of current telescopes and quantum efficiency of CCD arrays)
:-)
I wouldn't be surprised if a lot of the apparent 'explosion' visible in the images is due to sunlight illuminating the plume of dust produced by the impact. Comet nuclei are pretty dark, so I suppose the exposure times were probably cranked right up to see anything of the nucleus itself.
This is all guesswork, of course, but I remember a similar explanation of the 'explosions' visible when the Shoemaker Levy 9 comet fragments hit Jupiter. Mankind has kind of built our own tiny version of that!
Of course, the above could all be utterly incorrect...
Tedious Bloggy Stuff - hooray?
don't you need a gas to record sound?
Nope, you need a medium to transmit vibrations. Whales do just fine with a fluid, in fact a fluid is better, because it's denser. More molecules in closer contact. They "talk" to each other across hundreds of miles using low frequencies. That would be the whales. Molecules don't talk. They don't even "talk." Don't anthropomorphize molecules. They hate that.
Solids work great too. A microphone on the probe would have recorded a sound.
A microphone next to the probe would not, because because an insufficiently dense medium, like a gas, to carry the vibration.
KFG
No, really: Tunguska, June 30th 1908. :)
You obviously don't know what's going on. First of all, most of the data has not been received yet. Its still being transmitted to NASA from the probe. Right now we're only getting low res pictures because that's all that's been sent. The priority right now is data gathering, not data transmittal.
Second, automated image enhancement is pointless. As an amateur photographer, I know that each picture needs to be optimized manually, and using automatic settings often works, but not always. You'll get good pictures, but not 12 hours after impact. Plus I'm sure much of what they received wasn't good anyway and had to be thrown out.
Third, you obviously don't know the complexity of these projects. Most of the public doesn't really care about the low resolution pictures - they'll see the high res pictures when they're broadcast by the media. Which means that there's no point for NASA to deal with the 0.1% of the public who think they deserve to get access to those pictures.
Fourth, I'm really rather insulted by your pompous attitude regarding the people at NASA. No, I don't work at NASA. Nor can I call myself a scientist yet. But I'm an undergraduate physics major and so far my plans are to go on to grad school. Right now I'm spending the summer at the biggest NSF-funded project (not hard to figure out which one it is) and I will tell you that the people who run the project are brilliant and have no time to deal with whiners like you. If you really wanted to work on these kinds of missions, why didn't you dedicate your life to science instead of just whining about how you don't have access to all the data. Because I doubt you can figure out much from the data, and I find your arrogance to be purely insulting.