NASA Aircraft Videos Hayabusa Re-Entry 56
astroengine writes "Flying above the Australian Outback, NASA's converted DC-8 jet videoed the violent re-entry of the Japanese Hayabusa spacecraft. Flying in front of the disintegrating probe, the mission's sample return capsule can be seen speeding though the atmosphere. According to reports, the capsule landed safely and will be collected by helicopter in the morning." "Bad Astronomer" Phil Plait posts about the successful return as well.
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Just curious (Score:1)
What was the goal of the Hayabusa mission?
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land on asteroid, get bits into container, bring container back to earth using ion engines.
Re:Just curious (Score:5, Informative)
Re:Just curious (Score:4, Funny)
I recon they just stuck a meteorite in it before launch, just in case.
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Would it bring back bad luck by chipping a piece of meteorite?
Re:Just curious (Score:5, Informative)
http://en.wikipedia.org/wiki/Hayabusa [wikipedia.org]
So far so good (Score:5, Informative)
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For the pellet firing, it should have had two or more completely independent firing systems, greatly increasing the odds that at least one would fire. However, if it's a faulty design, then I guess the flaw would be duplicated also.
Re:So far so good (Score:5, Insightful)
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No, because you make 2 pellets at half size instead of one at full size.
Yes, such is more costly, but so is failure. As it was, they got zero pellets at zero size.
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You're still acting as if they knew the pellet gun might fail!
For that matter, why not just send two probes?
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You assume that a half-sized sample is half as valuable as a full-sized one. I'd argue that it's almost as valuable and that avoiding a complete pellet failure is far more important.
Mechanical mechanisms in space have a long history of problems. Space is a harsh environment where there's extreme temperatures and lubricants generally don't work well or have side-effects. And, Japan is still a toddler space-wise, so they need to be double careful.
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"For the pellet firing, it should have had two or more completely independent firing systems, greatly increasing the odds that at least one would fire. However, if it's a faulty design, then I guess the flaw would be duplicated also."
As it's already told, duplicating such a system would probably come at a (prohibitive) payload cost.
Anyway, if the systems were to be duplicated, they both would have been developed by different teams based off different designs in order to avoid your caveat.
bad timing (Score:1)
Oh oh (Score:3, Funny)
The last time someone fired pellet guns at a small asteroid, 60 mil years ago, the mother struck back with a vengeance.
Good point by the Bad Astronomer (Score:5, Informative)
Mr. Plait makes a good point. People tend to have this view of asteroids being solid rocks, probably because the Earth and other large rocky bodies are solid and the meteorites that make it to the Earth's surface are solid. However, that's not a valid assumption to make and recent science is showing this to be the case. Scientists are finding that some asteroids and various satellites of the outer planets are less dense than expected, suggesting that they're somewhat porous (i.e. masses of rubble instead of solid bodies). Science from the Cassini probe is showing that small bodies in orbit around Saturn are constantly being assembled and destroyed.
Personally, this view of asteroids being porous masses of loosely assembled rubble makes sense, especially from a planetary formation perspective. It's only when you get bodies more than a few hundreds of km in diameter that gravity starts to force the rubble to fuse into solid masses. The implication of all this that Mr. Plait points out is that nuking an asteroid will be akin to bombing a cloud. It's not going to move the asteroid at all, only disrupt it, causing not one impact but several. On the other hand, maybe it would make disrupting asteroids easier. Instead of one large impact, you have thousands of smaller bodies that have a greater chance of simply burning up on reentry.
One other thing that isn't touched on, but is of keen interest to the astronomical community is that the meteorites that we have here have spectra that are very different from the spectra of the asteroids we see in space. The current theory is that the surfaces of asteroids undergo some sort of weathering, which changes the spectra. By gaining physical samples of the surface of an asteroid, this theory can be tested by direct chemical analysis. Very exciting, if it was successful.
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On the other hand, maybe it would make disrupting asteroids easier. Instead of one large impact, you have thousands of smaller bodies that have a greater chance of simply burning up on reentry.
That is not necessarily a good thing.
A single large asteroid hits the surface and, largely, converts all its kinetic energy into heat. An awful lot of that heat radiates harmlessly off into space.
Turn your asteroid into dust and what happens instead is, yes, it all burns up in the atmosphere --- dumping the entire kinetic energy of the asteroid (which hasn't changed, remember!) into the atmosphere as heat, increasing the temperature massively. I forget the precise wording in the study I read but I belie
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I'm a little skeptical of this claim.
Can you elaborate on how the heat generated by the large asteroid (at ground level on impact) somehow ends up radiating off into space, yet the same heat generated higher up in the sky when the bits burn up in re-entry (closer to space) somehow doesn't end up radiating off into space?
As I see it, breaking up an asteroid allows us to convert the kinetic energy to heat higher up in the sky (and closer to space) than a ground level impact would be.
Do you have some links I c
Re:Good point by the Bad Astronomer (Score:4, Interesting)
What is true is that the energy in a single large meteor is sufficient to make the temperature of the air unbreathable over a large area. However, as you've noted, having the energy to do so and actually doing so are two separate ideas. I've not seen anything that went beyond "it could" into the mechanisms by which it would. Or, to say it another way, which would be more disruptive to the planet, a single piece of lead of 10,000 tons slamming into the earth, or 10,000 tons of feathers entering the atmosphere at the same point and with the same energy as the lead? Sure, they have the same energy, but you tell me which will cause more damage and why. No one knows, but he asserted the feathers would be more damaging, and you said something to the effect of "I don't believe you." I think I'd lean towards your side, but again, I don't think there's a genuine analysis of why and how that difference would happen.
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> Can you elaborate on how the heat generated by the large asteroid (at
> ground level on impact) somehow ends up radiating off into space...
Where else is most of it going to go? The part of the planet over the horizon from the explosion (i.e., almost all of it) is shielded by the planet.
> ...yet the same heat generated higher up in the sky when the bits burn up
> in re-entry (closer to space) somehow doesn't end up radiating off into
> space?
Half of it does. Unfortunately, the other half gets
Re:Good point by the Bad Astronomer (Score:4, Interesting)
What is going to couple the energy transfer from asteroid to atmosphere more effectively, one big rock or a bunch of little ones with the same net energy? The little ones, of course.
Now, the big rock will make a much bigger splash when it hits, creating quite the fireball -- which is a good thing, since heat radiates proportionally to the fourth power of the temperature difference, so a hot fireball will lose its energy to space a lot faster than a lot of smaller, cooler (but still hot!) ones. Yeah, the immediate vicinity is toast, but a lot of the energy is just, in effect, melting the ashes rather than heating up someplace else.
Or to put it another way (no, not a car analogy): would you rather have your whole body exposed to a temperature of say 400 degrees or one finger exposed to say 10,000? Hurts like hell either way, but the former kills you, the latter doesn't.
Background article (Score:5, Informative)
This article [planetary.org] is a great background article on the trials Hayabusa endured on it's way, while it was there and on its return to Earth. Read the article and be amazed that the probe made it home at all.
Reminded me of Apollo 13's problems and the hacks necessary to deal with them.
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Re-entry (Score:2)
Very interesting video clip. What I've been wondering for many years now, is that the Space Shuttle is on a predicted flight path, so they know where it is and at what time. Why hasn't it's re-entry been filmed properly? Why don't they put a video camera on the Shuttle on somewhere like the tail so we can see what it's really like outside as it re-enters the atmosphere.
The video over recent missions of the shuttle going up from various points, ie. main tank, booster rockets... are very interesting.
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What I've been wondering for many years now, is that the Space Shuttle is on a predicted flight path, so they know where it is and at what time. Why hasn't it's re-entry been filmed properly?
Well it has been. See for example http://www.youtube.com/watch?v=hK1RxQKCmCE [youtube.com] http://www.youtube.com/watch?v=XxGeo0ec-F4 [youtube.com] http://www.youtube.com/watch?v=S0mP4k--H5o [youtube.com]
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There has been video made in the past of shuttle reentry. In fact, there is a lot of video of the failed reentry of Columbia back in 2003. I know there is also video of various satellites that have reentered the atmosphere. All of it pretty much looks like this video, though the Columbia disaster is pretty heartbreaking.
It's "records" surely? (Score:2)
"Videos"? I'm sorry, when did "video" become a verb?
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"Videos"? I'm sorry, when did "video" become a verb?
Well, "video" is actually a verb to star with. It is a Latin word that means "I see." I don't know where you are, but to use "video" as a verb meaning to record a visual image seems common here in New England. I suspect that it is a shortening of "videotape" as a verb. The transition to "video" makes sense both as a shortening and as a response to the fact that most modern video cameras don't have tapes.
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Ok, not here in Australia - record or film are the verbs used here. To "video" sounds incredibly awkward to my mind, point about film being a noun/verb aside.
(and I knew the Latin meant something along those lines, but Australian English usage doesn't include that)
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It really irks me when people talk about "filming" things with their cell phones. Really. How much film does your cell phone hold? Oh, you didn't actually film anything?
There's nothing wrong with videoing things. It's ok. It's the 21st century now.
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I still hear "taping" for audio recordings, too.
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I still hear "taping" for audio recordings, too.
Weird, and I haven't heard that since the 90's.
In the circles I run in, everybody says 'record' for video or audio, specifying if necessary, but usually just through context.
I wonder if it's region, age, or something else. I may have presumed 'geekhood' as a criteria, but I think we can cancel that out within a slashdot discussion.
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But would you say "I'll video the event"? or the equivalent, "I'll audio your song"?
I use it as a noun in the sense of "I watched that video of..."
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Back in the 80's, before that people had super 8 cameras and used "film" as a verb.
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""Videos"? I'm sorry, when did "video" become a verb?" Back in the 80's, before that people had super 8 cameras and used "film" as a verb.
And this guys' name is TapeCutter, you know he's an expert.
Satelite reenters; town goes quiet... (Score:3, Funny)
I just got a phone call to join a bunch of people at an underground virus lab; should I worry that I'm an extraterrestrial biologist?
And, of course, I'm the single one out of the group. (hey, we're on /. , right?)
The real problem is that I always wanted to go by way of thermonuclear explosion; am I the wrong guy to get the override key?
gtg...
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So many drunks out that way the entire male population might survive.
What plane? (Score:2)
http://en.wikipedia.org/wiki/Boeing_YAL-1