Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 


Forgot your password?
Close
typodupeerror
×
Space Science

First Results From Deep Impact Mission 189

Posted by Zonk from the smash-and-learn dept.
jdoire wrote to mention a Physicsweb piece revealing some of the first bits of data from the Deep Impact mission. From the article: "Based on data from the flyby spacecraft and the impactor, Michael O'Hearn of the University of Maryland and colleagues say that Tempel 1 belongs to the Jupiter family of comets, although its overall shape and surface features are quite different from the nuclei of the two other comets that have been studied in detail -- Wild 2 and Borelly. They also report that Tempel 1 consists largely of extremely fine particles that seem to be very loosely bound together: in other words, the comet is more like a pile of powder than a solid rock." Looks like the Electric Universe folks were a bit off.
This discussion has been archived. No new comments can be posted.

First Results From Deep Impact Mission More

First Results From Deep Impact Mission

Comments Filter:

  • Posted on Technocrat.Net (Score:2, Interesting)

    by geomon ( 78680 )
    "The Washington Post reports that the comet struck by the Deep Impact projectile had higher than expected concentrations of carbon. The July collision with Comet Tempel 1 produced a cloud of ice and other debris that was analyzed by an accompanying space craft. Although the composition of the comet appears to be frozen water, other analytes found in the debris stream include formaldehyde and cyanide. I guess the EPA should be notified."

  • Sorry (Score:3, Interesting)

    by Saiyine ( 689367 ) on Thursday September 08, 2005 @10:31AM (#13509728) Homepage

    If the're "loosely bound together" how is that there were an impact at all? Wouldn't the probe just sunk into the comet?

    --
    Superb hosting [dreamhost.com] 4800MB Storage, 120GB bandwidth, $7,95.
    Kunowalls!!! [kunowalls.host.sk] Random sexy wallpapers (NSFW!).

    • Re:Sorry (Score:5, Informative)

      by TripMaster Monkey ( 862126 ) * on Thursday September 08, 2005 @10:33AM (#13509751)

      The same way the Shuttle on reentry 'impacts' the atmosphere, or the way a suicie from the Golden gate Bridge 'impacts' the water.

      If you're moving fast enough, it's sure gonna feel like an impact.

    • Re:Sorry (Score:3, Interesting)

      by geomon ( 78680 )
      I would agree that sounds like the case. However, my experience has been that snow packed loosely together into a projectile can hurt. I got pelted by nearly 100 snowballs as a freshman and one left a cut above my eye.

      No rocks or other debris was packed into the snow. It was a loose powder compressed by punk-assed kids - you guys know who you are. I'm still comin' for ya.

    • Re:Sorry (Score:2)

      by Anonymous Coward
      Think about a sandbox. It's not just "loosely bound" - it's not bound at all. However, I can gaurantee you you can still impact the sand in a sandbox.

    • Re:Sorry (Score:5, Funny)

      by forkazoo ( 138186 ) <wrosecrans@@@gmail...com> on Thursday September 08, 2005 @10:38AM (#13509808) Homepage
      The comet becomes terribly afraid whenever anything is about to hit it. This natural "tensing up," it what allows us to study it effectively.

      Also, moving at many thousands of kilometers per second means that you can impact almost anything and cause an explosion. If the probe gently touched down, it might well have settled into the comet very ently.

    • Re:Sorry (Score:2, Informative)

      by Anonymous Coward
      "Loosely bound" relative to solid rock. Also, from the article, although the outer layers of the comet were composed of tiny particles (~1 micron - 100 micron in size), the density of the comet's nucleus was about 600 kg per cubic metre, so the probe was never going to sink too far...

    • Re:Sorry (Score:5, Interesting)

      by smooth wombat ( 796938 ) on Thursday September 08, 2005 @10:41AM (#13509831) Journal
      When I saw the article (YESTERDAY!!) I thought about this also but came up with what I hope is a good analogy.

      If you have ever been to the beach or played in a really deep sandbox, you know that the top layer of sand moves about easily. You can dig your toes in without any effort. The sand is loosely bound together.

      However, if you drop a bucket (or anything else) onto the sand, that object will only sink in a small bit. Why? Other than the fact that there isn't much force behind dropping whatever onto the surface of the sand the sand itself compresses slightly from the impact.

      'But Deep Impact was the size of a washing machine and travelling at a bajillion miles an hour when it hit. You can't compare that to dropping a bucket on the beach!' I hear you say.

      Actually, you can compare the two. If you take the size of a bucket compared to the size of the beach, there is a huge difference. Even if you were to take a replica of Deep Impact and fire directly onto the beach at a speed approximating the impact speed on the comet I can guarantee you would get a similar result.

      The impact would produce a nice big explosion of particles and the copper impactor would probably disintegrate. However, the beach would still be there albeit with a nice big hole in it.

      Hope this long-winded explanation helps.

      • Re:Sorry (Score:2, Funny)

        by dosle ( 794546 )
        This all goes back to the saying "Why don't you go pound sand.".


        *returns to punching fine particles*

      • Re:Sorry (Score:3, Informative)

        by StrawberryFrog ( 67065 )
        The lower layers of an object will not compact in a zero-gravity environment.
        • The lower layers of an object will not compact in a zero-gravity environment.

          Zero-gravity is a misnomer. All matter possess gravity. Zero-gravity referrs a region of low Earth orbit where the gravitational effect of Earth is extremely low. But because you are still in orbit, you are still under the influence of Earth's gravity.

          • Re:Sorry (Score:4, Informative)

            by StrawberryFrog ( 67065 ) on Thursday September 08, 2005 @11:09AM (#13510091) Homepage Journal
            Correct, but the point remains: the comet was described as having the consitency of a snowdift.

            On the surface of earth, the bottom of a snowdrift compacts under the weight of snow on top of it. On a comet (i.e. a small body in a large orbital path around the sun) the same effect does not apply, and the snowdrift could be as loose as the top inch all the way through.

            • Re:Sorry (Score:5, Informative)

              by LurkerXXX ( 667952 ) on Thursday September 08, 2005 @11:57AM (#13510522)
              But there is this little thing called inertia...

              You've got many many metric tons of snowdrift, floating through space.

              You ram a refridgerator size probe REAL fast into one side of it.

              The 'snow' right where the fridge hits is going to move inward, but the many many metric tons of snow on the other side of it is going to want to stay right where they are (a body at rest tends to stay at rest). The movement inward of the snow under the probe's impact against all that 'resting mass' will cause the compression of the 'snow' in that area.

            • So it makes a deep hole. Think about it. The comet is a mile in diameter, and even if it is the consistency of a snowdrift, there is a load of mass in a one-mile-long-but-otherwise-fridge-sized cross-section of snowdrift. The impactor wasn't going nearly fast enough to stand a chance of punching all the way through, and its vaporization is really no surprise at all.
          • But because you are still in orbit, you are still under the influence of Earth's gravity.

            Yes, but the gravity you experience is zero. If you are free-falling, even in a gravitional field, you don't feel any force (apart from very tiny tidal effects).
          • Zero-gravity refers a region of low Earth orbit

            I'd have thought that zero gravity refers to any place where there is little or no net gravitational force. Low earth orbit, high earth orbit, medium Mars orbit, surface of a small comet in solar orbit ... take your pick.
            • I'd have thought that zero gravity refers to any place where there is little or no net gravitational force.

              As long as two chunks of matter are in space, there will be gravitational attraction.

    • Re:Sorry (Score:4, Informative)

      by elliotCarte ( 703667 ) on Thursday September 08, 2005 @11:00AM (#13510013)
      ...how is that there were an impact at all? Wouldn't the probe just sunk into the comet?

      I'm guessing that what you're really asking is why any debris was thrown from the surface of the comet instead of the impactor just uneventfully sinking into the surface. Think of it like this: If you take a bowl and fill it with talc powder or flour (a very loosely bound together substance) and shoot a projectile into it with a slingshot, would it just sink in without producing any debris (a small puff of powder or flour)? Add to this the fact that there's far less gravity holding the comet together than there is holding the powder down/together (in the bowl). Does that visualization help?

      It's an easy experiment. Try it. I might suggest a coffe can instead of a bowl though so that 1. you don't break the bowl and 2. you minimize the risk of the projectile flying back up and hitting you or someone/something else. Also use plenty of powder or flour as to slow the projectile enough that it can't hit the bottom and bounce back up and of course you want to wear safety glasses. Alternatively you could just view the images sent back from the mission (included in TFA) and trust that it's not all just a hoax.

  • Skip the middlemen (Score:5, Informative)

    by Anonymous Coward on Thursday September 08, 2005 @10:33AM (#13509748)

    and their advertising application masquerading as a "website"

    http://www.nasa.gov/mission_pages/deepimpact/media /spitzer-di-090705.html [nasa.gov]

  • A big powdery comet? Precious! (Score:4, Funny)

    by deft ( 253558 ) on Thursday September 08, 2005 @10:37AM (#13509801) Homepage
    Well dang, if that's all it is, c'mon in for a landing buddy. Man, we had you comets all wrong.

    Won't be a planet killer...more like a planet tickler...cute little fella.

  • Mining (Score:5, Interesting)

    by SumDog ( 466607 ) on Thursday September 08, 2005 @10:42AM (#13509840) Homepage Journal
    I think its cool that we are all ready at the point where we can crash probes into comets and examine them. I wonder how long it will be until we can actually pull a comet into earth orbit and mine it for resources.

    • Re:Mining (Score:4, Interesting)

      by lobsterGun ( 415085 ) on Thursday September 08, 2005 @10:52AM (#13509943)
      Based on the information revealed today, it might not ever be practical to move a comet into Earth's orbit.

      If the COMET was a big ball of rock it would just be a matter of attaching to it and then pushing it where it needs to go. But with the comet being in essence a big pile of sand, it would be much more difficult to move around with our current technology. (I'm basing this on the idea that as soon as we start pushing it, it will start coming apart)
      • Also, to consider, while I doubt it will be able to shift Earth's orbit (assuming we COULD hook into it)...what kind of cabling system do we need that COULD sustain that kind of pressure. Even if the thing moved at 1 MPH, it is so freaking massive that any kind of cable we could currently design would snap in half. We simply do not have a method to anchor these things. Though maybe it would be possible to shift its trajectory and crash it into the moon and then mine the stuff from the moon.
        • WTF are you talking about?
          I doubt it will be able to shift Earth's orbit
          I don't think anybody wants to screw with Earth's orbit.
          any kind of cable we could currently design would snap in half. We simply do not have a method to anchor these things.
          Why would we use a cable? The OP suggested putting it in orbit.

          Maybe I'm just missing something here.
          • Maybe I'm just missing something here.

            Yea you are missing something. How do you plan on putting this thing into orbit? It is moving at a high rate of speed, are you going to ask it and hope it will respond? You could try blasting it into orbit, but do you really want to mess with that many (probably nuclear) bombs?

            WTF are you talking about?

            What I am speaking about is getting this thing into orbit.

            I don't think anybody wants to screw with Earth's orbit.

            Well duh, but what you fail to realize

            • How do you plan on putting this thing into orbit? It is moving at a high rate of speed, are you going to ask it and hope it will respond? You could try blasting it into orbit, but do you really want to mess with that many (probably nuclear) bombs?

              That would be my guess as to how to move it, yes. Are you suggesting using a cable and winching it to Earth?

              what you fail to realize is that it will take a whole lot of mass to move the Earth, and simply put it, a comet of that size does not have the mass to do so.

              • I fail to see anywhere in this thread where anybody suggests that the comet should "move the Earth"
                OMG, do you not read your original posts? "I don't think anybody wants to screw with Earth's orbit." This CLEARLY suggests moving Earth out of orbit.

                What I fail to realize is from where the idea that Earth's orbit would be modified came.

                Apparantly reading your OP.

                Are you suggesting using a cable and winching it to Earth?

                If you took half a second to read my statements, and then THINK, you would re
      • But just think of all the valuable SLUSH you could mine from that thing! Why, you could... umm.. make.. snowcones, or something. Yeah...
        • We need something to slingshot back at the bugs. You know...the giant ones that shoot plasma out of their butt and can knock an asteroid on a collision course with earth from lightyears away?
      • It might be possible to wrap it in a large net (there are fishing nets that are over 16 kilometres long) and haul that around with thruster rockets.
    • With all the nice budget cuts from our oh-so-wonderful president, I wouldn't expect this anytime in the near future... despite the fact we should more or less be there already.

      (Sorry, but it's true)
      • With all the nice budget cuts from our oh-so-wonderful president

        Check again. Budget for NASA went down under Clinton and has gone up since Bush was in office. It also went up during the previous Bush administration.
        From here [newsmax.com]
        1993 $14.309 billion, existing NASA budget when Clinton took office;
        1994 $14.568 billion, $259 million increase, first Clinton budget;
        1995 $13.853 billion, $715 million decrease;
        1996 $13.885 billion, $32 million increase;
        1997 $13.709 billion, $176 million decrease;
        1998 $

        • They might be able to buy something if they weren't paying for the stuff they have lost through attrition and explosion.

          The space shuttle has got to go. Its a huge drain but it has to be replaced with the right combination of unmanned and manned launch capability.

          And then we're almost able to create the composites required for Arthur C Clark's 'space elevator'. (That man has done more for the space program than Werner von Braun. The comunication sattelite, the space elevator and Rama (as a concept explorati

        • AHEM....

          Even after Clinton's $715 million dollar cut, thats still, $17B BILLION in the 1995 budget when you adjust for inflation into 2004 dollars [nasa.gov]

          God, I wish we had clinton back instead of this idiot.
        • $16 billion in pork. Ridiculous.

          My household could use my $400 per year share for more worthwhile causes.

          I wish they'd break down every government budget line item in "dollars per constituent" instead of incomprehendible totals.

    • Re:Mining (Score:3, Insightful)

      by Rorschach1 ( 174480 )
      We can visit and study mountains, too. Moving them is another matter.

      Besides, it's asteroids you want to mine for minerals, not comets.
    • I'm going to go out on a limb and predict that we'll never, ever pull a comet into Earth orbit for the purpose of mining it. There's just no conceivable reason to do so: If you're going to take mining equipment into orbit, why not just take it to the comet?
    • Why bother? It's easier to send mining probes to a comet, refine what we need there, and send it back rather than trying to pull the whole damned thing to Earth. After all, it's easier to move 1 pound of gold (or whatever) than to move 100 pounds of gold ore.

      On another note, it would be far more economical to mine asteroids rather than comets.

  • Mirror of first bits (Score:5, Funny)

    by paz5 ( 542669 ) on Thursday September 08, 2005 @10:43AM (#13509852)
    10101110

  • Question (Score:5, Interesting)

    by Dutchmaan ( 442553 ) on Thursday September 08, 2005 @10:45AM (#13509870) Homepage
    Does this mean that using an significantly large explosive device is almost a feasible scenario for specific types of comets.

    I mean, I can understand not using that approach for something make of rock and ice, but with fine particles one would think that sufficient force would break it apart like a cue ball.

    Obiviously this is just fuzzy thinking, but does anyone have any scientific input to why this would or would not be an emergency solution to be put on the table for this specfic type of comet?

    • Re:Question (Score:4, Interesting)

      by Anonymous Coward on Thursday September 08, 2005 @10:53AM (#13509952)
      My instinct here is that trying to detonate a comet is not a great solution no matter the composition.

      You do not have quite the same threat of calving (i.e. splitting into two big chunks instead of one big chunk), but there is the possibility that either a) the explosion would just shove it (the beach/sand analogy above is good), or b) that you would face a sandblasting from billions of tiny particles.

      That might not seem so bad - hey, no impact crater! But the simultaneous atmospheric entry of that much material can generate so much heat as to start mass fires on the ground below (this is a normal side effect of debris reentry in a lot of impact models).

    • Re:Question (Score:3, Interesting)

      by Doc Ri ( 900300 )
      I think that it is relatively losely bound does not mean it is something like a cloud. If it were like that you would not have to worry about a collision in the first place. (As usual, depending on the energy -- with sufficient energy a 'dust cloud' can also kill you.)

      When you shoot a projectile at such a comet, parts if of it can become more compactified. (This is actually one scenario proposed for the formation of small yet compact objects in space.) It would be very hard to predict what exactly would
    • Maybe, but if you look at the 'after' pictures, we didn't put much of a dent in that huge dust/snow-drift with the equivalent of 5-10 tons of TNT.
    • With a significantly large explosive device you can blow up what ever you want it really just depends on what you mean by significantly large ;)
      1.3 trillion tonnes of antimatter and you can blow up the earth.
      But practiley no.
      Even though a comet maybe only loosely bound it still weighs a lot. So setting off a bomb is likely to make it just slightly looser bound but still a problem for earth.
    • Maybe I'm wrong, but I don't know that many people are concerned about comets per se; I gather that the concerns regarding Earth-impact events are more in regards near-earth asteroids and other more "solid" bodies, particularly their ability to get very close to Earth before anyone even NOTICES they are there.

      Comets, whether they were the hypothesized 'dirty snowballs' of yesterday or the 'powder-puff' of today, might be a mile or more across at the nucleus. But it seems to me that the corona around a come
      • While it is correct that the corona/tail of a comet makes it easy to identify within Jupiter's orbit, the speed (60+ km/s) of the long time comets (the ones form the Kuiper belt) would only leave less than one year from discovery to impact. The first 2 month's would likely go to determining the exact trajectory of said comet, and that leaves us with only 8 to 10 months to come up with a plan AND implementing said plan.

        In order to do something against a comet/asteroid you also have to give it a 'gentle nudge
  • "in other words, the comet is more like a pile of powder than a solid rock."

    NASA wants its Tang back.
  • What does this do to doomsday scenanios where we try to blow up some comet coming at us with nukes? If it is made of powder, doesn't this make it easier to to disperse the nasty comet by shooting nukes at it?

  • Its like a comet composed of garbage (Score:3, Funny)

    by MooseTick ( 895855 ) on Thursday September 08, 2005 @10:54AM (#13509958) Homepage
    I once saw a documentary about a comet that was made completely from garbage. It was nearly impossible to destroy because it was such a loose collection of items. This comet seems very similar.
  • -Impact in 3... 2... 1....
    *POOF*

  • Fine powder? (Score:2, Funny)

    by Mr.Fork ( 633378 )
    Uh oh. Don't let the cosmetic companies in on our cosmic find. Heaven forbid Channel or Revlon market a powder puff from comet dust. I can see it now. The funded research/harvesting rocket Delta rocket lifts off with 'Maybe it's Maybelline' on the side sliding past the live web-cam tower broadcast is just wrong. Ugh - cosmic cosmetics.

  • They thought the moon (Score:3, Interesting)

    by blair1q ( 305137 ) on Thursday September 08, 2005 @11:14AM (#13510125) Journal
    They thought to moon could be a big ball of loose powder, too.

    Neil Armstrong says he didn't know if they were going to land on the surface, or sink into it never to be seen again.

  • From the article: the density of the nucleus is about 600 kilograms per cubic metre.

    Can anyone give me examples of what that density is like? What is water's density?

    • Re:Density question (Score:2, Informative)

      by Doc Ri ( 900300 )
      Water's density is 1000 kg/m^3, so 600 kg/m^3 is pretty dense.
    • Water is 1000 kilograms per cubic meter.

      So the stuff is about as dense on average as pine wood. (Not a boat, just the wood.) Though it's probably particles that are denser than water with gaps.

      1 liter is 1000 grams, so a 10x10x10 cm block of water is one kilogram. It would take 1,000 of those blocks to make a cubic meter, thus 1,000 kilograms. So 600 kilograms per cubic meter = 6/10 as dense as water. Or something like that.

      • Thanks. I can completely understand pine, as I have used a chainsaw and understand the difference between it and, say oak (or stone). I realize that the article was written by someone who understands phrases like 600 Kg per cubic meter. It is handy, though, to give the reader an accurate assessment of scientific terms like that.

        One great technical term I read explained was that the planet Jupiter, because it was made up of gas only, would float in a body of water, were one able to find a body of water larg

        • Actually, Jupiter's density is somewhere around 1.33 g/cm^3.

          So it would sink despite being a gas giant.

          The writer of the article must have not realized that the gas of Jupiter gets really, really dense when crushed by the presure of the depths of the atmosphere.

          Anyway, there very well could be a solid core, last time I did much reading on it they still didn't know.

  • Tunguska Comet Impact - 1908 (Score:5, Informative)

    by infonography ( 566403 ) on Thursday September 08, 2005 @11:26AM (#13510220) Homepage
    http://en.wikipedia.org/wiki/Tunguska_event [wikipedia.org]

    There have been a wide range of theories about this, but a puffball comet explains a lot about what happened there. From Aliens;

    http://www.space.com/scienceastronomy/tunguska_eve nt_040812.html [space.com]

    to Victorian Era Superweapons testing ala League of Extraordinary Gentlemen (the Comic book, not the movie). I have tried to find the site on Google Earth but have not been lucky.
  • From the article: Finally, Horst Uwe Keller of the Max Planck Institute for Solar System Research and co-workers used the Rosetta mission - which is on its way to another comet called Churyumov Gerasimenko - to survey the collision at from a distance of 80 million kilometres over a period of 17 days. Again they found that the relative amount of organic material being ejected increased following the impact. Keller and co-workers also observed a dip in brightness about 200 seconds after the impact, which the
    • The military is currently researching railgun technology. The shells said railgun will fire are inert and will not explode in the same manner as conventional shells. They'll simply strike the unfortunate target with such force that it'll basically explode. Nasa did the same thing, just with more mass and more velocity, no chemical reaction could explode with the same force obtained by striking a target in this manner.

    • Re:Formation of a City-Sized Crater? (Score:4, Insightful)

      by Blitzenn ( 554788 ) * on Thursday September 08, 2005 @12:23PM (#13510758) Homepage Journal
      "Exactly what was in that impactor that could create a city-sized crater?"

      It is exactly the inordinate size of the crater that has caused them to beleive that the surface is like a 'pile of powder'. It wasn't that the impactor was so large or going so fast relative to the target, it was that the surface material reacted so violently in relation to the physical impact. That denotes that the surface material has little to no cohesive nature. What really makes that curious is why would it possibly stay together to begin with then? It is a relatively small body and should exhibit a very very small gravitation influence. Why would such material form a body that at least gives the illusion of cohesion in the abcense of the physics that we believe it takes create such a body?
      • The comet doesn't have much gravity, but it has enough.
        • " The comet doesn't have much gravity, but it has enough."

          It would make for an easy explaination, but unfortunately it has issues with a couple of principles. I am not going to spell out all of the theories of Gravity to you, but here is a link that is a good summary of where we have been, are and are going with the theory of gravity [laborlawtalk.com]. It is still a theory and we haven't got one yet the unifies itself with the rest of the physical world. That is truely the Holy Grail of Physics right now. Anyway, ther

          • Hmm... condescending attitude ("I am not going to spell out all of the theories of Gravity to you")...check.

            Gratuitous use of Capitals...check.

            Irrelevent invocation of Einstein...check.

            Cititation of of "widely thought" theory that no one has ever given significant credence to...check.

            Complete absence of calculation to back up any vague claims about what can or cannot be explained by known physics...check.

            Really, the quality of Trolls these days just ain't what it used to be.

            For what it's worth, there are tw

    • Answer: Kinetic energy (Score:2, Informative)

      by p3d0 ( 42270 )
      Exactly what was in that impactor that could create a city-sized crater?
      Kinetic energy. It's an amazing thing.

    • Exactly what was in that impactor that could create a city-sized crater?

      An awful lot of kinetic energy

  • Hmm... (Score:2)

    by jwdb ( 526327 )
    So that's where my collection of dust bunnies rolled off to...
  • Looks like the Electric Universe folks were a bit off.

    Ya think? ;-) Most proto- or pseudo-scientific theories don't get (or take) a lot of chances to test their theories in the field, so I've got to give the folks at thunderbolts.info [thunderbolts.info] credit for stating up front what they expected to see if their comet model held any water. The next test for electric universe [wikipedia.org] proponents is if/how they go about tweaking their theories in response to experimental observation.

    Granted, this one sample of cometary material does

  • All they wanted to do was trying to see if they can still score a point in the expensive hardware lobbing [anl.gov] contest, while actually crashing a spacecraft.

Slashdot Top Deals

Reality must take precedence over public relations, for Mother Nature cannot be fooled. -- R.P. Feynman

Close