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Moon NASA Science

Twin Probes Crash Into the Moon 79

Posted by timothy
from the as-promised dept.
SchrodingerZ writes "After their yearlong mission to map the Moon's gravitational field, twin probes Ebb and Flow crashed into the lunar surface, ending the GRAIL mission. The crashes were controlled events, each impacting 30 seconds apart from each other. The twin spacecraft were running low on maneuvering fuel and NASA, not wanting the craft to fall on historical sites such as the Apollo landing sites, redirected their flight patterns to impart the far (dark) side of the moon. Their impact sites were named after Sally Ride, the first American woman in space. 'During the news conference last week, Maria T. Zuber, the principal investigator, said the probes would be crashing into a "non-sunlit" part of the surface.' When the site becomes sunlit again in several weeks, the Lunar Reconnaissance Orbiter will attempt to take pictures of the craters the probes undoubtedly made in the lunar soil."
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Twin Probes Crash Into the Moon

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  • by craigminah (1885846) on Tuesday December 18, 2012 @10:34AM (#42325201)
    I'm sure the EPA or Al Gore is going to file a claim against NASA for lunar warming or polluting the surface of the moon.
    • And what are they gonna say if they crashed on the house of some of the men living on the dark side of the moon?

    • Re: (Score:2, Interesting)

      by scsirob (246572)

      How would you feel if some alien species arrives at our galaxy and decides to throw their used-up dilithium on your porch.
      What if the moon turns out to be made of cheese after all, and the probes punch a hole in the protective crust. The moon might deflate and we end up covered in cheese. Yuck!

      Sillyness besides, I find it quite amazing that the USA decides they can abuse the moon as their public junk yard and just dump their garbage there.

    • Mr. Gore, would you have preferred the alternative? If so, we can slam the next probe into Uranus.

  • Far (dark) side? (Score:2, Informative)

    by Anonymous Coward

    The moon doesn't have a permanent dark side any more than the earth does!!!! The far side is in fact the mainly bright side during a new moon.

    • Re:Far (dark) side? (Score:5, Informative)

      by SternisheFan (2529412) on Tuesday December 18, 2012 @10:44AM (#42325311)
      You are correct. From the NY Times linked article: "In my article last week about the impending demise of Ebb and Flow, I noted, "Unfortunately, since the action will happen on the dark side of the Moon, there will be nothing for earthlings to see." About a gazillion people, including Robert Kirshner, a Harvard astronomy professor, wrote in to ask, "Didn't you mean to write 'far side' and not 'dark side'?" The more annoyed wrote: "Dark Side of the Moon??? Come on now. You know that is not correct! You completely blew a potential teaching moment, to educate the public that the **FAR** side of the Moon is **NOT** dark! Instead you perpetuated yet another scientific misconception. No wonder we are facing a crisis in science literacy in the U.S. The New York Times can and should do better!" Except I really meant, "dark side" -the side of the Moon facing away from the Sun. What was confusing to many was a remembered tidbit about the Moon, that there is always one face towards Earth, and the other always out of view, and they presumed that the crashes will be on the far side and therefore blocked from view. If that were the case, "far side" would be correct.

      A smaller number of readers wondered why the spacecraft will crash when the maneuvering fuel runs out. The Moon has no atmosphere and therefore there is no friction to slow them down. But the Moon's gravity is uneven and the orbit is not perfectly circular. Without periodic course adjustments, it will become more chaotic and elliptical, and the ellipse will intersect with the surface of the Moon -i.e., crash."

    • by Anonymous Coward

      Even the summary says "would be crashing into a 'non-sunlit' part of the surface" (not "side") followed immediately by "When the site becomes sunlit again in several weeks...".

      Damn illiterates.

  • Dark != Far (Score:5, Informative)

    by tverbeek (457094) on Tuesday December 18, 2012 @10:40AM (#42325251) Homepage

    "redirected their flight patterns to [impact] the far (dark) side of the moon."

    Wrong. As TFA takes pains to explain, the "dark side of the Moon" and the "far side of the Moon" are not the same thing.
    An the impacts were on the near side of the Moon, while it is dark.

    • by Speare (84249)

      Was just going to comment on this.

      The moon has days and nights, just like the Earth. Also, the rotation of the moon just about exactly matches the revolution around the Earth, so we constantly see the same "side" of the moon's surface.

      I think the inaccurate term "dark side of the moon" to refer to the side we don't see originally came from the idea of radio darkness (no contact possible directly from Earth), but it's a persistent phrase even after people know the difference.

      • Re: (Score:3, Interesting)

        by stridebird (594984)

        ...the rotation of the moon just about exactly matches the revolution around the Earth

        I think we can say exactly, as it's not a coincidence that the rotations align like that, it's a stable configuration of two bodies in orbit

        http://en.wikipedia.org/wiki/Tidal_locking [wikipedia.org]

        • Re:Dark != Far (Score:4, Insightful)

          by Soft (266615) on Tuesday December 18, 2012 @11:32AM (#42325773)

          ...the rotation of the moon just about exactly matches the revolution around the Earth

          I think we can say exactly, as it's not a coincidence that the rotations align like that, it's a stable configuration of two bodies in orbit

          Yes but there's still libration [wikipedia.org]. Although the Moon's rotation and revolution periods are indeed exactly the same, its orbital speed changes slightly over each orbit. So "just about exactly" is justified too.

    • ... the impacts were on the near side of the Moon ...

      The summary is wrong then. Copy-pasta of the summary at time of posting:

      The twin spacecraft were running low on maneuvering fuel and NASA, not wanting the crafts to fall on historical sites such as the Apollo landing sites, redirected their flight patterns to impart the far (dark) side of the moon.

      Apparenlty, the near side is the darker side because of the lunar maria [wikipedia.org], which

      are less reflective than the "highlands" as a result of their iron-rich composi

  • by Anonymous Coward

    Create enormous collisions.

    Watch the video.

  • by gmuslera (3436) on Tuesday December 18, 2012 @10:46AM (#42325335) Homepage Journal
    No matter how it ends, Earth shoot first.
    • by Domint (1111399)

      No matter how it ends, Earth shoot first.

      Nah, in 20 years when we re-release the footage we'll just use a little cgi magic to clearly show the moon shot first and missed, hitting the cantina wall behind us.

  • Maybe someone can point out which elements/chemicals they are going to seek or can detect?

    Curious people want to know if Helium-3, water or even amino acid detection is in that mix.

    What can they potentially see? What have the sensor ground tests revealed?

  • by Andy Prough (2730467) on Tuesday December 18, 2012 @10:52AM (#42325397)
    "Oh, bye the way, which one's Pink?"
    • This [wikipedia.org] one.
      • This [wikipedia.org] one.

        From your Wiki link:

        The Pink in Pink Floyd Syd Barrett, of English progressive rock band Pink Floyd, came up with the band's name by juxtaposing the first names of Anderson and North Carolina bluesman, Floyd Council. [3] Barrett noticed the names in the liner notes of a 1962 Blind Boy Fuller album (Philips BBL-7512). The text, written by Paul Oliver, read: "Curley Weaver and Fred McMullen, (...) Pink Anderson or Floyd Council -these were a few amongst the many blues singers that were to be heard in the r

    • He's the drummer.

  • It is just me... (Score:5, Interesting)

    by Covalent (1001277) on Tuesday December 18, 2012 @10:53AM (#42325403)
    ...or doesn't it seem a bit odd to name the crash site after Sally Ride? I mean, name the Mountain after her...OK. But a crash site named after a (now dead) astronaut seems a little wrong.
    • by operagost (62405)
      Naming it after Christa McAuliffe seemed a bit inappropriate.
      • Naming it after Christa McAuliffe seemed a bit inappropriate.

        Ooo-ooh! That was 'dark' side of the moon humour.

    • It's been proposed to name the entire (currently unnamed) mountain after her, but IAU rules require a person to be dead for at least three years before you can name an astronomical feature after someone. Ms Ride has priority, but must wait.

    • If you're plunging your probe into a moon, where the sun don't shine, you could always name the impact crater after my brother-in-law. That would be a bit more appropriate.

    • by mcgrew (92797) *

      Thy crashed the probes into the site previously named after her.

  • Was not prepared for that headline this morning.

    Who subscribed me to Slashdot After Dark?

  • How likely would the probes be to crash into one of the historic sites? The surface area of the moon is, whatm almost four times that of the entire US? Oh, my, the probe fell exactly on the Quick-e-mart in SomeVille, Arizona!

  • While the Moon is tidally locked to the Earth so we can't directly observe much of the far side, the Moon has no permanently "dark side" that receives no sunlight. The more obvious difference between the two hemispheres is that the far side, probably because it's more exposed to incoming space debris, is more cratered than the near side.

    While crashing the space probes on the far side is much like throwing tear gas in a gas chamber, I wonder whether the far side is actually the more valuable side from a scie

    • I've read that Nasa decided to crash them on 'the far side' so as not to risk contamination of the 'historic sites' from previous missions.
  • Insert Apple maps joke here ___________
  • I wonder why they decided to crash both, on the very same day, on the same location.
    It does not make much sense unless they already docked in orbit or are running some experiment that needs this to happen.

    • I wonder why they decided to crash both, on the very same day, on the same location.

      Convenience. If you have to crash two probes, may as well do it in one go.

    • I wonder why they decided to crash both, on the very same day, on the same location.
      It does not make much sense unless they already docked in orbit or are running some experiment that needs this to happen.

      The two probes were orbiting in tandem, Flow (GRAIL B) always followed 20 swconds behind Ebb (GRAIL A). From what I understand this was actually implemented in software, i.e. the humans tell Ebb where to go and Flow follows.

    • They were running some experiment that needs this to happen. Two-probe gravametric mapping only works if your two probes precisely share a common orbit at close (in space terms) distance.

  • That's no moon. It's a space station.
  • Even if it said "each impacting 30 seconds apart from THE other"
    it would be twisted.

    Since they were TWIN probes, if the one impacted 30 seconds from
    the other, the other must have impacted 30 seconds from the one.

    • by gsslay (807818)

      You forgot to account for the wacky time dilation you get everywhere in space. The time each impacted relative to the other is entirely subjective to each.

      Or the submitter screwed up the English language, and slashdot doesn't do copy-editing. Whatever.

  • For a moment there I forgot that the "dark" side of the moon is actually only dark at the full moon...
  • Why didn't they name the two impact sites after Columbia and Challenger?
  • Does anyone find a little sick irony in naming a crash site after an astronaut who perished in a crash?

    • by Anonymous Coward

      Sally Ride died of cancer.

    • Considering she served on the accident investigation board of the Columbia accident (2003), and then died this year (2012) of pancreatic cancer, I say that there is no sick irony in naming this crash site after Sally Ride. Is there some other crash site named after an astronaut that perished in a crash?
  • C'mon with the IronSky jokes already,
      what an awful film that was

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