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Moon NASA Space Science

NASA's Twin GRAIL Craft On Their Way To the Moon 42

Posted by timothy
from the they-could-have-saved-gemini-for-this dept.
sighted writes "The twin lunar Gravity Recovery and Interior Laboratory (GRAIL) spacecraft lifted off from Cape Canaveral this morning. GRAIL-A is scheduled to reach the moon on New Year's Eve 2011, while GRAIL-B will arrive New Year's Day 2012. The two solar-powered spacecraft will fly in tandem orbits around the moon to measure its gravity field. Lunar explorers hope the mission will answer longstanding questions about the moon 'from crust to core.'"
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NASA's Twin GRAIL Craft On Their Way To the Moon

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  • by ctmurray (1475885) on Saturday September 10, 2011 @03:49PM (#37363840) Journal
    I am sure there is a good reason, I just cant find it. Seems like a long time to get to the moon.
  • by Anonymous Coward

    http://www.youtube.com/watch?v=HwRhhvt4YyY

    • by gr8dude (832945)

      Hmm.. if you pay attention to the voice, you notice they still use "miles per hour" and "miles" - I thought they switched to the metric system.

      • by arisvega (1414195)

        .. they still use "miles per hour" and "miles" - I thought they switched to the metric system.

        All the engineering know-how for the US space program is already laid down in inches, inches squared, lbs and the like. Miscalculations are perhaps easier to spot if one uses the S.I. system of units (errors will "stand out" more), but switching to something different from a proven method involves time, money and caveats.

        After all, their actions speak for themselves; these people know how to tune space missions, and have been doing so for years.

        • You're seeing the PR side of the mission, of course they're going to use imperial units because that's what non-scientific folks expect. The GRAIL mission used SI units during development and does do for mission operations. See http://moon.mit.edu/design.html [mit.edu] for more info.
  • by Thagg (9904) <thadbeier@gmail.com> on Saturday September 10, 2011 @04:13PM (#37363974) Journal

    The article unfortunately doesn't say this, but these satellites are very similar to the GRACE [wikipedia.org] pair of satellites still orbiting the earth. There are a couple of things that make this different.

    1) One of the limitations GRACE has is that the satellites have to orbit pretty high, to stay out of the influence of the Earth's atmosphere. Their orbits are about 300 miles high, and that limits the resolution of the gravity map to dozens of miles at very best. GRAIL will not have that limitation, and I hope they can fly the satellites much lower. The tidal forces of the Earth at the Moon are probably about 100 times stronger than our tides from the Moon, that might limit how low they can fly -- but it should allow a much more precise measurement of the Moon's gravity map than we have of Earth.

    2) One of the fascinating things about GRACE, that has proven more exciting than would have thought possible, is that the Earth's gravity is a function of time. GRACE is able to detect when large areas of earth are saturated with water, or changes in ocean currents, from the change in gravity. The Moon probably doesn't change at all. If they do detect changes, though...that would be exciting!

    • by EQ (28372)

      2) One of the fascinating things about GRACE, that has proven more exciting than would have thought possible, is that the Earth's gravity is a function of time. GRACE is able to detect when large areas of earth are saturated with water, or changes in ocean currents, from the change in gravity. The Moon probably doesn't change at all. If they do detect changes, though...that would be exciting!

      I wonder what will happen if they find a strong magnetic anomaly near Tycho crater?

      • by Hartree (191324)

        "I wonder what will happen if they find a strong magnetic anomaly near Tycho crater?"

        Then Metro Goldwyn Mayer and the MPAA will file a copyright infrngement suit against the universe.

  • as saying eve and day makes it hard to find out.

    • by Nyeerrmm (940927) on Saturday September 10, 2011 @04:21PM (#37364010)

      Technically, everything is done UTC, and the insertion burn for GRAIL-A is around 22:00 UTC on 31-Dec-2011, and GRAIL-B is after that.

      Of course, the people operating it are stationed in Pacific and Mountain time zones (JPL/DSN and Lockheed Martin in Denver), and that places the maneuvers mid-afternoon on those days.

  • by Anonymous Coward

    The mission is for "measuring" gravitation, not "recovering" it. Has it occurred to anyone else that a more straightforward name would be the lunar "Gravity Measurement And Interior Laboratory?" Or does the corresponding acronym bother someone?

  • by Nerdfest (867930) on Saturday September 10, 2011 @05:43PM (#37364370)
    I'm very much looking forward to this mission. Isn't this how we discover the monolith?
  • We have now built these units once. How about building another set and sending them to mars? Surely we can repeat this for equal or less money. The core of mars is actually important to look at. If we do this, we could then find out what it will take to re-start the magnetsphere and grow the atmosphere.

    Also, a slightly different idea is that we are looking at sending a SpaceX dragon to mars. How about sending it to one of the lunar poles? The moon should be easier to land at (1/6 Gs), and shorter to go
    • In what manner would you even restart a magnetosphere? I think we are a couple of orders of magnitude out of the realm of our current possibilities here.
    • by Nyeerrmm (940927)

      I think scientific interest would be more along the lines of using it more like GRACE, tracking climatic changes associated with carbon and water ice moving around. Additionally, you couldn't get data from as close to the surface, since you've got to stay out of the atmosphere, just like you do on Earth, making it harder to get 'crust to core' data.

      The other problem is that flying these things in formation is *hard*, and around Mars it would be even harder. You depend on tracking data to and from Earth, i

      • Another expense might be making the GRAIL orbiters dual-string (duplicate almost everything on a single orbiter, two main computers, two batteries, etc). According to http://moon.mit.edu/spacecraft.html [mit.edu] GRAIL is single-string because that matches the mission reliability requirements.

        Also - I was on the GRAIL development team and I'm currently working GRAIL mission operations, so I'd also be employed for a little while longer if we repeated this experiment at Mars.

      • Actually, I think that if we use an FH to launch to there, then multiple sats can go. Instead, of building up GRAIL for handling all of the work to earth, instead, send up a revamped MTO (ideally, 1-2 backbone sats, combined with a small network of microsats for relaying). I will say that I was not aware that GRAIL did not have a duplicate bus. That is surprising to me.

        I will say that if Grail can be made to work around Mars, it would point to interesting places to explore around Mars. Right now, we ar
  • The full name is of course: High Orbit Lunar trajectorY Gravity Recovery and Interior Laboratory, making it the HOLY GRAIL.
  • Sadly, there has been a delay in the mission. The probes will not be able to continue on their journey to the moon until NASA launches a shrubbery.

You can do this in a number of ways. IBM chose to do all of them. Why do you find that funny? -- D. Taylor, Computer Science 350

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