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

Posted by timothy on 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.'"

42 comments

  1. Why so long to the moon? by ctmurray · · Score: 2

    I am sure there is a good reason, I just cant find it. Seems like a long time to get to the moon.

    1. Re:Why so long to the moon? by srepetsk · · Score: 5, Informative

      Unlike the Apollo program missions, which took three days to reach the Moon, GRAIL will make use of a three- to four-month low-energy trans-lunar cruise via the Sun-Earth Lagrange point L1 to reduce fuel requirements, protect instruments and reduce the velocity of the two spacecraft at lunar arrival to help achieve the extremely low 50 km (31 mi) orbits with separation between the spacecraft (arriving 24 hours apart) of 175 to 225 km (109 to 140 mi). http://en.wikipedia.org/wiki/Gravity_Recovery_and_Interior_Laboratory

    2. Re:Why so long to the moon? by ctmurray · · Score: 1

      Thanks. I eventually found this in the press kit on the NASA site.

    3. Re:Why so long to the moon? by BasherFiveTwo · · Score: 0

      Proof the Apollo moon landings were fake!

  2. youtube of launch by Anonymous Coward · · Score: 1

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

    1. Re:youtube of launch by gr8dude · · Score: 2

      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.

      --
      The saddest poem
    2. Re:youtube of launch by arisvega · · Score: 1

      .. 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.

      --
      The three laws of thermodynamics:(1) You can't win. (2) You can't break even. (3) You can't even quit.
    3. Re:youtube of launch by flablader · · Score: 1

      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 for more info.

  3. These are analogous to successful GRACE pair by Thagg · · Score: 5, Informative

    The article unfortunately doesn't say this, but these satellites are very similar to the GRACE 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!

    --
    I love Mondays. On a Monday, anything is possible.
    1. Re:These are analogous to successful GRACE pair by EQ · · Score: 1

      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?

      --
      Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo! http://goo.gl/J9bkO
    2. Re:These are analogous to successful GRACE pair by Hartree · · Score: 2

      "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.

    3. Re:These are analogous to successful GRACE pair by Anonymous Coward · · Score: 0

      I don't think the tides are as much concern as the mass concentrations. There are stable low periselenium fairly eccentric (1:10?) orbits, but I don't know if GRACE will be on one of them, or if it'll simply fly "high enough" (30+ miles).

  4. what time Zone is the moon in? by Joe_Dragon · · Score: 1

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

    1. Re:what time Zone is the moon in? by Nyeerrmm · · Score: 5, Informative

      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.

  5. Re:Just what they want you to believe by Anonymous Coward · · Score: 0

    Wrong; actually they're going to plant the evidence they supposedly left behind on Apollo 11. :P

  6. They're just grail-shaped. by Anonymous Coward · · Score: 0

    Sir, are we ready to launch the g-, the g- g-g-- ...the what?

    The gr-, the g-g-g-

    THE GRAILS?!?!

    Uh, yes.

    YES!!!

    1. Re:They're just grail-shaped. by arisvega · · Score: 1

      Ready now? Okay.

      One,

      .. two ..

      Five!

      --
      The three laws of thermodynamics:(1) You can't win. (2) You can't break even. (3) You can't even quit.
  7. Re:Just what they want you to believe by lennier1 · · Score: 1

    There never were any moon landings.

    Proof: Not a single Apollo mission brought back any cheese!

  8. lies by Anonymous Coward · · Score: 0

    you take that back!

  9. GRAIL mission name called into question by Anonymous Coward · · Score: 2, Funny

    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?

    1. Re:GRAIL mission name called into question by obsess5 · · Score: 1

      Good one! :)

  10. Historic by Nerdfest · · Score: 2

    I'm very much looking forward to this mission. Isn't this how we discover the monolith?

    1. Re:Historic by DerekLyons · · Score: 1

      Nope. There was a reason why the monolith was initially called the Tycho MAGNETIC Anomaly.

  11. Is There A Reason... by Anonymous Coward · · Score: 0

    Why it'll take them months to get to the moon, when it only took a few days for the Apollos to get to the moon..?!

    1. Re:Is There A Reason... by Anonymous Coward · · Score: 0

      Saving Fuel

    2. Re:Is There A Reason... by fnj · · Score: 2

      Because it costs 4 bucks a gallon now, you know.

    3. Re:Is There A Reason... by Anonymous Coward · · Score: 0

      I wouldn't know, because I don't drive, and we don't use the outdated 'gallon' in Canada!

  12. I can see it now by Anonymous Coward · · Score: 0

    The holly grail to the mooon.

    in 3D at the theater near you...

  13. Re:Just what they want you to believe by Concerned+Onlooker · · Score: 1

    Who is the clueless person who modded your tongue-in-cheek post as flamebait? Sheesh.

    --
    http://www.rootstrikers.org/
  14. a couple of thoughts by WindBourne · · Score: 1

    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 to. If we can put down on the moon, then we can put down on mars. Simple as that.

    --
    I prefer the "u" in honour as it seems to be missing these days.
    1. Re:a couple of thoughts by Mindcontrolled · · Score: 2

      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.

      --
      Ubi solitudinem faciunt, pacem appellant.
    2. Re:a couple of thoughts by Anonymous Coward · · Score: 0

      Deflecting Solar Wind and CBR will not make the gravity high enough to retain an atmosphere.

    3. Re:a couple of thoughts by Nyeerrmm · · Score: 1

      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, in addition to the spacecraft-to-spacecraft range, and thats harder to do since its further away. Maintaining data to Earth on a higher-gain antenna while maintaining orbiter point would be difficult, since the pointing constraints are not guaranteed to get along. Plus trying to get them into synchronized orbits is hard enough around the Moon, so Mars sounds potentially nightmarish -- of course, for that you might just have to put them on a common bus and separate them after Mars entry. Additionally, you'd need a bigger motor than GRAIL/GRACE have, in order to achieve Mars orbit.

      Given the new development required -- new antennae, figuring out the pointing, a common bus with its own attitude control system and thrusters, and a larger launch vehicle, my WAG for the cost is probably around $800M (compared to ~$495M for GRAIL). Definitely doable under a New Frontiers program. Plus, my experience is with GRAIL and Mars orbiters, so I'd be employed for quite a while and thus like the idea.

    4. Re:a couple of thoughts by flablader · · Score: 1

      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 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.

    5. Re:a couple of thoughts by Anonymous Coward · · Score: 0

      Yeah, good thing that we did not start planning going to space until 1960. I mean nobody ever fired a rocket before then. Right?

    6. Re:a couple of thoughts by WindBourne · · Score: 1

      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 are basing the bulk of our exploration on what we see on the surface. However, by looking below the surface, we might find some interesting issues that make it worthwhile exploring deeper.

      I will say that my experience was with MGS, so not really up on lunar sats.

      --
      I prefer the "u" in honour as it seems to be missing these days.
  15. Backronym alert! by Asgerix · · Score: 1

    The full name is of course: High Orbit Lunar trajectorY Gravity Recovery and Interior Laboratory, making it the HOLY GRAIL.

    --
    Life is wet, then you dry.
  16. Mission Update by sjames · · Score: 1

    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.