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GRAIL Mission Video Released

Posted by Soulskill on from the stately-grace dept.

SchrodingerZ writes "A new video was released yesterday by NASA from the GRAIL mission probes, which ended their mission last month as they impacted the lunar surface. 'Dramatic' footage was captured by the probe Ebb on December 14th. The video was taken from the 'MoonKAM (Moon Knowledge Acquired by Middle school Students) cameras. It shows the view of Ebb flying at an altitude of 6 miles (10 km) above the Moon's northern hemisphere in the vicinity of Jackson crater (22.4N 163.1W).' Two videos were released, one from the fore and one from the aft of the probe, showing a forwards and backwards time lapse containing 931 and 1,489 pictures each of the lunar terrain. The footage was part of the probes' final systems check before they shut down and were sent into a controlled impact to a predetermined location."

6 of 36 comments (clear)

  1. Recorded with... by okor · · Score: 2

    ..an iPhone? What's with the weird aspect ratio? Also, this is amazing.

  2. Ask Slashdot question in the making... by jeffmeden · · Score: 4, Interesting

    Hey armchair astrophysicists... A thought occurred to me when watching this video. Since the moon has a negligible atmosphere, how close can a spacecraft reliably orbit it? Other than the ability to make sure eccentricity is near 0, what would stop a satellite from orbiting a few hundred meters above the tallest peak?

    1. Re:Ask Slashdot question in the making... by tjp · · Score: 4, Informative
      The whole purpose of this mission was to measure the variations in the moon's gravity by flying at a very low altitude. Consequently, those gravitational variations introduced changes in the orbit requiring relatively frequent corrections. It follows that the closer you orbit, the more actively you'll have to work to maintain that orbit. When you fly low over a mountain, the extra mass in that area will pull you down, and you'll have to correct for that with upward thrust.

      The moon's uneven gravity field presents a challenge to ground controllers planning trajectories for low-altitude lunar orbiters. The tug of lunar gravity can alter a satellite's orbit, requiring frequent rocket burns to adjust the spacecraft's path around the moon.

      Spaceflight Now, March 21, 2012

    2. Re:Ask Slashdot question in the making... by DerekLyons · · Score: 3, Insightful

      You can't reliably orbit the moon at low altitude without a large supply of fuel to keep reboosting your orbiter. Because of mascons, the moon's gravitational field is very "lumpy" (has regions of higher and lower gravity) and thus such orbits are unstable.

    3. Re:Ask Slashdot question in the making... by White+Yeti · · Score: 3, Interesting

      I've even heard it more-broadly stated that there are NO long-term stable lunar orbits. It's an issue for orbital debris: since (1) objects don't burn up on entry, and (2) an uncontrolled orbit is impossible to predict in the long term, therefor all lunar orbiters should be removed rather than abandoned and lunar deorbits should be targeted rather than random.

  3. I want to see it "kiss" the surface, darnit! by Tablizer · · Score: 2

    "Where's the Kaboom!? There's supposed to be a moon-shattering Kaboom!" -MM

    --
    Table-ized A.I.