GRAIL

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GRAIL-transit-Earth-Moon GRAIL-transit-Earth-Moon.png
GRAIL-transit-Earth-Moon
Animation of GRAIL-A's trajectory around Moon from 31 December 2011 to 30 April 2012 GRAIL-A * Moon Animation of GRAIL-A trajectory around Moon.gif
Animation of GRAIL-A's trajectory around Moon from 31 December 2011 to 30 April 2012
   GRAIL-A ·   Moon

Unlike the Apollo program missions, which took three days to reach the Moon, GRAIL made use of a three- to four-month low-energy trans-lunar cruise well outside the Moon's orbit and passing near the Sun-Earth Lagrange point L1 before looping back to rendezvous with the Moon. This extended and circuitous trajectory enabled the mission 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 25 hours apart) of 175 to 225 km (109 to 140 mi). [22] [30] The very tight tolerances in the flight plan left little room for error correction leading to a launch window lasting one second and providing only two launch opportunities per day. [29]

Science phase

The primary science phase of GRAIL lasted for 88 days, from 7 March 2012 to 29 May 2012. It was followed by a second science phase that ran from 8 Aug 2012 into early Dec 2012.

The gravity mapping technique was similar to that used by Gravity Recovery and Climate Experiment (GRACE), and the spacecraft design was based on XSS-11. [31]

The orbital insertion dates were December 31, 2011 (for GRAIL-A) and January 1, 2012 (for GRAIL-B). [28] The initial lunar orbits were highly elliptical near-polar, and were later lowered to near-circular at about 25-86 km altitude with a period of about 114 minutes. [32]

The spacecraft were operated over the 88-day acquisition phase, divided into three 27.3 day long nadir-pointed mapping cycles. Twice each day there was an 8-hour pass in view of the Deep Space Network for transmission of science and "E/PO MoonKam" data. [33]

The first student-requested MoonKam images were taken by Ebb from 2012 March 15-17 and downlinked to Earth March 20. More than 2,700 schools spanning 52 countries were using the MoonKAM cameras. [34]

Flow's MoonKam camera captured LRO as it flew by at a distance of about 12 miles (20 km) on May 3. It's the first footage of a moon-orbiting robotic spacecraft taken by another one. [35]

Terminal phase

Ebb and Flow's Final Moments.jpg
Ebb and Flow's final moments.
GRAIL's Final Resting Spot.jpg
GRAIL's final resting spot.
This animation shows the last three orbits of the spacecraft, with views of the impact site. The impact occurs on the night side of a waxing crescent Moon, so the view shifts from a natural color Moon to a false-color elevation map.
LRO flies over the north pole of the Moon, where it has a very good view of the GRAIL impact. The second part of this video is the view from LRO through LAMP's slit, showing the impact and the resulting plume.

Final experiment and mission end

At the end of the science phase and a mission extension, the spacecraft were powered down and decommissioned over a five-day period. The spacecraft impacted the lunar surface on December 17, 2012. [33] [36] [37] [38] [39] [40] Both spacecraft impacted an unnamed lunar mountain between Philolaus and Mouchez at 75°37′N26°38′W / 75.62°N 26.63°W / 75.62; -26.63 . Ebb, the lead spacecraft in formation, impacted first. Flow impacted moments later. Each spacecraft was traveling at 3,760 miles per hour (1.68 km/s). A final experiment was conducted during the final days of the mission. Main engines aboard the spacecraft were fired, depleting remaining fuel. Data from that effort will be used by mission planners to validate fuel consumption computer models to improve predictions of fuel needs for future missions. [41] NASA has announced that the crash site will be named after GRAIL collaborator and first American woman in space, Sally Ride. [42]

Moon – Oceanus Procellarum ("Ocean of Storms")
14-236-LunarGrailMission-OceanusProcellarum-Rifts-Overall-20141001.jpg
Ancient rift valleys – rectangular structure (visible – topography – GRAIL gravity gradients) (October 1, 2014).
PIA18822-LunarGrailMission-OceanusProcellarum-Rifts-Overall-20141001.jpg
Ancient rift valleys – context.
PIA18821-LunarGrailMission-OceanusProcellarum-Rifts-Closeup-20141001.jpg
Ancient rift valleys – closeup (artist's concept).

Results

Gravity passes through matter. In addition to surface mass, a high-resolution gravity field gives a blurred, but useful, look below the surface. Analyses of the GRAIL data have produced a series of scientific results for the Moon.

See also

Related Research Articles

<span class="mw-page-title-main">Mare Orientale</span> Lunar mare on the western border of the near side and far side of the Moon

Mare Orientale is a lunar mare. It is located on the western border of the near side and far side of the Moon, and is difficult to see from an Earthbound perspective. Images from spacecraft have revealed it to be one of the most striking large scale lunar features, resembling a target ring bullseye.

<span class="mw-page-title-main">Mare Moscoviense</span> Feature on the moon

Mare Moscoviense is a lunar mare that sits in the Moscoviense basin. It is one of the very few maria on the far side of the Moon. Like Mare Marginis, this mare appears to be fairly thin. However, it is clearly centered within a large impact basin. It is also much lower than either the outer basin floor or the farside highlands.

<span class="mw-page-title-main">Libration</span> Apparent oscillation of a minor body seen from the major body it orbits

In lunar astronomy, libration is the cyclic variation in the apparent position of the Moon perceived by Earth-bound observers and caused by changes between the orbital and rotational planes of the moon. It causes an observer to see slightly different hemispheres of the surface at different times. It is similar in both cause and effect to the changes in the Moon's apparent size due to changes in distance. It is caused by three mechanisms detailed below, two of which cause a relatively tiny physical libration via tidal forces exerted by the Earth. Such true librations are known as well for other moons with locked rotation.

<span class="mw-page-title-main">Discovery Program</span> Ongoing solar system exploration program by NASA

The Discovery Program is a series of Solar System exploration missions funded by the U.S. National Aeronautics and Space Administration (NASA) through its Planetary Missions Program Office. The cost of each mission is capped at a lower level than missions from NASA's New Frontiers or Flagship Programs. As a result, Discovery missions tend to be more focused on a specific scientific goal rather than serving a general purpose.

<span class="mw-page-title-main">Mass concentration (astronomy)</span> Region of a planet or moons crust that contains a large positive gravitational anomaly

In astronomy, astrophysics and geophysics, a mass concentration is a region of a planet's or moon's crust that contains a large positive gravity anomaly. In general, the word "mascon" can be used as a noun to refer to an excess distribution of mass on or beneath the surface of an astronomical body, such as is found around Hawaii on Earth. However, this term is most often used to describe a geologic structure that has a positive gravitational anomaly associated with a feature that might otherwise have been expected to have a negative anomaly, such as the "mascon basins" on the Moon.

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<span class="mw-page-title-main">Hertzsprung (crater)</span> Crater on the Moon

Hertzsprung is an enormous lunar impact crater, or impact basin, that is located on the far side of the Moon, beyond the western limb. In dimension, this formation is larger than several of the lunar mare areas on the near side. It lies in the northwestern fringe of the blast radius of the Mare Orientale impact basin. Nearby craters of note include Michelson across the northeast rim, Vavilov across the western rim, and Lucretius to the southeast.

<span class="mw-page-title-main">Near side of the Moon</span> Hemisphere of the Moon facing the Earth

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<span class="mw-page-title-main">Lunar orbit</span> Orbit of an object around the Moon

In astronomy, lunar orbit is the orbit of an object around the Moon.

<span class="mw-page-title-main">Maria Zuber</span> American astronomer (born 1958)

Maria T. Zuber is an American geophysicist who is the vice president for research at the Massachusetts Institute of Technology, where she also holds the position of the E. A. Griswold Professor of Geophysics in the Department of Earth, Atmospheric and Planetary Sciences. Zuber has been involved in more than half a dozen NASA planetary missions aimed at mapping the Moon, Mars, Mercury, and several asteroids. She was the principal investigator for the Gravity Recovery and Interior Laboratory (GRAIL) Mission, which was managed by NASA's Jet Propulsion Laboratory.

<span class="mw-page-title-main">Gravitation of the Moon</span>

The acceleration due to gravity on the surface of the Moon is approximately 1.625 m/s2, about 16.6% that on Earth's surface or 0.166 ɡ. Over the entire surface, the variation in gravitational acceleration is about 0.0253 m/s2. Because weight is directly dependent upon gravitational acceleration, things on the Moon will weigh only 16.6% of what they weigh on the Earth.

<span class="mw-page-title-main">Permanently shadowed crater</span> Permanently shadowed region of a body in the Solar System

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<span class="mw-page-title-main">GRAIL MoonKAM</span>

GRAIL MoonKAM (Moon Knowledge Acquired by Middle school students) was part of NASA’s GRAIL satellite mission to map the Moon’s gravity.

<span class="mw-page-title-main">Freundlich-Sharonov Basin</span> Crater on the Moon

The Freundlich-Sharonov Basin is a Pre-Nectarian impact basin on the far side of the Moon. It is named after the younger craters Freundlich near the northwest margin and Sharonov near the southwest margin. It lies east of Mare Moscoviense basin and northwest of Korolev basin.

<span class="mw-page-title-main">Schiller-Zucchius Basin</span> Feature on the moon

The Schiller-Zucchius Basin is a Pre-Nectarian impact basin on the near side of the Moon. It is named after the elongated crater Schiller at the northeast margin and fresh crater Zucchius near the southwest margin. This basin has received the unofficial designation 'Schiller Annular Plain' among lunar observers.

<span class="mw-page-title-main">Mendel-Rydberg Basin</span> Large lunar surface depression

The Mendel-Ryberg Basin is a Nectarian impact basin on the southwestern limb of the moon. It is named after the crater Mendel on the west margin and the smaller crater Rydberg north of the center of the basin. The basin is due south of the larger, younger Orientale basin, and ejecta and other geomorphological effects from the younger basin have overprinted the older one.

<span class="mw-page-title-main">Coulomb-Sarton Basin</span> Feature on the moon

The Coulomb-Sarton Basin is a Pre-Nectarian impact basin on the far side of the Moon. It is named after the crater Coulomb northeast of the center of the basin and the smaller crater Sarton just south of the center. The basin is not obvious on the lunar surface. There are only small fragments of inner rings and a rim, and the most indicative topographic feature is a smooth, low plain at the center.

<span class="mw-page-title-main">Dirichlet–Jackson Basin</span> Feature on the moon

The Dirichlet–Jackson Basin is a pre-Nectarian impact basin on the far side of the Moon. It is named after the craters Dirichlet and Jackson. It lies to the north of the similar-sized basin Korolev.

<span class="mw-page-title-main">Gravity of Mars</span> Gravitational force exerted by the planet Mars

The gravity of Mars is a natural phenomenon, due to the law of gravity, or gravitation, by which all things with mass around the planet Mars are brought towards it. It is weaker than Earth's gravity due to the planet's smaller mass. The average gravitational acceleration on Mars is 3.72076 ms−2 and it varies.

References

  1. 1 2 "Delta II Set to Launch NASA's GRAIL Mission". United Launch Alliance. 2011. Archived from the original on 1 September 2011. Retrieved 2 September 2011.
  2. ↑ "The GRAIL Mission: A Fact Sheet". Sally Ride Science. 2010. Archived from the original on 2010-04-28. Retrieved 2010-04-15.
  3. ↑ "GRAIL" (PDF). NASA. Retrieved November 30, 2022.
  4. 1 2 3 "About GRAIL". Massachusetts Institute of Technology. Retrieved 2011-03-12.
  5. ↑ Schontzler, Gail (18 January 2012). "Bozeman class wins contest to name satellites orbiting moon". Bozeman Daily Chronicle. Retrieved 2018-12-18.
  6. 1 2 3 Agle, DC. "Montana Students Submit Winning Names for NASA Lunar Spacecraft". NASA JPL.
  7. ↑ Delta II: The Industry Workhorse (PDF) (Report). United Launch Alliance. 2010. Archived from the original (PDF) on 30 September 2011. Retrieved 2 August 2011.
  8. ↑ Grey Hautaluoma (10 December 2007). "New NASA Mission to Reveal Moon's Internal Structure and Evolution". NASA. Retrieved 31 August 2011.
  9. ↑ Moon-bound twin GRAIL spacecraft launch success
  10. ↑ Spaceflight101 Archived 2015-02-11 at the Wayback Machine
  11. ↑ "First of NASA's GRAIL Spacecraft Enters Moon Orbit". NASA . Retrieved 1 January 2012.
  12. ↑ GRAIL Twins crash into the Moon to complete highly successful Mission Archived 2015-02-11 at the Wayback Machine
  13. ↑ "Press Kit. Gravity Recovery and Interior Laboratory (GRAIL) Launch" (PDF). NASA. August 2011. p. 7. Retrieved 4 December 2022.
  14. ↑ GRAVITY RECOVERY AND INTERIOR LABORATORY (GRAIL) MISSION: STATUS AT THE INITIATION OF THE SCIENCE MAPPING PHASE, 43rd Lunar and Planetary Science Conference (2012)
  15. ↑ Washington Post December 17, 2012
  16. 1 2 Konopliv, Alex S.; Park, Ryan S.; Yuan, Dah-Ning; Asmar, Sami W.; Watkins, Michael M.; Williams, James G.; Fahnestock, Eugene; Kruizinga, Gerhard; Paik, Meegyeong; Strekalov, Dmitry; Harvey, Nate (2013). "The JPL lunar gravity field to spherical harmonic degree 660 from the GRAIL Primary Mission: GRAIL LUNAR GRAVITY". Journal of Geophysical Research: Planets. 118 (7): 1415–1434. Bibcode:2013JGRE..118.1415K. doi:10.1002/jgre.20097. hdl: 1721.1/85858 . S2CID   16559256.
  17. 1 2 Lemoine, Frank G.; Goossens, Sander; Sabaka, Terence J.; Nicholas, Joseph B.; Mazarico, Erwan; Rowlands, David D.; Loomis, Bryant D.; Chinn, Douglas S.; Caprette, Douglas S.; Neumann, Gregory A.; Smith, David E. (2013). "High‒degree gravity models from GRAIL primary mission data". Journal of Geophysical Research: Planets. 118 (8): 1676–1698. Bibcode:2013JGRE..118.1676L. doi: 10.1002/jgre.20118 . hdl: 2060/20140010292 . ISSN   2169-9097.
  18. 1 2 Konopliv, Alex S.; Park, Ryan S.; Yuan, Dah-Ning; Asmar, Sami W.; Watkins, Michael M.; Williams, James G.; Fahnestock, Eugene; Kruizinga, Gerhard; Paik, Meegyeong; et al. (2014). "High-resolution lunar gravity fields from the GRAIL Primary and Extended Missions". Geophysical Research Letters. 41 (5): 1452–1458. Bibcode:2014GeoRL..41.1452K. doi: 10.1002/2013GL059066 .
  19. 1 2 Lemoine, Frank G.; Goossens, Sander; Sabaka, Terence J.; Nicholas, Joseph B.; Mazarico, Erwan; Rowlands, David D.; Loomis, Bryant D.; Chinn, Douglas S.; Neumann, Gregory A.; Smith, David E.; Zuber, Maria T. (28 May 2014). "GRGM900C: A degree 900 lunar gravity model from GRAIL primary and extended mission data". Geophysical Research Letters. 41 (10): 3382–3389. Bibcode:2014GeoRL..41.3382L. doi:10.1002/2014GL060027. PMC   4459205 . PMID   26074638.
  20. ↑ Gravity Recovery and Interior Laboratory: News & Features: NASA's GRAIL Moon Twins Begin Extended Mission Science Archived 2013-04-09 at the Wayback Machine . Solarsystem.nasa.gov. Retrieved on 2013-07-21.
  21. ↑ Gravity Recovery and Interior Laboratory: News & Features: NASA's GRAIL Creates Most Accurate Moon Gravity Map Archived 2013-05-11 at the Wayback Machine . Solarsystem.nasa.gov. Retrieved on 2013-07-21.
  22. 1 2 "GRAIL: Mission Overview". MIT . Retrieved 10 September 2011.
  23. 1 2 "Spacecraft and Payload". Massachusetts Institute of Technology.
  24. ↑ "GRAIL: Mission Operations & Data Processing". MIT. Archived from the original on 2012-03-05. Retrieved 2012-12-14.
  25. ↑ "About GRAIL MoonKAM". Sally Ride Science. 2010. Archived from the original on 2010-04-27. Retrieved 2010-04-15.
  26. ↑ "GRAIL Launch Press Kit" (PDF). NASA. Retrieved 31 August 2011.
  27. ↑ "Satellite Missions Catalogue - GRAIL". eoPortal.org. Retrieved December 3, 2022.
  28. 1 2 3 4 5 6 Harwood, William. "NASA launches GRAIL lunar probes". CBS News. Retrieved 11 September 2011.
  29. 1 2 Justin Ray (17 August 2011). "GRAIL Launch Window Chart". SpaceFlight Now. Retrieved 9 September 2011.
  30. ↑ "Mission Design". NASA. Archived from the original on 3 October 2011. Retrieved 10 September 2011.
  31. ↑ Taylor Dinerman (31 December 2007). "Is XSS-11 the answer to America's quest for Operationally Responsive Space?". The Space Review. Retrieved 31 August 2011.
  32. ↑ Grail mission news. March 2012
  33. 1 2 "GRAIL: Mission Design". MIT.
  34. ↑ "NASA GRAIL Returns First Student-Selected Moon Images". Jet Propulsion Laboratory .
  35. ↑ "Spacecraft Pass Each Other at the Moon".
  36. ↑ "NASA GRAIL Twins Complete Their Moon Impact". NASA. 17 December 2012. Retrieved 2012-12-17.
  37. ↑ Wall, Mike (13 December 2012). "Twin GRAIL probes readied for crash into Moon". NBC News. Retrieved 18 February 2013.
  38. ↑ Wall, Mike (11 December 2012). "Twin NASA Probes to Crash into Moon Next Week". Space.com. Retrieved 18 February 2013.
  39. ↑ "Twin NASA spacecraft prepare to crash into moon". Phys.org. 13 December 2012. Retrieved 13 December 2012.
  40. ↑ Knapp, Alex (14 December 2012). "NASA Prepares To Crash Its Probes Into The Moon". Forbes. Retrieved 2012-12-13.
  41. ↑ "NASA Probes Prepare for Mission-Ending Moon Impact". NASA, Jet Propulsion Laboratory. Retrieved 18 February 2013.
  42. ↑ Mike Wall (17 December 2012). "Moon Probes' Crash Site Named After Sally Ride". Space.com. Retrieved 18 February 2013.
  43. ↑ Zuber, M. T.; Smith, D. E.; Watkins, M. M.; Asmar, S. W.; Konopliv, A. S.; Lemoine, F. G.; Melosh, H. J.; Neumann, G. A.; Phillips, R. J.; et al. (2013). "Gravity Field of the Moon from the Gravity Recovery and Interior Laboratory (GRAIL) Mission". Science. 339 (6120): 668–671. Bibcode:2013Sci...339..668Z. doi:10.1126/science.1231507. ISSN   0036-8075. PMID   23223395. S2CID   206545934.
  44. ↑ Wieczorek, M. A.; Neumann, G. A.; Nimmo, F.; Kiefer, W. S.; Taylor, G. J.; Melosh, H. J.; Phillips, R. J.; Solomon, S. C.; Andrews-Hanna, J. C.; et al. (2013). "The Crust of the Moon as Seen by GRAIL". Science. 339 (6120): 671–675. Bibcode:2013Sci...339..671W. doi:10.1126/science.1231530. ISSN   0036-8075. PMC   6693503 . PMID   23223394.
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Gravity Recovery and Interior Laboratory
GRAIL.jpg
Artist's interpretation of the GRAIL tandem spacecraft above the lunar surface.
Operator NASA  / JPL [1] [2]
COSPAR ID 2011-046 (A, B)
SATCAT no. 37801, 37802
Website moon.mit.edu
Mission duration1 year, 3 months, 7 days, 9 hours
Spacecraft properties
Manufacturer Massachusetts Institute of Technology, LMSS
Launch mass202.4 kg (each) [3]
Dry mass132.6 kg (292 lb)
Power(Solar array / Li-ion battery)
Start of mission
Launch dateSeptember 10, 2011, 13:08:52.775 (2011-09-10UTC13:08:52Z) UTC
Rocket Delta II 7920H-10 D-356
Launch site Cape Canaveral SLC-17B
Entered serviceDecember 31, 2011 (Ebb)
January 1, 2012 (Flow)
Orbital parameters
Reference system Selenocentric
Regime Polar orbit [4]
Semi-major axis 1,788.0 kilometres (1,111.0 mi)
Periselene altitude 25 kilometres (16 mi)
Aposelene altitude 86 kilometres (53 mi)
Period 113 minutes
Lunar impactor
Impact dateGRAIL A: December 17, 2012, 22:28:51 UTC
Impact site 75°36′30″N33°24′15″E / 75.6083°N 33.4043°E / 75.6083; 33.4043
New Horizons spacecraft model 1.png
Proposals
Finalists
Candidates
  • Underline indicates active current missions
  • Italics indicate missions yet to launch
  • Symbol † indicates failure en route or before intended mission data returned

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