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LCROSS

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Template:Infobox Spacecraft The Lunar CRater Observation and Sensing Satellite (LCROSS) was a robotic spacecraft operated by NASA, which was launched on June 18, 2009, together with the Lunar Reconnaissance Orbiter as part of the shared Lunar Precursor Robotic Program, the first American mission to the Moon in over ten years. Together, LCROSS and LRO form the vanguard of NASA's return to the Moon.[1]

LCROSS was designed to watch as the launch vehicle's spent Centaur upper stage, with a nominal impact mass of 2,305 kg (5,081 lb), strikes the Cabeus crater[2] near the south pole of the Moon. LCROSS suffered a malfunction on August 22, depleting half of its fuel and leaving very little fuel margin in the spacecraft.[3] Impact occurred at the lunar South Pole on October 9, 2009, at approximately 12:35 UTC.

Mission

The LCROSS trajectory
File:NASA’s Lunar Reconnaissance Orbiter and Lunar Crater Observation and Sensing Satellite leave the launch pad.jpg
The Atlas V rocket carrying LRO and LCROSS.

LCROSS was a fast-track, low-cost companion mission to the LRO. The LCROSS payload was added after NASA moved the LRO from the Delta II to a larger launch vehicle. It was chosen from 19 other proposals.[4]

LCROSS launched with the LRO aboard an Atlas V rocket from Cape Canaveral, Florida, on June 18, 2009, at 21:32 UTC (17:32 EDT). On June 23, four and a half days after launch, LCROSS and its attached Centaur booster rocket successfully completed a lunar swingby and entered into polar Earth orbit with a period of 37 days, positioning LCROSS for impact on a lunar pole.[5][6]

Early in the morning on August 22, 2009, LCROSS ground controllers discovered an anomaly caused by a sensor issue, which had resulted in the spacecraft burning through 140 kilograms (309 pounds) of fuel, more than half of the fuel remaining at the time. According to Dan Andrews, the LCROSS project manager, "Our estimates now are if we pretty much baseline the mission, meaning just accomplish the things that we have to (do) to get the job done with full mission success, we're still in the black on propellant, but not by a lot."[7]

Lunar impact, after approximately three orbits, was projected for October 9, 2009, at 11:30 UTC, ± 30 minutes. The mission team initially announced that Cabeus A will be the target crater for the LCROSS dual impacts scheduled for 11:30 UTC on October 9, 2009,[8] but later refined the target to be the larger, main Cabeus crater.[9] In its final approach, the Shepherding Spacecraft and Centaur separated Oct. 8, 2009 at 21:50 EDT.[10]

The Centaur upper stage will act as a heavy impactor to create a debris plume that will rise above the lunar surface. Following four minutes after impact of the Centaur upper stage, the Shepherding Spacecraft will fly through this debris plume, collecting and relaying data back to Earth before impacting the lunar surface and creating a second debris plume. NASA expects the impact velocity will be over 9,000 km/h (5,600 mph).[11] The Centaur impact will excavate greater than 350 tonnes of lunar material and create a crater 20 m (66 feet) in diameter to a depth of 4 m (13 feet). The Shepherding Spacecraft impact will excavate an estimated 150 tonnes and with a crater 14 m (46 feet) in diameter to a depth of 2 m (6 feet). Most of the material in the Centaur debris plume will remain at (lunar) altitudes below 10 km (6.2 miles).[12]

It is hoped that spectral analysis of the resulting impact plume will help to confirm preliminary findings by the Clementine and Lunar Prospector missions which hinted that there may be water ice in the permanently shadowed regions. LCROSS will fly through the debris plume and will then crash itself into a different part of the crater approximately four minutes after the Centaur impact. Mission scientists estimate that the Centaur impact plume may be visible through amateur-class telescopes with apertures as small as 25 to 30 cm (10 to 12 inches).[13] Both impacts will also be monitored by Earth-based observatories and possibly by other orbital assets.

Spacecraft

LCROSS spacecraft (exploded view)

The LCROSS mission takes advantage of the structural capabilities of the Evolved Expendable Launch Vehicle Secondary Payload Adapter (ESPA) ring[14] used to attach LRO to the Centaur upper stage rocket. Mounted on the outside of the ESPA are six panels that hold the spacecraft's science payload, command and control systems, communications equipment, batteries, and solar panels. A small monopropellant propulsion system is mounted inside of the ring. Also attached are two S-Band omni antennas and two medium-gain antennas. The mission's strict schedule, mass, and budget constraints posed difficult challenges to engineering teams from NASA Ames Research Center and Northrop Grumman. Their creative thinking led to a unique use of the ESPA ring and innovative sourcing of other spacecraft components. Usually, the ESPA ring is used as a platform to hold six small deployable satellites; for LCROSS, it became the backbone of the satellite, a first for the ring. LCROSS also takes advantage of commercially available instruments and uses many of the already flight-verified components used on LRO.

LRO (top, silver) and LCROSS (bottom, gold) prepared for fairing

LCROSS is being managed by NASA's Ames Research Center and was built by Northrop Grumman. The LCROSS preliminary design review was completed on September 8, 2006. The LCROSS mission passed its Mission Confirmation Review on February 2, 2007[15] and its Critical Design Review on February 22, 2007.[16] After assembly and testing at Ames, the instrument payload, provided by Ecliptic Enterprises Corporation,[17] was shipped to Northrop Grumman on January 14, 2008, for integration with the spacecraft.[18] LCROSS passed its review on February 12, 2009.

Instruments

The LCROSS science instrument payload, provided by NASA's Ames Research Center, consists of a total of nine instruments consisting of one visible, two near infrared, and two mid-infrared cameras; one visible and two near-infrared spectrometers; and a photometer. A data handling unit (DHU) collects the information from each instrument for transmission back to LCROSS Mission Control. Due to the schedule and budget constraints, LCROSS takes advantage of rugged, commercially available components. The individual instruments went through a rigorous testing cycle that simulated launch and flight conditions, identifying design weaknesses and necessary modifications for use in space, at which point the manufacturers were allowed to modify their designs.[12]

Imagery

LCROSS lunar swingby photos[19]
  • One of the first images from the Lunar CRater Observation and Sensing Satellite (LCROSS) using the visible light camera during the swingby of the Moon. LCROSS has nine science instruments that collect different types of data which are complementary to each other. These instruments provide for a robust collection of data about the composition of the lunar regolith.
    One of the first images from the Lunar CRater Observation and Sensing Satellite (LCROSS) using the visible light camera during the swingby of the Moon. LCROSS has nine science instruments that collect different types of data which are complementary to each other. These instruments provide for a robust collection of data about the composition of the lunar regolith.
  • An infrared camera image from the Moon taken with the Lunar Crater Observation and Sensing Satellite (LCROSS) mid-infrared camera. LCROSS has nine science instruments that collect different types of data which are complementary to each other. These instruments provide for a robust collection of data about the composition of the lunar regolith.
    An infrared camera image from the Moon taken with the Lunar Crater Observation and Sensing Satellite (LCROSS) mid-infrared camera. LCROSS has nine science instruments that collect different types of data which are complementary to each other. These instruments provide for a robust collection of data about the composition of the lunar regolith.
  • Another visible light camera image of the Moon taken by the LCROSS spacecraft during lunar swingby.
    Another visible light camera image of the Moon taken by the LCROSS spacecraft during lunar swingby.

See also

Template:Space portal

References

  1. ^ "Lunar Precursor Robotic Program". NASA. Retrieved 2009-08-04.
  2. ^ "NASA's LCROSS Mission Changes Impact Crater". NASA. 2009-09-29. Retrieved 2009-09-29.
  3. ^ Stephen Clark (August 25, 2009). "Managers mull options after moon mission malfunction". Spaceflight Now.
  4. ^ Tariq Malik (2006-04-10). "NASA Adds Moon Crashing Probes to LRO Mission". Space.com. Retrieved 2006-04-11.
  5. ^ "NASA Moon Impactor Successfully Completes Lunar Maneuver". NASA. June 23, 2009.
  6. ^ "LCROSS Lunar Swingby Streaming Video". NASA. June 23, 2009.
  7. ^ CLARK, STEPHEN, Managers mull options after moon mission malfunction, SPACEFLIGHT NOW, Posted: August 25, 2009
  8. ^ "LCROSS Observation Campaign". NASA.
  9. ^ "Moon-crashing probe aimed at bigger target". MSNBC.
  10. ^ "NASA LCROSS". NASA.
  11. ^ "A Flash of Insight: LCROSS Mission Update". NASA. 2008-08-11.
  12. ^ a b Cite error: The named reference PressKit was invoked but never defined (see the help page).
  13. ^ "LCROSS Observation Campaign". NASA.
  14. ^ "EVOLVED EXPENDABLE LAUNCH VEHICLE SECONDARY PAYLOAD ADAPTER" (PDF). AIAA. Retrieved 2009-10-02. {{cite web}}: Cite has empty unknown parameter: |1= (help)
  15. ^ "NASA Moon-Impactor Mission Passes Major Review". www.nasa.gov. 2007-02-02.
  16. ^ "Lunar Crater Observation and Sensing Satellite Passes Critical Design Review". www.moondaily.com. 2007-03-02.
  17. ^ "Ecliptic provides key elements of LCROSS payload". www.spaceflightnow.com. 2008-03-03.
  18. ^ Jonas Dino. "NASA's Quest to Find Water on the Moon Moves Closer to Launch". NASA=2008-01-14. Retrieved 2008-02-10.
  19. ^ "Visible light camera image during lunar swingby". NASA. 2009-06-23. Retrieved 2009-08-10.

External resources

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