LCROSS launched as a secondary payload with Lunar Reconnaissance
    Orbiter (LRO) on June 18, 2009 5:32 Eastern Time.  After
    trans-lunar injection, LRO separated and performed its mission.
    The LCROSS Shepherding Spacecraft (SSC) remained attached to the
    spent Atlas upper stage, called the Centaur.  Over 112 days, the
    Shepherding Spacecraft adjusted the Centaur's course to bring it
    to an impact within the Cabeus Crater near the South Pole of the
    moon.
 
    LCROSS used the Centaur as a 2300 kg kinetic impactor with more
    than 200 times the energy of the Lunar Prospector (LP) impact to
    excavate more than 250 metric tons of lunar regolith.  The
    resulting ejecta cloud was observed from a number of
    Lunar-orbital and Earth-based assets, and the LCROSS spacecraft.
    After releasing the Centaur, the SSC flew toward the impact
    plume, sending real-time data to characterize the morphology,
    evolution and composition of the plume with a suite of cameras
    and spectrometers.  The SSC then became a 700kg impactor itself,
    providing a second opportunity to study the nature of the Lunar
    Regolith.
 
    Mission Phases
    ==============
 
    LCROSS and LRO launched on June 18, 2009 at 21:32 UTC aboard an
    Atlas V launch vehicle in the 401 configuration (4-meter
    fairing, no solid rocket boosters, single-engine Centaur).
    After achieving low-Earth orbit, the Centaur performed a 23
    minute coast, and then re-ignited to perform the trans-lunar
    injection (TLI) burn for both LCROSS and LRO.
 
    Three minutes after TLI, the Centaur separated from LRO and then
    maneuvered to increase separation to avoid contaminating LRO.
    To minimize the residual propellant species aboard the Centaur
    at lunar impact (potential contaminants of water measurements),
    the Centaur next performed a sequence of propellant depletion
    maneuvers with both cryogenic and hydrazine-based reaction
    control systems.  During these depetion maneuvers, the Centaur
    powered the SSC up and pointed its solar array at the sun.
    After the maneuvers were finished, the Centaur ceded attitude
    control to the SSC and shut down.
 
    ------
    Transfer Phase [6/18/2009 - 6/23/2009]
 
    The transfer phase covered the period from TLI to lunar
    swingby.
 
    This phase contained the QUICKLOOK and STARFIELD data collection
    periods.  Both periods were used to confirm instrument function
    and pointing prior to the lunar swingby.
 
    ------
    Lunar Swingby [6/23/2009]
 
    The lunar swingby was a gravity assist maneuver that placed
    LCROSS in a steeply-inclined, nearly circular orbit around Earth
    at approximately lunar distance.  Called a Lunar Gravity Assist
    Lunar Return Orbit (LGALRO), this trajectory returned LCROSS to
    the moon again after three orbits.
 
    Just after closest approach to the moon, the instruments were
    pointed at the surface and turned on to gather calibration data.
    The instruments were swept across the surface, pausing three
    times at targets on the surface with distinctive spectral
    characteristics.  Finally, the instruments were swept back and
    forth across the limb.  This limb-crossing data was used to
    confirm instrument pointing to within 0.1 degree.
 
    ------
    Cruise Phase
 
    Cruise phase activities included trajectory correction
    maneuvers and additional periods of payload data collection
    observing the Earth and Moon.
 
    Several 'Cold Side Bake' activities were also performed to
    reduce ice in the Centaur insulation that remained since launch.
    During these maneuvers, the SSC and Centaur were turned to place
    cold side of the spacecraft, which was normally in darkness, in
    sunlight.  Sublimating ice embedded in the insulation generated
    enough thrust to be detectible in doppler measurements.  If left
    in place, this ice could potentially have contaminated
    observations of the Centaur's impact.
 
    On the second half of the second Earth orbit, LCROSS experienced
    a major propellant loss stemming from a short-lived Inertial
    Reference Unit (IRU) glitch.  This was discovered immediately
    before the third Cold Side Bake event.  With the mission in
    jeopardy, LCROSS declared an emergency and transitioned to
    maximum DSN coverage to enable full-time monitoring.  Over the
    following two weeks, the flight team developed strategies to
    prevent another glitch and to minimize propellant usage during
    planned maneuvers.  With operational and software protections in
    place, the LCROSS project returned to a nominal operational
    posture on Day 78, albeit with a significantly smaller
    propellant margin.
 
    The deadline for final selection of the Centaur target crater
    was 30 days prior to impact.  This late date allowed the Team to
    use early data from LRO to improve the targeting decision.
    During the final two weeks of cruise, the Science Team twice
    refined the target location within the crater.
 
    ------
    Separation
 
    Centaur separation was performed successfully 9 hours 40 minutes
    prior to Centaur impact and, with the substantial change of mass
    properties, was accompanied by a transition to a completely new
    set of attitude control modes tuned for post-separation
    conditions.  One minute following separation, the SSC flipped
    180 degrees to point the payload at the receding Centaur.  These
    observations are contained in the SEPARATION data collection
    period.  Forty minutes after separation, the SSC performed the
    Braking Burn, a delta-v maneuver used to produce a 600 km
    separation between the Centaur and the SSC at the moment of
    Centaur impact.
 
    ------
    Impact
 
    Approximately one hour prior to centaur impact, the spacecraft
    was turned to point the instruments at the predicted impact
    location.  Fifty minutes of calibration data are contained in the
    PREIMPACT data collection.  Five minutes of data are contained in
    the IMPACT data collection, starting one minute prior to Centaur
    impact.
 
    The Centaur impacted the moon at 11:31:19.51 UTC on 10/9/2009 at
    -84.68 deg latitude, -48.69 deg longitude, Mean Earth frame.
 
    The SSC impacted the surface at 11:35:34 UTC.
 
    Earth-based Observations
    ========================
 
    The LCROSS project provided funding for four investigators to record
    Earth-based observations of the LCROSS impact using various observatory
    facilities, and to archive their data in the PDS. Many other Earth-based
    facilities also observed the impact. The four LCROSS-sponsored observers
    were:
 
    (1) Dr. Marc Buie, Southwest Research Institute in Boulder, CO, using the
    PHOTDOC and PHOTGJON cameras on the Magdalena Ridge Observatory 2.4-m
    telescope, Socorro, NM
 
    (2) Dr. Nancy Chanover, New Mexico State University, using the Agile
    camera on the Astrophysical Research Consortium 3.5-meter telescope at
    the Apache Point Observatory, Sunspot, NM
 
    (3) Dr. Faith Vilas, University of Arizona, using the CCD47 and CLIO
    cameras at the MMT Observatory, Tucson, AZ
 
    (4) Dr. Eliot Young, Southwest Research Institute in Boulder, CO, using
    three facilities: the Gemini North telescope at the Mauna Kea Observatory
    on the island of Hawaii; the SPEX spectrograph and imager on the
    3.0-meter Infrared Telescope Facility (IRTF) at the Mauna Kea Observatory;
    and the Near Infrared Spectrograph (NIRSPEC) on the 10-meter Keck II
    telescope, Keck Observatory, Kamuela, Hawaii.
 
 
    References
    ==========
 
    Ennico, K., et al., 'LCROSS Science Payload Ground Development, Test
    and Calibration Results', 39th Lunar and Planetary Science
    Conference, Lunar and Planetary Science Institute, No. 1391, League
    City, TX, 2008, p 1474.
 
    Strong, J., et al., 'Transport and Use of a Centaur Second Stage in
    Space', AIAA Space Ops 2010 Conference, Delivering on the Dream,
    AIAA, Washington, DC, 2010, Paper 2010-2197 (submitted for
    publication).
 
    Tompkins, P., et al., 'Flight Team Development in Support of LCROSS:
    A Class D Mission', AIAA Space Ops 2010 Conference, Delivering on
    the Dream, AIAA, Washington, DC, 2010, Paper 2010-2223 (submitted
    for publication).
 
    Tompkins, P., et al., 'Flight Operations for the LCROSS Lunar
    Impactor Mission', AIAA Space Ops 2010 Conference, Delivering on the
    Dream, AIAA, Washington, DC, 2010, Paper 2010-1986 (submitted for
    publication).
 
    Andrews, D., 'LCROSS Lunar Impactor: Pioneering Risk-Tolerant
    Exploration in a Search for Water on the Moon', Proceedings of the
    7th International Planetary Probe Workshop, Barcelona, Spain, June
    2010 (submitted for publication).
 
    Colaprete, A., et al., 'An Overview of The Lunar
    Crater Observation and Sensing Satellite (LCROSS) Mission - An ESMD
    Mission to Investigate Lunar Polar Hydrogen,' Bulletin of the
    American Astronomical Society, September, 2006, Vol. 38, p. 591.

PDS4 note: awaiting LID references to facilities and telescopes
- APACHE POINT OBSERVATORY 3.5M ARC RITCHEY-CHRETIEN ALTAZIMUTH REFLECTOR
- MMT OBSERVATORY
- MAGDALENA RIDGE OBSERVATORY 2.4-
- MAUNA KEA OBSERVATORY 3.0-M NASA INFRARED TELESCOPE FACILITY (IRTF)
- W.M. KECK OBSERVATORY 10-M KECK I RITCHEY-CHRETIEN ALTAZIMUTH REFLECTOR