Data Set Information
DATA_SET_NAME APACHE POINT OBSERVATORY 3.5M AGILE OBSERVATIONS OF LCROSS
DATA_SET_ID EAR-L-APO3.5M_AGILE-2-EDR-LCROSS-V1.0
NSSDC_DATA_SET_ID NULL
DATA_SET_TERSE_DESCRIPTION This archive contains observations of the 2009-10-09 impact of the LCROSS spacecraft on the moon by the AGILE instrument on the Apache Point Observatory 3.5m telescope.
DATA_SET_DESCRIPTION
Data Set Overview
  =================
 
    The NASA LCROSS (Lunar CRater Observation and Sensing Satellite) mission
    was designed to search for evidence of water ice in continuously
    shadowed crater floors at the Moon's north or south pole. LCROSS was a
    piggyback experiment to the Lunar Reconnaissance Orbiter (LRO), which
    was launched in June 2009. The LCROSS mission involved crashing the LRO
    upper stage into a shaded polar region of the Moon, throwing up lunar
    regolith high enough to be illuminated by the Sun and observed from
    Earth (and simultaneously observed from a 'chase satellite' following
    several minutes behind the booster).
 
    The main scientific goal of the LCROSS mission was to find
    spectrographic evidence of water in the illuminated plume. Estimates of
    the plume brightness by NASA/Ames Research Center (ARC) indicate that
    large telescopes such as Keck would probably be needed to detect water
    lines in the spectra with sufficient signal-to-noise. This conclusion is
    based on the estimated optical depth of the ejected water, which is
    related to the total regolith mass ejected and the expanding radius of
    the plume. Photometric observations of the evolving plume with smaller
    telescopes were sought to establish the plume radius as a function of
    time and provide an estimate of the ejecta mass, which is related to the
    surface brightness of the plume. These measurements could in turn be
    used to calculate the water vapor optical depth as a function of time
    for a given estimate of water vapor content in the regolith. Simulations
    conducted at NASA/ARC indicated that the plume will rise to a height of
    35 km above the lunar surface, which corresponds to an angular distance
    of 18 arcseconds as seen from Earth.
 
    We observed the Moon from the Apache Point Observatory (APO), which is
    located in the Sacramento Mountains of southern New Mexico, in an effort
    to characterize the LCROSS plume. Our observations addressed LCROSS
    Science Goal #4: Characterize the lunar regolith within a permanently
    shadowed crater on the Moon. Specifically, we proposed to set
    constraints on the ejecta mass by observing the time evolution of the
    expanding plume.
 
  Scientific Background
  ========================
    The NASA LCROSS (Lunar CRater Observation and Sensing Satellite) mission
    was designed to search for evidence of water ice in continuously
    shadowed crater floors at the Moon's north or south pole. The neutron
    spectrometer on the Lunar Prospector orbiter detected the signature of
    hydrogen concentrations in shaded areas of the moon's north and south
    poles (Feldman et al. 2001). The leading theory is that this hydrogen is
    locked in hydrous minerals or water ice.  In September 2009, results
    from the Cassini (Clark et al. 2009), Deep Impact (Sunshine et al.
    2009), and Chandrayaan-1 (Pieters et al. 2009) spacecraft all indicated
    the presence of surficial lunar water and hydroxyl.
 
    The LCROSS mission was designed to crash the LRO upper stage into a
    shaded polar region of the Moon, throwing up lunar regolith high enough
    to be illuminated by the Sun and observed from Earth and the shepherding
    spacecraft, which impacted the Moon's surface four minutes later.  The
    LRO/LCROSS spacecraft was launched on June 18, 2009, and crashed into
    the Cabeus crater near the Moon's south pole on October 9, 2009. The upper
    stage impacted the moon at 11:31:19.51 UTC at -84.68 deg latitude,
    -48.69 deg longitude, Mean Earth frame, and the shepherding spacecraft
    impacted the surface at 11:35:34 UTC.
 
    Ground-based observatories from Texas westward to Hawaii were enlisted
    to observe the impact, which occurred during nighttime hours in those
    locations.
 
  Observations
  =================
    The APO 3.5-m team acquired data on October 9, 2009, for approximately
    five hours prior to impact time and 1.5 hours following impact.
    Observing conditions were clear.
 
    Instrument
    ----------
    The Agile imager was used to acquire all APO 3.5-m observations.  A
    combination of a V filter and an ND 2.5 filter was used to reduce the
    brightness of the Moon to avoid saturation of the detector.  The
    instrument was used in 2 x 2 binned mode with the medium gain setting
    and the fast readout time.  During observations of the impact, the Agile
    dark slide was inserted partway into the optical path.  This resulted in
    an obscuration of part of the illuminated disk of the Moon as seen in
    the Agile field of view, which helped to reduce the amount of scattered
    light in the images.
 
    Observing Strategy
    ------------------
    Standard stars and other calibration data were acquired along with the
    images of the Moon.  These calibration files include the following:
    1) bias frames
    2) a dome flat (to illustrate the location of the dark slide)
    3) sky flats
    4) dark frames
    5) reference objects: 68 Psc, 1 Aur, Hipparcos 2942, Hipparcos 24813,
    Mars, and Uranus
 
    For most of the data acquisition, images were obtained using TUI, the
    telescope and instrument user interface software.  However, the
    observations of the Moon obtained close to the time of impact were
    obtained by typing a data acquisition command into a command line.  This
    was done to avoid a latency that occurred when writing numerous header
    cards with information obtained from the telescope hub computer.
    Consequently, the FITS headers for the impact sequence Moon images do
    not contain some information that is written to the FITS headers created
    when acquiring data through the user interface.
DATA_SET_RELEASE_DATE 2010-02-05T00:00:00.000Z
START_TIME 2009-10-09T11:19:26.500Z
STOP_TIME 2009-10-09T12:04:26.000Z
MISSION_NAME LUNAR CRATER OBSERVATION AND SENSING SATELLITE
MISSION_START_DATE 2009-04-27T12:00:00.000Z
MISSION_STOP_DATE 2009-10-09T12:00:00.000Z
TARGET_NAME BIAS
DARK
SKYFLAT
MARS
URANUS
MOON
1 AURIGAE
68 PSC
HIP 24813
HIP 2942
TARGET_TYPE CALIBRATION
CALIBRATION
CALIBRATION
PLANET
PLANET
SATELLITE
STAR
STAR
STAR
STAR
INSTRUMENT_HOST_ID APO35M
INSTRUMENT_NAME AGILE
INSTRUMENT_ID AGILE
INSTRUMENT_TYPE PHOTOMETER
NODE_NAME Geosciences
ARCHIVE_STATUS LOCALLY_ARCHIVED
CONFIDENCE_LEVEL_NOTE
Confidence Level Overview
  =========================
 
 
  Review
  ======
    This data set has been subjected to peer review according to Planetary
    Data System standards.
 
 
  Data Coverage and Quality
  =========================
 
 
  Limitations
  ===========
CITATION_DESCRIPTION Chanover, N.J., Apache Point Observatory 3.5m Agile Observations of LCROSS, NASA Planetary Data System, EAR-L-APO3.5M_AGILE-2-EDR-LCROSS-V1.0, 2010.
ABSTRACT_TEXT This archive contains observations of the 2009-10-09 impact of the LCROSS spacecraft on the moon by the AGILE instrument on the Apache Point Observatory 3.5m telescope. The archive consists of FITS images of the event and calibration data. This is one of several data sets of Earth-based observations of the impact.
PRODUCER_FULL_NAME NANCY J. CHANOVER
SEARCH/ACCESS DATA
  • LCROSS Analysts Notebook
  • LCROSS APO35M/AGILE FTP Resource
  • GEOSCIENCES WEB SERVICES