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
DATA_SET_TERSE_DESCRIPTION
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
PLANET
SATELLITE
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
    		•