PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "E. GUINNESS, 1998-09-04; E. GUINNESS, 1999-04-30" RECORD_TYPE = STREAM OBJECT = MISSION MISSION_NAME = "LUNAR PROSPECTOR" OBJECT = MISSION_INFORMATION MISSION_START_DATE = 1995 MISSION_STOP_DATE = UNK MISSION_ALIAS_NAME = "N/A" MISSION_DESC = " Mission Overview ================ The Lunar Prospector (LP) Mission consists of a spin-stablized orbiter spacecraft designed to perform continuous mapping of the Moon from a circular polar orbit. LP was selected as the third mission in NASA's Discovery program in February, 1995. The spacecraft was designed and built in about 2 years by Lockheed Martin Missiles and Space in Sunnyvale, CA. It was delivered for launch in late 1997 [BINDERETAL1998]. The LP spacecraft was launched on January 7, 1998 (UTC). The primary mapping mission began on January 16, 1998 and lasted for one year. During most of the mapping mission, the spacecraft mapped the surface from a 118-minute, circular, polar orbit 100 km above the moon's surface [BINDER1998]. For the final month of the primary mission (starting 12/19/98) the spacecraft was maneuvered into a 40 km orbit as a transition into a lower extended mission orbit. The transition orbit was used to collect gravity data in order to improve the moon's gravity model in preparation for monitoring the extended mission orbit. The extended mission began on January 16, 1999 and is expected to end in July 1999. The objective of the extended mission is to provide higher resolution mapping from a circular, polar orbit averaging 30 km above the moon's surface. The spacecraft was maneuvered in its 30 km extended mission orbit starting on January 29, 1999. The science goals of the Lunar Prospector Mission are to map the Moon's surface composition and its magnetic and gravity fields, and to determine the frequency and location of gas release events. A special emphasis of the science goals is to search for polar ice deposits. To meet these science goals the LP spacecraft carries five science instruments mounted on three booms. The instrument package includes a Gamma Ray Spectrometer (GRS), a Neutron Spectrometer (NS), an Alpha Particle Spectrometer (APS), a Magnetometer (MAG), and an Electron Reflectometer (ER). A sixth science investigation is a Doppler Gravity Experiment (DGE) that uses tracking data for mapping the gravity field. The gravity data is derived from tracking the LP spacecraft with the NASA Deep Space Network (DSN) with ground stations in California, Spain, and Australia [KONOPLIVETAL1998]. The LP science team consists of the PI, Alan Binder, and five Co-I's, and is divided into three groups. The Spectrometer Group consists of William Feldman and Binder. The Magnetics Group consists of Robert Lin, Mario Acuna, and Lon Hood. The Gravity Group consists of Alexander Konopliv. Mission Phases ============== LUNAR PROSPECTOR LAUNCH ----------------------- The Lunar Prospector spacecraft was launched on January 7, 1998 at 2:28:44 UTC on a Lockheed Martin Launch Vehicle 2 (Athena 2) from the Spaceport Florida commercial pad (Pad 46) at Cape Canaveral, Florida. After about three-quarters of an orbit around the Earth, a 64 second burn by the spacecraft's Trans Lunar Injection stage sent LP on a 105 hour cruise to the moon. The spacecraft was turned on at 56.5 minutes after launch. Spacecraft Id: : LP Target Name : MOON Mission Phase Start Time : 1998-01-07 Mission Phase Stop Time : 1998-01-07 Spacecraft Operations Type : ORBITER LUNAR PROSPECTOR CRUISE ----------------------- The Lunar Prospector spacecraft was inserted into a translunar coast after reaching a parking orbit around Earth. The Cruise Phase to the moon lasted for about 105 hours. The three spacecraft booms were deployed starting about 5 hours after launch. All five science instruments were turned on during cruise and collected science data for instrument check out and calibration. The MAG/ER was activated at about 1.33 hours after launch and the APS at about 3.5 hours after launch. The GRS and NS needed to degas and were not turned until about 24 hours after launch. Two trajectory correction maneuvers were performed during the Cruise Phase. Spacecraft Id: : LP Target Name : MOON Mission Phase Start Time : 1998-01-07 Mission Phase Stop Time : 1998-01-11 Spacecraft Operations Type : ORBITER LUNAR PROSPECTOR ORBIT INSERTION -------------------------------- The Lunar Prospector spacecraft was inserted into Lunar orbit by an initial Lunar Orbit Insertion (LOI) engine burn at 11:45 UTC on January 11, 1999. The initial capture orbit had a 11.8 hour period. Several additional engine firings put the spacecraft into its mapping orbit, which was a 100 +/- 20 km circular polar orbit with a 118 minute period. All five science instruments were operating and collecting data during the Orbit Insertion Phase. Spacecraft Id: : LP Target Name : MOON Mission Phase Start Time : 1998-01-11 Mission Phase Stop Time : 1998-01-16 Spacecraft Operations Type : ORBITER LUNAR PROSPECTOR PRIMARY MISSION -------------------------------- The Lunar Prospector Primary Mission lasted for one year as originally planned. The nominal mapping orbit during the Primary Mission had an altitude of 100 km above the moon's surface. Orbit maintenance maneuvers were required about every 56 days to correct for changes in the mapping orbit due to lunar gravity anomalies. The basic mapping strategy during the Primary Mission was for the science instruments to collect data continuously. The data were downlinked to Earth immediately and simultaneously transferred to a solid state recorder and then downlinked 53 minutes later. These delayed data frames were interleaved into the real-time data stream. The purpose of the delayed stream was to receive data acquired on the lunar farside when communications with the Earth were blocked by the moon. Late in the Primary Mission as the spacecraft batteries began to degrade and eclipses limited recharge time by the solar panels, the spacecraft transmitter was cycled off and on to conserve power. The transmitter was switched off when the spacecraft was on the lunar farside and communications with the Earth were not possible. This transmitter cycling began on September 16, 1998 and continued periodically throughout the rest of the Primary Mission and into the Extended Mission. The transmitter cycling was discontinued on March 24, 1999. At the start of the Primary Mission the LP spacecraft attitude as measured by the spin axis direction (+Z, which is perpendicular to the top of the spacecraft bus and in the direction of the omni antenna) was pointed to within a few degrees of north ecliptic pole. In October 1998, the spacecraft orientation was flipped by 180 degrees so that the spin axis pointed toward the south ecliptic pole. The reorientation was done so that the APS instrument could collect data that it missed due to an anomaly on one of its faces and to test for any asymmetries in the response of the other spectrometers. The maneuver was initiated on October 5, 1998 with the spacecraft being turned by 90 degrees (spin axis parallel to the ecliptic). This intermediate orientation provided calibration data for the GRS instrument. On October 7, 1998, the spacecraft was turned the final 90 degrees. The spacecraft maintained the ecliptic south orientation for the rest of the mission except for special procedures. On November 15, 1998, the spacecraft was turned by 80 degrees to avoid possible damage to the solar panels due to dust from Leonids meteor shower. This orientation minimized the cross sectional area of the solar panels in the direction of the shower. On November 19, 1998, the spacecraft was turned back to the attitude with the spin axis nearly parallel to the ecliptic south pole. There was no apparent damage to the spacecraft from the shower. Spacecraft Id: : LP Target Name : MOON Mission Phase Start Time : 1998-01-16 Mission Phase Stop Time : 1999-01-16 Spacecraft Operations Type : ORBITER LUNAR PROSPECTOR EXTENDED MISSION -------------------------------- The Lunar Prospector Extended Mission started on January 16, 1999 and is scheduled to last until the end of July 1999. The nominal mapping orbit during the Extended Mission has an altitude of 30 km above the moon's surface. Near the start of the Extended Mission, noise in the Alpha Particle Spectrometer instrument started to affect the Neutron Spectrometer causing the NS instrument to saturate. As a result, the APS was turned off on February 8, 1999 to allow the NS to collect clean data. The APS instrument was turned on again on April 21, 1999 and was collecting good data without noise. Spacecraft Id: : LP Target Name : MOON Mission Phase Start Time : 1999-01-16 Mission Phase Stop Time : 1999-07-31 (estimated) Spacecraft Operations Type : ORBITER " MISSION_OBJECTIVES_SUMMARY = " The overall goal of the Lunar Prospector (LP) Mission is to perform global mapping of the Moon in order to better understand the Moon's origin, evolution, current state, and resources. Specifically, LP mapped the surface abundances of key elements (U, Th, K, O, Si, Mg, Fe, Ti, Ca, Al, Gd, Sm, and H). As part of the elemental abundance mapping, LP determined that water ice exists in permanently shadowed areas near the lunar poles. LP made high-resolution measurements of the near-side crustal gravity field and measure long-wavelength gravity anomalies for the entire Moon. LP provided global measurements of lunar crustal magnetic fields and the induced dipole moment. LP will also attempt to determine the frequency and location of gas release events, as one of the major sources of the thin lunar atmosphere. " END_OBJECT = MISSION_INFORMATION OBJECT = MISSION_HOST INSTRUMENT_HOST_ID = LP OBJECT = MISSION_TARGET TARGET_NAME = MOON END_OBJECT = MISSION_TARGET END_OBJECT = MISSION_HOST OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BINDER1998" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BINDERETAL1998" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "KONOPLIVETAL1998" END_OBJECT = MISSION_REFERENCE_INFORMATION END_OBJECT = MISSION END