PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = MISSION MISSION_NAME = "DEEP SPACE PROGRAM SCIENCE EXPERIMENT" OBJECT = MISSION_INFORMATION MISSION_START_DATE = 1991-11-19 MISSION_STOP_DATE = 1994-05-07 MISSION_ALIAS_NAME = "CLEMENTINE 1" MISSION_DESC = " Mission Overview ================ The Deep Space Program Science Experiment (DSPSE), first in a planned series of technology demonstrations jointly sponsored by the Ballistic Missile Defense Organization (BMDO) and the National Aeronautics and Space Administration (NASA ), was launched on 1994-01-25 aboard a Titan IIG rocket from Vandenburg Air Force Base in California. The mission included two months of systematic lunar mapping (1994-02-26 through 1994-04-21), which was to have been followed by a flyby of the near-Earth asteroid Geographos (1994-08-31). A software error, combined with improbable hardware conditions, on 1994-05-07 led to accidental spin-up of the spacecraft and loss of attitude control gas. This precluded the flyby of Geographos. The spacecraft itself was affectionately known as Clementine since, as in the song of the same name, it would be 'lost and gone forever' after completing its short mission. Clementine's primary objective was qualification of light weight imaging sensors and component technologies (including a star tracker, inertial measurement unit, reaction wheel, nickel hydrogen battery, and solar panel) for the next generation of Department of Defense (DoD) spacecraft. DSPSE represented a new class of small, low cost, and highly capable spacecraft that fully embraced emerging lightweight technologies to enable a series of long-duration deep space missions. A second objective was return of data about the Moon and Geographos to the international civilian scientific community. BMDO assigned responsibility for the Clementine spacecraft design, manufacture, integration, and mission execution to the Naval Research Laboratory (NRL). Lawrence Livermore National Laboratory (LLNL) provided lightweight imaging sensors developed under the sponsorship of BMDO. Goddard Space Flight Center (GSFC) and the Jet Propulsion Laboratory (JPL) provided mission design and navigation services. The Deep Space Network (DSN) provided tracking through JPL. NASA was responsible for the scientific return from the mission. Further information on the Clementine Mission can be found in [NOZETTEETAL1994] and [REGEONETAL1994]. Mission Phases ============== Mission phases were defined for significant spacecraft activity periods. During orbital operations a 'cycle' was the time required for the Moon to rotate once under the spacecraft (about 28 days). The 'revolution number' refers to an observational pass over the moon. The revolution number was incremented by one each time the spacecraft passed over the south pole prior to the beginning of data acquisition. Revolution number was used in lieu of orbit number because of the way the orbit number was defined by the mission. The orbit number was incremented each time the spacecraft passed through the equatorial plane on the sunlit side of the Moon. Thus, the orbit number generally changed in the middle of an observational pass. This proved to be awkward in defining the data acquired by a single pass over the Moon. PRE-LAUNCH ---------- Clementine moved from concept to launch in a little over two years. Significant events during the Pre-Launch phase of the mission included: 1991-11-19 Naval Research Laboratory (NRL) briefed by the Space Defense Initiative Organization (SDIO) on the Clementine concept 1992-01-12 NRL tasked with 2 month Clementine study 1992-02-25 NRL tasked by SDIO to be Clementine lead 1992-03-16 Clementine Concept Definition Review 1992-04-01 Clementine Concept Definition completed; begin Program Management and System Design 1992-05-01 Begin Systems Engineering and Testing 1992-05-13 Clementine System Requirements Review 1992-06-01 Begin Ground Subsystems Development 1992-07-30 Preliminary Design Review 1992-10-20 Launch Range Introduction (Review) 1992-11-05 Sensor Critical Design Review 1992-11-16 Spacecraft Vehicle Critical Design Review 1993-06-01 Begin Spacecraft Integration 1993-07-01 Begin Ground System Integration and Testing 1993-10-01 Begin Spacecraft Assembly Testing 1993-12-01 Begin Launch Operations and Testing Spacecraft Id : CLEM1 Target Name : MOON Mission Phase Start Time : 1991-11-19 Mission Phase Stop Time : 1994-01-25 Spacecraft Operations Type : ORBITER LAUNCH ------ The Clementine spacecraft was launched on 1994-01-25, from Vandenburg Air Force Base in California. It went into a 226-km by 259-km geocentric orbit at an inclination of 67 degrees. Spacecraft Id : CLEM1 Target Name : MOON Mission Phase Start Time : 1994-01-25 Mission Phase Stop Time : 1994-01-25 Spacecraft Operations Type : ORBITER LOW EARTH ORBIT --------------- The Low Earth Orbit phase extended from the end of the Launch phase until Clementine was spun up to 60 revolutions per minute and the kick motor was fired, changing its trajectory to a highly elliptical orbit which would encounter the Moon. During this Low Earth Orbit phase on-board systems were checked out and the spacecraft was three-axis stabilized. Spacecraft Id : CLEM1 Target Name : MOON Mission Phase Start Time : 1994-01-25 Mission Phase Stop Time : 1994-02-03 Spacecraft Operations Type : ORBITER EARTH PHASING LOOP A -------------------- Earth Phasing Loop A began at the end of the Low Earth Orbit phase and lasted until Lunar Orbit Insertion. This phase included two phasing loop orbits, the second of which allowed encounter with the Moon. Spacecraft Id : CLEM1 Target Name : MOON Mission Phase Start Time : 1994-02-03 Mission Phase Stop Time : 1994-02-19 Spacecraft Operations Type : ORBITER LUNAR ORBIT INSERTION --------------------- The Lunar Orbit Insertion phase extended from the end of Earth Phasing Loop A until the beginning of Lunar Mapping. During this phase the spacecraft was placed in a lunar orbit ranging from 400 to 2940 kilometers above the surface; the orbit period was 5 hours. Lunar Orbit Insertion occurred during revolution 0. Spacecraft Id : CLEM1 Target Name : MOON Mission Phase Start Time : 1994-02-19 Mission Phase Stop Time : 1994-02-19 Spacecraft Operations Type : ORBITER LUNAR MAPPING ------------- Lunar Mapping extended from the end of Lunar Orbit Insertion until the beginning of Lunar Departure. During this phase the instruments were checked out, sequences were developed and tested for mapping operations, two complete cycles of systematic mapping were completed, and the spacecraft was prepared for leaving lunar orbit. The following sub-phases can be defined for the Lunar Mapping phase: Engineering Checkout and Operational Rehearsals (revolutions 1-31) Systematic Mapping Cycle 1 (revolutions 32-164) Systematic Mapping Cycle 2 (revolutions 165-300) Post-Systematic Mapping (revolutions 301-350) Spacecraft Id : CLEM1 Target Name : MOON Mission Phase Start Time : 1994-02-19 Mission Phase Stop Time : 1994-05-03 Spacecraft Operations Type : ORBITER LUNAR DEPARTURE --------------- The Lunar Departure Phase extended from the completion of Lunar Mapping until the beginning of Earth Phasing Loop B. During this phase, the spacecraft was removed from lunar orbit. The burn for Lunar Departure began on 1994-05-04 at 03:24:15 and lasted 278 seconds; it took place when the spacecraft was near 40 degrees N latitude. This phase included parts of revolutions 350-351. Spacecraft Id : CLEM1 Target Name : MOON Mission Phase Start Time : 1994-05-03 Mission Phase Stop Time : 1994-05-04 Spacecraft Operations Type : ORBITER EARTH PHASING LOOP B -------------------- Earth Phasing Loop B extended from completion of the Lunar Departure phase until loss of on-board attitude control on 1994-05-07. During this phase the spacecraft was to have been checked out in preparation for its flight to Geographos. Spacecraft Id : CLEM1 Target Name : MOON Mission Phase Start Time : 1994-05-04 Mission Phase Stop Time : 1994-05-07 Spacecraft Operations Type : ORBITER " MISSION_OBJECTIVES_SUMMARY = " The primary objective for DSPSE was demonstration of high technology BMDO components. These included the four advanced light weight sensors provided by LLNL, two Inertial Measurement Units, reaction wheel assemblies, GaAS/Ge solar arrays, the NiH2 common pressure vessel battery, advanced release mechanisms, composite structures, and a high- performance 32-bit Reduced Instruction Set Computer (RISC) microprocessor. DSPSE used the Moon (and would have used Geographos) as targets on which to test the detection and acquisition capabilities of the sensors at realistic closing velocities while evaluating the effects of long-term exposure to a deep space environment [REGEONETAL1994]. The second objective for DSPSE was use of the on-board technology to acquire data that would be of interest to the international civilian science community. Within the Lunar Mapping phase of the mission, the highest science priority was acquisition of global multispectral image data. These images represent the first global data set in digital form for the Moon. The color of the Moon in the visible and near-infrared is diagnostic of both composition and exposure history of the regolith material. Filters were chosen to provide the continuum response of the Moon to solar illumination and to detect variations at particular wavelengths which would indicate presence of specific minerals, such as plagioclase feldspar. Sensor coverage is shown in the table below: Instrument Field of View Wavelengths (degrees) (micrometers) ------------ -------------- ---------------- UVVIS 5.6 x 4.2 0.415 +/- 0.020 0.750 +/- 0.005 0.900 +/- 0.015 0.950 +/- 0.015 1.000 +/- 0.015 0.625 +/- 0.225 NIR 5.6 x 5.6 1.100 +/- 0.030 1.250 +/- 0.030 1.500 +/- 0.030 2.000 +/- 0.030 2.600 +/- 0.030 2.780 +/- 0.060 LWIR 1.0 x 1.0 8.750 +/- 0.750 HIRES 0.4 x 0.3 0.415 +/- 0.020 0.560 +/- 0.005 0.650 +/- 0.005 0.750 +/- 0.010 0.600 +/- 0.200 LIDAR Transmitter 1.064 0.532 LIDAR Receiver 0.057 0.750 +/- 0.350 Star Tracker 28 x 43 0.750 +/- 0.350 Throughout the Lunar Mapping phase of the mission, the LIDAR system acquired high resolution profiles of lunar topography. Over those parts of each revolution where radio tracking of the spacecraft was possible, variations in the gravity field of the Moon could be measured. The combination of topography profiles and gravity maps places important constraints on the interior structure of the Moon. The data acquired by Clementine allow identification of major compositional provinces as well as detailed study of complex areas. For example, the South Pole - Aitken Basin was not only discovered to be a major depression [ZUBERETAL1994] but it was also found to be compositionally anomalous [LUCEYETAL1994]. Within the South Pole - Aitken Basin is an extensive region near the south pole which may be an impact basin 300 km in diameter, parts of which are never illuminated by the Sun [SHOEMAKERETAL1994]. If so, water molecules may be drawn to the 'cold trap' and accumulate in significant quantity over millions of years [NOZETTEETAL1994]. The combination of 11-color mapping from the imaging sensors, topography from the laser altimeter, gravity information from radio tracking, and other data represents a major improvement in knowledge about the Moon. A discussion of impact crater results has been presented by [PIETERSETAL1994], ancient multi-ring basins have been discussed by [SPUDISETAL1994], and the Aristarchus region has been described by [MCEWENETAL1994]. OBSERVATION STRATEGY ==================== The observation strategy during Lunar Mapping was constrained primarily by the volume of data that could be downloaded during each revolution (100 MBytes maximum per revolution). During revolutions when the transmission path was partially obstructed (as during occultations near new and full Moon), the downlink was reduced to as little as 60 MB. Against these downlink constraints, Clementine personnel balanced observation and compression strategies to achieve the following objectives: (1) global coverage in 5 UVVIS and 6 NIR bands, (2) continuous LWIR imaging under each revolution strip, (3) HIRES polar imaging, and (4) additional HIRES imaging. Clementine personnel further desired double imaging with the UVVIS, at long and short exposure times (or different gain/offset states) in order to acquire the best possible signal-to-noise ratio (SNR) without saturation. Mission planners also sought to reduce the data rate by using an on-board data compression system. Compression ratios achieved were about 5:1 for the UVVIS long exposures, 12:1 for the UVVIS short exposures, 2.2:1 for the NIR, 1.6:1 for the LWIR, and 3:1 for the HIRES. These compression ratios varied primarily as a function of high-frequency noise and scene contrast. LWIR images had about five percent bad pixels and about ten percent noisy pixels. Because of the poor LWIR compression ratio and because the array was small (128 x 128), the LWIR data were acquired uncompressed. In the HIRES an intensifier reduced resolution; a resolution element was equivalent to about 3-4 pixels. Mission planners expected to achieve high compression ratios (>10:1) but were thwarted by two types of high-frequency noise: (1) a 'honeycomb' pattern from the intensifier, and (2) shot noise resulting from use of low gain states during flight. The HIRES was of greater importance to the planned Geographos observations and some of its components were believed to have limited lifetimes, so measures were taken during the Lunar Mapping phase to minimize its use. To satisfy the constraints and goals outlined above, the nominal plan for each systematic mapping revolution was: Observation Compression Number Volume Ratio of (MB) Frames --------------------------------------------------------------- UVVIS 5-color long exposure 5:1 820 18 UVVIS 5-color short exposure 12:1 820 8 NIR 6-color pole-to-pole 2.2:1 1044 32 10-deg. lat uncompressed UVVIS/NIR 1:1 7 LWIR pole-to-pole 1:1 870 14 HIRES 750-nm lat +/- 50-90 8:1 600 8 HIRES 4-filter, 10 deg.latitude 12:1 400 4 Dark frames/star cal frames 1:1 68 4 LIDAR altimetry N/A N/A 0* --------------------------------------------------------------- TOTALS: 4622 95 *LIDAR altimetry data volume was non-zero but small compared with 1 MB. The 95 MB/revolution rate was easily returned in the absence of downlink anomalies and occultation constraints. For revolutions including long occultations the strategy recommended by the science team was to reduce the data volume by dropping the HIRES color, compressing all of the UVVIS/NIR, and compressing the LWIR. In practice this was followed only approximately because staffing was insufficient to tailor operations on short time scales. There were approximately 10 spacecraft upsets or downlink problems during Lunar Mapping that resulted in loss of all or part of the data from a revolution. Gaps from mapping cycle 1 were filled in cycle 2 (at lower resolution in the southern hemisphere), and gaps in the early part of mapping cycle 2 (longitudes 0-100 W) were recovered during the post-mapping period. For the latter parts of cycle 2 (longitudes 0-230 E), a strategy was implemented to fill gaps in revolutions immediately following an upset by pointing the spacecraft to the east and using several revolutions carefully to recover fully from what had been lost on one. Most of the HIRES and LWIR observations were sacrificed during these late recovery efforts, which were largely successful; but there may remain small gaps (< 1% of the lunar surface) in the UVVIS/NIR mapping. At specific wavelengths, gaps are larger." END_OBJECT = MISSION_INFORMATION OBJECT = MISSION_HOST INSTRUMENT_HOST_ID = "CLEM1" OBJECT = MISSION_TARGET TARGET_NAME = "MOON" END_OBJECT = MISSION_TARGET END_OBJECT = MISSION_HOST OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "LUCEYETAL1994" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "MCEWENETAL1994" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "NOZETTEETAL1994" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "PIETERSETAL1994" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "REGEONETAL1994" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "SHOEMAKERETAL1994" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "SPUDISETAL1994" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "ZUBERETAL1994" END_OBJECT = MISSION_REFERENCE_INFORMATION END_OBJECT = MISSION END