Investigation Information |
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IDENTIFIER | urn:nasa:pds:context:investigation:mission.deep_space_program_science_experiment::1.1 |
NAME |
DEEP SPACE PROGRAM SCIENCE EXPERIMENT |
TYPE |
Mission |
DESCRIPTION |
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) of the DoD 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 [NOZETTE&GARRETT1994] 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. PRELAUNCH --------- Clementine moved from concept to launch in a little over two years. Mission milestones 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 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 Lunar Orbit Summary =================== Mapping of 100% of the lunar surface was done in two lunar days (two Earth months). In order to obtain full coverage during these two months, the required image overlap for the UVVIS and NIR cameras was ~15% in the down track and ~10% in the cross track directions. This required an inclination of the orbit at 90 degrees plus-or-minus 1 degree with reference to the lunar equator and a periselene of the lunar orbit maintained at an altitude of 425 plus-or-minus 25 km. To provide the necessary cross-track separation for the alternating imaging strips to cover the entire surface of the moon, the orbital period was approximately 5 hours, during which the moon rotated approximately 2.7 degrees beneath the spacecraft. Images were taken and recorded only in the region of periselene, leaving sufficient time to replay the data to Earth. The best data for lunar mineral mapping is obtained if the solar phase angle is less than 30 degrees. The solar phase angle is defined as the angle between the vector to the Sun and the vector to the spacecraft from a point on the Moon's surface. To maximize the time period in which the solar phase angle is less than 30 degrees the plane of the lunar orbit should contain the Moon-Sun line half way through the two-month lunar mapping period. Therefore, insertion into the lunar orbit was selected so that, as the Moon-Sun line changes with Earth's motion about the Sun, the Moon-Sun line will initially close on the orbital plane, and then lie in the orbital plane half-way through the mapping mission. The angle between the Moon-Sun line and the orbital plane was close (less than 5 degrees) for approximately five weeks before becoming zero. Table 1 contains a list of Clementine's orbital parameters. Table 1 Clementine Orbital Parameters ------------------------------------- Orbital Period: 4.970 hr < P < 5.003 hr Altitude of Periselene: 401 km < radius < 451 km Eccentricity: 0.35821 < e < 0.37567 Right Ascension: -3 deg < Omega <+3 deg(referred J2000) Inclination: 89 deg < i < 91 deg Argument of Periselene: -28.4 deg < w < -27.9 deg (1st month) 29.6 deg < w < 29.2 deg (2nd month) Orbit determination and monitoring was done on a continuous basis throughout the lunar pre-mapping phase. The gravitational potential field of the moon has not been fully mapped, and large lunar mass concentrations perturbed the orbit, so maintenance burns were required to maintain the orbit characteristics. The number of these burns was minimized to avoid unnecessary disruptions to the systematic mapping. To this end, required periapsis burns were performed away from periselene in the direction of the near pole. The spacecraft was three-axis stabilized and capable of autonomous, open loop inertial pointing with an accuracy of 0.05 degree, 0.87 milliradian, or better. This accuracy was required to support use of the high resolution camera because of its narrow field of view for imaging selected target sites during the lunar mapping mission. Reconstruction of spacecraft attitude to 0.03 degree was generally achieved. To help accomplish attitude determination, the spacecraft had two inertial measurement units (IMU) and two star trackers. Because of a solar exclusion angle constraint, one of the two star trackers had to be covered during lunar orbit. To meet the aforementioned pointing requirements, during lunar orbit a star tracker image was processed and the spacecraft attitude knowledge was updated at 10 second intervals or less. The spacecraft was able to execute controlled, relative pointing motion about a pointing vector for scanning across targets over a range of 75 milliradians. During lunar imaging, the spacecraft had to maintain a NADIR pointing attitude. This required a greater than 180 degree rotation over the approximately 1.5-2.0 hour period during each lunar orbit. The spacecraft was also required to maintain an angular bias about the X-axis from NADIR to permit an imaging groundtrack parallel but offset from the NADIR groundtrack. The spacecraft was required to point to the Earth center, and to a specified tracking station site on the Earth, for the dumping of data using the high-gain directional antenna. LUNAR ORBITS TYPE A AND B ------------------------- The polar configuration of Clementine's orbit provided significant redundant coverage at the poles. To take advantage of the polar convergence, two types of observational scenarios, designated type A and B, were developed to provide stereo observations at the higher latitudes. Type A orbits (even numbered orbits) made NADIR observations from pole to pole. Type B orbits (odd numbered orbits) made NADIR observations for most of the orbit but would switch to oblique viewing at the north pole for orbit numbers 32-164 and oblique viewing of the south pole for orbit numbers 165-300. The alternating NADIR and oblique observations provide stereo coverage. Oblique viewing was achieved at greater than 50 degrees north and 50 degrees south latitude down to the poles. |
START DATE |
1991-11-19T12:00:00.000Z |
STOP DATE |
1994-05-07T12:00:00.000Z |
REFERENCES |
Asmar, S.W., and R.G. Herrera, Radio Science Handbook, JPL D-7938, Volume 4,
Jet Propulsion Laboratory, Pasadena, CA, 22 January 1993. Lucey, P., P.D. Spudis, M. Zuber, D. Smith, and E. Malaret, Topographic-Compositional Units on the Moon and the Early Evolution of the Lunar Crust, Science, 266, 1855-1858, 1994. McEwen, A., M.S. Robinson, E.M. Eliason, P.G. Lucey, T.C. Duxbury, and P.D. Spudis, Clementine Observations of the Aristarchus Region on the Moon, Science, 266, 1858-1861, 1994. Nozette, S. and H.B. Garrett, Mission Offers a New Look at the Moon and a Near-Earth Asteroid, EOS, Vol. 75, No. 14, p. 161 and 163, 1994. Nozette, S., P. Rustan, L.P. Pleasance, D.M. Horan, P. Regeon, E.M. Shoemaker, P.D. Spudis, C.H. Acton, D.N. Baker, J.E. Blamont, B.J. Buratti, M.P. Corson, M.E. Davies, T.C. Duxbury, E.M. Eliason, B.M. Jakosky, J.F. Kordas, I.T. Lewis, C.L. Lichtenberg, P.G. Lucey, E. Malaret, M.A. Massie, J.H. Resnick, C.J. Rollins, H.S. Park, A.S. McEwen, R.E. Priest, C.M. Pieters, R.A. Reisse, M.S. Robinson, D.E. Smith, T.C. Sorenson, R.W. Vorder Breugge, and M.T. Zuber, The Clementine Mission to the Moon: Scientific Overview, Science, 266, 1835-1839, 1994. Pieters, C., M.I. Staid, E.M. Fischer, S. Thompkins, and G. He, The Sharper View of Impact Craters from Clementine Data, Science, 266, 1844-1848, 1994 Regeon, P.A., R.J. Chapman, and R. Baugh, Clementine -- The Deep Space Program Science Experiment (DSPSE),Paper IAA-L-0501, IAA International Conference on Low-Cost Planetary Missions, Laurel, MD: The Johns Hopkins University Applied Physics Laboratory, 12-15 April 1994. Rustan, P., Flight-Qualifying Space Technologies with the Clementine Mission, EOS, Vol. 75 No. 14, 1 p., 1994. Shoemaker, E., M.S. Robinson, and E.M. Eliason, The South Pole Region of the Moon as Seen by Clementine, Science, 266, 1851-1854, 1994. Spudis, P., R.A. Reisse, and J.J. Gillis, Ancient Multiring Basins on the Moon Revealed by Clementine Laser Altimetry, Science, 266, 1848-1851, 1994 Zuber, M., D.E. Smith, F.G. Lemoine, and G. Neumann, The Shape and Internal Structure of the Moon from the Clementine Mission, Science, Vol. 266, pp. 1839-1843, 1994. |