PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = " 2004-06-15 S.McLaughlin Created 2005-02-03 S.McLaughlin Resolved liens " OBJECT = MISSION MISSION_NAME = "DEEP IMPACT" OBJECT = MISSION_INFORMATION MISSION_START_DATE = 2005-01-12 MISSION_STOP_DATE = 2005-08-03 MISSION_ALIAS_NAME = "DI" MISSION_DESC = " This description was paraphrased from A'Hearn, et al. (2005) [AHEARNETAL2005] with permission from the Deep Impact project. Mission Overview ================ The goal of the Deep Impact mission is to understand the physical and chemical properties of a comet as a function of depth below the surface. To reach this goal, Deep Impact will reproduce the impact of a boulder onto a cometary nucleus at a speed characteristic of collisions in the asteroid belt. The mission will deliver an Impactor spacecraft of approximately 360 kg onto the nucleus of 9P/Tempel 1 at a relative speed of 10.2 km/s. The kinetic energy of the Impactor, about 19 gigajoules, is expected to produce a crater with a diameter of 100 m and a depth of 25 m in about 200 seconds (Shultz and Ernst 2005 [SCHULTZ&ERNST2005] and Richardson, et al. 2005 [RICHARDSONETAL2005]). Deep Impact consists of two spacecraft, launched together on January 12, 2005, and flying together until one day before impact on July 4, 2005. On July 3, the two spacecraft separate and are on a course to impact comet Tempel 1. The Impactor immediately goes into auto-navigation mode using an algorithm that ensures that it will impact the comet in an illuminated area. The Impactor will observe the comet with a visible CCD (ITS) until the impact. Shortly after separation, the Flyby spacecraft performs a trajectory correction maneuver to allow it to pass approximately 500 km below the nucleus, as seen from the Sun. The Flyby spacecraft will record the encounter with the High Resolution telescope's visible CCD (HRIV) and infrared imaging spectrometer (HRII) as well as with the Medium Resolution telescope's visible CCD (MRI). Deep Impact is the eighth mission in NASA's Discovery Program. It was proposed and accepted as a partnership between the University of Maryland, which manages the science and the outreach, the Jet Propulsion Laboratory, which manages the hardware development and flight operations, and Ball Aerospace and Technologies Corporation, which provides the hardware. The Science Data Center for the mission is located at Cornell University. The center maintains all data for the mission, including ground-calibrations, from all instruments accessible All data are accessible over the Internet to every member of the Deep Impact science team. For a detailed description of the mission see A'Hearn, et al. (2005) [AHEARNETAL2005] and Blume (2005) [BLUME2005]. For discussions of the science objectives of the project and expected results, see Mastrodemos, et al. (2005) [MASTRODEMOSETAL2005], Hampton, et al. (2005) [HAMPTONETAL2005], Klaasen, et al. (2005) [KLAASENETAL2005], Belton, et al. (2005) [BELTONETAL2005], Lisse, et al. (2005) [LISSEETAL2005], Sunshine, et al. (2005) [SUNSHINEETAL2005], Richardson, et al. (2005) [RICHARDSONETAL2005], Schultz and Ernst (2005) [SCHULTZ&ERNST2005], Thomas, et al. (2005) [THOMASETAL2005], Meech, et al. (2005) [MEECHETAL2005], Yoemans, et al. (2005) [YEOMANSETAL2005], and McFadden, et al. (2005) [MCFADDENETAL2005]. Mission Phases ============== Information in this section is based on a publication by Klaasen, et al. (2005) [KLAASENETAL2005] about the anticipated flight data. This section will be updated as flight data are archived into the PDS. Four mission phases are defined for each period of significant spacecraft activity periods. These are Cruise, Approach, Tempel 1 Encounter, and Post-Encounter. Several phases are divided into subphases. A brief description of each phase is provided below. For detailed descriptions of the phases, subphases, and expected data see Klaasen, et al. (2005) [KLAASENETAL2005]. CRUISE ------ Mission Phase Start Time : 2005-01-12 Mission Phase Stop Time : 2005-05-04 (Impact-60 days) The cruise begins at the launch vehicle lift-off and ends 60 days before the impact with Tempel 1 on July 4, 2005 at 06:08 UTC. This phase includes spacecraft separation from the launch vehicle, establishment of attitude, communications, and tracking of the spacecraft, and activation and checkout of the spacecraft subsystems. During this phase, instrument calibration is planned to begin within a few days after launch and will occur approximately every month. Calibration targets include the Moon, Earth, stars, nebulae, and galactic clusters. The duration of this phase is 126 days. APPROACH -------- Mission Phase Start Time : 2005-05-04 (Impact-60 days) Mission Phase Stop Time : 2005-07-03 (Impact-26 hours) Scientific data acquisition begins during the approach phase. The objectives of this phase are to determine the size of the nucleus, map the albedo, color and spectral variations of the surface, determine the rotational state of the nucleus, and monitor the activity of the nucleus. Other objectives include identifying large-scale structure in the coma, mapping the evolution of the inner coma over a full rotation period, and searching for satellites to constrain the mass of the nucleus. During this period, the HRII, HRIV, and MRI instruments will acquire data at decreasing sampling frequencies. During this phase, the solar phase angle of the nucleus increases by about 0.5 degree/day, beginning at 28 degrees and reaching 60 degrees at Impact minus 7 days. The nominal 6-km diameter nucleus will by spatially resolved, to one pixel, by the HRIV instrument about 3 days before the impact. Throughout this phase, the nucleus is expected to unresolved by the HRII and MRI instruments. TEMPEL 1 ENCOUNTER ------------------ Mission Phase Start Time : 2005-07-03 (Impact-26 hours) Mission Phase Stop Time : 2005-07-06 (Impact+60 hours) The Tempel 1 encounter phase is composed of four subphases, based on the types of planned observation sequences: - Pre-impact : Impact-25 hours to Impact-2 seconds - Impact : Impact-3 seconds to Impact+24 seconds - Post-Impact : Impact+24 seconds to Impact+760 seconds* - Lookback : Impact+760 seconds* to Impact+60 hours * = Shield Mode starts at I+760 seconds and extends to I+40 minutes During the pre-impact subphase, the Impactor is released from the Flyby at a distance of 864,000 km from the comet. The Impactor ITS begins acquiring and transmitting over an S-band link to the Flyby spacecraft. The frequency of the data sampling increases as the resolution improves and impact approaches. The pixel scales of the four instruments as a function of time before impact are: -- Pixel Scale (meters) -- Time ITS HRIV MRI HRII ------- ----- ----- ----- ----- I-20 hr 7200 ~1480 7350 ~7000 I-1 hr 363 90 453 440 I-2 s 0.1 17 86 86 During the impact subphase, the instruments on the Flyby spacecraft record the development of the crater and start of the ejecta flow. The pixel scales of the instruments as a function time are: Pixel Scale (meters) Time HRIV MRI HRII ------- ------ ------ ----- I-3 s 17 86 86 I+1 s 17 85 86 I+24 s 17 84 83 During the post-impact subphase, the crater develops and ejecta continues to flow outward. Crater formation is expected to take nominally four minutes. The instruments on the Flyby spacecraft continue to records these processes but with decreasing sampling frequency. At Impact+760 seconds, the Flyby goes into shield mode (SM) to protect the instruments from dust impacts during the closest approach of Tempel 1. Shield mode continues through I+40 minutes. During this phase, the pixel scales of the instruments as a function time are: Pixel Scale (meters) Time HRIV MRI HRII ------- ------ ------ ------ I+24 s 17 84 83 I+470 s 7 38 39 SM 1.4 7 7 The lookback subphase begins with the Flyby spacecraft in shield mode. It remains in this mode for about 22 minutes after closest approach until the dust-impact hazard zone has been passed. At this time, the spacecraft performs an attitude maneuver to point its instruments back toward the nucleus. The HRIV instrument continues to image the impact site for another 12 hours and the MRIV and HRII instruments continue to record the impact for 60 hours. During this phase, the pixel scales of the instruments as a function time are: Pixel Scale (meters) Time HRIV MRI HRII ------- ------ ------ ------ SM+31 m 36 ~181 ~190 SM+2 hr 145 725 744 SM+12 hr 871 4354 4370 SM+24 hr n/a 8709 8725 SM+36 hr n/a 13063 13080 SM+48 hr n/a 17418 17435 SM+60 hr n/a 21772 21790 POST-ENCOUNTER ------------ Mission Phase Start Time : 2005-07-06 (Impact+60 hours) Mission Phase Stop Time : 2005-08-03 During the post-encounter phase, the Flyby spacecraft transmits data stored in buffer memory back to Earth, Tempel 1 is monitored, and several cruise calibrations are performed. The mission may be extended for study and Flyby of another comet or asteroid. " MISSION_OBJECTIVES_SUMMARY = " The overall scientific objectives of the Deep Impact mission are to: 1) Dramatically improve the knowledge of the physical characteristics of cometary nuclei and directly assess the interior of cometary nucleus by producing an high- velocity impact on the surface of comet 9P/Tempel 1. 2) Determine properties of the surface layers such as density, strength, porosity, and composition from the resultant crater and its formation. 3) Study the relationship between the surface layers of a cometary nucleus and the possibly pristine materials of the interior by comparison of the interior of the crater with the surface before impact. 4) Improve our understanding of the evolution of cometary nuclei, particularly their approach to dormancy, by comparing the interior and the surface. " END_OBJECT = MISSION_INFORMATION OBJECT = MISSION_HOST INSTRUMENT_HOST_ID = "DIF" OBJECT = MISSION_TARGET TARGET_NAME = "9P/TEMPEL 1 (1867 G1)" END_OBJECT = MISSION_TARGET OBJECT = MISSION_TARGET TARGET_NAME = "CALIBRATION" END_OBJECT = MISSION_TARGET END_OBJECT = MISSION_HOST OBJECT = MISSION_HOST INSTRUMENT_HOST_ID = "DII" OBJECT = MISSION_TARGET TARGET_NAME = "9P/TEMPEL 1 (1867 G1)" END_OBJECT = MISSION_TARGET OBJECT = MISSION_TARGET TARGET_NAME = "CALIBRATION" END_OBJECT = MISSION_TARGET END_OBJECT = MISSION_HOST OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "AHEARNETAL2005" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BELTONETAL2005" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BLUME2005" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "HAMPTONETAL2005" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "KLAASENETAL2005" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "LISSEETAL2005" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "MASTRODEMOSETAL2005" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "MCFADDENETAL2005" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "MEECHETAL2005" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "RICHARDSONETAL2005" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "SCHULTZ&ERNST2005" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "SUNSHINEETAL2005" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "THOMASETAL2005" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "YEOMANSETAL2005" END_OBJECT = MISSION_REFERENCE_INFORMATION END_OBJECT = MISSION END