PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "2004-06-15 S.McLaughlin Created 2005-02-03 S.McLaughlin Resolved liens from Oct 2004 thermal-vac review 2005-12-21 S.McLaughlin Updated mission stop date, impact time, and description of mission phases 2006-02-20 S.McLaughlin Added post-encounter cruise section per B.Semenov/NAIF; added Feb 10 aliveness test. 2006-05-26 DI:McLaughlin Resolved liens from Apr 2006 peer review " OBJECT = MISSION MISSION_NAME = "DEEP IMPACT" OBJECT = MISSION_INFORMATION MISSION_START_DATE = 2005-01-12 MISSION_STOP_DATE = 2005-07-13 MISSION_ALIAS_NAME = "DI" MISSION_DESC = " Mission Overview ================ The goal of the Deep Impact mission was to understand the physical and chemical properties of a comet as a function of depth below the surface. To reach this goal, Deep Impact reproduced the impact of a boulder onto a cometary nucleus at a hypervelocity speed, characteristic of collisions in the asteroid belt. The mission delivered an impactor spacecraft of approximately 360 kg onto the nucleus of 9P/Tempel 1 at a relative speed of 10.3 km/s. The kinetic energy of the impactor, about 19 gigajoules, produced a crater with a diameter between 100 and 250 meters in about 200 seconds (A'Hearn, et al. (2005) [AHEARNETAL2005A], Schultz and Ernst (2005) [SCHULTZ&ERNST2005], and Richardson, et al. (2005) [RICHARDSONETAL2005]). The impact was imaged by the flyby spacecraft. Initial results from the encounter are discussed by A'Hearn, et al. (2005) [AHEARNETAL2005A], who estimated an impact time of about 05:44:36 UTC on July 4, 2006 2005 (Earth-received time 05:52:02 UTC). The approach solar angle for both spacecraft was about 62.9 degrees. Deep Impact consisted of two spacecraft, launched together on 12 January 2005, and which flew together until one day before impact on 4 July 4 July 4, 2005. On July 3, the two spacecraft separated while on a course to impact comet Tempel 1. The They immediately went into auto-navigation mode using an algorithm that ensured that itthe impactor would impact hit an illuminated area of the nucleus. The impactor observed the comet with a visible CCD (ITS) until several seconds before the impact. Shortly after separation, the flyby spacecraft performed a trajectory correction maneuver so that it passed approximately 500 km below the nucleus, as seen from the sun. The flyby spacecraft recorded the encounter and the impact 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). Initial results were reported byin A'Hearn, et al. (2005) [AHEARNETAL2005A] in Science. The mission, science objectives, instrumentation, and expected results were described in a special edition of Space Science Reviews (SSR) dedicated to the Deep Impact. See A'Hearn, et al. (2005) [AHEARNETAL2005B], Blume (2005) [BLUME2005], 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], and Yeomans, et al. (2005) [YEOMANSETAL2005], and McFadden, et al. (2005) [MCFADDENETAL2005]. These SSR papers were included on the documentation volume, DIDOC_1000, of the Deep Impact archive. The world-wide Earth-based observing campaign for the mission was described by Meech, et al. (2005) [MEECHETAL2005] in the SSR edition. McFadden, et al. (2005) [MCFADDENETAL2005] discussed the Education and Public Outreach component of the mission. Calibration of Deep Impact instruments and the calibration pipeline were discussed in Klaasen, et al. (2006) [KLAASENETAL2006]. This calibration paper was included on the Deep Impact documentation volume. Mission Phases ============== Three Four primary phases are defined for the archive of flight-related data: thermal-vacuum ground calibrations (TV), cruise, and 9P encounter, and 9P Post Encounter Cruise.. THERMAL-VACUUM GROUND CALIBRATIONS (TV1-TV5) -------------------------------------------- Data acquired during ground-based thermal-vacuum tests TV1 through TV4 TV5 were archived in the PDS. The science team used these data is the change above correct? for pre-flight calibration analysis. TV# Instruments Tested Test Period --- -------------------- -------------------- TV1 HRII 2002 June-July TV2 HRII, HRIV 2002 August-September TV3 ITS 2003 January TV4 HRII, HRIV, MRI 2003 February-March TV5 HRII, HRIV, MRI, ITS 2004 June-July CRUISE ------ Mission Phase Start Time : 2005-01-12 (DOY 012) Mission Phase Stop Time : 2005-04-30 (DOY 120, Impact-65 days) The cruise phase began at the lift-off of the launch vehicle. This phase included checkout of the HRII, HRIV, and MRI instruments in the second and third days after launch. Science calibrations began shortly after checkout, then were performed approximately once every month. The best sets of data for science calibrations were acquired during the April, May, and June 2005 and during the post-impact calibration in July. Calibration targets included the Moon, Earth, stars, nebulae, and galactic clusters. Comet 9P/Tempel 1 was not imaged for scientific purposes during this phase. Details of the cruise calibrations are available in the 'Deep Impact Instrument Calibration' paper by Klaasen, et al. (2006) [KLAASENETAL2006]. 9P ENCOUNTER ------------ Mission Phase Start Time : 2005-05-01 (DOY 121, Impact-64 days) Mission Phase Stop Time : 2005-07-13 (DOY 194, Impact+9 days) Scientific data acquisition began and ended during this phase. On the approach to 9P/Tempel 1, the objectives were 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 included 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 (none were found). During approach, the HRII, HRIV, and MRI instruments acquired data at decreasing increasing sampling frequencies, and is the change above correct? science calibrations were performed in early May and June. During approach, the solar phase angle of the nucleus increased by about 0.5 degree/day, beginning at 28 degrees and reaching 60 degrees at impact minus 7 days. About 3 days from impact the HRIV instrument spatially resolved the nucleus. The HRII and MRI instruments did not resolve the nucleus until the day before impact. Due to pointing errors, the HRII instrument was not imaging the comet until June 20. About 24 hours before the scheduled impact, the flyby craft released the impactor at a distance of about 864,000 km from the comet. The impactor ITS instrument began acquiring and transmitting data over an S-band link to the flyby craft. The frequency of data sampling increased as impact approached and the resolution improved. About 18 hours before impact, a small set of calibration data (darks and internal stimulator frames) were acquired for each instrument. The pixel scales of the four instruments as a function of time before impact were: Pixel Scale (meters/pixel) 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 The last ITS image was taken about 05:44:31 UT with an estimated pixel scale of 0.26 meters/pixel. During the impact, the instruments on the flyby craft recorded the development of the crater and start of the ejecta flow. As impact processes continued, HRII, HRIV, and MRI recorded data at decreasing sampling rates. At impact+760 seconds, the flyby craft This is the second time we have read that sampling rates were decreasing; is this correct? And whether rates decreased or increased is not meaningful unless we know the initial sampling rates. Perhaps the rates themselves could be included in this summary; then we wouldn't have to interpret "increase" and "decrease". went into shield mode (SM) to protect the instruments from dust impacts during closest approach of Tempel 1. Shield mode continued through I+40 minutes. During the encounter event, pixel scales of the instruments were: Pixel Scale (meters/pixel) Time HRIV MRI HRII ------- ------ ------ ------ I-3 s 17 86 86 I+1 s 17 85 86 I+24 s 17 84 83 I+24 s 17 84 83 I+470 s 7 38 39 SM 1.4 7 7 Perhaps you need to explain more clearly what "shield mode" was; I would have assumed no data collection, yet all instruments appear to be continuing with data collection at the best resolution of the encounter. If you meant these were the resolution just before SM, then perhaps substituting something like "I+759 s" would be better than "SM" in the "Time" column. 760 seconds plus 22 minutes does not equal 40 minutes, even accounting for the "about" in front of "22" (below). The flyby craft remained in shield mode for about 22 minutes, through closest approach and until the dust-impact hazard zone had been passed. After shield mode, the spacecraft performed an attitude maneuver, flipping over and pointing its instruments back toward the nucleus. During lookback mode, the HRIV instrument continued to image the impact site for another 12 hours. The MRIV and HRII instruments continued to monitor the comet for 60 hours, until 6 July 18:00 UT. During this subphase, the pixel scales of the instruments were: Pixel Scale (meters/pixel) 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 At impact, data determined to be less critical were stored in buffer memory. During lookback, the flyby craft transmitted these stored data back to Earth. However, the buffers on one of the processors were not cleared of impact data, causing some lookback images to be lost. The last science calibration started about two days after impact and continued until 13 July, thus concluding the scientific activities of the mission. 9P POST-ENCOUNTER CRUISE ------------------------ Mission Phase Start Time : 2005-07-13 (DOY 194, Impact+9 days) Mission Phase Stop Time : 2009 This phase begins after the end of the DI mission; should this section be included? Since the flyby spacecraft and its instruments survived the encounter with Tempel 1, a trajectory correction maneuver was performed on July 20 to put the spacecraft into an orbit for Earth return in late 2007, favoring an extended mission. On August 9, 2005, the flyby craft was put into sleep mode. On February 10, 2006, an aliveness test was performed on the spacecraft. The results of the wake-up and pointing activities indicated it was healthy for an extended mission. In the Deep Impact SPICE archive, the SP-kernel providing the trajectory of the flyby spacecraft extends through 2009, and the SP-kernel providing the ephemeris of Tempel 1 extends through 2050. There are no science data from the science instruments for this phase. Mission Data ============ The following mission-related data are archived at the PDS: - Pre-launch, thermal-vac calibration (HRII, HRIV, MRI, ITS) - Raw science and calibration imaging from flight (HRII, HRIV, MRI, and ITS) - Reduced science imaging from flight (HRII, HRIV, MRI, and ITS), initially in physical units of radiance (uncleaned); cleaned, radiance and I-over-F data sets are planned for a future delivery - Raw and reduced navigation images from flight (HRIV, MRI, ITS) - Radio science data from flight - SPICE data, including 5-Hz telemetry from the Attitude Determination and Control System (ADCS) as a CK C-kernel - Higher-level products, such as a shape model, deconvolved HRIV images, and spectral image cubes (planned for a future delivery) - Select data from the Earth-based observing campaign This mission overview was paraphrased from A'Hearn, et al. (2005) [AHEARNETAL2005B] with permission from the Deep Impact project. " MISSION_OBJECTIVES_SUMMARY = " The overall scientific objectives of the Deep Impact mission were to: 1) Dramatically improve the knowledge of the physical characteristics of cometary nuclei and directly assess the interior of a cometary nucleus by producing a 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 comparing the interior of the crater with the surface prior to impact; and 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 = "AHEARNETAL2005A" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "AHEARNETAL2005B" 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 = "KLAASENETAL2006" 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