Mission Information
MISSION_START_DATE 2005-01-12T12:00:00.000Z
MISSION_STOP_DATE 2005-07-13T12:00:00.000Z
The mission overview 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 reproduced                  
    the impact of a boulder onto a cometary nucleus at a 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 10.2 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],           
    Shultz and Ernst (2005) [SCHULTZ&ERNST2005], and                          
    Richardson, et al. (2005) [RICHARDSONETAL2005]).                          
    Initial results of the encounter are discussed by                         
    A'Hearn, et al. (2005) [AHEARNETAL2005A], which estimated                 
    an impact time of 4 July 2005 at about 05:44:36 UTC                       
    (Earth-received time 05:52:02 UTC).                                       
    Deep Impact consisted of two spacecraft, launched together                
    on 12 January 2005, and flew together until one day before                
    impact on 4 July 4 2005.  On July 3, the two spacecraft separated         
    while on a course to impact comet Tempel 1.  The Impactor                 
    immediately went into auto-navigation mode using an algorithm             
    that ensured that it would impact the comet in an illuminated area.       
    The Impactor observed the comet with a visible CCD (ITS)                  
    until seconds before the impact.  Shortly after separation,               
    the Flyby spacecraft performed a trajectory correction maneuver           
    to allow it to pass 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).                      
    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.                                             
    The mission, science objectives, instrumentation, and expected results    
    are described in a special edition of Space Science Reviews (SSR)         
    dedicated to the Deep Impact.  See A'Hearn, et al. (2005)                 
    [AHEARNETAL2005], 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 are included on the documentation volume of the          
    Deep Impact archive.                                                      
    Plans for the world-wide Earth-based observing campaign for the           
    mission are described by Meech, et al. (2005) [MEECHETAL2005]             
    in the SSR edition.  McFadden, et al. (2005) [MCFADDENETAL2005]           
    discuss the Education and Public Outreach component of Deep Impact.       
    Analysis of TV and flight calibration data and Deep Impact calibration    
    pipeline are discussed in Klaasen et al. (2006) [KLAASENETAL2006].        
    This Deep Impact calibration paper is included on the documentation       
    volume of the Deep Impact archive.                                        
  Mission Phases                                                              
    Information in this section is based on a publication about the           
    anticipated flight data by Klaasen, et al. (2005) [KLAASENETAL2005].      
    This section will be updated as flight data are archived into             
    the PDS.                                                                  
    Although several phases were defined for mission operations,              
    four general phases are defined for the archive of flight-related         
    data:  thermal-vacuum ground calibrations (TV), 9P cruise, and            
    9P encounter, and 9P post-encounter cruise.                               
    THERMAL-VACUUM GROUND CALIBRATIONS (TV1-TV5)                              
      Currently, data acquired during TV1 through TV4 are archived            
      in the PDS.  The science team used these data for pre-flight,           
      calibration analysis.  TV5 data is expected to be archived              
      in 2006.                                                                
      TV#   Instruments Tested    Start Time  Stop Time                       
      ---   --------------------  ----------  ----------                      
      TV1   HRII                  2002-06-27  2002-07-02                      
      TV2   HRII, HRIV            2003-08-15  2002-09-03                      
      TV3   ITS                   2003-01-16  2003-01-30                      
      TV4   HRII, HRIV, MRI       2003-02-23  2003-03-12                      
      TV5   HRII, HRIV, MRI, ITS  2004-06-30  2004-07-01                      
    9P CRUISE                                                                 
      Mission Phase Start Time  : 2005-01-12 (DOY 012)                        
      Mission Phase Stop Time   : 2005-04-30 (DOY 120, Impact-65 days)        
      The 9P cruise phase began at the lift-off of the launch vehicle.        
      This phase includes checkout of the HRII, HRIV, and MRI instruments     
      in the first 2-3 days after launch.  Science calibrations began         
      shortly after checkout, then were performed approximately once          
      every month.  The best sets of science calibrations were                
      acquired during the April, May, and June calibrations and               
      the post-impact calibration in July.  Calibration targets               
      include 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 Calibration paper by Klaasen et al. (2006)           
    9P ENCOUNTER                                                              
      Mission Phase Start Time  : 2005-05-01 (DOY 178, Impact-64 days)        
      Mission Phase Stop Time   : 2005-07-13 (DOY 194, Impact+9 days)         
      Scientific data acquisition began during this phase.  On the            
      approach of 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         
      sampling frequencies, and 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 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.  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 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 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 impact 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                                     
      The Flyby remained in shield mode for about 22 minutes, through         
      closest approach and until the dust-impact hazard zone has been         
      passed.  While in this mode, the spacecraft performed an attitude       
      maneuver to point its instruments back toward the nucleus.  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             
      phase, 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                                    
      During lookback, the Flyby began transmitting data stored in            
      buffer memory back to Earth.  However, near the end of Tempel 1         
      imaging, the buffers on one of the processors were not cleared,         
      so some data were 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  : 2005-05-14 (DOY 194, Impact+9 days)         
      Mission Phase Stop Time   : 2009                                        
      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 which favors an extended mission.         
      On August 9, 2005, the Flyby 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.                       
      The SPICE SP-kernel providing the trajectory the Flyby                  
      spacecraft extends to 2009.  The SP-kernel providing the                
      ephemeris of Tempel 1 extends through 2050.                             
  Mission Data                                                                
    The following data acquired are being archived at the PDS:                
    - TV imaging (HRII, HRIV, MRI, ITS)                                       
    - Raw science imaging from flight (HRII, HRIV, MRI, ITS)                  
    - Reduced science imaging from flight (HRII, HRIV, MRI, ITS),             
      initially in physical units of radiance (uncleaned); cleaned,           
      radiance and I-over-F sets are planned for 2006                         
    - Raw navigation imaging from flight (MRI, ITS)                           
    - Telemetry (5-Hz) from the Attitude Control and Determination            
      System (ADCS)                                                           
    - Radio science data from flight                                          
    - SPICE data                                                              
    - Select data from the Earth-based observing campaign
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.