Mission Information
MISSION_NAME EPOXI
MISSION_ALIAS EPOXI
MISSION_START_DATE 2007-09-26T12:00:00.000Z
MISSION_STOP_DATE 2011-02-06T12:00:00.000Z
MISSION_DESCRIPTION
The following material was adapted from the EPOXI mission web site.

  Mission Overview
  ================
    EPOXI, a Mission of Opportunity for the NASA Discovery program, is the
    combination of two independently proposed scientific investigations
    utilizing the Deep Impact (DI) flyby spacecraft as an extended mission:
    EPOCh (Extrasolar Planet Observation and Characterization) and DIXI
    (Deep Impact eXtended Investigation).

    From 22 January through 31 August 2008, EPOCh took advantage of the
    permanent on-orbit defocus of the High Resolution telescope (HRI) by
    using the High Resolution Visible CCD (HRIV) to collect over 172,000
    usable, photometric-quality, visible light images of eight known
    transiting planet systems (hot Jupiters):  HAT-P-4, HAT-P-7, GJ 436,
    TrES-2, TrES-3, XO-2, XO-3, and WASP-3.  Time series of continuous
    50-second integrations in a subframe mode of 128x128 or 256x256 pixels
    with the clear #6 optical filter extending from 350 to 1000 nanometers
    were used to observe each system for about three weeks, typically
    covering five or more transits as well as secondary eclipses.  An
    exception is XO-3 which was observed only briefly before the spacecraft
    unexpectedly entered safe mode.  The transiting planet systems were
    observed in the integrated light of the planet and star; no spatially
    resolved image of the planet was possible.  The out-of-focus HRI
    telescope defocuses the images to about 10 pixels or 4 arcseconds at
    full-width half-max and introduces visible structure.  Each target
    series was typically bracketed by a set of dark and internal stimulator
    lamp frames to monitor changes in the HRIV CCD detector for calibration
    purposes.

    On 18-19 March, 28-29 May, and 4-5 June 2008, EPOCh also observed Earth
    with the HRIV CCD and the High Resolution Infrared Imaging Spectrometer
    (HRII) to characterize it as an analog for extrasolar planets.  The
    observations comprised imaging in seven optical narrow-band (100
    nanometer) filters and 2- to 5-micron infrared spectroscopy over a full
    Earth rotation.  The optical images used a 512x512-pixel subarray of
    the HRIV CCD detector at a scale of about 0.4 arcsec/pixel, and each
    frame of the HRII spectrometer was 512 (wavelength) by 128 pixels
    (spatial, 2 arcsec/pixel).  HRIV CCD images were acquired once every
    hour with three filters centered on 350, 750 and 950 nanometers and
    once every 15 minutes with the 450-, 550-, 650- and 850-nanometer
    filters.  Infrared spectra were obtained twice per hour by scanning the
    slit of the HRII spectrometer over the earth, using three scans to
    ensure coverage of the entire disk; the slit was aligned perpendicular
    to the terminator during the scans.  The spacecraft orbit was
    approximately in the plane of the ecliptic which provided an equatorial
    view of Earth with about 62 to 77 percent of the disk illuminated. Each
    of the three Earth observing periods lasted approximately 24 hours.
    During the 29 May observation, the Moon transited Earth as seen from
    the spacecraft (0.3 AU from Earth).

    EPOCh continued observations in 2009.  These included Earth at both
    northern and southern latitudes using the same sequence from 2008.
    Additionally that same sequence was used to observe Mars with the
    HRII and HRIV instruments in November 2009.  On 5-8 October 2009, EPOCh
    continuously imaged the exoplanet microlensing event MOA-2009-BLG-266
    by reusing the sequence from the HRIV exoplanet transit observations
    in 2008.

    DIXI consisted of a flyby of comet 103P/Hartley 2 in November 2010 to
    study a second comet with the same set of instrumentation as was used by
    the Deep Impact mission during the encounter with comet 9P/Tempel 1 in
    July 2005.  Closest approach to 103P/Hartley 2 occurred at 13:59:47.31
    UTC on 4 November 2010 at a distance of 694 km and a flyby speed of
    12.3 km/s.  The spacecraft flew under the comet on a slightly northward
    trajectory in an ecliptic reference frame, then rotated to keep the
    body-mounted instruments pointed at the comet for departure imaging.
    Over 100,000 visible images and IR spectra of 103P/Hartley 2 were taken,
    beginning on 5 September, 60 days before encounter, and continuing
    through 26 November 2010, three weeks after the flyby.

    103P/Hartley 2 passed perihelion on 28 October, only seven days before
    DIXI flyby, and was known to be more active than comet 9P/Tempel 1.
    Since the DIXI encounter occurred at a smaller heliocentric distance
    than Deep Impact, the project realized a significant improvement to
    the signal-to-noise ratio of all visible and IR measurements.

    Finally various in-flight calibrations were performed throughout the
    EPOXI mission, from October 2007 to February 2011.


  Mission Phases
  ==============
    The EPOXI mission has five main phases:  Cruise 1, EPOCh, Cruise 2,
    DIXI/Hartley 2 Encounter, and Cruise 3.  Most phase include several
    events or activities.  The timeline for the mission and description
    of the phases and events are described below.

    Mission Timeline
    ----------------
      Phases and Events                     Start Date/DOY  Stop Date/DOY
      ------------------------------------  --------------  --------------
      Cruise 1                              2007-09-26/269  2008-01-21/021
        Spacecraft Wakeup                   2007-09-26/269  2007-09-26/269
        Instrument Checkout                 2007-10-04/277  2007-10-04/277
        EPOCh Photometry Test               2007-11-04/308  2007-11-09/313
        Instrument Checkout Retest          2007-12-04/338  2007-12-04/338
        HRIV Scattered Light Calibration    2007-12-17/351  2007-12-17/351
        Lunar Calibration                   2007-12-29/363  2007-12-29/363
        Earth Flyby #1                      2007-12-31/365  2007-12-31/365
        Standard Cruise Calibration         2008-01-09/009  2008-01-09/009
        HRII Dark Retake for Lunar Cal      2008-01-16/016  2008-01-17/017

      EPOCh                                 2008-01-22/022  2008-08-31/244
        Exoplanet Transit Observations      2008-01-22/022  2008-08-31/244
        Earth Observations (#1)             2008-03-18/078  2008-03-19/079
                           (#4)             2008-05-28/149  2008-05-29/150
                           (#5)             2008-06-04/156  2008-06-05/157
        Standard Cruise Calibration         2008-06-23/175  2008-06-25/177

      Cruise 2                              2008-09-01/245  2010-09-02/245
        HRII Reciprocity Test               2008-09-18/262  2008-09-18/262
        HRII Dark Flush Test                2008-09-26/270  2008-09-26/270
        HRII Encounter Darks Rerun          2008-10-02/276  2008-10-02/276
        HRII Dark Gap Test                  2008-10-08/282  2008-10-08/282
        Interplanetary Internet Test        2008-10-15/289  2010-11-15/319
        HRIV PSF Calibration                2008-12-17/352  2008-12-17/352
        Earth Flyby #2                      2008-12-29/364  2008-12-29/364
        HRII Subframe Gain Calibration      2009-01-26/026  2009-01-26/026
        EPOCh Earth North Pole              2009-03-27/086  2009-03-28/087
        HRII Lunar Radiometry & Flats       2009-06-01/152  2009-06-02/153
        HRII Lunar Rad. & Antisat Filter    2009-06-09/160  2009-06-09/160
        HRII Linearity Calibration          2009-06-18/169  2009-06-18/169
        Distant Earth Flyby #1              2009-06-29/180  2009-06-29/180
        EPOCh Earth South Pole #1 (partial) 2009-09-27/270  2009-09-28/271
        Checkout after HRI Turnoff          2009-09-30/273  2009-09-30/273
        HRIV Mechanical Checkout            2009-10-01/274  2009-10-01/274
        EPOCh Earth South Pole #2 (full)    2009-10-04/277  2009-10-05/278
        EPOCh Microlensing MOA-2009-BLG-266 2009-10-05/278  2009-10-08/281
        HRII Radiometric Cal #1 (Beta Hyi)  2009-10-13/286  2009-10-24/297
        HRII Dark Subframe Test             2009-11-20/324  2009-11-20/324
        EPOCh Mars                          2009-11-20/324  2009-11-21/325
        HRII Lunar Flats/Radiometric Cal #1 2009-12-05/339  2009-12-05/339
        HRII Lunar Flats/Radiometric Cal #2 2009-12-12/346  2009-12-12/346
        HRII Lunar South Pole Radiometry    2009-12-18/352  2009-12-18/352
        Distant Earth Flyby #2              2009-12-28/362  2009-12-28/362
        Standard Cruise Calibration         2010-02-16/047  2010-02-16/047
        HRII NoSave Flush Test              2010-04-20/110  2010-04-20/110
        HRII Radiometric Cal #2 (Beta Hyi)  2010-05-03/123  2010-05-17/137
        Earth Flyby #3                      2010-06-27/178  2010-06-27/178
        MRI Dosido Fast Slew Test           2010-07-12/193  2010-07-12/193

      DIXI/Hartley 2                        2010-09-03/246  2010-11-28/332
        HRIV PSF Calibration                2010-09-03/246  2010-09-03/246
        Approach Imaging                    2010-09-05/248  2010-11-03/307
          E-60 to E-50 days (VIS only)      2010-09-05/248  2010-09-15/258
          E-50 to E-40 days (VIS only)      2010-09-15/258  2010-09-25/268
          HRII Spectrometer Cooldown        2010-09-25/268  2010-10-01/274
          Pre-Encounter Standard Cruise Cal 2010-09-28/271  2010-09-29/272
          E-34 to E-8 days (Start HRII)     2010-10-01/274  2010-10-27/300
          E-8 days to E-18 hours            2010-10-27/300  2010-11-03/307
        Encounter Imaging                   2010-11-03/307  2010-11-06/310
          E-18 hours to E+2 days            2010-11-03/307  2010-11-06/310
          Flyby and Closest Approach        2010-11-04/308  2010-11-04/308
        Departure Imaging                   2010-11-06/310  2010-11-26/330
          E+2 to E+12 days                  2010-11-06/310  2010-11-16/320
          E+12 to E+21 days                 2010-11-16/320  2010-11-26/330
        Post-Encounter Standard Cruise Cal  2010-11-27/331  2010-11-28/332

      Cruise 3                              2010-11-29/333  2011-02-06/037
        HRII 50-Frame Extended Linear. Cal  2011-02-05/036  2011-02-06/037
    ----------------------------------------------------------------------


    Cruise 1
    --------
      Start Time : 2007-09-26 (DOY 269)
      Stop Time  : 2008-01-21 (DOY 021)

      Spacecraft Wakeup and Instrument Checkout
      -----------------------------------------
        After 25 months in hibernation, the Deep Impact spacecraft was
        woken on 26 September 2007.  The spacecraft functioned as
        expected.  On 4 October 2007, the HRII (High Resolution Infrared
        Imaging Spectrometer), HRIV (High Resolution Visible CCD), and
        MRI (Medium Resolution Visible CCD) instruments were turned on
        for the first time in more than two years.  A brief checkout
        test was performed and confirmed the mechanical components were
        functioning.  The three science instruments exhibited nominal
        behavior of background levels although several HRII detector
        pixels had a different response when compared to Deep Impact.
        After checkout, several Trajectory Correction Maneuvers (TCM)
        were performed in November and December 2007 to alter the
        trajectory of the spacecraft to put it on course to flyby the
        Earth for a gravity-assist to reach comet 103P/Hartley 2 in 2010.

      EPOCh Photometry Test
      ---------------------
        On 4-9 November 2007, EPOCh photometry tests were performed.
        During these tests, the HRIV instrument observed a bright (V=9)
        visual binary star (HD 80607) for 12 continuous hours to check
        pointing and photometric stability.  The observations were taken
        using the 256-by-256 sub-array mode of the HRIV CCD.  The
        spacecraft successfully captured the star images and held them on
        the sub-array for the full duration of the test.  However the
        images were unexpectedly offset by about 59 microradian (12.2
        arcsec).  This was due to stellar aberration which was not
        included for stellar observations during the Deep Impact mission.
        After correcting for aberration, the spacecraft pointing was
        within specifications.

      Instrument Checkout Retest
      --------------------------
        Instrument Checkout Retest:  On 4 December 2007 a retest of the
        October instrument checkout sequence was performed for the three
        science instruments.  The focus of this retest was to determine
        if HRII pixels that had an odd response during checkout had
        changed or improved.

      HRIV Scattered Light Calibration
      --------------------------------
        On 17 December 2007, a calibration for scattered light using
        Earth's moon was performed for the HRIV instrument.  Many of these
        images were obtained with the moon outside but near the field of
        view of the HRIV CCD to allow analysis of the amount of light that
        is scattered into the field of view from bright objects just
        outside or within the field of view.

      Lunar Calibration and Earth Flyby #1
      ------------------------------------
        On 29 December 2007, as the spacecraft approached Earth, the HRIV,
        HRII, and MRI instruments used the Moon as a target to acquire
        data for recalibration purposes.  Due to a minor error in the
        lunar calibration sequence, a series of HRII dark frames were not
        recorded.  A retest to acquire the missing HRII darks was
        scheduled for 16 January 2008.  At 19:29:20.66 UTC on 31 December
        2007, the flyby spacecraft achieved its closest approach to Earth
        at an altitude of only 15,567.63 km above eastern Asia.

      Standard Cruise Calibration
      ---------------------------
        On 9 January 2008, the first of the standard cruise calibrations
        for the HRII, HRIV, and MRI instruments was performed.  The
        calibration sequence included observations of several standard
        stars, both solar analogs and hot stars with few absorption lines
        in their spectra for absolute calibration of all instruments, a
        stellar cluster for checking geometric distortion in the cameras,
        and a planetary nebula for checking the wavelength calibration of
        the spectrometer.  This sequence was designed such that it could
        be rerun, with few if any changes, after completion of the EPOCh
        observations and then again just before and just after the
        observing program for comet 103P/Hartley 2.

      HRII Dark Retake for Lunar Cal
      ------------------------------
        Due to a minor error in the lunar calibration sequence that was
        executed in December, a series of HRII dark frames was not recorded.
        However that sequence was successfully rerun on 16-17 January 2008.

    EPOCh
    -----
      Start Time : 2008-01-22 (DOY 022)
      Stop Time  : 2008-08-31 (DOY 244)

      EPOCh observations of eight known extrasolar planetary systems
      transits began on 22 January 2008 with the HAT-P-4 system and ended
      nearly six months later with the HAT-P-7 system on 31 August 2008.
      Taking advantage of the permanent on-orbit defocus of the HRI
      telescope, EPOCh used the HRIV CCD to collect over 172,000 usable,
      photometric-quality, visible light images of eight known transiting
      planet systems.  Time series of continuous 50-second integrations in a
      subframe mode of 128x128 or 256x256 pixels with the clear #6 optical
      filter extending from 350 to 1000 nanometers were used to observe each
      system for about three weeks, typically covering five or more transits
      as well as secondary eclipses.  An exception is XO-3 which was
      observed only briefly before the spacecraft unexpectedly entered safe
      mode.  In most instances, the 128x128-pixel subarray size was used.
      The 256x256-pixel subarray was utilized during some transit and
      secondary eclipse periods to ensure that pointing jitter did not cause
      the star to fall beyond the edges of the subarray.  Each series was
      typically bracketed by a set of dark and internal stimulator lamp
      frames to monitor changes in the HRIV CCD detector for calibration
      purposes.

      The transiting planet systems were observed in the integrated light of
      the planet and star; no spatially resolved image of the planet was
      possible.  The out-of-focus HRI telescope defocuses the images to
      about 10 pixels or 4 arcseconds at full-width half-max and introduces
      visible structure.

      The following extrasolar planetary systems were the targets for EPOCh
      transit photometry and are described in Ballard, et al. (2009)
      [BALLARDETAL2009]:

        Stellar       #Transits
        Target  V_mag  Observed Points of Interest
        ------- ----- --------- -------------------------------------------
        HAT-P-4 11.22     10    Low density planet, large radius for
                                its mass
        XO-3     9.91      1    Eccentric orbit, second planet suspected
        TrES-3  12.40      7    Short period (31 hours), reflected light
                                target
        XO-2    11.18      3    Fainter component in wide visual binary,
                                metal rich
        GJ 436  10.67      8    Eccentric orbit, unseen planet suspected,
                                star is M-dwarf
        TrES-2  11.41      7    Kepler target, additional planets possible
        WASP-3  10.64      8    Strongly heated, reflected light and
                                visible thermal emission possible
        HAT-P-7 10.50      8    Kepler target, even more strongly heated
                                than WASP-3

      On 18-19 March, 28-29 May, and 4-5 June 2008, EPOCh also observed
      Earth with the HRIV CCD and the High Resolution Infrared Imaging
      Spectrometer (HRII) to characterize it as an analog for extrasolar
      planets.  The observations comprised imaging in seven optical
      narrow-band (100 nanometer) filters and 2- to 5-micron infrared
      spectroscopy over a full Earth rotation.  Because the HRI telescope
      is defocused, the spatial resolution as observed is about 4 arcsec in
      each case.

      The optical images of Earth used a 512x512-pixel subarray of the HRIV
      CCD detector at a scale of about 0.4 arcsec/pixel, and each frame of
      the HRII spectrometer was 512 (wavelength) by 128 pixels (spatial,
      2-arcsec/pixel scale).  HRIV CCD images were acquired once every hour
      with three filters centered on 350, 750 and 950 nanometers and once
      every 15 minutes with the 450-, 550-, 650- and 850-nanometer filters.
       Infrared spectra were obtained twice per hour by scanning the slit
      of the HRII spectrometer over the earth, using three scans to ensure
      coverage of the entire disk; the slit was aligned perpendicular to
      the terminator during the scans.  The spacecraft orbit was
      approximately in the plane of the ecliptic which provided an
      equatorial view of Earth with about 62 to 77 percent of the disk
      illuminated.  Each of the three Earth observing periods lasted
      approximately 24 hours.  During the 29 May observation, the Moon
      transited Earth as seen from the spacecraft (0.3 AU from Earth).

      The following table chronologically lists EPOCh observations.  For
      most stellar exoplanet transit targets, preview imaging was performed
      to determine if the pointing bias needed to be modified for that
      target series.  Scheduled Earth observations #2 and #3 were canceled
      due to a telecommunications anomaly (see below).

        Target   Start Date/DOY  Stop Date/DOY   Comments
        -------  --------------  --------------  --------------------------
        HAT-P-4  2008-01-22/022  2008-02-12/043
        XO-3     2008-02-12/043  2008-02-17/048  S/C entered safe mode
        TrES-3   2008-03-06/066  2008-03-08/068
        XO-2     2008-03-09/069  2008-03-11/071  Preview for pointing bias
        TrES-3   2008-03-11/071  2008-03-18/078
        Earth    2008-03-18/078  2008-03-19/079  Obs #1
        XO-2     2008-03-20/080  2008-03-28/088
        GJ 436   2008-05-04/125  2008-05-27/148
        Earth    2008-05-28/149  2008-05-29/150  Obs #4
        Earth    2008-06-04/156  2008-06-05/157  Obs #5
        TrES-2   2008-06-28/180  2008-06-29/181  Preview for pointing bias
        HAT-P-4  2008-06-29/181  2008-07-08/190
        TrES-2   2008-07-08/190  2008-07-17/199
        WASP-3   2008-07-17/199  2008-07-19/201  Preview for pointing bias
        TrES-2   2008-07-20/202  2008-07-30/212
        WASP-3   2008-07-30/212  2008-08-08/221
        HAT-P-7  2008-08-08/221  2008-08-10/223  Preview for pointing bias
        WASP-3   2008-08-10/223  2008-08-16/229
        HAT-P-7  2008-08-16/229  2008-08-31/244

      After the observations of XO-3 on 17 February 2008 were downlinked,
      the spacecraft autonomously entered safe mode as it was turning to
      an optimal attitude to transmit data to Earth.  EPOXI mission
      controllers believed the safe mode was triggered when one of the
      reaction wheels, which helps maintain spacecraft attitude,
      experienced slightly higher temperatures than what the on-board fault
      protection software would allow.  After some engineering data was
      slowly brought down to Earth, controllers determined the
      spacecraft could be brought out of safe mode without triggering new
      problems.  On 29 February the spacecraft successfully exited safe
      mode and began downlinking the EPOCh images taken before safe mode
      was entered.

      On 6 March 2008, EPOCh observations were restarted with TrES-3 as
      the target.  EPOCh imaging continued without problems until a
      telecommunication anomaly occurred after the March 28th downlink of
      5000 photometric HRIV frames of transiting planet system XO-2.  This
      was the largest volume of data in a single downlink for EPOXI to
      date.  Following this downlink, EPOCh observations were paused to
      investigate the cause of an 8-dB (33%) loss of downlink signal and
      some slightly elevated temperatures on the spacecraft as it passed
      through perihelion.  As the spacecraft cooled over three weeks (a
      combination of moving further from the sun and all instruments being
      turned off), telemetry strength returned, and the project restarted
      EPOCh by first downlinking the images of XO-2 that had been stored on
      board the spacecraft since the end of March.  Telecommunications
      functioned as expected and observations of stellar exoplanet transit
      targets resumed with the remaining scheduled target, GJ 436.  The
      fourth and fifth sets of Earth observations were performed in late
      May and early June as planned, and a standard cruise calibration for
      the three instruments was successfully performed on 23-25 June 2008.

      During the telecom anomaly, observations of these scheduled targets
      were missed:  the end of the XO-2 sequence, TrES-2, the second and
      third sets of Earth observations, and the beginning of GJ 436.  As a
      result of skipping these targets, the EPOCh investigation could no
      longer meet some of its objectives.  Therefore NASA approved
      contingency observations starting on 27 June 2008 and continuing
      through 31 August 2008 to replace the science lost during the safe
      mode entry and telecom problems experienced in the spring.  The
      targets for the contingent observations were TrES-2, HAT-P-4
      (revisit), WASP-3, and HAT-P-7.

      While waiting for the EPOCh contingency observations to begin, a
      standard cruise calibration was performed on 23-25 June 2008 for the
      HRII and HRIV instruments.  The sequence was very similar to that
      used for the calibration performed on 9 January 2008, except the MRI
      instrument was turned off because of thermal and telecommunication
      concerns.  Also a trajectory correction maneuver was performed to
      put the flyby spacecraft on course for a rendezvous with Hartley 2
      on 4 November 2010.

      Since the second and third sets of EPOCh Earth imaging were canceled
      because of the telecommunications anomaly, NASA approved a request
      from the team to perform two Earth observations in 2009.


    Cruise 2
    --------
      Start Time  : 2008-09-01 (DOY 245)
      Stop Time   : 2010-09-02 (DOY 245)

      Various calibration sequences and tests as well as several Earth
      flybys were performed for this phase.  During Cruise 2, EPOCh continued
      observing Earth as as a contingency for the two observing periods that
      were lost in early 2008 because the telecommunications anomaly.  EPOCh
      also observed Mars as an extrasolar planetary analog and an exoplanet
      microlensing event named MOA-2009-BLG-266.

      HRII Reciprocity Test
      -------------------
        On 18 September 2008, an HRII reciprocity test was performed to
        determine the background signal level of the READ and RESET frames
        of the IR spectrometer as a function of the past history of
        integration delay times and the timing gap between sets of frames
        using the diagnostic imaging mode (number 6).  The ultimate
        objective of this test along with the HRII Dark Flush, HRII Dark
        Gap, and HRII Subframe Gain tests performed over the next four
        months is to develop a more accurate model of the variation in the
        background level of the IR spectrometer.

      HRII Dark Flush Test
      --------------------
        On 26 September 2008, an HRII dark frame flush test was performed
        to determine the type of IR spectrometer instrument operation
        needed to remove all traces of the residual (previous) image.

      HRII Encounter Darks Rerun
      --------------------------
        On 02 October 2008, a set of HRII dark frames for several IR
        exposure IDs from the Deep Impact Tempel 1 encounter sequence was
        acquired by the HRII spectrometer.  The exposures were those
        acquired from about 19 minutes before the impact with Tempel 1
        through the first few hours of lookback imaging.

      HRII Dark Gap Test
      ------------------
        On 10 October 2008, an HRII dark gap test was performed to
        characterize the change in the residual image and the dark level
        in the IR spectrometer as a function of wait time and number of
        readouts after acquiring data in the subframe imaging modes
        (numbers 2 and 3).

      First Interplanetary Internet Test
      ----------------------------------
        From mid-October to mid-November 2008, the first deep space
        communications network, also known as the Interplanetary Internet,
        was successfully tested using the Deep Impact flyby spacecraft.
        Using software called Delay-Tolerant Networking (DTN) dozens of
        images were transmitted to and from the flyby spacecraft located
        more than 32 million kilometers from Earth.

      HRIV PSF Calibration
      --------------------
        On 17 December 2008, additional data were acquired for improving
        point spread functions (PSF) for the HRIV CCD.  Analysis of early
        EPOXI calibration data and EPOCh stellar observations indicated
        the PSFs had changed since mid-2005 when the functions were last
        generated for Deep Impact.  The project plans to rerun this
        sequence in 2010 for the Hartley 2 flyby.

      Earth Flyby #2
      --------------
        At about 21:40 UTC on 29 December 2008, the Deep Impact flyby
        spacecraft achieved its closest approach to Earth at an altitude
        of only about 43,450 km, about midway between New Zealand and
        Tierra Del Fuego and at a latitude of about 49 degrees south.

      HRII Subframe Gain Calibration
      ------------------------------
        On 26 January 2009, an HRII subframe gain calibration was
        conducted to observe differences in the IR spectrometer signal
        response rates when observing an external radiance source to
        differentiate between gain and offset effects when using the
        various subframe modes.  The test was performed by scanning the
        spectrometer across the moon at multiple speeds with various
        subframe modes while the HRI telescope barrel was warm.

      EPOCh Earth North Pole
      ----------------------
        On 27-28 March 2009, EPOCh observed Earth at high northern latitudes
        for 24 hours with the HRIV CCD and the IR spectrometer to continue
        characterizing it as an analog for extrasolar planets.  The
        observations comprised narrow band filter images (350-950
        nanometers) and 2- to 5-micron infrared spectroscopy, over a full
        Earth rotation. Observations were acquired once per hour with the
        filters centered on 350, 750 and 950 nanometers, whereas the 450-,
        550-, 650-, and 850-nanometer data were taken every 15 minutes.
        Infrared spectral scans of the Earth's disk were acquired twice per
        hour.

      HRII Lunar Radiometry & Flats
      -----------------------------
        On 1-2 June 2009, the HRII spectrometer acquired a series of
        north/south scans of the moon for lunar radiometry and east/west
        scans along IR slit for flats.  These data were the best obtained
        to date for the purpose of generating flat fields for the IR
        spectrometer.

      HRII Lunar Radiometry & Anti-saturation Filter
      ---------------------------------------------
        On 9 June 2009, the HRII spectrometer imaged the moon using
        north/south scans to better characterize the effects of the
        anti-saturation filter in the IR spectra.

      HRII Linearity Calibration
      --------------------------
        On 18 June 2009, HRII darks were acquired to check the linearity
        of the IR spectrometer.  The sequence was identical to the one
        used during standard cruise calibrations for linearity.

      Distant Earth Flyby #1
      ----------------------
        A distant flyby of Earth occurred on 29 June 2009 at a geocentric
        distance of about 1,350,000 km.

      EPOCh Earth South Pole #1 (partial)
      -----------------------------------
        On 27-28 September 2009, EPOCh observed Earth at high southern
        latitudes with the HRIV CCD and the IR spectrometer using the same
        sequence as the observations at northern latitudes in March 2009
        to continue characterizing it as an analog for extrasolar planets.
        However the sequence ended prematurely because HRI was turned off
        by fault protection although the spacecraft was fine.  MRI remained
        on.

      Checkout after HRI Turnoff & HRIV Mechanical Checkout
      -----------------------------------------------------
        Before repeating the Earth South Pole observation, a standard
        imaging checkout of the HRII, HRIV, and MRI instruments was
        performed after HRI was powered up on 30 September 2009.  Also
        a mechanical checkout of HRIV was performed on 01 October:
        a miniature HRIV Earth observing sequence that cycled through
        the filters 21 times was run to check for 5-V telemetry channel
        noise.  The results of the tests were satisfactory.

      EPOCh Earth South Pole #2 (Full)
      --------------------------------
        On 04-05 October 2009, EPOCh successfully acquired a full set of
        observations (24 hours) of Earth with the HRIV CCD and the IR
        spectrometer using the same sequence as the observations at high
        northern latitudes in March 2009 to continue characterizing it as an
        analog for extrasolar planets. The observations comprised narrow
        band filter images (350-950 nanometers) and 2- to 5-micron infrared
        spectroscopy, over a full Earth rotation. Observations were acquired
        once per hour with the filters centered on 350, 750 and 950
        nanometers, whereas the 450-, 550-, 650-, and 850-nanometer data
        were taken every 15 minutes. Infrared spectral scans of the Earth's
        disk were acquired twice per hour.

      EPOCh Microlensing MOA-2009-BLG-266
      -----------------------------------
        On 05-08 October 2009, HRIV imaged about four days the known
        exoplanet microlensing event named MOA-2009-BLG-266, where the
        foreground lensing star and its exoplanet bend light of the source
        star.  EPOCh reused the sequence from the HRIV exoplanet transit
        observations in 2008 to obtain these data.  A second campaign to
        observe MOA-2009-BLG-266 in early 2010 for parallax measurements
        was canceled in preparation for the Hartley 2 encounter.

      HRII Radiometric Cal #1 (Beta Hyi)
      ----------------------------------
        From 13 October to 24 October 2009, the HRII spectrometer imaged
        the star Beta Hyi to improve the radiometric calibration for that
        instrument.

      HRII Dark Subframe Test
      -----------------------
        On 20 November 2009, the HRII spectrometer acquired dark frames
        to further characterize the response for the subframe imaging modes
        (numbers 2 and 3).

      EPOCh Mars Obs
      --------------
        On 20-21 November 2009, EPOCh observed Mars for 24 hours with the
        HRIV CCD and the IR spectrometer, reusing the Earth sequence, to
        characterize it as an analog for extrasolar planets and look for
        methane.  The observations comprised narrow band filter images
        (350-950 nanometers) and 2- to 5-micron infrared spectroscopy, over
        nearly a full Mars rotation.  Observations were acquired once per
        hour with the filters centered on 350, 750 and 950 nanometers,
        whereas the 450-, 550-, 650-, and 850-nanometer data were taken
        every 15 minutes. Infrared spectral scans of Mars' disk were
        acquired twice per hour.

      HRII Lunar Flats/Radiometric Cal #1 and
      HRII Lunar Flats/Radiometric Cal #2
      -----------------------------------
        On 05 and 12 December 2009 as the spacecraft approached Earth, the IR
        spectrometer made north/south scans of the moon for radiometry and
        east/west scans along the slit for lunar flats and a radiometric
        calibration.

      HRII Lunar South Pole Radiometry
      --------------------------------
        On 18 December 2009, about 10 days before the distant flyby of Earth
        the IR spectrometer made north/south scans of the lunar south pole
        for radiometric analysis.

      Distant Earth Flyby #2
      ------------------------------
        Another distant flyby of Earth occurred 28 December 2009 at a
        geocentric distance of about 1,330,000 km.

      Standard Cruise Calibration
      ---------------------------
        A full, standard cruise calibration for HRII, HRIV, and MRI was
        completed on 16 February 2010.

      HRII NoSave Flush Test
      ----------------------
        On 20 April 2010, tested an HRII sequence designed to reduce the
        amount of charge buildup that results in abnormally high signals in
        the first 1 to 4 images of a multi-frame IR exposure.  The sequence
        consisted of flushing the IR detector before science imaging by
        alternating between saving frames of one exposure ID for science
        and not saving those from the next exposure (i.e., flush frames).

      HRII Radiometric Cal #2 (Beta Hyi)
      ----------------------------------
        From 03 May to 17 May 2010, the HRII spectrometer imaged the star
        Beta Hyi to further improve the radiometric calibration for that
        instrument.

      Earth Flyby #3
      --------------
        The final near flyby of Earth for the EPOXI mission occurred on 27 Jun
        2010 at a geocentric distance of about 30,426 km.

      MRI Dosido Fast Slew Test
      --------------------------
        On 12 July 2010, the MRI Dosido fast slew sequence involved a
        test of the observing strategy planned from 8 days to one day
        before the Hartley 2 encounter that included periods during which
        the spacecraft attitude was maneuvered once per hour between the
        Earth downlink attitude and the comet viewing attitude.  The
        spacecraft was slewed at a high rate between these two attitudes,
        and the Deep Space Network was required to lockup on the downlink
        quickly every hour.  MRI images of dark space were taken each hour
        at the comet viewing attitude as they will be during the actual
        encounter sequence in early November 2010.


    DIXI/Hartley 2
    --------------
      Start Time  : 2010-09-03 (DOY 246)
      Stop Time   : 2010-11-28 (DOY 332)

      HRIV PSF Calibration
      --------------------
        On 03 September 2010, the HRIV CCD imaged Canopus to monitor the
        point spread functions (PSF) for that instrument. Analysis of HRIV
        calibration data since 2005 and EPOCh stellar observations in 2008
        indicate the PSFs can change over time.

      Approach Imaging: E-60 to E-50 Days (VIS only)
      ----------------------------------------------
        The MRI and HRIV visible instruments began imaging 103P/Hartley 2
        every six hours on 05 September 2010, 60 days before the encounter
        (E-60 days) encounter and continued for 10 days.  However due to
        thermal issues with a traveling wave tube amplifier the entire HRI
        system including the HRIV CCD was turned off on 06 September until
        20 September.  MRI continued its imaging sequence as planned through
        E-50 days.  The comet was observed for 16 hours at a time with 8
        hours devoted to downlinking the data.

      Approach Imaging: E-50 to E-40 Days (VIS only)
      ----------------------------------------------
        From 15 to 25 September 2010, the imaging cadence for MRI increased
        to every two hours. On 20 September the HRIV CCD was turned on, and
        it begin imaging 103P/Hartley 2 once every two hours for the
        duration of the period.  The comet was observed for 16 hours at
        a time with 8 hours devoted to downlinking the data.

      Pre-Encounter Standard Cruise Calibration
      -----------------------------------------
        A full, standard cruise calibration for HRII, HRIV, and MRI was
        performed on 28-29 September 2010.

      Approach Imaging: E-34 to E-8 Days (Start HRII)
      -----------------------------------------------
        From 01 to 28 October 2010, MRI and HRIV imaged 103P/Hartley 2 about
        every 5 minutes while the HRII spectrometer scanned for outbursts
        once every 30 minutes.  The instruments observed the comet for 16
        hours per day allowing for 8 hours of downlinking; the same sequence
        was repeated daily yielding one full cycle per day.  Data from the
        6th cycle on 06 October 2010 (DOY 279) were never downlinked because
        of a pointing problem with the Deep Space Network.  Those data had
        to be erased on board the spacecraft to make room for the next daily
        cycle and could not be recovered.

      Approach Imaging: E-8 Days to E-18 Hours
      ----------------------------------------
        From 28 October to 03 November 2010, the MRI and HRIV imaged
        103P/Hartley 2 continuously and HRII scanned the comet about every
        hour for 16 hours per day allowing for 8 hours of downlinking
        punctuated by hourly maneuvers, called dosido, to observe the comet.
        During this imaging phase there was only a single downlink of all
        images with zero margin; thus some images were occasionally lost as
        expected.  The first cycle (DOY 300/301) was abbreviated such that
        the first comet-imaging session was only 6-hours long, followed by
        the standard 8-hour dosido.

      Encounter Imaging: E-18 Hours to E+2 Days
      ------------------------------------------
        From 03 to 06 November 2010, the HRII, HRIV, and MRI performed high
        resolution encounter imaging of 103P/Hartley2.  The HRIV and MRI
        instruments began sampling about once every two hours until one
        hour before encounter when the cadence changed to once every 15
        minutes.  At E-30 minutes the instruments began continuously
        imaging of the comet.  At E+30 minutes simultaneous observing and
        data playback began with samples being taken every 30 minutes.

        During the encounter imaging period, HRII infrared scans occurred
        every two hours until four hours prior to encounter when the
        cadence increased to hourly then more frequently one hour before
        closest approach.  About one hour after closest approach, regular
        infrared sampling at 30-minute intervals resumed.

      Departure Imaging: E+2 to E+12 Days
      -----------------------------------
        From 06 to 16 November 2010, the HRII spectrometer scanned
        103P/Hartley 2 every 15 minutes while the MRI CCD imaged the
        comet every 2 minutes and HRIV once every hour.

      Departure Imaging: E+12 to E+21 Days
      ------------------------------------
        From 16 to 26 November 2010, the HRII spectrometer scanned
        103P/Hartley 2 every 30 minutes, and HRIV performed rotation
        sampling at the same cadence.  MRI performed rotation sampling
        every 30 minutes and imaging using gas filters every two to four
        hours.

      Post-Encounter Standard Cruise Calibration
      -----------------------------------------
        A full post-encounter standard cruise calibration for HRII, HRIV,
        and MRI was performed on 27-28 November 2010.  The sequence was
        nearly identical to the pre-encounter calibration performed in
        September.


    Cruise 3
    --------
      Start Time : 2010-11-29 (DOY 333)
      Stop Time  : 2011-02-06 (DOY 037)

      HRII 50-Frame Extended Linearity Calibration
      --------------------------------------------
        From 05 to 06 February 2011, the HRII spectrometer took 50 dark
        frames for a set of integration times and for each imaging mode
        to gather enough data to perform a thorough analysis of the
        linearity of each active pixel in the IR focal plane array.


  Recommended Reading
  ===================

    Relevant Publications from Deep Impact
    --------------------------------------
      Information about the design of the Deep Impact mission, scientific
      objectives, and instrumentation that are relevant to EPOXI are found
      in the work by A'Hearn, et al. (2005) [AHEARNETAL2005B], Blume
      (2005) [BLUME2005], Hampton, et al. (2005) [HAMPTONETAL2005],
      Klaasen, et al. (2005), Mastrodemos, et al. (2005)
      [MASTRODEMOSETAL2005], Thomas, et. al. (2005) [THOMASETAL2005], and
      Yeomans, et al. (2005) [YEOMANSETAL2005].  The calibration of the
      Deep Impact instruments and the resulting data processing pipeline
      are explained by Klaasen, et al. (2008) [KLAASENETAL2006] and
      Klaasen, et al. (2005) [KLAASENETAL2005].  Image restoration to
      correct for the HRI defocus is described by Lindler, et. al (2007)
      [LINDLERETAL2007].

      Initial results from the encounter at comet 9P/Tempel 1 in July 2005
      are described by A'Hearn, et al. (2005) [AHEARNETAL2005A].  A
      summary of the results from Deep Impact are presented by A'Hearn and
      Combi, (2007) [AHEARN&COMBI2007], A'Hearn and Combi, (2007)
      [AHEARN&COMBI2007B], and A'Hearn and Combi, (2007)
      [AHEARN&COMBI2007D].  Three volumes of Icarus are dedicated to
      results from Deep Impact.  Please see Combi and A'Hearn, (2007)
      [COMBI&AHEARN2007], Combi and A'Hearn, (2007) [COMBI&AHEARN2007B],
      and A'Hearn and Combi, (2007) [AHEARN&COMBI2007C].  Belton, et al.
      (2011) [BELTONETAL2011] discuss how the central horizontal gap of
      the VIS CCDs was handled for aperture photometry of 9P/Tempel 1.

    EPOXI
    -----
      For a brief overview of the EPOXI mission including the EPOCh and
      DIXI investigation, see A'Hearn (2008) [AHEARN2008], A'Hearn, et al.,
      (2008) [AHEARNETAL2008], Deming, et al., (2007) [DEMINGETAL2007],
      Deming, et al., (2008) [DEMINGETAL2008], and Deming, et al., (2008b)
      [DEMINGETAL2008B].

      Initial results from the EPOCh investigation are presented by
      Ballard, et al., (2008b) [BALLARDETAL2008B], Ballard, et al., (2009)
      [BALLARDETAL2009], Christiansen, et al., (2008)
      [CHRISTIANSENETAL2008], and Hewagama, et al. (2008)
      [HEWAGAMAETAL2008].

      Detailed results based on the EPOCh observations of transiting planet
      systems are presented in conference proceedings by Christiansen, et
      al., (2009) [CHRISTIANSENETAL2009], Ballard, et al., (2009b)
      [BALLARDETAL2009B], and Ballard, et al., (2010) [BALLARDETAL2010B] as
      well as in publications by Ballard, et al., (2010) [BALLARDETAL2010],
      Christiansen, et al., (2010) [CHRISTIANSENETAL2010], Christiansen, et
      al., (2011) [CHRISTIANSEETAL2010B], and Ballard, et al., (2011)
      [BALLARDETAL2011].

      Detailed results based on the EPOCh Earth observations are presented
      in publications by Cowen, et al., (2009) [COWANETAL2009] and
      Livengood, et al., (2009) [LIVENGOODETAL2009] and in conference
      proceedings by Robinson, et al. (2009) [ROBINSONETAL2009].

      Rieber and Sharrow, (2009) [RIEBER&SHARROW2009] discuss the design
      approach for EPOCh exoplanet transit imaging as well as the pointing
      stability of the flyby spacecraft.

      Initial results from the DIXI investigation are presented in
      A'Hearn, et al., (2011) [AHEARNETAL2011].  Sunshine, et al., (2009)
      discuss the variability of OH/H2O on the lunar surface based on
      HRII calibration data [SUNSHINEETAL2009].  Klassen, et al, (2011)
      [KLAASENETAL2011] describe the changes implemented to the EPOXI
      pipeline for processing Hartley 2 data.


  Mission Data
  ============
    The following mission-related data are or will be archived at the PDS:

      o Raw HRII, HRIV, and MRI science and calibration observations
        acquired throughout the mission,

      o Calibrated EPOCh exoplanet transit observations, including
        exoplanet microlensing event MOA-2009-BLG-266, in units of
        radiance (HRIV only),

      o Calibrated EPOCH Earth observations in units of radiance (HRII
        and HRIV) and I/F (HRIV),

      o Calibrated EPOCH Mars observations in units of radiance (HRII
        and HRIV) and I/F (HRIV),

      o Raw and calibrated science observations acquired during the
        approach to and encounter with comet Hartley 2 (HRII, HRIV,
        and MRI),

      o Raw and calibrated navigation images acquired during the
        approach to comet Hartley 2 (HRIV and MRI),

      o Radio science data from the Hartley 2 encounter,

      o SPICE data, including 5-Hz telemetry from the Attitude
        Determination and Control System (ADCS) as a CK kernel,

      o Higher-level products, including light curves for EPOCh stellar
        transit (exoplanet) targets, EPOCh color maps of Earth, and a
        shape model and surface temperature maps for Hartley 2, and

      o Select data from the Earth-based observing campaign for the
        Hartley 2 encounter.
MISSION_OBJECTIVES_SUMMARY
Mission Objectives
  ==================

    The scientific objectives of the EPOCh investigation of the EPOXI
    mission are:

      o Observe transits by known extrasolar planets (hot Jupiters) to
        search for perturbations due to terrestrial planets in low-order
        resonances,

      o Search those same systems for secondary occultations of the hot
        Jupiter by the star, and

      o Characterize the Earth as an analog for extrasolar planets by
        observing its rotational light curve and integrating over the
        disk at wavelengths sensitive to vegetation (red edge), Rayleigh
        scattering, and clouds.

    The general scientific objective of the DIXI investigation of the EPOXI
    mission is to study a second comet with the same set of instrumentation
    as was used at comet Tempel 1 to help determine which cometary features
    are primordial and which are the result of subsequent evolutionary
    processes.  Specific goals include:

      o Search for outbursts and if found produce spectral maps of
        these events and correlate the outbursts with surface features,

      o Obtain infrared spectral maps of gasses in the innermost coma
        and investigate the distribution of dust and gas in the coma,

      o Search for frozen volatiles on the surface of the comet,

      o Perform broad band imaging to determine the size of the nucleus
        and produce a shape model,

      o Map the brightness and color variations of the surface and locate
        topographical features that disclose the processes by which the
        comet was formed, and

      o Map the temperature of the surface to assess the thermal
        conductivity of the interior and the migration of subsurface
        volatiles.
REFERENCE_DESCRIPTION