Mission Information
MISSION_NAME NEXT
MISSION_ALIAS
MISSION_START_DATE 2004-02-12T12:00:00.000Z
MISSION_STOP_DATE 2011-03-25T12:00:00.000Z
MISSION_DESCRIPTION
One-sentence Mission Result Summary
===================================
 
  The small changes in comet 9P/Tempel 1 between two observed perihelia,
  in 2005 by Deep Impact and in 2011 by Stardust-NExT, were most obvious
  in the vicinity of smooth flows [VEVERKAETAL2011].
 
 
Mission overview
================
 
  Stardust-NExT was an extended mission that used the Stardust (SDU)
  spacecraft to effect a flyby of comet 9P/Tempel 1 at 178 km on
  15 February, 2011 (40 days post perihelion) and obtain high-resolution
  images of the coma and nucleus, as well as measurements of the
  composition, size distribution and flux of dust emitted into the coma.
  The SDU spacecraft had been launched in 1999 and had already flown by
  comet 81P/Wild 2 in January, 2004 as part of the prime Stardust mission
  ([BROWNLEEETAL2003] [SEMENOVETAL2004A], [RYNOETAL2004A]
  [SEMENOVETAL2008]).
 
  The 2005 impact by the Deep Impact (DI) mission on 9P/Tempel 1 excavated
  ejecta with an optical depth such that the cameras on the DI flyby
  spacecraft could not image the surface in the impact area.  Therefore the
  size of and character of the crater that had been excavated could not be
  determined ([AHEARNETAL2005A], [AHEARNETAL2005B]) by the DI mission.
 
  Mission activities included a plan to update knowledge of the rotational
  phase of the comet sufficiently well to view significant portions of the
  hemisphere studied by Deep Impact in 2005 and imaging the crater
  excavated by the impactor [BELTONETAL2011] [MEECHETAL2011].
 
  Stardust-NExT was a low-cost, low-risk mission to complete and expand
  the investigation of comet Tempel 1 initiated by Deep Impact, and for
  the first time assess the changes in the surface of a comet between two
  successive perihelion passages.  It provided important new data that
  may be used to assess how Jupiter family comets (JFCs) evolve and how
  they were formed 4.6 billion years ago.
 
  The investigation of comets addresses each of the three strategic
  objectives for solar system exploration enunciated in NASA's Space
  Science Enterprise Strategy (SSES) 2003:
 
    To learn how the solar system originated and evolved to its current
    state.
 
    To understand how life begins and determine the characteristics of
    the solar system that led to the origin of life.
 
    To catalog and understand the potential impact hazard to Earth from
    space.
 
  ([WEILERETAL2003])
 
  Stardust-NExT contributed significantly to the first and last of these
  objectives.  Stardust-NExT was designed to obtain essential new data,
  capitalize on the discoveries of earlier missions to determine how
  cometary nuclei were constructed at the birth of the solar system,
  and increase our understanding of how they have evolved since then.
 
  The investigations on the Stardust-NExT mission included:
 
    Cometary coma and nucleus imaging (Navigation Camera a.k.a. NAVCAM,
    [NEWBURNETAL2003])
 
    Comet particle composition measurements (Cometary and Interstellar
    Dust Analyzer a.k.a. CIDA [KISSELETAL2003])
 
    Dust flux measurements (Dust Flux Monitor Instrument a.k.a. DFMI,
    [TUZZOLINOETAL2003])
 
  The Sample Return Capsule (SRC) had been returned to Earth in 2006 and
  was no longer part of the in-flight spacecraft [FARNHAM&SEMENOV2006].
 
 
Mission phases
==============
 
  Based on NAVCAM activities, and particle instruments' general inactivity
  before and after the Tempel 1 encounter, there were four logical mission
  phases for Stardust-NExT:  CRUISE; APPROACH; ENCOUNTER; DEPARTURE.
 
  N.B. Because of differences in sensing range between the imaging and
       particle instruments, these logical mission phases correspond only
       approximately to instrument-specific operational data collection
       periods or subphases as defined in instrument data catalogs for the
       Stardust-NExT data sets.
 
       For the particle instruments, CIDA and DFMI, there are only
       two phases:  CRUISE and ENCOUNTER.  APPROACH and DEPARTURE, as
       defined here, are combined and considered to be CRUISE.
 
       For the NAVCAM, operational mission subphases were defined as CO
       (CHECKOUT), C5 and C6 (CRUISE 5 and 6), and TE (TEMPEL ENCOUNTER),
       and those two-letter acronyms were used in the NAVCAM PRODUCT_IDs
       and FILE_NAMEs.  C6 was not intentional but was added when the
       NAVCAM image count was reset during C5, temporarily causing problems
       in the ground data system.  An earlier mission phase, C4 (CRUISE 4)
       was defined but no NAVCAM data were taken during that phase.
       Details of these two-letter NAVCAM 'subphase' designations have been
       provided in the NAVCAM data set.
 
 
  CRUISE
  ------
 
    Performed instrument checkout and calibration activities:  All
    instruments were in CRUISE configuration when turned on:  NAVCAM and
    DFMI were off except for calibrations; CIDA was on nearly continuously.
    Minimal science data were taken except for CIDA.  NAVCAM activities
    included characterization of photometric (stars), geometric (star
    clusters), bias and dark (shutter closed), and post-decontamination
    (post-bake) behaviors.  Navigation maneuvers were performed including
    Tempel 1 time of arrival adjustment in February, 2010 to maximize the
    probability of optimizing imaging of both previously seen and unseen
    comet surface including the DI crater.
 
        Mission Phase Start Date  2007-01-17 (2004-02-12 for CIDA)
         Mission Phase Stop Date  2010-12-16
      Spacecraft Operations Type  CRUISE
                    Target Names  CALIBRATION, INTERSTELLAR PARTICLES,
                                  NON SCIENCE
 
 
  APPROACH:
  ---------
 
    Performed NAVCAM imaging of coma for science and navigation starting
    sixty days before Encounter (E-60d) closest approach through two days
    before encounter.  All instruments were in cruise configuration when
    turned on.  CIDA was off.  DFMI was off except for calibration.
    NAVCAM coma observations started with eight-image sets every 2-6 days,
    increasing later to up to ~100 images per day, interrupted only for
    calibration and decontamination.  Significant scattered light was
    observed for most of these images, due to the spacecraft attitude and
    mirror angle used, which prevented coma detection.  The coma was first
    detected in summed images at E-28d when the sequences were modified to
    use a spacecraft attitude which minimized scattered light.  Approach
    phase ended with a two-day standdown of instrument operations to
    prepare for ENCOUNTER phase (below).  Because of the standdown, there
    is a discontinuity (gap) between the APPROACH stop date and the
    ENCOUNTER start date.
 
        Mission Phase Start Date  2010-12-17
         Mission Phase Stop Date  2011-02-13
      Spacecraft Operations Type  CRUISE
                    Target Names  9P/TEMPEL 1 (1867 G1), CALIBRATION,
                                  INTERSTELLAR PARTICLES, NON SCIENCE
 
 
  ENCOUNTER
  ---------
 
    Performed close-up science measurements of comet 9P/Tempel 1 on
    15 February, 2011; all instruments were in encounter configuration
    when turned on.  NAVCAM took seventy-two high-spatial resolution
    brightness-compressed images over T +/- ~4minutes; four of these were
    coma observations for which the comet nucleus was intentionally
    overexposed.  CIDA was on continuously.  DFMI was on for T +/- ~20
    minutes.  Auto-navigation software performed flawlessly and kept the
    bulk of the comet nucleus in all NAVCAM images.  Before and after the
    encounter, the spacecraft was in two-day standdowns of instrument
    operations to downlink data.  Because of the standdowns, there are
    discontinuities (gaps) between the APPROACH stop date and the
    ENCOUNTER start date, and between the ENCOUNTER stop date and the
    DEPARTURE start date.
 
        Mission Phase Start Date  2011-02-15
        Time of Closest Approach  2011-02-15T04:39:10
         Mission Phase Stop Date  2011-02-15
      Spacecraft Operations Type  ENCOUNTER
                    Target Names  9P/TEMPEL 1 (1867 G1), NON SCIENCE
 
 
  DEPARTURE
  ---------
 
    Performed NAVCAM imaging of coma for science, similar to APPROACH phase
    above.  All instruments were in cruise configuration when turned on.
    CIDA was off.  DFMI was off except for a final calibration.  NAVCAM
    imaging was stopped at E+10d after the coma was determined to be too
    faint for further scientific utility.  Remaining spacecraft fuel was
    burned to exhaustion on 26 March in a final maneuver to allow
    validation and/or calibration of fuel estimation techniques used on
    this and other missions.  The Stardust spacecraft was left in a safe
    orbit (it will not come near Earth for the foreseeable future) and will
    boot to a safe configuration in the event the solar panels supply power
    to the processing unit.
 
        Mission Phase Start Date  2011-02-17
         Mission Phase Stop Date  2011-02-25
      Spacecraft Operations Type  CRUISE
                    Target Names  9P/TEMPEL 1 (1867 G1), CALIBRATION,
                                  INTERSTELLAR PARTICLES, NON SCIENCE
 
 
[AHEARNETAL2005A] A'Hearn, M.F., M.J.S. Belton, W.A. Delamere, J. Kissel,
K.P. Klaasen, L.A. McFadden, K.J. Meech, H.J. Melosh, P.H. Schultz, J.M.
Sunshine, P.C. Thomas, J. Veverka, D.K. Yeomans, M.W. Baca, I. Busko, C.J.
Crockett, S.M. Collins, M. Desnoyer, C.A. Eberhardy, C.M. Ernst, T.L.
Farnham, L. Feaga, O. Groussin, D. Hampton, S.I. Ipatov, J.-Y. Li, D.
Lindler, C.M. Lisse, N. Mastrodemos, W.M. Owen, J.E. Richardson, D.D.
Wellnitz, and R.L. White, Deep Impact: Excavating Comet Tempel 1, Science,
310, 258-264, 2005, doi:10.1126/science.1118923,
http://www.sciencemag.org/content/310/5746/258.abstract,
http://www.sciencemag.org/content/310/5746/258.full.pdf.
 
[AHEARNETAL2005B] A'Hearn, M.F., M.J.S. Belton, A. Delamere, and W.H. Blume,
Deep Impact: A Large-Scale Active Experiment on a Cometary Nucleus, Space
Science Reviews, 117, 1-21, 2005, doi:10.1007/s11214-005-3387-3.
 
[BELTONETAL2011] Belton, M.J.S., Meech, K.J., Chesley, S., Pittichova, J.,
Carcich, B., Drahus, M., Harris, A., Gillam, S., Veverka, J., Mastrodemos,
N., Owen, W., A'Hearn, M.F., Bagnulo, S., Bai, J., Barrera, L., Bastien, F.,
Bauer, J.M., Bedient, J., Bhatt, B.C., Boehnhardt, H., Brosch, N., Buie, M.,
Candia, P., Chen, W.-P., Chiang, P., Choi, Y.-J., Cochran, A., Crockett,
C.J., Duddy, S., Farnham, T., Fernandez, Y.R., Gutierrez, P., Hainaut, O.R.,
Hampton, D., Herrmann, K.A., Hsieh, H., Kadooka, M.A., Kaluna, H., Keane, J.,
Kim,  M.-J., Klaasen, K., Kleyna, J., Krisciunas, K., Lara, L.M., Lauer,
T.R., Li,  J.-Y., Licandro, J., Lisse, C.M., Lowry, S.C., McFadden, L.,
Moskovitz, N., Mueller, B., Polishook, D., Raja, N.S., Riesen, T., Sahu,
D.K., Samarasinha, N., Sarid, G., Sekiguchi, T., Sonnett, S., Suntzeff, N.B.,
Taylor, B.W., Thomas, P., Tozzi, G.P., Vasundhara, R., Vincent, J.-B.,
Wasserman, L.H., Webster-Schultz, B., Yang, B., Zenn, T., Zhao, H.,
Stardust-NExT, Deep Impact, and the accelerating spin of 9P/Tempel 1, Icarus,
Volume 213, Issue 1, May 2011, Pages 345-368.
http://dx.doi.org/10.1016/j.icarus.2011.01.006
 
[BROWNLEEETAL2003] Brownlee, D. E., P. Tsou, J. D. Anderson, M. S. Hanner, R.
L. Newburn, Z. Sekanina, B. C. Clark, F. Horz, M. E. Zolensky, J. Kissel, J.
A. M. McDonnell, S. A. Sandford, and A. J. Tuzzolino, Stardust: Comet and
interstellar dust sample return mission, J. Geophys. Res., 108, (E10), 8111,
2003
 
[FARNHAM&SEMENOV2006] Farnham, T.L., Semenov, B., STARDUST DUST COLLECTOR
GEOMETRY, SDU-C-SRC-6-GEOMETRY-V1.0, NASA Planetary Data System, 2006.
 
[KISSELETAL2003] Kissel, J., A. Glasmachers, E. Grun, H. Henkel, H. Hofner,
G. Haerendel, H. von Hoener, K. Hornung, E. K. Jessberger, F. R. Krueger, D.
Mohlmann, J. M. Greenberg, Y. Langevin, J. Silen, D. Brownlee, B. C. Clark,
M. S. Hanner, F. Hoerz, S. Sandford, Z. Sekanina, P. Tsou, N. G. Utterback,
M. E. Zolensky, and C. Heiss, Cometary and Interstellar Dust Analyzer for
comet Wild 2, J. Geophys. Res., 108, (E10), 8114, 2003
 
[MEECHETAL2011] Meech, K.J., Pittichova, J., Yang, B., Zenn, A., Belton,
M.J.S., A'Hearn, M.F., Bagnulo, S., Bai, J., Barrera, L., Bauer, J.M.,
Bedient, J., Bhatt, B.C., Boehnhardt, H., Brosch, N., Buie, M., Candia, P.,
Chen, W.-P., Chesley, S., Chiang, P., Choi, Y.-J. et al., 2011. Deep Impact,
Stardust-NExT and the Behavior of Comet 9P/Tempel 1 From 1997-2010, Icarus,
in press.
 
[NEWBURNETAL2003] Newburn Jr., R. L., S. Bhaskaran, T. C. Duxbury, G.
Fraschetti, T. Radey, and M. Schwochert, Stardust Imaging Camera, J. Geophys.
Res., 108, (E10), 8116, 2003
 
[RYNOETAL2004A] Ryno, J., B.V. Semenov, J. Kissel, J. Silen, and C.H. Acton,
STARDUST CIDA DATA, SDU-C/D-CIDA-1-EDF/HK-V1.0, NASA Planetary Data System,
2004.
 
[SEMENOVETAL2004A] Semenov, B.V., A.J. Tuzzolino, J.A.M. McDonnell, H.W.
Taylor, and C.H. Acton, STARDUST DFMI WILD 2 ENCOUNTER EDR DATA,
SDU-C-DFMI-2-EDR-WILD2-V1.0, NASA Planetary Data System, 2004.
 
[SEMENOVETAL2008] Semenov, B.V., R.L. Newburn, H.W. Taylor, C. Hash, and C.H.
Acton, T.L. Farnham, STARDUST NAVCAM IMAGES OF WILD 2,
SDU-C-NAVCAM-2-EDR-WILD2-V2.0, NASA Planetary Data System, 2008.
 
[TUZZOLINOETAL2003] Tuzzolino, A. J., T. E. Economou, R. B. McKibben, J. A.
Simpson, J. A. M. McDonnell, M. J. Burchell, B. A. M. Vaughan, P. Tsou, M. S.
Hanner, B. C. Clark, and D. E. Brownlee, Dust Flux Monitor Instrument for the
Stardust mission to comet Wild 2, J. Geophys. Res., 108, (E10), 8115, 2003
 
[VEVERKAETAL2011] J. Veverka, Klaasen, K., A'Hearn, M., Belton, M., Brownlee,
D., Chesley, S., Clark, B., Economou, T., Farquhar, R., Green, S., Harris,
A., Groussin, O., Kissel, J., Li, J.-Y., Meech, K., Melosh, J., Richardson,
J., Schultz, P., Silen, J., Sunshine, J., Thomas, P., Bhaskaran, S.,
Bodewits, D., Carcich, B., Cheuvront, A., Farnham, T., Sackett, S., Wellnitz,
D., Wolf, A., Return to Comet Tempel 1: Results from Stardust-NExT, Icarus
(tentative), May, 2011, in press.
 
[WEILERETAL2003] Weiler, E.J., 2003 Space Science Enterprise Strategy,
National Aeronautics and Space Administration, 01 October, 2003.
http://spacescience.nasa.gov/admin/pubs/strategy/2003/SpSciEntStrat(low).pdf
MISSION_OBJECTIVES_SUMMARY
Science Goals
=============
 
  The science goals at the comet flyby were satisfied by high-resolution
  imagery and included:
 
    Document surface changes between two perihelion passages.
 
    Extend geologic mapping to elucidate nature of layering and constrain
    models of interior structure.
 
    Image the Deep Impact crater, if possible, to understand crater
    formation on comets and derive further information of the structure
    of the outer layers of the nucleus.
 
  An additional opportunity, though not a formally declared science goal,
  was to extend the study of smooth flows to understand their source and
  origin.
 
  The Stardust-NExT Mission also collected data during instrument
  calibrations at intervals during cruise phase, to aid in interpreting
  mission data.
REFERENCE_DESCRIPTION A'Hearn, M.F., M.J.S. Belton, W.A. Delamere, J. Kissel, K.P. Klaasen, L.A. McFadden, K.J. Meech, H.J. Melosh, P.H. Schultz, J.M. Sunshine, P.C. Thomas, J. Veverka, D.K. Yeomans, M.W. Baca, I. Busko, C.J. Crockett, S.M. Collins, M. Desnoyer, C.A. Eberhardy, C.M. Ernst, T.L. Farnham, L. Feaga, O. Groussin, D. Hampton, S.I. Ipatov, J.-Y. Li, D. Lindler, C.M. Lisse, N. Mastrodemos, W.M. Owen, J.E. Richardson, D.D. Wellnitz, and R.L. White, Deep Impact: Excavating Comet Tempel 1, Science, 310, 258-264, 2005, doi:10.1126/science.1118923.

A'Hearn, M.F., M.J.S. Belton, A. Delamere, and W.H. Blume, Deep Impact: A Large-Scale Active Experiment on a Cometary Nucleus, Space Science Reviews, 117, 1-21, 2005, doi:10.1007/s11214-005-3387-3.

Belton, M.J.S., K.J, Meech, S. Chesley, Y. Pittichova, B. Carcich, M. Drahus, A. Harris, S. Gillam, J. Veverka, N. Mastrodemos, W. Owen, M.F. A'Hearn, S. Bagnulo, J. Bai, L. Barrera, F. Bastien, J.M. Bauer, J. Bedient, B.C. Bhatt, H. Boehnhardt, N. Brosch, M. Buie, P. Candia, W.-P. Chen, P. Chiang, Y.-J. Choi, A. Cochran, C.J. Crockett, S. Duddy, T. Farnham, Y.R. Fernandez, P. Gutierrez, O.R. Hainaut, D. Hampton, K.A. Herrmann, H. Hsieh, M.A. Kadooka, H. Kaluna, J. Keane, M.-J.Kim, K. Klaasen, J. Kleyna, K. Krisciunas, L.M. Lara, T.R. Lauer, J.-Y. Li, J. Licandro, C.M. Lisse, S.C. Lowry, L. McFadden, N. Moskovitz, B. Mueller, D. Polishook, N.S. Raja, T. Riesen, D.K. Sahu, N. Samarasinha, G. Sarid, T. Sekiguchi, S. Sonnett, N.B. Suntzeff, B.W. Taylor, P. Thomas, G.P. Tozzi, R. Vasundhara, J.-B. Vincent, L.H. Wasserman, B. Webster-Schultz, B. Yang, T. Zenn, and H. Zhao, Stardust-NExT, Deep Impact, and the accelerating spin of 9P/Tempel 1, Icarus, Volume 213, Issue 1, p. 345-368, 2011, doi:10.1016/j.icarus.2011.01.006.

Brownlee, D.E., P. Tsou, J.D. Anderson, M.S. Hanner, R.L. Newburn, Z. Sekanina, B.C. Clark, F. Horz, M.E. Zolensky, J. Kissel, J.A.M. McDonnell, S.A. Sandford, and A.J. Tuzzolino, Stardust: Comet and interstellar dust sample return mission, J. Geophys. Res., 108, (E10), 8111, 2003, doi:10.1029/2003JE002087.

Farnham, T.L., B. Semenov, STARDUST DUST COLLECTOR GEOMETRY, SDU-C-SRC-6-GEOMETRY-V1.0, NASA Planetary Data System, 2006.

Kissel, J., A. Glasmachers, E. Grun, H. Henkel, H. Hofner, G. Haerendel, H. von Hoerner, K. Hornung, E.K. Jessberger, F.R. Krueger, D. Mohlmann, J.M. Greenberg, Y. Langevin, J. Silen, D. Brownlee, B.C. Clark, M.S. Hanner, F. Hoerz, S. Sandford, Z. Sekanina, P. Tsou, N.G. Utterback, M.E. Zolensky, and C. Heiss, Cometary and Interstellar Dust Analyzer for comet Wild 2, J. Geophys. Res., 108, (E10), 8114, 2003, doi:10.1029/2003JE002091.

Meech, K.J., J. Pittichova, B. Yang, A. Zenn, M.J.S. Belton, M.F. A'Hearn, S. Bagnulo, J. Bai, L. Barrera, J.M. Bauer, J. Bedient, B.C. Bhatt, H. Boehnhardt, N. Brosch, M. Buie, P. Candia, W.-P. Chen, S. Chesley, P. Chiang, Y.-J. Choi, A. Cochran, S. Duddy, T.L. Farnham, Y. Fernandez, P. Gutierrez, O.R. Hainaut, D. Hampton, K. Herrmann, H. Hsieh, M.A. Kadooka, H. Kaluna, J. Keane, M.-J. Kim, J. Kleyna, K. Krisciunas, T.R. Lauer, L. Lara, J. Licandro, S.C. Lowry, L.A. McFadden, N. Moskovitz, B.E.A. Mueller, D. Polishook, N.S. Raja, T. Riesen, D.K. Sahu, N.H. Samarasinha, G. Sarid, T. Sekiguchi, S. Sonnett, N. Suntzeff, B. Taylor, G.P. Tozzi, R. Vasundhara, J.-B. Vincent, L. Wasserman, B. Webster-Schultz, and H. Zhao, Deep Impact, Stardust-NExT and the Behavior of Comet 9P/Tempel 1 From 1997-2010, Icarus, Volume 213, Issue 1, pp. 323-344, May 2011, doi:10.1016/j.icarus.2011.02.016.

Newburn, R.L., Jr., S. Bhaskaran, T.C. Duxbury, G. Fraschetti, T. Radey, and M. Schwochert, Stardust Imaging Camera, J. Geophys. Res., v. 108, no. E10, p. 8116, 2003, doi:10.1029/2003JE002081.

Ryno, J., B.V. Semenov, J. Kissel, J. Silen, and C.H. Acton, STARDUST CIDA DATA, SDU-C/D-CIDA-1-EDF/HK-V1.0, NASA Planetary Data System, 2004.

Semenov, B.V., A.J. Tuzzolino, J.A.M. McDonnell, H.W. Taylor, and C.H. Acton, STARDUST DFMI WILD 2 ENCOUNTER EDR DATA, SDU-C-DFMI-2-EDR-WILD2-V1.0, NASA Planetary Data System, 2004.

Semenov, B.V., R.L. Newburn, H.W. Taylor, C. Hash, and C.H. Acton, T.L. Farnham, STARDUST NAVCAM IMAGES OF WILD 2, SDU-C-NAVCAM-2-EDR-WILD2-V2.0, NASA Planetary Data System, 2008.

Tuzzolino, A.J., T.E. Economou, R.B. McKibben, J.A. Simpson, J.A.M. McDonnell, M.J. Burchell, B.A.M. Vaughan, P. Tsou, M.S. Hanner, B.C. Clark, and D.E. Brownlee, Dust Flux Monitor Instrument for the Stardust mission to comet Wild 2, J. Geophys. Res., 108, (E10), 8115, 2003, doi:10.1029/2003JE002086.

Veverka, J., K. Klaasen, M. A'Hearn, M. Belton, D. Brownlee, S. Chesley, B. Clark, T. Economou, R. Farquhar, S. Green, A. Harris, O. Groussin, J. Kissel, J.-Y. Li, K. Meech, J. Melosh, J. Richardson, P. Schultz, J. Silen, J. Sunshine, P. Thomas, S., Bhaskaran, D. Bodewits, B. Carcich, A. Cheuvront, T. Farnham, S. Sackett, D. Wellnitz, and A. Wolf, Return to Comet Tempel 1: Results from Stardust-NExT, Icarus (tentative), 2011, in press, preprint included in all Stardust-NExT PDS data sets.

Weiler, E.J., 2003 Space Science Enterprise Strategy, National Aeronautics and Space Administration, 01 October, 2003, http://spacescience.nasa.gov/admin/pubs/strategy/2003/SpSciEntStrat(low).pdf