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Medium Resolution Instrument (MRI)

NSSDCA ID: 2005-001A-02

Mission Name: Deep Impact/EPOXI
Principal Investigator:Dr. Michael F. A'Hearn


The Medium Resolution Instrument (MRI) is designed to provide visible images with a wider field of view than the High Resolution Instrument (HRI) to provide science context to the observations, navigation, and to act as a backup to HRI. The MRI consists of a telescope, filter wheel, and Charged-Couple Device (CCD) camera. The telescope is of Cassegrain design, f/17.5 with a 12 cm diameter aperture and a 2.1 m focal length. It houses light baffles and zerodur glass primary and secondary mirrors. The filter wheel has two clear apertures and eight filters. The filters include some of the same filters used on the HRI and also have filters designed to isolate CN and C2. The camera uses a 1024 x 1024 split frame transfer CCD. The field of view is 10 milliradians (0.587 degrees, or 10 microradians/pixel) allowing a surface resolution of 7 meters at 700 km. The full field of view is expected to be 1.2 times larger than the comet nucleus at closest approach, so the entire nucleus will be visible by the instrument throughout the encounter. Full frame readout time is 1.8 seconds, faster readout of centered sub-frames is also possible.

The impactor also carries an imaging device, the Impactor targeting Sensor (ITS) which is identical to the MRI except that it doesn't have a filter wheel. It will be able to take images with a resolution of 0.2 meters/pixel at a distance of 20 km.

Alternate Names

  • Deep Impact Medium Resolution Instrument - Visible CCD
  • DeepImpact/MRI
  • MRI
  • urn:nasa:pds:context:instrument:dif.mri

Funding Agency

  • NASA-Office of Space Science Applications (United States)


  • Planetary Science: Small Bodies

Additional Information

Questions and comments about this experiment can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. Michael F. A'HearnPrincipal InvestigatorUniversity of Maryland

Selected References

  • Hampton, D. L., et al., An Overview of the Instrument Suite for the Deep Impact Mission, Space Sci. Rev., 117, No. 1-2, 43-93, Mar. 2005.
  • Wellnitz, D. D., et al., The location of the impact point of the Deep Impact Impactor on Comet 9P/Tempel 1, Icarus, 222, No. 2, 487-491, doi:10.1016/j.icarus.2012.08.003, Feb. 2013.
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