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Rock Abrasion Tool (RAT)

NSSDCA ID: 2003-027A-06

Mission Name: Spirit
Principal Investigator:Dr. Steven W. Squyres


The Rock Abrasion Tool (RAT) is a device containing a grinding wheel designed to remove dust and weathered material from the surface of a rock to expose a fresh surface. The fresh surface, which is more likely to represent the original rock before alteration, can then be studied by the other rover instruments. It is mounted on the rover arm, or instrument deployment device and is placed by the arm against the target rock.

The RAT is 7 cm in diameter and 10 cm long. It uses two diamond matrix wheels. Each wheel has two teeth which cut out a circular area as the head rotates at high speed. The grinding wheels can also slowly revolve around each other, sweeping the two circular areas over a 4.5 cm diameter cutting region. The wheels can penetrate by fractions of a millimeter as commanded, creating a hole as deep as 0.5 cm. Penetration into the rock is slow and designed to minimize alteration of the petrologic fabric, chemistry, or mineralogy. Currents and temperatures will be monitored during the grinding opeation to infer information on the rock properties. Grinding operations take about 2 hours for a dense basalt.

Alternate Names

  • RAT
  • Spirit/RAT
  • urn:nasa:pds:context:instrument:rat.mer2

Facts in Brief

Mass: 0.75 kg
Power (avg): 30 W

Funding Agency

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


  • Planetary Science: Geology and Geophysics

Additional Information

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



NameRoleOriginal AffiliationE-mail
Prof. Raymond E. ArvidsonDeputy Principal InvestigatorWashington
Dr. Steven W. SquyresPrincipal InvestigatorCornell

Selected References

  • Gorevan, S. P., et al., Rock Abrasion Tool: Mars Exploration Rover mission, J. Geophys. Res., 108, No. E12, 8068, doi:10.1029/2003JE002061, 2003.

Diagram of Rock Abrasion Tool Image of end of MER robot arm Diagram of Rock Abrasion Tool
Diagram of the Rock Abrasion Tool, drawing of the suite of instruments on the end of the rover arm, and image of the RAT

RAT Technical Briefing (PDF file)
NASA Selects 28 Participating Scientists for Mars Rover Mission - NASA Press Release 29 May 2002

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