Geophysical reconnaissance asteroid surface probe (GRASP)

Kieran A. Carroll, Robert E. Zee, Henry Spencer, Martin Connors

Research output: Contribution to journalConference articlepeer-review


Here we describe a small (12U cubesat) sized spacecraft designed to make geophysical measurements on the surface of an asteroid, and the asteroid science objectives which can be addressed using those measurements. The “Geophysical Reconnaissance Asteroid Surface Probe� (GRASP) spacecraft is designed to be a low-cost means for conducting fundamental asteroid science, as well as for exploring for possible natural resource deposits in asteroids. To that end, GRASP's design is based on the “Microspace� approach that has been used on many successful, very low-cost and high-capability nanosats and microsats in low Earth orbit (LEO). This design approach enables GRASP to be robust against many types of operational failures. Previous and current asteroid exploration missions have carried primarily instruments which measure the surface properties of the asteroid target, determining geomorphology and surface geochemistry. Surface observations alone leave many important questions unanswered, for example questions about the composition and structure of the interiors of asteroids and comets, to the extent to which the interiors of these bodies are not completely reflected in their surface composition. Answering these questions will shed further light on the evolution of the Solar system, and techniques which can “see� interior properties can help do so. Such techniques will also be valuable in future asteroid resource-prospecting endeavours, in places where bulk composition varies significantly from proximate surface composition. This is the domain of geophysics, the branch of geoscience that uses instruments sensitive to subsurface properties, analyzing data from those to infer subsurface composition and structure. GRASP employs two geophysical techniques, surface gravimetry and magnetometry; the former using the “Vector Gravimeter/Accelerometer� (VEGA) instrument to measure the gravity vector on the asteroid's surface, the latter employing magnetometers at the ends of GRASP's legs, in close proximity to any magnetized rocks on the asteroid's surface. GRASP is equipped with a rocket-based propulsion system allowing it to rove by hopping, capable of visiting 100 stations spread about the surface of an asteroid 1 km or smaller in size; gravity measurements from these stations can be inverted to estimate the asteroid's internal density distribution. GRASP would be carried to its target asteroid as a secondary payload aboard a larger asteroid-rendezvousing “mothership� mission, which would release GRASP to land on the asteroid's surface, after which it would provide communications relay between Earth and GRASP, eliminating the need for GRASP to carry a high-delta-V propulsion capability or a long-range communications capability.

Original languageEnglish
JournalProceedings of the International Astronautical Congress, IAC
Publication statusPublished - 2018
Event69th International Astronautical Congress: #InvolvingEveryone, IAC 2018 - Bremen, Germany
Duration: 1 Oct. 20185 Oct. 2018


  • Asteroids
  • Geophysics
  • Magnetometry
  • Surface gravimetry


Dive into the research topics of 'Geophysical reconnaissance asteroid surface probe (GRASP)'. Together they form a unique fingerprint.

Cite this