The Miniature Radio-Frequency instrument (Mini-RF) is a
synthetic aperture radar
Synthetic-aperture radar (SAR) is a form of radar that is used to create two-dimensional images or 3D reconstruction, three-dimensional reconstructions of objects, such as landscapes. SAR uses the motion of the radar antenna over a target regi ...
(SAR) instrument on the
Lunar Reconnaissance Orbiter
The Lunar Reconnaissance Orbiter (LRO) is a NASA robotic spacecraft currently orbiting the Moon in an eccentric Polar orbit, polar mapping orbit. Data collected by LRO have been described as essential for planning NASA's future human and robotic ...
(LRO), which is currently in orbit around the
Moon
The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...
. It has a resolution of 30 m/pixel and two wavelength bands, a primary band at 12.6 cm and a secondary band at 4.2 cm.
Overview
Previous
SAR instruments, such as the radar on the
Magellan
Ferdinand Magellan ( – 27 April 1521) was a Portuguese people, Portuguese explorer best known for having planned and led the Magellan expedition, 1519–22 Spanish expedition to the East Indies. During this expedition, he also discovered t ...
mission to
Venus
Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...
, were large, massive, power-hungry, and expensive. Intended as a demonstration of cheap, lightweight SAR technology, the Mini-RF instrument was designed in response to these concerns. Because it was a technology demonstration, Mini-RF is sometimes not included in lists of
LRO's instruments.
Radar is one of the few remote sensing tools capable of distinguishing water ice from other forms of water
thought to be present of the Moon, such as hydrated minerals and water
adsorbed
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a f ...
onto the lunar surface. Although the
LCROSS
The Lunar Crater Observation and Sensing Satellite (LCROSS) was a robotic spacecraft operated by NASA. The mission was conceived as a low-cost means of determining the nature of hydrogen detected at the polar regions of the Moon. Launched immedi ...
mission, which deliberately crashed a probe into the lunar surface to look for water, detected water in Cabeus Crater, Mini-RF did not detect the presence of thick deposits of water ice at the LCROSS impact site, however, the presence of less than 10 cm sized ice fragments could not be ruled out.
In January, 2011, after completion of Mini-RF's primary mission objectives, NASA announced that the Mini-RF transmitter had suffered a critical failure. The receiver continues working, allowing occasional
bistatic radar
Bistatic radar is a radar system comprising a transmitter and receiver that are separated by a distance comparable to the expected target distance. Conversely, a conventional radar in which the transmitter and receiver are co-located is called ...
measurements, where the radar signal is transmitted from the Earth, reflected off the Moon, and received by the Mini-RF.
Controversy
The original principal investigator of Mini-RF,
Stewart Nozette, was arrested for espionage. Nozette was replaced by Ben Bussey, then of APL, the
Applied Physics Laboratory
The Johns Hopkins University Applied Physics Laboratory (or simply Applied Physics Laboratory, or APL) is a not-for-profit university-affiliated research center (UARC) in Howard County, Maryland. It is affiliated with Johns Hopkins University ...
where Mini-RF was assembled from components developed by a consortium of industry team members. Bussey accepted a position at NASA Headquarters and was replaced by the current principal investigator, Wes Patterson, also of APL.
References
External links
Nasa Radar Tandem Searches For Ice On The Moon{{Webarchive, url=https://web.archive.org/web/20120405012806/http://www.nasa.gov/mission_pages/Mini-RF/news/radar_tandem_searches.html , date=2012-04-05
Space synthetic aperture radar
Lunar Reconnaissance Orbiter