Main Theme Radar and subsurface penetration
Mission Responsibility NASA
Launch Date 12 August 2005
End of Mission 2008
Current phase Phase E
SHARAD (SHAllow-RADar) is one of the main instruments on board the Mars Reconnaissance Orbiter (MRO), NASA's planetary exploration spacecraft launched in August 2005 and operating in Mars' orbit since the end of 2006. The purpose of the MRO mission is global mapping of the surface (in visible and near infrared), investigation of the subsurface, identification of future landing sites for spacecraft and future communications and navigation support to Martian missions. SHARAD is radar that penetrates the subsurface and is used for exploring the Martina subsurface on board the Mars Reconnaissance Orbiter. The radar is studying the subsurface of the first hundred meters with a vertical resolution of about 20 metres, horizontal at about one hundred metres in trajectory, while perpendicularly the resolution is in the order of a kilometre depending on subsurface characteristics and local surfaces. The radar instrument points to the nadir with functioning and impulses on two modalities of radar and altimeter. In order to isolate, the reflectors of the subsurface use the synthetic aperture technique. The instrument consists of an antenna and an electronic system working at a wavelength range centred at MHz +/- 5 MHz This configuration enables the analysis of dielectric properties in the subsurface, thereby maintaining low clutter at the surface. The frequencies selected can penetrate the ionosphere. The total cycle of transmission and reception of each impulse is a few milliseconds. The signal received is therefore down-converted, transformed from analogical to digital and compressed.
The main objective of SHARAD is to select and map in selected areas the dielectric interfaces up to a depth of one kilometre and to interpret the interfaces in geological and geophysical terms. The selection of interfaces in the subsurface is the first step for reconstructing Martian geology, for the definition of the structures and the configurations of levels and formations. Frequencies have been selected on the basis of current models of Mars' subsurface to identify the presence of water deposits or ice layers and to study the structure of polar ice deposits.
The scientific instrument was developed in Italy and supplied to NASA by ASI as a Facility Instrument with the scientific guidance of a Principal Investigator who was selected by ASI following a competition in the person of Dr. Roberto Seu of the INFOCOM Department of the Università “La Sapienza” of Rome. The industry which was responsible for the industrial production was Alenia Spazio which today is Thales Alenia Space of Rome that has thus established its know-how in this sector.
It is the first Italian facility instrument on board a completely American mission. ASI has participated with the direct involvement of staff in delivery and integration of the instrument phases, as well as the launch campaign on the basis of agreements between the agencies and a Memorandum of Understanding signed on 21 January 2004 that also includes the management, archiving and distribution of data of which ASI's ASDC is in charge.