Shallow Radar (SHARAD)

Shallow Radar (SHARAD)
Name	Shallow Radar (SHARAD)
Mission	Mars Reconnaissance Orbiter
Operator	NASA
Manufacturer	Jet Propulsion Laboratory
Launch	2005
Orbit	Martian orbit
Instrument type	radar sounder
Wavelength	15 MHz (approx.)

Shallow Radar (SHARAD) Shallow Radar (SHARAD) is a subsurface sounding radar instrument aboard the Mars Reconnaissance Orbiter designed to probe the upper kilometers of the Martian crust and polar layered deposits. Developed by teams at the Jet Propulsion Laboratory, University of Rome La Sapienza, and partners in the Italian Space Agency, SHARAD complements orbital assets such as the Mars Global Surveyor and Mars Odyssey while coordinating with landed missions like Mars Pathfinder and Curiosity (rover). The instrument’s observations have informed studies linked to the Valles Marineris, Hellas Planitia, and Olympus Mons regions and influenced planning for missions such as Mars 2020 and proposals like ExoMars.

Mission overview

SHARAD was selected as part of the payload on the Mars Reconnaissance Orbiter to perform high-resolution radar sounding of the Martian subsurface, operating in concert with instruments such as the High Resolution Imaging Science Experiment and the Context Camera. Managed by NASA and scientific teams at the Italian Space Agency and Sapienza University of Rome, SHARAD’s objectives were set during programmatic reviews involving stakeholders including the National Research Council (United States) and advisory input from researchers at Caltech and the University of Arizona. The instrument’s mission planning was influenced by earlier concepts from the Magellan (spacecraft) and later integrated into studies for polar processes examined by European Space Agency missions.

Instrument design and capabilities

SHARAD uses a nadir-pointing, synthetic aperture radar architecture with a central frequency near 15 MHz, dual linear polarization capability, and a deployable antenna developed at the Jet Propulsion Laboratory with contributions from the Italian Space Agency. The radar design drew on heritage from terrestrial sounders used by teams at MIT and the University of Colorado Boulder, and engineering practices from spacecraft such as Cassini–Huygens and Voyager 2. The instrument’s transmitter, receiver, and digitizer subsystems were assembled by contractors including groups at Lockheed Martin and electronics specialists at Honeywell International. SHARAD achieves vertical resolution on the order of a few meters in dielectric materials and horizontal resolution governed by orbital altitude similar to instruments aboard Mars Express and was calibrated via comparisons with active radar remote sensing studies from NOAA and the Jet Propulsion Laboratory’s planetary radar group.

Science objectives and discoveries

Primary science goals included mapping dielectric interfaces, detecting buried ice, characterizing stratigraphy of the polar caps, and investigating geologic units such as the Medusae Fossae Formation and the Amazonis Planitia volcanic plains. SHARAD data revealed extensive subsurface reflectors in Planum Boreum and Planum Australe, supporting hypotheses about excess ice storage analogous to terrestrial glacial units studied in Greenland and Antarctica. Discoveries attributed to SHARAD have informed interpretations of layered deposits in Valles Marineris, potential paleolake basins near Gale Crater, subsurface structure beneath Isidis Planitia, and buried channels in the Arcadia Planitia region. These findings intersect with work on climate cycles tied to orbital forcing studied by researchers affiliated with Caltech, Massachusetts Institute of Technology, Cornell University, University of Oxford, and Pennsylvania State University. SHARAD contributed to assessments of hazards and resources pertinent to human exploration discussed by panels at NASA Headquarters and analyses supporting Mars Sample Return planning involving European Space Agency collaboration.

Data processing and products

Raw waveforms from SHARAD were processed into radargrams using pipelines developed at the Jet Propulsion Laboratory, Italian Space Agency centers, and science teams at Sapienza University of Rome. Data products included focused and unfocused radargrams, clutter-simulated returns, dielectric property maps, and reflector picks distributed through NASA Planetary Data System nodes and archived for use by investigators at institutions such as University of California, Berkeley, University of Arizona, Brown University, and University of Texas at Austin. Processing workflows incorporated algorithms from signal processing groups at Stanford University and University of Michigan and leveraged software frameworks common to missions like Magellan (spacecraft) and Cassini–Huygens. Derived products enabled cross-correlation with datasets from the Mars Orbiter Laser Altimeter, the Compact Reconnaissance Imaging Spectrometer for Mars, and the Thermal Emission Imaging System.

Calibration, limitations, and uncertainties

Calibration of SHARAD employed in-flight maneuvers, comparisons with terrestrial test ranges at institutions like NASA Ames Research Center and models developed in collaboration with JPL and Sapienza University of Rome. Limitations include signal attenuation in basaltic and volcanic terrains such as Tharsis Montes, clutter from steep topography in regions like Noctis Labyrinthus, and ambiguity in dielectric constants when discriminating ice from hydrated minerals encountered in places like Meridiani Planum. Uncertainties stem from assumptions about scattering mechanisms, loss tangents informed by lab work at Caltech and University of Colorado, and resolution trade-offs similar to constraints faced by teams working on Mars Advanced Radar for Subsurface and Ionosphere Sounding concepts. Assessment of error budgets paralleled reviews by panels at National Academies of Sciences and incorporated lessons from terrestrial radar missions coordinated with European Space Agency partners.

Operational history and mission timeline

SHARAD was launched with the Mars Reconnaissance Orbiter in 2005, entered Martian orbit in 2006, and commenced routine operations following commissioning that involved teams at Jet Propulsion Laboratory, Italian Space Agency, and partner research centers. Major campaign milestones included targeted sounding of polar layered deposits during austral and boreal seasons, coordinated observations with the Phoenix (spacecraft) landing site, and campaign alignments with imaging passes by the High Resolution Imaging Science Experiment. Over the mission, SHARAD operations evolved through software updates, sequencing changes approved by NASA program managers, and science team proposals from institutions such as University of Rome Tor Vergata and University of Colorado Boulder. The instrument continues to contribute to long-term studies informing international mission concepts including ExoMars and Mars 2020 planning efforts.

Category:Missions to Mars