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First MRO PSG Meeting Pasadena Dec. 5-7, 2001 SHARAD Experiment

First MRO PSG Meeting Pasadena Dec. 5-7, 2001 SHARAD Experiment. Prepared by: Enrico Flamini/Leila V. Lorenzoni – ASI – project office Angioletta Coradini – CNR – ASI project scientist Roberto Seu – INFOCOM – Team Leader Arturo Masdea – INFOCOM – Experiment Manager

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First MRO PSG Meeting Pasadena Dec. 5-7, 2001 SHARAD Experiment

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  1. First MRO PSG MeetingPasadena Dec. 5-7, 2001SHARAD Experiment Prepared by: Enrico Flamini/Leila V. Lorenzoni – ASI – project office Angioletta Coradini – CNR – ASI project scientist Roberto Seu – INFOCOM – Team Leader Arturo Masdea – INFOCOM – Experiment Manager Roberto Orosei – CNR – Science Team

  2. Scientific value: subsurface geology • Globally, depth of penetration could vary from tens of meters in materials with high losses (wet clays or brines), or as deep as 5 km in homogeneous, low-loss polar ice. • SHARAD radar should make significant new scientific data available toward addressing critical scientific problems on Mars, including the existence and distribution of buried paleochannels, regolith layering. • It will also provide an improved understanding of the electromagnetic properties of the “stealth” Martian subsurface, further insights into the nature of patterned ground, and other morphologies suggestive of the presence of water at present or in the past.  • In addition, it should be possible to answer certain kinds of geologic questions, such as the character of the surface below the polar ice caps and the nature of some of the layered terrain.

  3. Scientific Value: subsurface water detection The surface of Mars will not be uniformly amendable to using radar sounding in the search for water It will be possible to find conditions of favorable radar viewing geometry, interface scattering, surface and volume scattering, and material properties, which may allow us to see useful reflections of aqueous layers from orbit When strong internal reflections do occur, they will be identifiable as aqueous only by contextual inferences drawn from the characteristic geological context of water habitats Orbital radar data can be improved by in situ observations (e.g. magnetotelluric methods) Methods better than radar sounding for the detection of Water at planetary scale are not yet identified

  4. SHARAD and MRO

  5. Science Floor • Profiling of areas suspected of hosting hydrothermal or other near-surface reservoirs of liquid water/brine (e.g. “weeping layers”) will indicate areas of potential interest, and should effectively inform plans for subsequent surface investigations designed to “follow the water.” However, detected subsurface interfaces will be identifiable as aqueous only by contextual inferences drawn from the characteristic geological context of water habitats. • vertical resolution: ~10 m • horizontal resolution: hundreds of meters to km’s • penetration depth: hundreds of meters

  6. Science Floor • Mapping of the thickness, extent and continuity of the layers within the polar deposits will provide otherwise inaccessible information on prior variations in the vertical and areal extent of the polar deposits, flow in the internal structure of the caps, existence of peripheral ice deposits that may have been associated with local discharges of sub-polar or sub-permafrost groundwater and, if penetration down to the base of the caps can be achieved, evidence of past or present basal melting or basal lakes. • vertical resolution: ~10 m • penetration depth: from few hundred meters to 1 km

  7. Receiver antenna Transmitter antenna 9 Km 5.4 Km 300 m 6 Km 5 Km Sharad Smart Lander Error Ellipse Marsis In situ and borehole analysis Magneto-telluric active and passive

  8. Science Observations • Science observations will begin with the deployment of the antenna, which will take place only after the end of aerobraking; after deployment, the spacecraft can only perform limited accelerations. • During instrument data collection, S/C shall always be oriented such that the antenna dipole is orthogonal to the nadir axis: the antenna axis needs to be positioned within 10 degrees of desired nadir-looking direction (TBC). • If the orientation of the solar panels will be more than TBD degrees from the direction orthogonal to the antenna axis, Sharad measurements could be jeopardized.

  9. Observing Geometry SHARAD is a nadir looking radar sounder with synthetic aperture capabilities

  10. Observing Modes • Instrument Modes shall belong to any of the following two classes: • Support Modes • Operation Modes • The Support Modes are used for warm-up, to keep the instrument ready to operate with reduced power consumption, and for auxiliary tasks such as failure recovery, SW patching and troubleshooting. • The Operation Modes are those in which the instrument performs its nominal science data acquisitions and may also include calibration modes.

  11. Observing Modes • OPERATION MODES

  12. Observing Modes • Data Rate

  13. Data Processing • Operate on level 2 data from archive • Calibration and other corrections are considered already applied to the data • Aim at extracting high level products, directly usable for science interpretation • Joint processing of multiple radar sweeps: • - echoes collected along an orbit (or part) • - echoes from multiple overlapping or close orbits • - echoes collected at multiple frequencies in the orbit (if applicable) • Joint processing of data collected from MARSIS and other instruments (TBC)

  14. SHARAD Concept • SHARAD system is conceived as a dual frequency shallow radar providing measurements at the centre frequencies 17.5 and 22.5 Mhz. • At these centre frequencies the radar will trasmit two radar pulses shortly separated in time within the same radar sweep. • Each radar pulse is linear frequency modulated over a 5 Mhz bandwidth to provide 30 meters resolution in free space. • Echoes from the two bands (15 - 20 Mhz) (20 - 25 Mhz) are treated independently on board. • On ground, echoes are processed still independently through SAR based techniques to enhance the azimuth resolution and therefore clutter reduction • Possible stepped chirp technique for finer range resolution.

  15. Instrument Requirements To meet these objectives, an HF nadir looking synthetic aperture radar will be designed, of relatively large bandwidth to meet the range resolution requirement. Synthetic aperture processing allows improvement of the along track spatial resolution and, consequently, also reduction of the off-nadir ground clutter echo.

  16. SHARAD System Preliminary Parameters • Antenna: half wave dipole ~7 m length (tip-to-tip) • Centre Frequencies: 17.5 & 22.5 MHz • Radiated Peak Power: 10 W • Pulse Length: 300 s • Pulse Bandwidth: 5 MHz • Pulse Repetition Frequency: ~150 Hz • Vertical Swath Range: 40 s (6 Km - free space)

  17. Mechanical Configuration • Baseline: • Antenna (Ant) • Transmitter (Tx) • RadioFrequency and Digital (RDS) • Physical Dimensions (CBE) • RDS ==> 22 x 25 x 20 cm • TX ==> 45 X 15 X 10 cm • Antenna ==> 45 x 25 x 10 cm (Stowed configuration)

  18. Mass And Power Current Best Estimates

  19. H/W & S/W Heritage

  20. Processing Characteristics • SHARAD is presently planning to pre-process the return echoes on board, exclusively using its own Digital subsystem resources • The on-board processing will be possibly limited to some coherent processing in order to meet the S/C requirements in terms of produced data rate and volume and, at the same time, to maintain the highest possible flexibility in the ground processing • No data compression processing is planned for the telemetry data produced by SHARAD

  21. Calibration requirements • The objective of the calibration is to determine the expected uncertainty in the geophysical characteristics of the surface and subsurface as measured by SHARAD. • The calibration of SHARAD is similar to the calibration of a SAR system but has the added complexity of the matching between the sounder electronics with the antenna. • The calibration of the electronics system gain will follow standard procedures and will be performed on ground. • SHARAD is presently planning to perform also the TX-Antenna calibration on ground. In any case this calibration will be performed also while in orbit around Mars, using the echoes received from very flat surfaces according to a TBD procedure every TBD orbits.

  22. Cruise/Transition Orbit • During the cruising phase towards Mars, heaters, powered by dedicated power line, will be used under S/C control to keep the instrument equipment within the survival temperature range. • Health and safety checkout will be performed every TBD days, together with measurements in receive-only mode to characterize the noise environment.

  23. Mapping Orbit Operations • In the off state, heaters, powered by dedicated power line, will be used under S/C control to keep the instrument equipment within the survival temperature range. • At every switch-on of the radar a certain amount of time (of the order of 3 minutes, TBC) is required to pass the instrument into operation. • Within a single orbit, the instrument will be operated in any of its observation modes, in any desired sequence. • Within an orbit, the radar can be operated continuously or discontinuously. • The time limit is set by the portion of overall data volume allocated to SHARAD vs. the selected operational mode selected.

  24. Instrument Performance Evaluation • The SHARAD Team will provide specific software to the Mission Operations System with the capabilities to monitor the status of the experiment. • A quick look capability for the status of the instrument will be achieved by sorting out and interpreting only the housekeeping source packets. This will provide a check of the state-of-health of the instrument before any data analysis is performed. • The monitoring of the instrument status will provide inputs for subsequent instrument operations planning (selection of operating modes, amplifier gain, calibration sequences, etc.).

  25. Sequence Designs • Total coverage of polar deposits through night-side observations is the minimum requirement for science operations. • We require access to all latitudes when spacecraft is on the night side, although coverage is required to be continuous only over the polar deposits. • Limited day-side observations of polar deposits and targets subject to variations over time can be required.

  26. Experiment Data Records • Raw data from SHARAD will be a sequence of pulse echoes from the Martian surface. • Raw data from SHARAD will be organized by frames, i.e. a sequence of pulses transmitted with identical instrument parameters. • Aperture synthesis is achieved by processing the pulses within a single frame.

  27. Quantity, Quality, And Continuity • For a typical data rate of 1 Mbps estimated for scientific observations, with a half-hour data collection period in four orbits per sol, a total raw data volume of ~900 Mbytes per sol can be hypothesized (~600 Gbytes for the nominal mission duration). • SHARAD will operate on those portions of the Martian surface where the signal-to-clutter ratio is compatible with subsurface interface detection. It is currently estimated that ~40% of the Martian surface will satisfy this requirement. • Mapping of the polar deposits requires that data acquisition be uninterrupted over arcs comparable to their latitude extent (of the order of 1000 km).

  28. Organization Chart ASI Project Office Enrico Flamini Angioletta Coradini Sylvie Espinasse Science Team D. Biccari, U. Roma, Italy C. Federico, U. Perugia, Italy V. Formisano, IFSI/CNR, Roma, Italy P. Lombardo, U. Roma, Italy L. Marinangeli, IRSPS, Pescara, Italy R. Orosei, IAS/CNR, Rome, Italy G. Picardi, U. Roma, Italy S.B. Serpico, U. Genova, Italy J. Plaut, JPL, Pasadena, CA, USA B. Campbell, Smithsonian Inst., Washington DC, USA Team Leader Roberto Seu U. Roma, Italy Co-Team Leader R. Phillips, Washington Univ., St. Louis, MO, USA Experiment Manager Arturo Masdea U. Roma, Italy Industry PM & IM G. Braconi & C. Zelli Italy System Design Italy Digital SS Italy RF SS Italy Antenna SS Italy System AIV/AIT Italy

  29. Information Release Plan - Public Release • The SHARAD Team will comply fully with guidelines of the MRO Education and Public Outreach plan: • it will be responsive to requests for public relations material from the Project Scientist or from the relevant NASA offices. • it will submit material concerning the goals and approach of the SHARAD experiment for the MRO Web Site during the development phase of the mission. • during operations, it will make available experiment updates on a weekly (TBC) basis for inclusion on the Web Site. • If appropriate and feasible, real-time access to a portion of the SHARAD data stream will be considered.

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