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MARSIS

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Illustration of Mars Express with MARSIS antenna deployed

MARSIS(Mars Advanced Radar for Subsurface andIonosphereSounding) is a low frequency, pulse-limitedradarsounder andaltimeterdeveloped by the University of Rome La Sapienza and Alenia Spazio (today Thales Alenia Space Italy).[1]The Italian MARSIS instrument, which is operated by theEuropean Space Agency,is operational and orbits Marsas an instrumentfor the ESA'sMars Expressexploration mission.

The MARSIS Principal Investigator is Giovanni Picardi from the University of Rome "La Sapienza", Italy.[2]It featuresground-penetrating radarcapabilities, which usessynthetic aperturetechnique and a secondary receiving antenna to isolate subsurface reflections.[3]MARSIS identified buried basins on Mars.[4]MARSIS was funded byASI (Italy)and NASA (USA).[5]The processor runs thereal-time operating systemEONIC Virtuoso.[6]

Deployment[edit]

MarsSouthPole
Site of Subglacial Water
(25 July 2018)

On May 4, 2005,Mars Expressdeployed the first of its two 20-metre-longradarbooms for the MARSIS experiment. At first the boom didn't lock fully into place;[7]however, exposing it to sunlight for a few minutes on May 10 fixed the glitch.[8]The second 20 m boom was successfully deployed on June 14. Both 20 m booms were needed to create a 40 mdipole antennafor MARSIS to work; a less crucial 7-meter-long monopole antenna was deployed on June 17. The radar booms were originally scheduled to be deployed in April 2004, but this was delayed out of fear that the deployment could damage the spacecraft through a whiplash effect. Due to the delay it was decided to split the four-week commissioning phase in two parts, with two weeks running up to July 4 and another two weeks in December 2005.

The deployment of the booms was a critical and highly complex task, requiring effective inter-agency cooperation between ESA, NASA, industry partners, and public Universities.

Science[edit]

MARSIS transmits a series of modulated chirps atfrequenciesbetween 1.8 and 5.0 MHz in subsurface sounding mode, with a 1 MHz bandwidth. It also emits chirps sweeping between 0.1 and 5.4 MHz when ionosphere sounding. Depending on the mode, the pulsewidth is 30, 91 or 250 μs, and the nominalPulse repetition frequencyis 130 Hz. Transmitted power is either 1.5 or 5 W.[3]

Nominal science observations began during July 2005.[9]

A 2012 paper by the MARSIS team measured a difference between thedielectric constantof the northern and southern high-latitude regions.[10]This is evidence that the material that fills the northern basin is a lower-density material, which could be interpreted as evidence of an ancient northern ocean.[11]

Using MARSIS data, 22 Italian scientists reported in July 2018 the discovery of asubglacial lakeonMars,1.5 km (0.93 mi) below thesouthern polar ice cap,and extending horizontally about 20 km (12 mi), the first known stable body ofwater on Mars.[12][13][14][15]

Size of the MARSIS antenna (horizontal line) compared to the spacecraft and a human silhouette

See also[edit]

  • LRS,Lunar radar sounder (LRS) is a orbiting low frequency radar sounder and altimeter over Earth's Moon
  • RIME,Radar for Icy Moons Exploration (RIME) is a orbiting low frequency radar sounder and altimeter for Jupiter's Icy moons
  • SHARAD,The Mars SHAllow RADar sounder (SHARAD) radar (20 MHz) on the later launched Mars Reconnaissance Orbiter complements MARSIS capabilities.[16]
  • Tianwen-1,The Tianwen-1 mission plans an Orbiter Subsurface Radar (OSR) and rover based Ground-Penetrating Radar (GPR) for Mars
  • WISDOM (radar),Water Ice and Subsurface Deposit Observation on Mars (WISDOM) is a ground-penetrating radar on the ExoMars rover

References[edit]

  1. ^Flamini, E.; Fois, F.; Calabrese, D.; Bombaci, O.; Catallo, C.; Croce, A.; Croci, R.; Guelfi, M.; Zampolini, E.; Picardi, G.; Seu, R.; Mecozzi, R.; Biccari, D.; Cartacci, M.; Cicchetti, A.; Masdea, A.; Alberti, G.; Maffei, S.; Papa, C. (2007). "Sounding Mars with SHARAD & MARSIS".2007 4th International Workshop on, Advanced Ground Penetrating Radar.pp. 246–251.doi:10.1109/AGPR.2007.386561.ISBN978-1-4244-0886-3.S2CID25906305.
  2. ^"MARSIS: Subsurface Sounding Radar/Altimeter".esa.int. ESA. 25 October 2017.
  3. ^ab"MARSIS instrument home page".Due to severe limitations on the available mass, the antennas are of a novel design, each consisting of a folding composite tube that supports a pair of wires constituting the conductive element of the antenna. The antennas are deployed by pyrotechnic release mechanisms.
  4. ^MARSIS FINDS BURIED BASINS IN CHRYSE PLANITIADec 2006
  5. ^Buried Basins Discovered by RadarUndated
  6. ^Calabrese, D. (2003-12-16)."MARSIS Flight User Manual"(PDF).esac.esa.int.Retrieved2022-06-25.
  7. ^Glitch strikes Mars Express's radar boom - space,New Scientist,May 9, 2005
  8. ^Mars Express's kinky radar straightened out - space,New Scientist,May 12, 2005
  9. ^ESA Portal,Mars Express radar ready to work
  10. ^Jérémie Mouginot, Antoine Pommerol, Pierre Beck, Wlodek Kofman and Stephen M. Clifford, "Dielectric map of the Martian northern hemisphere and the nature of plain filling materials,"Geophysical Research Letters, 39,No. 2, 19 Jan 2012 (abstract)(article at UCI) accessed Nov. 17 2014
  11. ^Emily Lakdawalla,"Has Mars Express MARSIS data proved that Mars once had a northern ocean?"Planetary Society, February 7, 2012 (accessed Nov. 17 2014)
  12. ^Orosei, R.; et al. (25 July 2018)."Radar evidence of subglacial liquid water on Mars"(PDF).Science.361(6401): 490–493.arXiv:2004.04587.Bibcode:2018Sci...361..490O.doi:10.1126/science.aar7268.hdl:11573/1148029.PMID30045881.
  13. ^Chang, Kenneth;Overbye, Dennis(25 July 2018)."A Watery Lake Is Detected on Mars, Raising the Potential for Alien Life - The discovery suggests that watery conditions beneath the icy southern polar cap may have provided one of the critical building blocks for life on the red planet".The New York Times.Retrieved25 July2018.
  14. ^"Huge reservoir of liquid water detected under the surface of Mars".EurekAlert.25 July 2018.Retrieved25 July2018.
  15. ^Halton, Mary (25 July 2018)."Liquid water 'lake' revealed on Mars".BBC News.Retrieved25 July2018.
  16. ^R. Oroseiet al.,"Science results from the MARSIS and SHARAD subsurface sounding radars on Mars and their relevance to radar sounding of icy moons in the Jovian system",EPSC2010-726, European Planetary Science Congress 2010, Vol. 5 (accessed Nov. 17 2014)

External links[edit]

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