page_title: MARSIS
section_title: Science
hierarchical_section_title: MARSIS / Science
context_page_description: MARSIS is a low frequency, pulse-limited radar sounder and altimeter developed by the University of Rome La Sapienza and Alenia Spazio. The Italian MARSIS instrument is operational on the European Space Agency, Mars Express orbiter mission.
  The MARSIS Principal Investigator is Giovanni Picardi from the University of Rome "La Sapienza", Italy. It features ground-penetrating radar capabilities, which uses synthetic aperture techniques and a secondary receiving antenna to isolate subsurface reflections. MARSIS identified buried basins on Mars. MARSIS was funded by ASI and NASA.
context_section_description: MARSIS transmits a series of modulated chirps at frequencies between 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 mode the pulsewidth is 30, 91 or 250 μs and the nominal Pulse repetition frequency is 130 Hz. Transmitted power is either 1.5 or 5 W.
  Nominal science observations began during July 2005.
  A 2012 paper by the MARSIS team measured a difference between the dielectric constant of the northern and southern high-latitude regions.  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.
  Using MARSIS data, 22 Italian scientists reported in July 2018 the discovery of a subglacial lake on Mars, 1.5 km (0.93 mi) below the southern polar ice cap, and extending horizontally about 20 km (12 mi), the first known stable body of water on Mars.
caption: Size of the MARSIS antenna (horizontal line) compared to the spacecraft and a human silhouette