Mars Express illustration highlighting MARSIS antenna

MARSIS (Mars Advanced Radar for Subsurface and

Ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays ...

Sounding) is a low frequency, pulse-limited

radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...

sounder and

altimeter An altimeter or an altitude meter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, the measurement of depth under water. Ty ...

developed by the University of Rome La Sapienza and Alenia Spazio (today Thales Alenia Space Italy). The Italian MARSIS instrument, which is operated by the

European Space Agency The European Space Agency (ESA) is a 23-member International organization, international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 ...

, is operational and orbits Mars as an instrument for the ESA's ''

Mars Express ''Mars Express'' is a space exploration mission by the European Space Agency, European Space Agency (ESA) exploring the planet Mars and its moons since 2003, and the first planetary mission attempted by ESA. ''Mars Express'' consisted of two ...

'' exploration mission. The MARSIS Principal Investigator is Giovanni Picardi from the University of Rome "La Sapienza", Italy. It features

ground-penetrating radar Ground-penetrating radar (GPR) is a geophysical method that uses radar pulses to image the subsurface. It is a non-intrusive method of surveying the sub-surface to investigate underground utilities such as concrete, asphalt, metals, pipes, cables ...

capabilities, which uses synthetic aperture technique and a secondary receiving antenna to isolate subsurface reflections. MARSIS identified buried basins on Mars. MARSIS was funded by ASI (Italy) and NASA (USA). The processor runs the

real-time operating system A real-time operating system (RTOS) is an operating system (OS) for real-time computing applications that processes data and events that have critically defined time constraints. A RTOS is distinct from a time-sharing operating system, such as Unix ...

EONIC Virtuoso.

Deployment

Mars-SubglacialWater-SouthPoleRegion-20180725

On May 4, 2005, ''Mars Express'' deployed the first of its two 20-metre-long

booms for the MARSIS experiment. At first the boom didn't lock fully into place;Glitch strikes Mars Express's radar boom - space
''New Scientist'', May 9, 2005 however, exposing it to sunlight for a few minutes on May 10 fixed the glitch.Mars Express's kinky radar straightened out - space
''New Scientist'', May 12, 2005 The second 20 m boom was successfully deployed on June 14. Both 20 m booms were needed to create a 40 m

dipole antenna In radio and telecommunications a dipole antenna or doublet is one of the two simplest and most widely used antenna types, types of antenna; the other is the monopole antenna, monopole. The dipole is any one of a class of antennas producin ...

for 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

MARSIS transmits a series of modulated chirps at

frequencies Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...

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 the 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.ESA Portal
Mars Express radar ready to work
/ref> A 2012 paper by the MARSIS team measured a difference between the

dielectric constant The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insul ...

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 A subglacial lake is a lake that is found under a glacier, typically beneath an ice cap or ice sheet. Subglacial lakes form at the boundary between ice and the underlying bedrock, where liquid water can exist above the lower melting point of ic ...

Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...

, below the southern polar ice cap, and extending horizontally about , the first known stable body of

water on Mars Although very small amounts of liquid water may occur transiently on the surface of Mars, limited to traces of dissolved moisture from the atmosphere and thin films, large quantities of ice are present on and under the surface. Small amounts of ...

References

External links

ESA - MARSIS Finds Buried Basins in Chryse Planitia

ESA - Buried Basins in Northern Lowlands

buried basins and ice - eSA

{{Satellite and spacecraft instruments Spacecraft instruments Geophysical imaging Mars Express Space radars

Deployment

Science

See also

References

External links