MARSIS
Encyclopedia
MARSIS is a low frequency, pulse-limited radar
sounder and altimeter
used on the ESA Mars Express
mission. It features ground-penetrating radar
capabilities, which uses synthetic aperture
techniques and a secondary receiving antenna to isolate subsurface reflections.
booms for the MARSIS experiment. At first the boom didn't lock fully into place; however, exposing it to sunlight for a few minutes on May 10 fixed the glitch. The second 20 m boom was successfully deployed on June 14. Both 20 m booms were needed to create a 40 m dipole antenna
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 ESA, NASA, Industry and public Universities.
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
sounder and altimeter
Altimeter
An altimeter 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 underwater.-Pressure altimeter:...
used on the ESA Mars Express
Mars Express
Mars Express is a space exploration mission being conducted by the European Space Agency . The Mars Express mission is exploring the planet Mars, and is the first planetary mission attempted by the agency. "Express" originally referred to the speed and efficiency with which the spacecraft was...
mission. It features ground-penetrating radar
Ground-penetrating radar
Ground-penetrating radar is a geophysical method that uses radar pulses to image the subsurface. This nondestructive method uses electromagnetic radiation in the microwave band of the radio spectrum, and detects the reflected signals from subsurface structures...
capabilities, which uses synthetic aperture
Synthetic aperture radar
Synthetic-aperture radar is a form of radar whose defining characteristic is its use of relative motion between an antenna and its target region to provide distinctive long-term coherent-signal variations that are exploited to obtain finer spatial resolution than is possible with conventional...
techniques and a secondary receiving antenna to isolate subsurface reflections.
Deployment
On May 4, 2005, Mars Express deployed the first of its two 20-metre-long radarRadar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
booms for the MARSIS experiment. At first the boom didn't lock fully into place; however, exposing it to sunlight for a few minutes on May 10 fixed the glitch. The second 20 m boom was successfully deployed on June 14. Both 20 m booms were needed to create a 40 m dipole antenna
Dipole antenna
A dipole antenna is a radio antenna that can be made of a simple wire, with a center-fed driven element. It consists of two metal conductors of rod or wire, oriented parallel and collinear with each other , with a small space between them. The radio frequency voltage is applied to the antenna at...
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 ESA, NASA, Industry and public Universities.