Unusual Deposit Found on Mars
New details have recently been found concerning the Medusae Fossae Formation deposits found on Mars. The European Space Station’s Mars Express orbiter has a radar system that located facts unknown up to now, with the first direct measurement of the depth and electrical properties of these materials giving clues as to their beginnings.
NASA’s Jet Propulsion Laboratory, Pasadena CA, manages NASA’s roles in the Mars Express Mission. Using its Mars Advanced Radar for Subsurface and Ionospheric Sounding (Marsis) Mars Express has been gathering data on the Medusae Fossae Formation Deposits. Mars Express flew over the deposits many times in 2006 and 2007 taking radar soundings as it went. The Medusae Fosse Formation is made up of enigmatic deposits. They could represent some of the youngest deposits on the surface of the red planet. They are located near the Martian equator along a divide between highlands and lowlands.
Radar observations have found that the formation is massive deposits more than 2.5 kilometers (1.4 miles) thick in places. The depth, revealed by instruments, is based on the time it takes for the radar beam to pass through the layers and bounce off the plains material underneath. The deposits are found to be associated with region’s that absorb certain wavelengths of Earth - based radar that is fascinating scientists. They are called “stealth” regions because they give no radar echo.
However, the radar instrument on Mars Express uses longer wavelengths than Earth - based radar experiments. At these wavelengths, the radar waves mostly pass through the deposits, creating subsurface echoes when the radar signal reflects off the plain material beneath. Several resumes have been offered for the origin and composition of these deposits. They could be volcanic ash deposits from now - buried vents or nearby volcanoes. Or they could be deposits of wind - blown materials eroded from Martian rocks Or they could be ice - rich deposits. Similar to layered ice deposits at the poles of the planet, but formed when the spin axis of Mars tilts over, making the equatorial region colder.
Reaching conclusions is hard even with the new data. The layers could be poorly packed, fluffy, dusty material as suggested by the Marsic data which showed the electrical properties of the layers. The question then arises as to how porous material from wind - blown dust can be more than two kilometers (more than a mile) thick and yet not be compacted under the weight of the overlying material. There is no other strong evidence for the presence of ice in the equatorial regions of Mars today even though the electrical properties are consistent with water - ice layers. “If there is water - ice at the equator of Mars, it must be buried at least several meters below the surface”, said co-author Jeffrey Plaut of JPL. This is because the water vapor pressure on Mars is so low that any ice near the surface would quickly evaporate. So the questions of Mars Medusae Fossae Formation continue.
This entry was posted on Wednesday, February 20th, 2008 at 12:24 pm and is filed under Space Agency News. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
