Mars May Have Porous Crust
TEHRAN (Tasnim) – The NASA scientists found evidence that Mars' crust is not as dense as previously thought, a clue that could help researchers better understand the Red Planet's interior structure and evolution.
A lower density likely means that at least part of Mars' crust is relatively porous. At this point, however, the team cannot rule out the possibility of a different mineral composition or perhaps a thinner crust.
"The crust is the end-result of everything that happened during a planet's history, so a lower density could have important implications about Mars' formation and evolution," said Sander Goossens of NASA's Goddard Space Flight Center in Greenbelt, Maryland. Goossens is the lead author of a Geophysical Research Letters paper describing the work.
The researchers mapped the density of the Martian crust, estimating the average density is 2,582 kilograms per meter cubed. That's comparable to the average density of the lunar crust. Typically, Mars' crust has been considered at least as dense as Earth's oceanic crust, which is about 2,900 kilograms per meter cubed.
The new value is derived from Mars' gravity field, a global model that can be extracted from satellite tracking data using sophisticated mathematical tools. The gravity field for Earth is extremely detailed, because the data sets have very high resolution. Recent studies of the Moon by NASA's Gravity Recovery and Interior Laboratory, or GRAIL, mission also yielded a precise gravity map.
The data sets for Mars don't have as much resolution, so it's more difficult to pin down the density of the crust from current gravity maps. As a result, previous estimates relied more heavily on studies of the composition of Mars' soil and rocks.
From the new model, the team generated global maps of the crust's density and thickness. These maps show the kinds of variations the researchers expect, such as denser crust beneath Mars' giant volcanoes.
The researchers note that NASA's InSight mission -- short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport -- is expected to provide the kinds of measurements that could confirm their finding. This Discovery Program mission, scheduled for launch in 2018, will place a geophysical lander on Mars to study its deep interior.