NASA's New Gravity Map Gives Most Detailed View of Mars to Date

Mars, shown with all its gravity.
Mars, shown with all its gravity.
Image courtesy of NASA

NASA has come up with yet another way to get a totally different view of the Red Planet. 

This time, the federal space agency made a map using the pull of gravity to illustrate the surface of Mars as well as providing new information about what lies beneath the Martian crust, creating one of the most accurate maps of Mars in existence. 

NASA scientists constructed the map by spending more than a decade tracking the gravitational wobbles and reactions of three spacecraft orbiting the planet, the Mars Global Surveyor, the Mars Odyssey and the Mars Renaissance Orbiter. The researchers used Doppler and range-tracking data collected by NASA's Deep Space Network antennas located around Earth to make a gravitational chart of the planet. As NASA explains it, Mars is lumpy, like all planets, so the gravitational pull will be stronger on a spacecraft when it's passing over something taller, like a mountain, and weaker when it's passing over something a lot farther away from the spacecraft, like a canyon.

"Gravity maps allow us to see inside a planet, just as a doctor uses an X-ray to see inside a patient," explained Antonio Genova of the Massachusetts Institute of Technology, who led the study at NASA's Goddard Space Flight Center.

The gravitational mapping has left NASA scientists with one of the clearest pictures ever constructed of how Mars is actually laid out. They now know how the divide between the smoother northern lands of the planet and the rocky, cratered southern lands actually splits. Also, the NASA team observed the gravitational pull of the sun and the two Martian moons and how that worked on the planet, and figured out that Mars definitely has a liquid outer core of molten rock.

The researchers also found out new details about the polar ice caps on Mars. After observing how the planet's gravity changed over 11 years — 11 years is an entire solar cycle for Mars — the team figured out that a massive amount of carbon dioxide freezes to become an impressive Martian polar ice cap during the Martian version of a winter. And the polar ice cap doesn't play favorites. In fact, it moves between the north and south poles with each change of season in each hemisphere.

While studying the Red Planet's gravity, researchers have been able to see gravitational anomalies as small as about 62 miles across. They've also figured out that the Martian crust is about 75 miles thick. Information like this has also helped scientists spot new-to-them anomalies, like the surprisingly low-gravity Acidalia Planitia and Tempe Terra. It's believed water once ran through a system of buried channels between these two points, delivering waters and sediments from Mars's southern highlands into the northern lowlands billions of years ago, as we've reported. (Back when Mars had a much wetter climate.) 

So now NASA has a really good map of the Martian surface, and a better idea of what lies beneath it. That can only help in the quest to actually get astronauts to that planet by the 2030s. Right now, it's hard to say who's more into the idea of going to Mars. Congress has not been shy about pushing NASA officials to get to Mars and to do it as quickly as possible, even coming up with decent funding to ensure the Martian dream continues to move toward becoming a reality, as we've previously reported.  At the same time, NASA officials themselves have been very clear that they've got their eyes on the Red Planet and nothing else. 


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