NASA has released a new gravity map of Mars, providing the most detailed look at the Red Planet's hidden interior.
Lead author Antonio Genova of the Massachusetts Institute of Technology (MIT) said that gravity maps allow them to see inside a planet, just as a doctor uses an X-ray to see inside a patient.
Genova added that the new gravity map will be helpful for future Mars exploration, because better knowledge of the planet's gravity anomalies helps mission controllers insert spacecraft more precisely into orbit about Mars. Furthermore, the improved resolution of this gravity map will help the researchers understand the still-mysterious formation of specific regions of the planet.
The improved resolution of the new gravity map suggests a new explanation for how some features formed across the boundary that divides the relatively smooth northern lowlands from heavily cratered southern highlands.
Also, the team confirmed that Mars has a liquid outer core of molten rock by analyzing tides in the Martian crust and mantle caused by the gravitational pull of the sun and the two moons of Mars.
Finally, by observing how Mars' gravity changed over 11 years, the period of an entire cycle of solar activity, the team inferred the massive amount of carbon dioxide that freezes out of the atmosphere onto a Martian polar ice cap when it experiences winter. They also observed how that mass moves between the South Pole and the North Pole with the change of season in each hemisphere.
The map was derived using Doppler and range tracking data collected by NASA's Deep Space Network from three NASA spacecraft in orbit around Mars: Mars Global Surveyor (MGS), Mars Odyssey (ODY) and the Mars Reconnaissance Orbiter (MRO). Like all planets, Mars is lumpy, which causes the gravitational pull felt by spacecraft in orbit around it to change.
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"With this new map, we've been able to see gravity anomalies as small as about 100 kilometers (about 62 miles) across, and we've determined the crustal thickness of Mars with a resolution of around 120 kilometers (almost 75 miles)," said Genova. "The better resolution of the new map helps interpret how the crust of the planet changed over Mars' history in many regions."
The study is published online in the journal Icarus.