Mars is getting crowded. The Red Planet now has seven robots studying it, following the arrival of two new orbiters in September: NASA’s MAVEN (Mars Atmosphere and Volatile Evolution) and MOM (Mars Orbiter Mission), the Indian space agency’s first Mars spacecraft.
Both showed up just in time for a rare spectacle. On October 19, comet Siding Spring whizzed past Mars at a distance of just under 140,000 kilometers, a near miss in planetary terms. As a precaution against the high-speed dust particles flying off the comet, MAVEN and two other NASA orbiters temporarily hunkered down on the far side of the planet. They survived unscathed, and one sent back pictures of the comet’s nucleus, the first ever seen in a pristine comet from the farthest reaches of the solar system (SN Online: 10/22/14).
MAVEN, the first probe dedicated to studying the Martian upper atmosphere, embarked on a year-long mission to measure how the solar wind strips that atmosphere away. Over billions of years, this atmospheric erosion has transformed the planet from warm and wet — and presumably more hospitable to life — to cold and dry (SN Online: 10/15/14).
For all the excitement in orbit, there was still plenty of action on the surface. NASA’s decade-old Opportunity rover discovered evidence for the most ancient Martian environment where life could have existed, roughly 4 billion years ago (SN: 2/22/14, p. 10). Opportunity’s odometer also turned over 40 kilometers, breaking a Soviet moon rover’s record for longest distance driven on an extraterrestrial body.
Meanwhile, NASA’s Curiosity reached Mount Sharp, a 5-kilometer-high pile of sediments that the rover had been driving toward since landing in 2012. Curiosity suffered wheel damage from rock punctures but continued to gather rock and soil samples to flesh out the picture of where and when Mars might have been conducive to life.