The spectacular images NASA's Curiosity rover has returned from the surface of Mars reveal an ultra-dry environment, like the Mojave Desert after a 3-billion-year drought.
Data from Curiosity and its predecessors make clear that water ran there once and the planet probably was habitable. Over the eons, something happened. The next U.S. mission to Mars will look to the red planet's pink skies for clues as to what caused the Martian climate to change so dramatically.
“Today we see a cold, dry atmosphere,” says Bruce Jakosky, principal investigator on the Mars Atmosphere and Volatile Evolution (Maven) mission. “Where did the water go? Where did the carbon dioxide from an early thick atmosphere go? What really drove the climate change that we see evidence for on Mars?”
After examining the planet's surface in spectacular detail for decades, scientists are ready to dip into the atmosphere from orbit to expand the search. Drawing on heritage from earlier spacecraft that aero-braked to achieve orbit around Mars, Maven will use its bat-like solar arrays for stability as it skims through the thin upper atmosphere from elliptical orbit and makes the occasional “deep dive” for in-situ measurements.
“There are two places that the atmosphere can go,” says Jakosky, a planetary scientist at the University of Colorado's Laboratory for Atmospheric and Space Physics (LASP) in Boulder. “It can go down into the crust, and we don't see evidence for the big reservoir of crustal minerals that would be indicative that that's where it has gone. The other place it can go is up, and be lost to space. Most of the effort over the past several decades has focused on the surface and subsurface. We're the first mission devoted solely to understanding the upper atmosphere and the role of loss to space.”
Set for launch on an Atlas V 401 in a 20-day window that opens Nov. 18, Maven is a relatively low-cost Scout-class mission. It was the only NASA mission to the red planet left standing after the agency bailed out of a three-year cooperative-exploration planning effort with the European Space Agency (AW&ST Feb. 20, 2012, p. 33).
Capped at $671 million—including the launch vehicle, reserves and an Electra UHF transceiver that will serve as a backup communications relay for future Mars surface missions—Maven has reached Kennedy Space Center on budget and schedule for final testing and integration with the Atlas. Jakosky and other mission managers attribute that achievement to heritage hardware and a willingness to resist “requirements creep” after NASA selected the mission in 2008.