Was Mars Ever Habitable?

If all goes according to plan, on November 25^th the Mars Science Laboratory (MSL) rover Curiosity will leave the Earth and begin its journey to Mars. Any delays due to weather or other factors should be accommodated by a launch window that extends until December 18^th. The spacecraft will use a new landing system to arrive at its landing site on Mars in August, 2012, and the rover carries an impressive array of scientific instruments. The rover is about twice as large as the Mars Exploration Rovers Spirit and Opportunity, thereby enabling it to navigate terrain characterized by larger obstacles (such as rocks) as it travels up to about 200 meters (219 yards) per Martian day.

The new landing system for the Mars Science Laboratory replaces the airbag system utilized by the Pathfinder and Mars Exploration Rovers during landing. The new landing system enables much larger rovers and science instrument payloads to be delivered to the surface of Mars than was previously possible and opens the door for future missions geared towards the eventual return of samples for the Red Planet. Upon entering the Martian atmosphere, the MSL spacecraft will first steer itself through the upper atmosphere before deploying a parachute and then using rockets and a tether to lower the Curiosity rover to the surface. Curiosity’s mission is geared towards understanding whether Mars is or ever could have been habitable. Recent data from NASA’s orbiting spacecraft (Odyssey and the Mars Reconnaissance Orbiter) and the Mars Exploration Rovers suggests the planet has had a long and complicated history of changing environmental conditions and landscapes. Curiosity will follow those missions by deploying a diverse complement of instruments to interrogate the rocks and soils in the vicinity of the landing site. The “next generation” of instruments carried by Curiosity comprises a “mobile laboratory” and should lead to a quantum leap in our understanding of Mars’ potential habitability and how the surface of Mars evolved over time.

Images of Gale Crater, the selected landing site for the Mars Science Laboratory. The first image shows the regional context of Gale Crater (labeled on the left and discussed above) with colors representing the elevation of the land surface (purple lowest and red highest). The second image shows an example of high priority science targets for exploration near the ellipse (yellow box in first image shows the location) and the last image shows science targets within the target landing ellipse (white box in the first image shows the location).

Advances in landing precision enable consideration of smaller landing sites than was possible during prior missions and made it possible to access the selected landing site within Gale crater. Gale crater is attractive to scientists because there is a five kilometer (three mile)-thick section of layered rocks deemed likely to enable study of changing conditions on Mars over a time when the abundance and duration of water on the surface was decreasing over time. As water is an important factor in evaluating potential habitability, the chance to access the rocks that record the changes from relatively wetter to drier present an opportunity to learn a great deal about Mars as a planet and its potential as a possible abode for life. Curiosity is an important step in the long term study of Mars and sets the stage for future missions that will be focused on whether there is or ever was life on Mars. By helping to understand whether the planet was habitable and, if so, for how long, MSL will help identify the likely environments and potential targets for future sample return and the eventual search for possible life. The excitement should begin the day after Thanksgiving, so while resting after eating all that turkey, tune in to NASA TV and watch as Curiosity counts down towards lift-off and the start of an exciting new chapter in our understanding Mars and the solar system. Visitors to our Museum in DC can also watch the launch, targeted for 10:25 am ET Nov 25, on the giant screen in the Moving Beyond Earth gallery. John Grant co-led the process for selecting the landing site for the 2011 Mars Science Laboratory rover.