’s Mars Science Laboratory survived its “seven minutes of terror” to touch down gently on the surface of Mars late on Aug. 5, setting the stage for years of robotic hands-on exploration aimed at learning if the Red Planet could ever support life.
Controllers at thein Pasadena, Calif. applauded each step of the way down, as clear signals received via a “bent pipe” relay through the Mars Odyssey orbiter reached Earth. When the car-sized nuclear-powered Curiosity rover touched down, applause shifted to cheers and hugs as the tension finally broke. For some of the blue-shirted controllers, the landing marked the culmination of eight years of work. For planetary scientists, the work is just beginning.
The rover is set to explore sedimentary layers as it climbs the mountain in the middle of Mars’ equatorial Gale Crater, using a robotic arm with a toolkit of drills and scoops to collect rock and soil samples for analysis in a compact chemistry lab inside the rover body.
For features that are nearby but still beyond reach of the arm, the rover has a laser that will vaporize rocks and soils for spectral analysis. It also carries a weather station and equipment to measure surface radiation.
To set its chemical measurements in context, Curiosity has a variety of cameras able to take close-up images of rocks, two mast-mounted 2-megapixel cameras for 3-D imaging, and separate telephoto and wide-angle imagery. A Russian-built instrument will shoot neutrons into the ground below the rover, looking for water bound into minerals there down to a depth of about 20 inches.
says Curiosity is searching for the chemistry necessary for life, and not for evidence of life itself, but it does not rule out the latter possibility. As it climbs up the mountain collecting and analyzing samples, scientists hope to learn about the history of the planet and the role played by water in shaping the environment over time.
The landing followed the entry, descent and landing script to the letter, beginning with separation of the cruise stage that carried the rover to Mars. Controllers saw a brief and expected communications drop-out as the separated stage passed between the entry capsule and Earth.
With a clear signal through Odyssey, controllers tracked the MSL as it entered the atmosphere, slowed through a series of turns designed to bleed off speed and popped its supersonic parachute, an early danger point.
“Things went so fast, but as soon as I saw the parachute actually open and start slowing down, I told [NASA Administrator] Charlie Bolden we’re halfway there,” says JPL director Charles Elachi.
Things went faster after that, with the heat shield falling away, the descent stage dropping out of the backshell and the monopropellant engines firing and slowing the descent through the final kilometer toward the surface. The sky crane worked as advertised, lowering Curiosity to the surface on nylon cables, and then cutting them to fly a safe distance away from the rover.
The link through Odyssey remained strong as the orbiter dipped down beside the mountain and further out of sight of the relay satellites, allowing thumbnail images collected by rear- and forward-facing hazard-avoidance cameras through transparent dust shields. Although low resolution, the forward image clearly showed the rover’s shadow on the surface of Mars. Even with the late hour in the U.S., the NASA websites displaying the images all crashed briefly with overload.
It will be a day or so before engineers know exactly where Curiosity is on the surface, but it clearly is close to its touchdown target. Telemetry indicated the landing left 140kg of fuel unspent, an indication of how little of the margin designed into the sky crane system was needed.
John Grotzinger, the mission’s chief scientist, says the next two weeks or so will be spent checking out the rover’s 10 instruments, followed by a short drive. Images and scientific data will be collected and sent to Earth during the checkout period, and scientists will spend at least a year checking out the terrain around the landing site before moving up the mountain.
“We just don’t want to rush,” Grotzinger says.