The Strange Attraction of Gale Crater
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Sept. 29, 2011: Curiosity is about to go to Mars. The car-sized rover, also known as the Mars Science Lab, is scheduled for launch in late November or early December 2011 from the Kennedy Space Center. After an eight-month voyage to Mars, Curiosity will land at the foot of a 3 mile high mountain in a crater named "Gale."
It sounds a little odd—a mountain in the middle of an impact crater. Wouldn't the impact have smashed it flat? Some scientists believe the 96 mile wide crater filled in with sediments over time and relentless Martian winds carved a mountain in the center, where it now stands nearly three times higher than the Grand Canyon is deep.
Because of its history, this strangely sculpted mountain is the ideal place for Curiosity to conduct its mission of exploration into the Red Planet's past. Joy Crisp, MSL Deputy Project Scientist from NASA's Jet Propulsion Laboratory, explains:
"This may be one of the thickest exposed sections of layered sedimentary rocks in the solar system. The rock record preserved in those layers holds stories that are billions of years old -- stories about whether, when, and for how long Mars might have been habitable."
Today the Red Planet is a radiation-drenched, bitterly cold, bleak world. Enormous dust storms explode across the barren landscape and darken Martian skies for months at a time. But data from the Mars Reconnaissance Orbiter suggest that Mars once hosted vast lakes and flowing rivers.
"Gale Crater and its mountain will tell this intriguing story," says Matthew Golombek, Mars Exploration Program Landing Site Scientist from JPL. "The layers there chronicle Mars' environmental history."
In the gentle slopes around the mountain, Curiosity will prospect for organic molecules, the chemical building blocks of life. Mars Reconnaissance Orbiter has found an intriguing signature of clay near the bottom of the mountain and sulfate minerals a little higher up. Both minerals are formed in the presence of water, which increases potential for life-friendly environments.
"All the types of aqueous minerals we've detected on Mars to date can be found in this one location," explains Golombek.
Clay settles slowly in water and forms little platelets that conform around things, hardening over time and encasing them in ''casts." Clay could seal organics off from the outside environment much like it preserved dinosaur bones on Earth.
"If organics ever existed on Mars, they could be preserved in the clay."
Even on planet Earth, teeming with life, finding billion year-old well-preserved organics is difficult. But Curiosity will find them if they're present in the samples it takes. The rover is equipped with the most advanced suite of instruments for scientific studies ever sent to the Martian surface1. When these are brought to bear on Gale crater’s mysteriously layered mountain, the odds of a discovery will be at an all-time high.
As seasoned travelers know, however, the journey is just as important as the destination. Curiosity can travel up to 150 meters per Mars day, but will stop often to gather and analyze samples.
"It could take several months to a year to reach the foot of the mountain, depending on how often the rover stops along the way," says Golombek. "There will be plenty to examine before getting to the central mound."
A high-resolution camera on the rover's mast will take pictures and movies of the scenery, taking Earthlings on an extraterrestrial sightseeing tour.
"As Curiosity climbs toward higher layers, you'll see spectacular valleys and canyons like those in the U.S. desert southwest. The walls on either side of the rover will rise over 100 feet. The sights alone will be worth the trip."
Stay tuned for updates from the Red Planet.
Mars Science Laboratory -- Curiosity's home page
1Curiosity will carry the biggest, most advanced suite of instruments for scientific studies ever sent to the martian surface, continued: For example, the Sample Analysis at Mars or "SAM" instrument inside the rover's body can detect a fainter trace of organics and identify a wider variety of them than any instrument yet sent to Mars. Its vents open to the atmosphere so it can "sniff" the air bird-dog style for evidence of its quarry. It can also "sniff" gases released after baking a sample in its oven. SAM is not restricted to soil samples. It can also analyze samples from inside rocks courtesy of the drill on Curiosity's robotic arm.
"Mounted on the rover's mast is ChemCam--a laser that can aim at a rock and vaporize a small spot on it, producing a plasma cloud we can analyze to learn that rock's chemistry," adds Joy Crisp.
In addition to ChemCam, the mast sports a high-resolution camera called, naturally, Mastcam. It will take pictures and video of geological structures and features, like craters, gullies, and dunes. The rover's robotic arm is equipped with a brush to remove dust from rock surfaces, a drill to collect rock powder, and a scoop to collect soil. "Once a sample or rock powder or soil has been collected, Curiosity shakes it through a sieve and into a portioner and then delivers sample portions to one or both of the two analysis instruments inside the body of the rover," says Crisp. "In other words, the rover does the prep work a human in a lab usually does. We'll send the rover a sequence of commands to enable it to do all this." The rock powder and soil samples will be examined for organic molecules by SAM and for mineralogy by an X-ray diffraction instrument. The arm also wields its own unique instruments. One of them is APXS, the Alpha Particle X-Ray Spectrometer, which will measure the abundance of chemical elements in the dust, soils, rocks, and processed samples. The other arm instrument MAHLI, the Mars Hand Lens Imager, will return color images like those of typical digital cameras and act like a geologist's magnifying lens. Its images can be used to examine the structure and texture of rocks, dust, and frost at the micrometer to centimeter scale. On the back of the rover is an instrument that can measure the hydrogen abundance in the ground under the rover and identify interesting soils and rocks worthy of further investigation. Curiosity will also carry instruments for observing Martian weather and measuring cosmic and solar energetic radiation bombarding the planet's surface.
Learn more about Curiosity's instruments at http://mars.jpl.nasa.gov/msl/mission/instruments/