Mars-based research craft sent another surprise to scientists today. After celebrating the successful landing Sunday night of the Mars Phoenix Lander and its first detailed images of the Mars’ northern arctic circle, the NASA team released another first-ever image.
A camera on a separate craft, one orbiting Mars, caught an image of the Phoenix Lander suspended from its parachute just before it descended onto the Red Planet’s northern plains on May 25. The image, taken by the Mars Reconnaissance Orbiter, marks the first time one spacecraft has photographed another one in the act of landing on Mars. Scientists unveiled the image today at a Lander press briefing at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
The orbiter took the image from about 760 kilometers above the surface of the Red Planet, shortly after Phoenix opened its parachute while descending through the Martian atmosphere. The image reveals an apparent 10-meter-wide parachute fully inflated. Bright pixels below the parachute show a dangling Phoenix. The image also faintly detects the cords attaching the backshell and parachute. Phoenix’s surroundings look dark but correspond to the fully illuminated Martian surface, which is much darker than the parachute and backshell.Monday, Phoenix returned information that it was in good health after its first night on Mars, and the Phoenix team sent the spacecraft its to-do list for the day, relaying those commands through another Mars-orbiting craft, Mars Odyssey. As scientists began their analysis of dozens of the first images recorded by Phoenix, which focused on about one-thirtieth of the surrounding, flat landscape, they found evidence suggesting ice was still active in the region and was likely to be just below the surface, as had been expected. “The pictures look a little bleak but the science can be absolutely fascinating,” said Phoenix principal investigator Peter Smith of the University of Arizona in Tucson. Cracks in shallow troughs suggest ice is still modifying the surface, buckling and creating polygonal shapes as it expands and contracts during summer and winter, he noted. Cracks rapidly fill in with dust and couldn’t be seen if they weren’t fresh. In addition, said Smith, “we notice some of the rock patterns don’t line up with some of the polygons; it’s like they’re remnants of perhaps more-ancient surface.” In about a week, he said, “we’re going to be touching and pushing on [the rocks] with our robotic arm.” Over the next day or two, the arm, a unique feature of the Phoenix Lander, will be freed from its stowed, landing position. Seals will be punctured on other instruments, readying them for operation. Mission scientists hope to soon record images of the region, which is about 2 square meters, where the arm will dig. Differences in color and texture in this region could provide important clues about soil composition there. As the robot arm digs, it will look for signs whether ice in the past had briefly become liquid, providing a more supportive environment for life. “We’ll be looking for alterations of structure to tell us if ice is melted,” and if the ice has preserved organic material, Smith says. These questions may not be answered for several months. The lander began delivering images within hours of its safe landing on Mars’ northern plains. Radio signals received at 7:53 p.m. EDT May 25 confirmed that the lander had survived a difficult seven-minute descent and touchdown 15 minutes earlier. The signals were relayed by the Mars Odyssey spacecraft, which was orbiting overhead. The craft reached its destination after journeying 675 million kilometers since its Aug. 4, 2007, launch from Earth. The mission is designed to last for 90 Mars days but could survive for an additional 60 days. By that time, the sun at the north polar region, now omnipresent, will have sunk below the horizon. “We’re going to operate until Mars freezes over,” says Phoenix mission manager Barry Goldstein of JPL.