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Planetary News: Mars (2006)Mars Reconnaissance Orbiter's HiRISE Camera Returns New Pictures of Spirit and Viking LandersBy A.J.S. Rayl
They're here! New pictures from the HiRISE camera onboard the Mars Reconnaissance Orbiter (MRO) clearly show 3 additional NASA spacecraft that have landed on Mars: the Spirit rover active on the surface since January 2004 and the two Viking landers that successfully reached the surface in 1976. The images, which were taken by the High Resolution Imaging Science Experiment, more simply known as the HiRISE camera, were released officially late yesterday and are among the earliest from MRO's primary science phase, which began in November. More than build on the dramatic photographs of Spirit's twin rover, Opportunity, at the edge of a Martian crater in October, these latest images underscore the fact that a new era of Mars exploration has begun. In addition to offering providing new portraits of these robotic emissaries, the images provide scientists valuable high-resolution information about the surrounding terrain at each site, which helps in understanding orbital data as well as planning activities for surface missions. "We know these sites well at ground level through the eyes of the cameras on Spirit and the Viking landers," said Alfred McEwen, principal investigator for HiRISE, and a professor at the University of Arizona (UA) in Tucson. "Applying that knowledge as we view the new orbital images will help us interpret what we see in orbital images from other parts of Mars never seen from ground level." "This is the first time we've had this coupled power of the orbiter in orbit that can see the rover on the ground and then the rover on the ground using the orbital images to plan where we're going to go," noted Steve Squyres, principal investigator for rover science and a professor of astronomy at Cornell University. "It's an extraordinarily powerful combination." While the rovers and MRO and HiRISE are the first to demonstrate that combination, it is something, Squyres predicted, that "will be used extensively in the future."
The day the images of Opportunity were processed and viewable, the MER team "actually used it for tactical planning," Squyres, who is also a member of the HiRISE team, told The Planetary Society in an earlier interview. "It influenced our decision. It was a very useful image," he said. A second image of the Opportunity site that has been combined with the first for a stereo view has also been released. When Spirit's handlers received the HiRISE image last week, they too began using it, though not in quite the same way. Since Spirit is en route back to Home Plate, the HiRISE image didn't change the tactical planning for this rover. But the view of Spirit in the midst of the Columbia Hills will be utilized by the scientists and engineers who plan the rover's daily activities in coming sols and already it appears has impacted the rover's coming agenda. "We can see Spirit and we can see a lot of the details in the Inner Basin," said Ray Arvidson, deputy principal investigator for the rovers and a professor of earth and planetary sciences at Washington University in St. Louis. "You can see all the layers we've been looking at from the McMurdo panorama [which Spirit spent a good part of the winter imaging]," he elaborated. The team almost immediately began to "relate this back to the McMurdo panorama" [which Spirit spent a good part of the winter imaging], he said, to put together the stratigraphic pattern and see how Home Plate fits within that.
The view of Viking Lander 1 from HiRISE reveals the spacecraft's back shell about 260 meters (850 feet) away and the heat shield nearly four times that distant. The lander returned the first view from the surface of Mars and kept operating for more than 6 years after its July 20, 1976, landing. "The biggest surprise is that you can still see what appears to be the parachute after 30 years," said Tim Parker of the Jet Propulsion Laboratory (JPL), whose calculations helped determine where to point the orbital camera for seeing the Viking landers. Viking Lander 2, unlike Spirit and Viking Lander 1, had not been detected previously in images from the recently silent Mars Global Surveyor (MGS). One feature that had been considered a possibility in an earlier image turned out to be the Viking Lander 2's back shell, about 400 meters (a quarter mile) from the lander easily discerned in this newer image from the higher-resolution camera.
Parker is identifying some individual nicknamed rocks in the Viking-site images that are prominent in famous photographs taken by the landers, such as Ankylosaurus, a rough rock about a meter (3 feet) long near Viking Lander 2, and the larger Big Joe near Viking Lander 1. NASA made imaging of the Viking Lander 2 site an especially high priority for MRO to help in evaluation of candidate landing sites for the Phoenix Mars Lander mission, being prepared for launch next summer. Phoenix will land at a far northern site, and the Viking Lander 2 site, though not as high-latitude as where Phoenix will go, is the most comparable site of any seen from the surface of Mars. "The Viking Lander 2 site, with its combination of lander-based and orbiter-based imaging, gives us an important anchor for evaluating the ground roughness and boulder densities at sites where we have only orbital imaging," explained Arvidson, who also chairs the Phoenix Landing Site Working Group. The new images are available online at the following: |
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