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News
Mars Rover landing a bull's-eye : News : Oswego Ledger-Sentinel : Hometown Newspaper for Oswego and Montgomery, IllinoisMars Rover landing a bull's-eye
| Former area residents contribute to mission's success
| by Nancy Atkinson
| 1/8/2004
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Oswego native Chris Potts and his team of navigators for the Mars Exploration Rovers (MER) achieved unprecedented success with the landing of the first rover, Spirit, on Jan. 3, basically hitting a bull's-eye on Mars' surface, and landing in a “sweet spot.”
“My hat is off to the navigation team because they did a fantastic job of getting us right where we wanted to be,” said Steve Squyres of Cornell University, principal investigator for the science payload. “We hit the sweet spot...we're in a marvelous place.”
“Every aspect of the landing worked perfectly,” said Potts, the MER Navigation Team Chief. “The navigation was outstanding. In fact, it was much better than anyone could have predicted.”
Farouz Naderi, Mars Program Manager at the Jet Propulsion Laboratory (JPL), said that in over a dozen practice entry and landing simulations, there were always problems. The real landing, however, was perfect.
The navigation team hit their target on Mars' atmosphere within 600 feet, and hit the projected landing site in Gusev Crater within 6 miles, which was mostly due to winds, atmospheric effects, and the bouncing of the lander, Potts said.
To land in a precise location on Mars after traveling over 300 million miles, Potts and his team at JPL had to meet the challenge of calculating the exact speeds of a rotating Earth, a rotating Mars, and a rotating spacecraft, while they all simultaneously are spinning in their own orbits around the Sun.
On Monday, NASA released a 3-D panoramic view of the landing site, taken by Spirit's stereoscopic camera. The pictures from Mars show a mostly flat surface, with scattered small rocks, and pockmarks that may be impact craters. The terrain looks different from any of the sites examined by NASA's three previous successful landers -- the two Vikings in 1976 and Mars Pathfinder in 1987.
One depression, dubbed “Sleepy Hollow” by the mission scientists, may be the first destination for the rover's travels. It measures about 30 feet across and lies approximately 40 feet north of the lander.
“It's a hole in the ground,” said Squyres. “It's a window into the interior of Mars.”
The rovers' mission is to investigate the soil and rocks on Mars to look for clues if there was ever liquid water on Mars' surface, which could have possibly sustained life. Gusev Crater is believed to be an ancient lakebed, with a dried river system emanating from the edge of the crater.
During the entry and landing, the spacecraft with Spirit aboard maintained radio contact with flight controllers at JPL through a series of tones designed to let the flight controllers know the status of the lander. The flight team was even able to detect that the lander was bouncing on the surface of Mars, but the tones suddenly stopped and there was no signal from the lander for several minutes. The flight control room erupted when the spacecraft sent the signal that it was sitting safely on the red planet.
“There was a lot of jumping, hugging and even a few tears of relief here at JPL,” said Potts. “There were definitely some tense moments when we lost the signal after confirmation of bouncing on the surface. Mars just wanted us to wait a bit longer, but everything has been extremely smooth since.”
Spirit's twin rover, Opportunity, will reach its landing site on Jan. 24 to begin a similar examination of a site on the opposite side of the planet. Potts and his team have little time to rest on their laurels of Spirit's successful landing.
“There are some issues to be decided very soon regarding a possible change to the Opportunity flight path angle at entry,” Potts explained. “This would be a response to a dust storm that occurred and its effect on (Mars') atmosphere. We've got a lot of work to do to prepare for the possibility of a trajectory change this Saturday. The decision won't be made until later this week, but much has to be done now in case the decision is to go forward with the maneuver.”
“We're all very excited with how things have gone so far, but with Opportunity landing less than 3 weeks away and surface operations underway, things are even busier than ever.”
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