Sharp-eyed orbiter dispatched to Mars
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: August 12, 2005
A Lockheed Martin Atlas 5 rocket boosted NASA's Mars Reconnaissance Orbiter into space today, kicking off a $720 million mission to sniff out underground ice deposits, to map the red planet's geology with unprecedented clarity and to monitor its tenuous, dusty atmosphere in an ongoing scientific assault.
The 4,800-pound solar-powered satellite, equipped with a 10-foot-wide antenna to beam a torrent of data back to Earth, also will serve as a communications satellite, relaying measurements and observations from current and future Mars landers while using its own ultra-high-resolution camera and other instruments to identify possible landing sites.
With six sophisticated instruments, including a giant 1.2-gigapixel camera capable of photographing objects as small as a kitchen table, the Mars Climate Orbiter is expected to beam back some 34 terabits of data over the life of the mission. That's three to four times the combined output of two spacecraft already in orbit around Mars, along with NASA's Cassini Saturn orbiter and the Magellan Venus orbiter.
"Mars Reconnaissance Orbiter is a weather satellite, a geological explorer, a communications satellite and an exploration pathfinder hunting for landing sites of the future for both robotic and human," said Doug McCuistion, Mars exploration program director at NASA headquarters.
"It lays the groundwork for the landing of the Phoenix mission in 2008 and the Mars Science Laboratory (nuclear-powered rover) in 2010. It will provide data relay for both of those spacecraft as well as the rovers (now on Mars) and future missions."
It turned out to be a software glitch caused by a nearby lightning strike during a thunderstorm earlier in the day. There were no significant problems today and 58 minutes after climbing away through a clear blue sky, MRO was gently released from the rocket's spent upper stage. Within 20 minutes, its two solar arrays and its main dish antenna unfolded and locked in place as planned.
"It's been a long road, it's been five long years to get here and we're up, we're on our way to Mars," said project manager James Graf of the Jet Propulsion Laboratory. "We have a spacecraft that is performing nominarlly. ... To an engineer, that means absolutely perfectly. It's going great."
It will take the spacecraft seven months to reach its target, covering some 310 million miles in a long arc that will put MRO just in front of Mars next March. Flying over the planet's south pole, MRO's six main engines will have to fire for about 25 minutes, slowing the craft by some 2,200 mph. That will be just barely enough for Mars' gravity to capture the craft in a long elliptical orbit.
That first orbit will have a low point of about 186 miles and a high point of nearly 30,000 miles. Over the next six months, MRO's thrusters will fire at the high point of each orbit, setting up repeated low-altitude passes through the planet's extreme upper atmosphere. This aerobraking process will provide the atmospheric friction needed to slowly bleed off energy and circularize the orbit at an altitude of roughly 200 miles.
It is a critical maneuver with little margin for error. NASA's Mars Climate Orbiter was lost during orbit insertion in 1999, victim of an embarrassing navigation error. Richard Zurek was the project scientist then and now.
"You don't want to be a flyby, you want to go into orbit," he said. "We've lost a spacecraft before at this point. So getting into orbit and then going through aerobraking (is difficult). We've got more margin with this spacecraft than with others. The big (solar) arrays give us more area and we've a little more flexible about balancing drag versus heating of the spacecraft."
After fine tuning the final orbit and calibrating MRO's instruments, two years of full-time science observations will begin in November 2006.
"It's going to take us another 16 months before we're really ready to open for business and then that firehose will be ready to start flowing," said Zurek.
The "firehose" is the expected 5.6-megabits-per-second flow of data from MRO's instruments through big dish antenna. "If you want to start an intensive investigation of the planet itself, you have to start increasing your ability to cover vast portions of the surface, you need to increase that coverage and you need to do it at a much higher resolution," said Graf.
"When you couple those two things together, that translates into more and more data. So what we have done is taken a major step forward in the capability of this spacecraft to return data."
The Mars Global Surveyor and Mars Odyssey spacecraft currently in orbit around Mars send back data at a few thousand bits per second. With MRO, "we can get upwards of 34 terabtis of data being brought back in our two years of science operations. ... We are going to be awash in data, which will enable us to better understand the planet as a whole."
One instrument that will consume a large part of MRO's bandwidth is the High Resolution Imaging Science Experiment, a 145-pound camera built by Ball Aerospace and managed by Alfred McEwen of the University of Arizona.
The HiRSE camera is built around a 20-inch primary mirror and 14 CCD detectors. It is the largest camera ever built for operation beyond Earth's orbit.
Taking photographs across 3.5-mile-wide swaths of martian terrain, the HiRSE camera should be able to resolve surface features as small as 40 inches across. McEwen's team plans to process 1,000 full-resolution images and another 9,000 lower-resolution pictures during the primary science phase of the mission.
"It's basically a big digital camera," McEwen said. "Only this one has a primary mirror that's half a meter in diameter and that will be the largest camera to ever leave Earth orbit, the largest telescope. It's also a gigapixel camera, or a 1,200 megapixel camera.
That translates into full-resolution images measuring up to 20,000 pixels wide and 60,000 pixels long.
"To see all of a HiRSE image at full resolution, you would need 1,200 of your typical computer monitors stacked up," McEwen said.
MRO's Compact Reconnaissance Imaging Spectrometer will search for the spectral fingerprints of surface minerals that might have formed in the presence of water while another camera will snap images across broad 18.6-mile-wide swaths to provide context, showing features as small as a tennis court. The Mars Color Imager will provide global views of the entire planet and its changing atmosphere and the Mars Climate Sounder will monitor atmospheric water vapor, dust and ice.
MRO is not content to focus on the visible parts of the red planet. The Shallow Subsurface Radar will penetrate up to a mile beneath the surface in search of buried ice deposits.
"We want to see the details of both the surface composition, it's structure, while we're also monitoring the atmosphere, learning more about the present climate," Zurek said.
"We also want to look and follow up on a discovery the Odyssey spacecraft made that there is ice present in much of the upper yard or so of Mars's surface. Now it's not everywhere, but it is extensive and we want to know whether or not that layer of ice is just a thin layer that's in equilibrium with today's atmosphere or whether it represents just the tip of the iceberg, so to speak, a cryosphere that extends much deeper.
"The Italian Space Agency has provided to NASA a radar that will look at the near subsurface, complimenting the radar that's being flown today on the (European Space Agency's) Mars Express," Zurek said. "We're looking for things near the surface deeper than a yard, up to a mile below the surface, depending on what the materials are like."
Michael Meyer, chief scientist for NASA's Mars exploration program, said MRO will make major contributions in a variety of disciplines and help answer "whether or not life ever started on that planet and if not, why not?"
"And then last but not least, (MRO will study) what kind of resources may be available and also, perhaps, what hazards might be there on Mars for future explorers. So within this, the MRO plays a very grand step in our exploration."
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