MARS PROBES TAKE ON TOUGH CHALLENGES HAMPTON, Va. -- If engineers at this NASA center have their way, the agency's armada of
future Mars spacecraft will seem to arrive at the Red Planet by materializing out of thin air. Their plan involves using the lean and mean Martian atmosphere to brake spacecraft into orbit around Mars. But getting a lander down to a select spot on the fourth planet from the Sun, while avoiding harsh, rough-and-tumble terrain, is an exacting science.
For that reason, atmospheric, materials and high-speed specialists at NASA'a Langley Research Center in Hampton, Virginia are revving up their computers and wind tunnels to help shape Mars exploration plans over the next decade and beyond.
Confidence builders
Langley is focused on several upcoming Mars missions, specifically, Mars '01, '03 and '07 spacecraft, said Mary Kae Lockwood, team leader for planetary exploration in the center's vehicle analysis branch.
She said that researchers are simulating aerocapture and aerobraking techniques for safely swinging payloads into Mars orbit.
Mars aerocapture is a fuel-saving technique whereby a spacecraft dives deep into the Martian atmosphere, slowing itself down to attain an orbit around the planet.
Aerobraking is when a spacecraft gradually dips into the planet's upper atmosphere to reach a final Mars orbit over a number of days.Work is also ongoing to mimic how spacecraft can take a fiery plunge through
Mars' atmosphere, then autonomously maneuver across the Martian sky to a precise landing area, Lockwood said.
A "smart lander" glides through thin Mars air to a precise landing
"Being able to demonstrate and mature new technologies more gradually in several upcoming missions will help us prepare for the Mars return sample mission," Lockwood told SPACE.com
A recent revamp of NASA's Mars plans has pushed returning samples from the Red Planet to a launch in 2014. Originally, it was hoped such a venture could be underway much sooner. But the sample-return mission has proven costly, as well as technologically challenging.
Langley's work on Mars missions now underway can hasten the day of the sample-return project, Lockwood said.
Prasun Desai, an aerospace engineer at Langley, pointed out why returning to Earth precious scoops of Martian soil and rock is a tough task. "To this point, we've only done half the mission. We go there and stop. That second leg of coming all the way back requires a lot more infrastructure," he said.
Next page: Airbags and a "smart lander"
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Putting on the aerobrakes
The next aerobraking adventure for NASA comes with the 2001 Mars Odyssey spacecraft set for launch on April 7, 2001.
Langley experts are helping script the months of delicate maneuvering required to place Odyssey into orbit around Mars.
Arriving at Mars in late October, the new orbiter will begin skimming about the planet's atmosphere and do so for upwards of 70 days, said Richard Powell, a Langley senior research engineer.
"It will take some 300 orbits over those 70 days to get down into the orbit we want," Powell said. When exactly the Odyssey will drop into the final two-hour Mars orbit depends on how volatile the Martian atmosphere becomes, which can be stirred up by massive dust storms.
"If the atmosphere is exactly the same every pass, we would be there really quick. If the atmosphere is giving us some difficulty, we obviously take a more conservative approach, Powell said.
Sensors mounted on Odyssey will assure that the probe and its large solar array don't take too much of a heat load as the spacecraft repeatedly skims through the Martian upper atmosphere, Powell said.
Experience gained in aerobraking the Mars Global Surveyor -- now carrying out science duties while circling the planet -- has been a bonus, Powell said. However, the yet-to-be-lofted Mars orbiter will be aerobraking in a different part of the atmosphere than its predecessor, he said.
Wrap around airbags
Langley also is busy defining the entry, descent and landing profiles for the twin Mars exploration
rovers to be rocketed spaceward in June 2003, Desai said. Reaching Mars in early 2004, each rover will be wrapped in airbags akin to those used in 1997 to cushion the bouncy touchdown of Mars Pathfinder and the Sojourner mini-crawler.
The 2007 Mars rover sits at right, dwarfing the 1997 Sojourner (far left) and 2003 wheeled robots.
Safely depositing the two rovers on Mars in 2004, however, won't be a mirror image of the earlier Mars Pathfinder landing, Desai said. The mass and incoming flight angles of the vehicles are different, he said.
As they plummet toward Mars' surface, each of the rover-carrying spacecraft, said Desai, will transmit data on their condition.
"They will have a more detailed dictionary, better than Pathfinder, allowing us to isolate particular events during the entry, descent and landing," Desai said.
Out maneuvering
NASA proposes to build and launch to Mars in 2007 a sophisticated long-range, long-duration mobile science laboratory.
A Langley team is busy defining a "smart lander" -- a spacecraft shell that holds the robotic lander as it aerobrakes and maneuvers itself through the thin Martian atmosphere.
"It's an exciting mission from the technology standpoint, as well as the possibility for science," Lockwood said.
Plopping heavy robotic hardware onto Mars requires use of a smart lander that not only plows through Mars' atmosphere, but thinks for itself as it glides and banks toward a pre-selected landing zone.
Langley engineers are studying different spacecraft shapes, called aeroshells, capable of "aero-maneuvering" at Mars. The hope is to shrink a Mars landing zone from the usual 62-mile to 124-mile (100-kilometer to 200-kilometer) footprint down to a mere 2 miles (3 kilometers). It would be the most unique Mars entry ever attempted, Lockwood said.
"This would be a significant increase in capability. Scientists can select more interesting landing sites," she said. "We are aiming at offering the most capability possible with the technology we'll have."
On-board smarts
Once free of the aeroshell, the advanced 2007 lander is to be imbued with on-board smarts that scan the landing area, then pick and choose the safest resting spot.
"Many of these technologies we're working towards, like aerocapture, hazard detection and precision landing, not only enable a Mars sample return, but feed directly into making a human mission to Mars possible," Lockwood said.
"There are going to be significant advances made in the years to come. I think we're all ready to go," she said.
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