05.20.08

Kathy Barnstorff
kathy.barnstorff@nasa.gov
757-864-9886/344-8511 (mobile)RELEASE: 08-032

08-032: LANGLEY RESEARCHERS WORK TO HELP PHOENIX LAND ON MARS



HAMPTON, Va. - NASA scientists and engineers expect to have an out of 
this world Memorial Day weekend, even though they'll be hard at work. 
Their mission is to land a spacecraft safely on Mars Sunday evening.



Three researchers from NASA's Langley Research Center in Hampton, Va. 
are part of the team working to guide the Mars Phoenix Lander to a 
soft landing on the northern polar regions of Mars, a never-before 
explored area of the Red Planet. Their primary responsibility is to 
help during entry, descent and landing (EDL) or "seven minutes of 
terror" as it's sometimes called.



"Seven minutes of terror means that the spacecraft has seven minutes 
from entry into the Martian atmosphere until touchdown," said Langley 
aerospace engineer Jill Prince. "You can't fix any possible problems 
in those seven minutes when they're actually happening, because it 
takes 15 minutes for the signal from Phoenix to reach earth."



Prince will be in the mission control room at NASA's Jet Propulsion 
Laboratory (JPL) in Pasadena, Calif., Sunday, May 25. She'll be at 
the console running computer simulations of entry, descent and 
landing scenarios and hoping to celebrate a successful landing as 
early as 7:53 p.m. EDT. Two other Langley engineers will be nearby 
with other EDL team members.



Phoenix launched on August 4 last year for the 422 million mile 
journey to Mars. It's preparing to begin a three-month mission to 
taste and sniff fistfuls of Martian soil and buried ice. The 
solar-powered three-legged robotic lander will manipulate a 7.7-foot 
arm to scoop up samples of underground ice and soil lying above the 
ice. Onboard laboratory instruments will analyze the samples. Cameras 
and a Canadian-supplied weather station will supply other information 
about the site's environment.



One research goal is to assess whether conditions at the site ever 
have been favorable for microbial life. The composition and texture 
of soil above the ice could give clues to whether the ice ever melts 
in response to long-term climate cycles. Another important question 
is whether the scooped-up samples contain carbon-based chemicals that 
are potential building blocks and food for life.



But first Phoenix must make it through the challenging Mars 
atmosphere. "When we hit the atmosphere we're doing almost 13,000 
miles an hour," said Eric Queen, Langley research engineer. "The 
friction of the atmosphere slows us down until we get to about 900 
miles an hour. At that point we open a parachute and that slows us 
down further. Eventually we drop off the parachute and we have 
rockets that fire on the vehicle to come to a soft landing." 



Computer simulations at Langley showed there could be an issue with 
the parachute falling on top of the lander in low wind, so Queen said 
researchers suggested adding a "backshell avoidance maneuver. When 
Phoenix drops away from the parachute it actually moves to the side 
so that it can land safely and the parachute can go its own way." 



Langley's expertise in Mars landers started decades ago when it led 
the Viking project in the 1970s. Viking successfully landed two 
spacecraft on Mars in 1976. Researchers are still using data from 
those missions today.



"Many aspects of the design are still relying on the technology, the 
heritage of the Viking vehicle itself. The capsule shape is very 
similar," said Prasun Desai, Langley Mars Phoenix Lander lead. 
"Viking also did a soft landing on Mars back in the mid-70s and we're 
doing the same here. So we're relying on a lot of the heritage that 
Viking pioneered." 



Phoenix uses hardware from a spacecraft built for a 2001 launch that 
was canceled in response to the loss of a similar Mars spacecraft 
during a 1999 landing attempt. Researchers who proposed the Phoenix 
mission saw the unused spacecraft as a resource for pursuing a new 
science opportunity. 



The Phoenix mission is led by the University of Arizona, Tucson, with 
project management at JPL. The development partnership is with 
Lockheed Martin, Denver. International contributions are from the 
Canadian Space Agency; the University of Neuchatel, Switzerland; the 
universities of Copenhagen and Aarhus, Denmark; the Max Planck 
Institute, Germany; and the Finnish Meteorological Institute.



For more information about Mars Phoenix Lander please go to:



http://www.nasa.gov/phoenix

	
-end-