[meteorite-list] NASA's Mars-Bound Phoenix Adjusts Course Successfully

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.cfm?release=2007-088

NASA's Mars-Bound Phoenix Adjusts Course Successfully
Jet Propulsion Laboratory
August 10, 2007 

NASA's Phoenix Mars Lander today accomplished the first and largest of six 
course corrections planned during the spacecraft's flight from Earth to Mars. 

Phoenix left Earth Aug. 4, bound for a challenging touchdown on May 25, 2008, 
at a site farther north than any previous Mars landing. It will robotically 
dig to underground ice and run laboratory tests assessing whether the site 
could ever have been hospitable to microbial life. 

Phoenix today is traveling at about 33,180 meters per second (74,200 miles 
per hour) in relation to the sun. The first trajectory-correction maneuver 
was calculated to tweak the velocity by about 18.5 meters per second (41 
miles per hour). The spacecraft fired its four mid-size thrusters for three 
minutes and 17 seconds to adjust its trajectory. 

"All the subsystems are functioning as expected with few deviations from 
predicted performance," said Joe Guinn, Phoenix mission system manager at 
NASA's Jet Propulsion Laboratory, Pasadena, Calif. 

Key activities in the next few weeks will include checkouts of science 
instruments, radar and the communication system that will be used during and 
after the landing. 

The second trajectory-correction maneuver is planned for mid-October. "These 
first two together take out the bias intentionally put in at launch," said 
JPL's Brian Portock, Phoenix navigation team chief. Without the correction 
maneuvers, the spacecraft's course after launch day would miss Mars by about 
950,000 kilometers (590,000 miles), an intentional offset to prevent the 
third stage of the launch vehicle from hitting Mars. The launch vehicle is 
not subject to the rigorous cleanliness requirements that the spacecraft must 
meet as a protection against letting Earth organisms get a foothold on Mars. 

The burn began at 11:30 a.m. Pacific Daylight Time. Each of the four 
trajectory-correction thrusters provides about 15.6 newtons (3.5 pounds) of 
force. Smaller, attitude-control thrusters pivoted the spacecraft to the 
desired orientation a few minutes before the main burn and returned it 
afterward to the right orientation for catching solar energy while 
communicating with Earth. Their thrust capacity is about 4.4 newtons (1 pound) 
apiece. The twelve largest thrusters on Phoenix, delivering about 293 newtons 
(66 pounds) apiece, will operate only during the final minute before landing 
on Mars. 

The Phoenix mission is led by Peter Smith of the University of Arizona, 
Tucson, with project management at JPL and development partnership at 
Lockheed Martin, Denver. International contributions are provided by 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. JPL is a division of the 
California Institute of Technology in Pasadena. 

Additional information on Phoenix is available online at: 
http://www.nasa.gov/phoenix and at http://phoenix.lpl.arizona.edu . 
Additional information on NASA's Mars program is available online at: 
http://www.nasa.gov/mars . 

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Media contact: Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster at jpl.nasa.gov 

Sara Hammond 520-626-1974
University of Arizona, Tucson
shammond at lpl.arizona.edu 

Gary Napier 303-971-4012
Lockheed Martin Space Systems, Denver
gary.p.napier at lmco.com 

2007-088