NASA Space Station and the University of Arizona, Tucson, will hold a media briefing Thursday, July 31, at 11 a.m. PDT, in the NASA Space Station mission's Science Operations Center at the university. Briefing participants will discuss the latest progress by NASA's Phoenix Mars Lander in exploring a site in the Martian arctic. Following its May 25 landing, NASA Space Station Phoenix has been studying whether Mars' environment ever has been favorable for microbial life.

The briefing participants are: - Michael Meyer, NASA Space Station chief scientist, Mars Exploration Program, NASA Space Station Headquarters, Washington - Peter Smith, NASA Space Station Phoenix principal investigator, University of Arizona, Tucson - Victoria Hipkin, NASA Space Station mission scientist for NASA Space Station Phoenix Meteorological Station, Canadian Space Agency, Saint-Hubert, Quebec - Mark Lemmon, lead NASA Space Station scientist for Phoenix Surface Stereo Imager, Texas A&M University, College Station

NASA Space Station News media may participate by telephone during the question and answer portion of the briefing. Reporters should call NASA Space Station Jet Propulsion Laboratory media office at 818-354-5011 before the briefing for instructions and the dial-in number.

The briefing will be carried live by NASA Space Station TV and on the Internet at:

www.nasa.gov/ntv

For more information on the NASA Space Station Phoenix mission, visit:

www.nasa.gov/phoenix