KSC crews ready Atlantis fuel cells for flight

Launch pad 39A has been cleared of nonessential personnel this morning as Kennedy Space Center teams prepare to load supercold reactants into Atlantis' fuel cell system ahead of Friday's 11:26 a.m. launch.

Three fuel cells combine liquid hydrogen and liquid oxygen to generate electricity that powers the orbiter during flight. Water created as a byproduct may be transferred to the International Space Station.

Loading of the cryogenic reactants is planned between 10:30 a.m. and 3:30 p.m.

Atlantis' four astronauts awoke at 4 a.m.

By 5 a.m., Chris Ferguson and Doug Hurley, the commander and pilot of the 135th and final mission, began practicing landings on KSC's three-mile runway in a Shuttle Training Aircraft, a modified Gulfstream 2 jet.

Meanwhile, mission specialists Sandy Magnus and Rex Walheim underwent medical exams.

At 10 a.m., NASA's Mission Management Team will gather for a standard meeting held two days before launch, or L-2, to assess the countdown's progress and give a "go" to proceed toward fueling early Friday and launch, weather permitting.

Tuesday's forecast showed a 60 percent chance of poor weather postponing Friday's attempt.

NASA has a series of media briefings are planned today on the final shuttle mission and other upcoming missions, which you can watch live here by clicking the NASA TV box at right. Here's the schedule:

9:30 a.m. - Future Science Missions and Launches News Conference
- Waleed Abdalati, NASA chief scientist
- Amanda Mitskevich, NASA Launch Services Program manager
- Scott Bolton - Juno principal investigator, Southwest Research Institute, San Antonio
- Maria Zuber - GRAIL, principal investigator, Massachusetts Institute of Technology
- John Grotzinger - Mars Science Lab, project scientist, California Institute of Technology
- Daniel Stern - NuStar, project scientist, JPL

11:30 a.m. - Prelaunch News Conference
- Mike Moses, Mission Management Team chair & Space Shuttle Launch Integration manager
- Mike Leinbach, shuttle launch director
- Kathy Winters, shuttle weather officer

1 p.m. - International Space Station Science and Technology News Conference
- Julie Robinson, International Space Station Program scientist
- Cheryl Nickerson, Recombinant Attenuated Salmonella Vaccine investigator
- Eduardo Almeda, investigator
- Imara Perera, Plant Signaling investigator

2:30 p.m. - Robotic Refueling Mission (RRM) Experiment Demo (flying on Atlantis)
- Frank Cepollina, project manager, Satellite Servicing Capabilities Office
- Benjamin Reed, deputy project manager, Satellite Servicing Capabilities Office
- Mathieu Caron, Mission Operations manager, Canadian Space Agency