NASA formally established April 5 as the launching date for the shuttle Discovery on a 13-day re-supply mission to the International Space Station, following a Flight Readiness Review at the Kennedy Space Center on Friday.
The lift off is scheduled for 6:21 a.m., EST.
Discovey’s crew of seven astronauts has trained to deliver research gear and other supplies intended to sustain the 220 mile high orbiting laboratory long after NASA’s space shuttle fleet is retired, currently scheduled for late September.
The astronauts plan three spacewalks to replace an external ammonia coolant tank and a gyroscope used to manage the internal temperatures of the station and keep the one million pound outpost oriented as it orbits the Earth.
The flight is the second of five missions planned by NASA in 2010 to complete the assembly of the International Space Station, while bringing the near three decade long shuttle program to a close. President Obama has asked Congress to extend station operations from 2016 until at least 2020, a measure that has the support of NASA’s 14 international partners as well as many U.S. lawmakers.
During Friday’s readiness review, top space agency managers were briefed on mission preparations and plans. The agenda included an assessment of a leaky helium valve in the system that pressurizes Discovery’s aft, right orbital steering system.
The small leak was discovered earlier this month and caused by a valve unexplicably stuck in the open position. During the flight, the helium pressures will be managed using a pair of downstream regulators to compensate.
“We understand the failure well enough to go fly,” said Bill Gerstenmaier, NASA’s associate administrator for space operations, who chaired the readiness review. “We reviewed that in detail. We’re ready to go fly.”
Managers were not influenced by pressure to meet the shuttle’s scheduled retirement date, John Shannon, NASA’s shuttle program manager, told a news briefing.
If shuttle managers had decided to repair the valve, Discovery would have been rolled from the launch pad to a hangar. The flight would have been re-scheduled for July and NASA would have proceded with a mission now set for mid-May.
Even with the juggling of the schedule, the agency could retire the shuttle fleet by the end of December, using funds from the NASA’s fiscal 2011 budget, Shanned added.
The 2011 fiscal year begins Oct. 1, and the proposed spending plan includes $600 million for another three months of shuttle operations.
Veteran astronaut Alan Poindexter will lead Discovery’s mission.
His crew includes pilot Jim Dutton; flight engineer Dottie Metcalf-Lindenburger; lead robotics officer Stephanie Wilson; spacewalkers Rick Mastracchio and Clay Anderson. Naoko Yamazaki of the Japan Aerospace Exploration Agency will supervise an ambitious cargo exchange.
The cargo includes three major pieces of scientific equipment:
1. The Window Observational Research Facility, or WORF, which includes cameras, spectral sensors and camcorders for Earth observations. The assembly will surround a high quality optical window in the station’s U. S. Destiny laboratory module for studies of climate change, land and sea formations as well as weather-related crop damage.
2. The Muscle Atrophy Research and Exercise system rack, or MARES, will provide a means of assessing which exercise regimes are the most effective in countering the loss of muscle mass experienced by astronauts during their lengthy exposures to weightlessness.
3. The Minus Eighty Laboratory Freezer for ISS, or MELFI, will preserve blood, urine and saliva specimens gathered as part of astronaut medical experiments. The freezer will store samples of plants and microbes collected as part other biological experiments as well.
Discovery will also deliver a new water generating device, called Sabatier. The device mixes carbon dioxide gathered from the breathing air of the space station with hydrogen to produce drinking water and methane that is vented outside the station.
As time permits, the Discovery astronauts intend to focus on educational activities that illustrate advances in robotics.
Metcalf-Lindenberger, a former high school Earth science and astronomy teacher as well as a cross-country coach, will lead the effort, which is expected to include question and answer sessions with students at the Naval Post Graduate School of Monterey, Calif., and the Eastern Guilford High School of Gibsonville, N. C.
She joined NASA in 2004 as the agency’s fourth educator astronaut.
Currently, NASA scheduling shows the shuttle program’s final missions scheduled for launching on May 14, July 29and Sept. 16.
Each of the final missions is intended to equip the orbital laboratory with scientific equipment and other supplies needed to sustain station operations well beyond the shuttle’s retirement.
A 32-page study released this week by NASA Inspector General Paul Martin predicted a high probability the final mission would not be launched until January 2011.
The space agency has budgeted $54 million in workforce overtime to help meet the internal September 2010 projection.
The Inspector General’s projections are based on historical averages for days between shuttle launches, both for the entire history of the program as well as the historical record since missions resumed in the aftermath of the 2003 shuttle Columbia accident.
An additional extension beyond December could force NASA to take funding from other agency activities.