A "significant" hydrogen gas leak from part of the space shuttle Discovery has forced NASA to scrub the craft's planned liftoff until at least the end of the month.
Discovery and her six-astronaut crew, led by commander Steven W. Lindsey, were initially set to launch on its final flight from Florida's Kennedy Space Center on Monday. But a series of last-minute issues—including helium and nitrogen leaks in one of the craft's engine pods, electrical glitches in a backup computer controller in one of the main engines, and bad weather—led to multiple delays.
Space shuttle managers decided this morning to cancel Friday's launch after a hydrogen gas leak was discovered at the Ground Umbilical Carrier Plate, or GUCP, an attachment point between Discovery's external tank and a 17-inch (43-centimeter) pipe that vents hydrogen gas exhaust safely away from the shuttle.
After discussing the issue, NASA announced today that the shuttle will fly no earlier than November 30 at 4:05 a.m. ET, the start of the last launch window for the year. (Find out how to vote for the wake-up songs to be played during Discovery's final flight.)
If Discovery doesn't fly at the end of November, "the next window of opportunity is February, which is when STS-134 is scheduled to happen," said NASA spokesperson Joshua Buck.
The shuttle Endeavour is currently due to conduct STS-134, the final planned shuttle mission before the fleet is retired. If Discovery's launch rolls to February, Endeavour's flight would be pushed back, possibly to June.
"But right now, we're still looking toward that November 30 window [for Discovery's launch], and hopefully that won't be a problem," Buck said.
Workers are currently draining the shuttle's external tank so they can inspect the vent line. Mission managers also will look closely at a crack in the external tank foam that was discovered as supercold liquid hydrogen and liquid oxygen were being drained from the tank.
"We won't know what's gone wrong with the GUCP until we get our hands on it, which will be tomorrow afternoon sometime," launch director Michael Leinbach told reporters today.
"Right now it's a lot of speculation, but the hardware was obviously talking to us—it leaked significantly ... so we elected to scrub, obviously, and that was the best course of action."
Discovery's Mission Jam-Packed With Tasks
When Discovery does lift off, the mission will be the 39th and final voyage for the "workhorse" space shuttle, the oldest and most reliable bird in NASA's fleet. Discovery's rich history includes the deployment of the Hubble Space Telescope and two successful "return to flight" missions following the loss of the shuttles Challenger and Columbia.
"Discovery is not going out easy," Leinbach told reporters during a Tuesday briefing. "She's giving us a little bit of trouble. But that's fine. She'll fly perfectly when she does."
The 11-day mission, officially called STS-133, is jam-packed with activities, including two six-hour spacewalks during which flight engineers Timothy Kopra and Alvin Drew will perform maintenance work and install new components for the International Space Station (ISS).
One of the spacewalk tasks involves threading a power extension cable between the station's Unity and Tranquility nodes to provide a backup power source for the latter compartment.
STS-133 will also see the installation of Leonardo, the final module for the U.S. section of the ISS. Weighing in at a hefty 21,817 pounds (9,896 kilograms), Leonardo will provide nearly 2,500 cubic feet (70 cubic meters) of extra space for stowage and scientific use once it's in place.
In a task that signals the possible future of the U.S. space program, NASA will test a laser-guided navigation system called DragonEye on behalf of Space Exploration Technologies (SpaceX). The California-based private spaceflight company built the Dragon spacecraft, which has been tapped to fly certain missions for the space agency following the shuttles' retirement. (See a picture of SpaceX's launch vehicle, the Falcon 9 rocket, during a test flight.)
Robot, Mice to Join Discovery Crew
Robonaut2 (picture) is an experimental humanoid robot designed by General Motors that is intended to assist astronauts inside, and eventually outside, the space station. NASA officials have said they're hopeful robots will play an important role in future space missions.
"The combined potential of humans and robots is a perfect example of the sum equaling more than the parts. It will allow us to go farther and achieve more than we can probably even imagine today," John Olson, director of NASA's Exploration Systems Integration Office in Washington, D.C., said in a statement earlier this year.
Discovery's crew will also be accompanied by 16 mice that are part of a science experiment aimed at understanding why spaceflight makes humans more vulnerable to infections by viruses and bacteria. (Related: "Spiders, Urine Recycler Aboard for Space Shuttle Launch.")
"We're going to study the effects of spaceflight on the immune system, and in particular the innate immune system, which is responsible for first detecting pathogens in the body and reacting to them," Roberto Garofalo, principal investigator of the Mouse Immunology-2 (MI2) experiment, told National Geographic News.
Each space mouse will have its own self-contained module with automatic food and water dispensers. Once Discovery returns to Earth, scientists will infect the animals with the respiratory syncytial virus (RSV) and compare their health to a group of control mice that remained on Earth.
The team chose the RSV virus because there is evidence that astronauts are more susceptible to certain respiratory infections, such as influenza, following spaceflight, said Garofalo, an immunologist at the University of Texas Medical Branch in Galveston.
Shuttle "Making" Collector's Items
Discovery will also carry a few items that don't have any practical use in space, but which should make some people back on Earth very happy.
Tucked away in one of the payload bay's tool carriers are about 30,000 space shuttle commemorative patches, said Robert Pearlman, editor of the space history and artifacts website collectSPACE.com.
"The patches will be given out to [NASA] employees" when Discovery returns, Pearlman said. "It's a thank you to the team that has made Discovery and the other orbiters a success."