(usatoday.com) - Despite some extra risk, NASA hopes next month to launch a space shuttle at night for the first time since the deadly Columbia accident almost four years ago.
If shuttle managers give the go-ahead this month, shuttle Discovery will blast off at 9:36 p.m. ET Dec. 7 on a 12-day mission to build the International Space Station.
Launching at night limits the view of airborne debris, which can smash into the ship as it lifts off. NASA has more than 100 cameras near the launch pad and on the spacecraft to monitor liftoff, but they won't work as well in the dark, reports Trend.
"We'll learn more on a day launch about where a piece (of debris) may have come off, there's no doubt about it," NASA safety chief Bryan O'Connor says. "But we also have benefits to launching at night, and we're trying to weigh those."
Since the Columbia accident in 2003, all shuttle astronauts have been required once they reach orbit to inspect the ship with sensors, separate from those used during launch, that can detect cracks as tiny as 0.02 inches long. So every crew should see any damage to the ship and either fix it or wait at the space station to be rescued.
What the scrutiny in orbit can't find is a near hit: a potentially deadly piece of debris that leaves no trace because it doesn't strike the shuttle. Detecting such events is key to improving safety on future missions.
Discovery commander Mark Polansky says he thinks there's little risk because of the inspection his crew will do in orbit. Even so, "you'd rather have more data than less," he adds. "What you lose is the potential to see some event that ... would be of issue for the next launch."
In 2003, a piece of insulation from Columbia's fuel tank slammed into the ship during ascent. The resulting hole went unnoticed, and the vehicle crumbled during re-entry, killing the crew of seven.
Shuttle program manager Wayne Hale decreed that the first three missions after the accident would launch during the day, to provide the best possible views of the fuel tank and other sources of debris. All three flights landed safely, the most recent on Sept. 21.
Hale and other NASA managers are eager to resume night launches to ease the pressure on the shuttle, which will be retired in 2010. All station construction must be finished by then because no other vehicle is strong enough to tote the station's pieces to orbit.
It would be virtually impossible for the shuttle to finish building the station by 2010 if it could launch only during the day. Such a requirement would cut into the time NASA has available to launch a shuttle so it can meet up with the station.
Resuming night launches actually reduces some risks, says Joseph Dyer, head of a panel that monitor's NASA's safety practices.
"By opening up the (launch) windows ... it takes a little bit of the schedule pressure off," he says. That means fewer mistakes and more time for careful work.
NASA would have liked to return to night launches before now, but Discovery's fuel tank unleashed a barrage of debris in 2005 during the first launch after the accident. Again, NASA had to redesign the protective foam that surrounds the tank.
It worked: On the two flights this year, the tank lost little foam.
The "risk-benefit scale was highly in favor of daylight launches for the first two to three flights," O'Connor says. "That scale is about even right now."
Engineers are trying to make up for the darkness with other ways to study the liftoff:
Radar. Three radar dishes one on land and two on ships in the Atlantic Ocean will be trained on the launch. Interpreting the results is "quite an art," Hale said this year. "Looking at small things next to the shuttle," he said, is like "looking at a candle that's in front of a blowtorch."
Infrared. A NASA jet flying north of the shuttle's path at roughly 60,000 feet will carry a camera that will capture images by looking at infrared rays.
Rocket glare. The cameras that depend on visible light during the launch will be able to take some pictures by using the bright light emitted by the shuttle's rockets as an improvised flash.
Top shuttle officials aren't sure how much they'll be able to see with these methods.
"We're giving up some (imagery), but it's difficult to quantify," Hale says, adding that Discovery's flight will tell engineers the kind of pictures they can expect.
On the other hand, NASA won't have to worry about the vultures that buzz the launch pad in the day and can turn into flying debris.
Night launches bring a new flying hazard, Hale says: "You do have to worry about owls."