(영어번역사시험)Space Shuttle: Same Old Damage, Same Old Worries(09.05.13)Here are three things NASA can do to become a safer agency: stop flying Atlantis, stop flying Endeavour, stop flying Discovery.Those, of course, are NASA's three space shuttles, and once the last ofthe snakebit ships is finally mothballed, here's one more piece ofadvice: Don't ever build anything like them again.
The shuttle Atlantis is once again in orbit — this time for afinal servicing visit to the venerable Hubble Space Telescope — andonce again the world is sweating out reports of damage to thespacecraft's thermal tiles caused by debris shed from the external fueltank during liftoff on Monday. It was just that kind of mishap that doomed the shuttle Columbiaand its seven-member crew back in 2003, allowing superheated gases topenetrate the ship during re-entry and causing it to disintegrate. Thatwas the second shuttle to be lost in flight, after the explosion of Challengerin 1986. The hope now is that the three surviving ships can limp alongwithout any further accidents for nine more missions — through 2010 or2011 — after which construction of the International Space Station(ISS) will be complete and the orbiters can be retired. (See pictures of the Hubble Space Telescope.)
First, however, NASA has to get through the current flight, and thatbecame a dicier matter when reports came down this afternoon thatsensors under the shuttle's skin and a camera at the end of its roboticarm discovered a scattering of dings across a 21-in. stretch in theleading edge of the right wing, affecting four or five tiles. NASA wasquick to call for calm.
"The preliminary analysis is that the damage is not very deep andthis is not something we're very worried about," said mission managerLeRoy Cain at an afternoon press conference on Tuesday. "It looks likesomething just chattered away on the edge there."
If it does turn out that the damage is more serious than that, itwill be occurring on a particularly bad mission. Most of the shuttles'trips to orbit these days are for visits with the ISS. The station is aroomy place — by spacecraft standards at least — and if a shuttle'sunderside is found to be too badly damaged to allow a safe re-entry,the astronauts could simply bunk down in the ISS until another shuttleor Russian Soyuz ships could bring them home.
But that's not an option on this mission. The Hubble orbits at analtitude of about 350 miles and an inclination of 28.5 degrees. The ISSorbits lower — roughly 220 miles above the earth — and at a muchsharper 51.6-degree angle. It's not hard for a spacecraft to change itsaltitude, but shifting its orbital plane is monstrously hard andenergy-consuming, and the shuttle would never be able to pull off sucha maneuver. So, the fallback for this crew is another whole orbiter,the shuttle Endeavour, which has been poised on Pad B at Cape Canaveral since before Atlantis launched, just in case a rescue is needed.
As dangerous as it can be to fly the shuttles, the agency has done acommendable job of getting the debris problem under control since theloss of Columbia. Cameras on the underside of the ship sendback live streaming videos throughout the launch phase, allowingcontrollers to monitor any foam or other material that is shed enroute. Analysis of Atlantis' tapes show a relatively smalldebris hit at the 106-sec. mark in the ascent — at precisely the momentskin sensors also detected a strike in the area in which the dings havebeen spotted. That area, at about the spot where the wing meets theship, isn't the best possible place to suffer damage, since the heatbuildup there can be considerable during re-entry, but it's not theworst either, since other areas get a whole lot hotter. (See pictures of animals in space.)
"It's not as dangerous as if it had occurred farther back," saysCain. "The same amount of damage in another area would have been moreproblematic."
So sanguine is NASA about this problem — or, at least, so sanguineis it trying to appear — that while Cain says engineers will spend thenight analyzing the images and data from Atlantis, he does notthink the inspection will yield anything to cause further worry. "Weprobably won't even need a focused inspection in this area," says Cain."Still, we want them to take the time and review the data."
Meantime, back in Florida, Endeavour waits in case it's needed. There too, people are feeling a little jumpy. Earlier today, Pad B was struck by lightning — though Endeavour shook it off without any damage.
(영어번역사시험)Space Shuttle: Same Old Damage, Same Old Worries(09.05.13)
