Atlantis Win Puts NASA Back On Track For Space Station Construction
Night Launches, Hubble Telescope Repair Mission Considered
The flawless Space Shuttle Atlantis mission STS-115 marked a turning point for NASA, permitting the space agency to enter a full-speed catch-up sprint to finish construction of the International Space Station (ISS) by the 2010 deadline.
“I’m very confident that we will complete construction of the space station by 2010,” NASA Administrator Michael Griffin said after Atlantis safely landed.
Atlantis, in its book-perfect performance, also has raised confidence that no further safety fixes may be required for the once-troublesome external shuttle fuel tank. And that, in turn, may mean that NASA may be able to drop its daylight-only launches policy, and return to night launches. That would help NASA maintain its daunting missions schedule over the next four years.
As well, the Atlantis mission showed the value of astronauts “camping out” in an air lock before beginning spacewalks, a procedure permitting them to save about an hour in purging nitrogen from their blood so as to avoid suffering the painful “bends” when leaving the ship on spacewalks. In each spacewalk, Atlantis mission specialists finished all their tasks ahead of time, and went on to perform extra work.
This success story ended well. Atlantis, with no visible damage, in an early morning return to its home planet slipped smoothly onto the runway at Kennedy Space Center 12 days and 4.9 million miles after its trouble-free but last-minute launch. During its flight, Atlantis delivered a giant 17.5-ton truss that shuttle crew members in spacewalks attached to the space station.
The crew for the mission included Commander Brent Jett, Pilot Chris Ferguson and mission specialists Joe Tanner, Heidemarie Stefanyshyn-Piper, Dan Burbank, and Steve MacLean, a Canadian astronaut.
Tanner and Piper performed two spacewalks, and Burbank and MacLean performed one extra-vehicular activity, to attach a gigantic P3/P4 truss to the space station, a structural component weighing 17.5 tons. They were aided by giant mechanical arms, one on the shuttle, the other on the space station, operated by other astronauts. Attached to the truss are giant solar arrays that, when unfurled, stretch some 240 feet. They will provide about one-fourth of the electrical power for the space station when it’s completed. The spacewalkers also installed a signal processor and transponder that transmits voice and data to the ground and performed other tasks to upgrade and protect the ISS systems.
That was a critical achievement, because the truss and its vast solar array had to be installed before other components could be trucked into space and attached to the ISS, including giant-sized laboratories made in Europe and Japan.
Now NASA begins a relentless rhythm of shuttle missions to finish assembling the giant station, an artificial moon that will weigh nearly 1 million pounds when complete.
The next shuttle mission, STS-116, will involve a holidays-season voyage of Space Shuttle Discovery, which currently is expected to launch sometime around 5:30 p.m. ET Dec. 14, although an earlier launch might be considered.
Discovery will deliver a third truss segment, a SPACEHAB module and other key components during its 20th mission to the International Space Station.
The crew will be Commander Mark Polansky, Pilot William Oefelein, and mission specialists Robert Curbeam, Joan Higgenbotham, Nicholas Patrick and Christer Fuglesang of the European Space Agency.
A brilliant performance by Atlantis and its crew was a welcome milepost for NASA leaders, showing the space agency finally got its groove back.
NASA had lost years from its ISS construction schedule because of the Space Shuttle Columbia disaster in 2003. As Columbia launched, a large chunk of insulating foam broke off from the external fuel tank and hit the leading edge of a wing on the orbiter vehicle, punching a hole in the wing.
Later, when Columbia returned to Earth, searing hot gases of reentry rushed through the hole into the wing and heated structural components until they failed. Both the orbiter and crew were lost.
No shuttles flew until last year, when Space Shuttle Discovery launched. That provided information on the foam loss problem that helped NASA to devise a series of fixes. And they worked.
This year, Discovery flew again in a July 4 launch, and it was picture-perfect. There was little foam loss, and it involved only small pieces tearing off late in the ascent, above most of the atmosphere that can accelerate foam sections to lethal speeds.
When Discovery arrived at the ISS, no major damage was visible. And when it landed, it was pronounced clean, although there were some very minute bits of damage found in later inspections.
Similarly, after Atlantis landed yesterday, Mike Leinbach, shuttle launch director, said that the spacecraft “looked as good as or better than Discovery did” after it landed in July. “Atlantis is home, and it feels good to have her back.”
Acing this mission provided NASA leaders with confidence that the fixes they devised for the foam-loss problem are effective.
LeRoy Cain, who directs launch integration activities at Kennedy Space Center, said it would have been “hard to come close to having a day as good as” the landing of Discovery two months ago, but Atlantis approximated that level of achievement, which Cain termed “landing … by the numbers.” After seeing Atlantis on the ground, and finding no major damage, Cain pronounced the spacecraft “extraordinarily clean.”
Safety measures that NASA devised for the shuttle fleet not only have worked, they have performed better than computer models would lead one to expect, Griffin said.
For example, a fix on the ice frost ramp on the outside of the external fuel tank “appears to perform better than analyses would indicate it should,” he told journalists.
Overall, he said, the safety fixes have “performed very well for the last two missions,” the Discovery and Atlantis voyages.
This might mean, he said, that further safety changes that NASA had proposed might not be needed. “We’ll look very carefully at whether or not we need to make [further] changes,” Griffin said. “We are prepared to go down either path,” with more alterations or with a decision to leave the shuttle as it now exists. NASA leaders haven’t yet made that choice, however. “That is in no way a done deal in either direction,” he said.
The Atlantis mission also had to deal with other safety issues.
For example, the Atlantis launch was delayed repeatedly. There was a nearby lightning strike as a storm passed by, and NASA responded by delaying liftoff so engineers could check myriad electronic systems in the spacecraft to ensure that none of them was fried.
Then Hurricane Ernesto neared Florida, and a NASA weather forecast showed the storm might pass near or over the launch area, so officials were forced to begin moving Atlantis from Launch Pad 39B back to the Vehicle Assembly Building.
But as the shuttle moved along, carried by the crawler, the weather forecast changed abruptly, showing that high winds were unlikely to threaten it. So NASA officials stopped Atlantis in mid-transit and ordered it back to the launch pad, which Griffin praised as a “gutsy decision.”
Then, as Atlantis was in countdown and poised on the launch pad, a sensor glitch forced a one-day delay before liftoff.
In space, Atlantis underwent repeated painstaking inspections to ensure that the spaceship had incurred no damage. Atlantis was given an exhaustive examination upon arrival at the space station, and again after undocking from the ISS.
But then, as reentry day neared, small objects were found floating alongside Atlantis as it cruised at thousands of miles an hour. Astronauts and ground personnel wondered whether something important fell off the orbiter vehicle, but close inspections of the spacecraft showed nothing amiss, so the spacecraft could be cleared for reentry.
After Atlantis undocked from the station, it did the first full fly around of the facility since prior to the Space Shuttle Columbia accident. The maneuver helped ground crews get a better perspective on the ISS environment and overall exterior health.
STS-115 was one of the most photographed shuttle missions ever, with more than 100 high-definition, digital, video and film cameras documenting the launch and climb to orbit. Data from these images, as well as station and shuttle crew inspection, helped to clear the Atlantis thermal protection system for return only two and a half days after launch.
After undocking, the Atlantis crew participated in a first-ever three-way call with the Expedition 13 crew aboard the International Space Station and the three crew members of the Soyuz spacecraft on its way to the station. All 12 astronauts in space at that time were able to have a conversation.
Safety concerns have limited shuttles to daytime-only launches, because NASA experts wanted to have sunlight shining on the shuttle orbiter and tank to see just how much foam insulation might break loose during an ascent, after the safety fixes.
Now that two consecutive launches have seen little foam loss, NASA may return to night liftoffs, if not with the December Discovery launch, then perhaps soon thereafter, Cain indicated.
“We’re going to make a decision,” he said. “It’s extremely important to us” to ensure that the shuttle launch schedule is maintained, and night launches would provide NASA with far more opportunities to get each shuttle off the ground. “My personal expectation is we are” going to go with nighttime launches, Cain said.
Whether or not dark launches are authorized, Cain said he sees nothing now that would block NASA from launching Discovery in December.
NASA also is considering a launch of a space shuttle on a servicing mission for the Hubble Space Telescope, which Griffin said he would like to green-light if it’s feasible.
“I think Hubble is important,” Griffin said. The giant eye in the heavens “has revealed fundamental things about the universe” that humans otherwise never would have learned, he said, making the Hubble one of the great scientific assets of all time, he added.
Thus he would like to repair the telescope if that’s feasible, working around “new constraints.” That was an apparent reference to NASA budget straits, where some funding for space science and research programs is being diverted to support manned missions returning to the moon and then voyaging onward to Mars and beyond.
Addressing the Hubble mission question, “If we can do it safely, we want to do it,” he said. This would be a different mission from the space station assembly flights now planned.
There is no time for dithering on this issue, Griffin indicated. Rather, if this is to be done, then “we have to do it soon.” Griffin said he is targeting early 2008 for any possible Hubble mission.
While “the Hubble is fragile itself,” and requires delicate handling, “it is not outmoded,” Griffin said.