Space Shuttle Endeavour Damaged In Launch; Repairs Mulled

By | August 13, 2007 | Uncategorized

Foam May Have Ripped Gash In Orbiter Vehicle

Space Shuttle Endeavour suffered damage, a gash more than an inch long plus perhaps as many as four other hits, in heat tiles on the underside of the spacecraft during its ascent after launch from Pad 39A at Kennedy Space Center.

The hit, possibly from ice-covered foam insulation tearing free from the Endeavour external fuel tank, forced astronauts to make minute inspections of the spaceship heat shield.

Several astronauts used the shuttle robotic arm and 50-foot-long Orbiter Boom Sensor System (OBSS) to collect imagery of the five areas on the underside of the orbiter vehicle that may have been damaged during the climb to orbit last week.

The problem arose during the Endeavour STS-118 mission to continue construction work on the International Space Station (ISS), with which Endeavour now is docked.

STS-118 Mission Specialists Tracy Caldwell and Barbara Morgan and Commander Scott Kelly operated the shuttle’s robotic arm. STS-118 Pilot Charles Hobaugh and ISS Expedition 15 Flight Engineer Clay Anderson were at the controls of the ISS robotic arm.

Data collected during inspections of the tile damage are being reviewed by experts and engineers at Mission Control Center in Houston.

After data are analyzed, a decision will be made later today whether to have spacewalking astronauts repair the damage. That could be done in several ways. For example, a type of filler material, a black goop, can be used to fill a cavity in heat shielding.

If the tile repair is made, that would mean the fix would be performed during a spacewalk.

Other repair methods include application of a black thermal paint, or, alternatively, what would amount to installation of another heat tile over the damaged tile, a NASA spokeswoman at John Space Center said.

At press time, she said, there is no announcement of a spacewalk to perform repairs, during or in addition to the four extravehicular activities already announced.

An announcement of plans to deal with the damage is expected later today.

The gouge in the damaged tile is 1.12-inch deep, roughly all the way through the tile.

During reentry of Endeavour on Aug. 22 as it moves at about 12,000 miles per hour, friction with the atmosphere could heat the area near the damaged tile to roughly 2,300 degrees Farenheit.

NASA officials, however, are cautiously considering any spacewalk to repair the damage, because that would necessitate having an astronaut negotiate from the side of the orbiter vehicle facing the space station to the underside of the Endeavour orbiter facing toward the empty void of space.

As expected, the Endeavour mission was extended yesterday to a full two weeks from the nominal 11 days officially planned, an extra three days. That extra time in space was made possible by a new capability to flow electrical power from the space station into the shuttle, conserving shuttle power.

That extra time aloft also facilitates the move to four spacewalks from the originally-planned three.

The new timeline means that Endeavour now will undock from the space station on Aug. 20 and land Aug. 22.

Astronauts also had brief communications difficulties between the airlock and ground personnel, which were resolved by switching to a different circuit.

News of the damage to Endeavour came as a surprise, since initial assessments of the liftoff showed a mostly clean ascent.

For example, an hour after the liftoff, NASA Administrator Michael Griffin, Associate Administrator Bill Gerstenmaier, shuttle Launch Director Mike Leinbach and LeRoy Cain, the launch integration manager, were ebullient, lauding the seemingly flawless flight.

The apparently clean STS-118 performance was especially pleasing, given the brief two-months turnaround time since the last shuttle liftoff, when Space Shuttle Atlantis flew in June, Cain said. “Flying the two missions … in the [tight] timeframe that we had was going to be an extreme challenge for us. But … we made the turn between STS-117 and 118” at great speed.

A replay of video from a camera on the Endeavour external fuel tank showed no large pieces of foam insulation ripped loose from the tank, and appeared to spot only four or five small pieces snapping off, which was seen as a good sign after a torn-off foam chunk in 2003 caused the loss of Space Shuttle Columbia and its crew of seven.

Then, a large chunk of foam smashed an undetected hole in the leading edge of a wing on the Columbia orbiter vehicle. Later, as the orbiter began its return to Earth, fiery hot gases of reentry rushed into the wing and heated it to the point of structural failure.

Since then, NASA has taken extensive actions to prevent foam loss problems, both in hardware changes and safety inspection procedures to spot any damage that might nonetheless occur. Those changes all were incorporated on Endeavour, which last flew in 2002, before the Columbia tragedy.

As well, O-rings in the Endeavour solid rocket boosters performed well, without problems. While there are some isolated small spots in the Endeavour booster O-rings where rubber isn’t fully mixed and therefore is stiff and hard, overall the O-rings easily meet specifications.

Two decades ago, on Jan. 28, 1986, O-rings failed on the boosters of Space Shuttle Challenger shortly after launch, causing the loss of both the ship and crew, including teacher Christa McAuliffe.

Another teacher-astronaut, Morgan, was the backup to McAuliffe for that flight.

Morgan never got the chance to fly to space until the launch of Endeavour Wednesday evening, a years-long wait to realize a dream of reaching orbit.

“She is having a whale of a time right now,” Leinbach said of Morgan.

For those who think that astronauts with the right stuff must be young people, it might be worth noting that youth lasts far more decades than it once did. Two astronauts on this flight making their first trips into space are more than half a century old: Canadian Space Agency astronaut Dafydd “Dave” Williams is 53 years old, and Morgan is 55.

One minor problem just before the Endeavour launch came from a sensor indicating the shuttle hatch wasn’t closed tightly and there might be an air leak once the shuttle entered space. Two of 19 sensors didn’t show closure. But technicians checked the hatch closure, both while standing outside and again while inside the shuttle, watching latches work. They concluded the sensors reading was faulty, and the hatch closure was solid, so the shuttle was good to go.

Another minor problem in pre-launch times was in the backup flight software, which was not a big deal, according to briefers.

Building On Orbit

Astronauts in the shuttle and space station crews teamed up to push ahead with construction of the space station.

Saturday, crew members working inside and out in a spacewalk attached the S5 (Starboard 5) truss to the ISS.

While this component is smaller than some that astronauts have wrestled into place, it still tips off at roughly 5,000 pounds, or 2.5 tons. Good thing there’s hardly any gravity up there. The S5 provides clearance between sets of solar arrays on the truss structure.

The S5 was attached to the end of the Starboard 4 truss to set the stage for the addition of the Starboard 6 truss and its solar arrays during a future shuttle mission.

“It’s less than two inches from some critical electronic components that we want to make sure we don’t come in contact with,” a crew member said. “So that’s a very tight clearance.”

Both shuttle and Expedition 15 space station crew members played key roles in the installation.

Hobaugh and Anderson operated the space station robotic arm to move the S5 into place. Outside, spacewalkers Williams and Rick Mastracchio provided guidance and completed the installation.

Meanwhile, Kelly, Caldwell and Mission Specialist Alvin Drew, an Air Force lieutenant colonel, assisted from inside.

Morgan operated the shuttle robotic arm to provide video of the operation. Such videos are critical for training future astronaut construction crews. For example, videos of astronauts last year having to shake stuck solar array panels to coax them into retracting into the stowed position aided other astronauts performing a similar feat on a later mission.

Crew members also engaged in more prosaic work, such as transferring cargo between the shuttle and space station. And even that was no minor matter, with supplies weighing over 5,000 pounds. This will be the last space shuttle resupply mission to the space station for a year to 15 months, so it was crammed with staples.

Williams and Mastracchio made their second spacewalk. The spacewalk began at 11:31 a.m. ET. The astronauts replaced a faulty control moment gyro in the ISS Z1 truss. The station has four gyros that are used to control the station’s attitude.

Their first space stroll saw them install that S5 truss.

Crowded Flight Manifest

Another plus in the launch of Endeavour is that it went off after just a one-day delay. In contrast, in the prior launch, Space Shuttle Atlantis was delayed for months when a violent storm hammered hail onto the external fuel tank, forcing NASA technicians to make an enormous number of repairs to the foam insulation.

Delays can be a critical matter, because only the space shuttles have the size and brawn to loft immense, and immensely heavy, structural components into orbit that are required to finish construction of the space station.

Time is of the essence, since the space shuttle fleet is to retire on Sept. 30, 2010.

Some analysts question whether NASA can manage to get the remaining 14 shuttle missions launched on schedule before that 2010 deadline, noting that involves an average of about 4.5 flights per year. They ask what a major delay in flights might mean.

But Griffin discounted such concerns, noting that NASA has executed that many shuttle flights annually for many years, as a matter of routine.

The remaining manifest of space shuttle flights works out to about one flight every 2.5 months, or 4.5 flights per year, “and that’s our historical average over now 26 years of flying [shuttles] that includes down time for two accidents, hail storms, hurricanes, flow liner cracking, I mean on and on, Teflon wire bundles.

“So if we just stay on plan with our historical average of 4 1/2 flights a year, we will finish easily,” he said.

Griffin added that he respects the presidential directive that the space shuttle fleet will retire in 2010, and said he has no idea whether the next president elected next year might decide to make an exception to go a few months beyond that.

“But I don’t think we’re going to need to know,” he said. “I think we’re going to keep moving along just like we are right now. We’re going to finish the station up on time, and then we’ll move forward into the new era.”

That referred to the Constellation Program to produce the next-generation U.S. spacecraft, the Orion crew exploration vehicle and the Ares lifter rocket, which will debut about 2015, some five years after the shuttle fleet retires. Meanwhile, the United States, the nation that first put a man on the moon, won’t even be able to place an astronaut in low Earth orbit.

“It is unseemly for the United States to be dependent on other nations” to gain access to space, Griffin said. “It does concern us.” But he said somehow the space program will soldier on, adding, “We will survive it. It won’t be easy.”

True, the United States can go to the Russians, other nations or commercial launch providers to place American astronauts in space, he indicated. And, true, they are allies in the exploration of space. But that is money that could have been spent on U.S. capabilities. “We will be buying rides from the Russians,” Griffin said. And that is “money we are not spending on” U.S. space endeavors.

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