Category: Space Station

NASA announced their final decision on Thursday: they won’t have the astronauts repair the space shuttle Endeavour. According to the agency, the gouge in the shuttle’s tiles doesn’t pose a threat to the orbiter during reentry, and attempting to fix it might actually be more risky.

The decision was made on Thursday afternoon, after mission managers had met for 5 hours. They announced the consensus opinion of hundreds of NASA engineers, most of who felt that the massive data they had acquired on the gouge was correct. The computer simulations and arc jets tests gave them all the data they needed. NASA had always felt that the crew wasn’t at risk during reentry, but they wanted to avoid expensive and lengthy repairs to the orbiter once it was back on Earth. Any delays will compress an already tight schedule.

In the end, the NASA managers just couldn’t justify sending the astronauts back out into space to make the repairs. The 3rd spacewalk, cut short by a damaged glove, demonstrates the risks the astronauts take every time they head out into space.

One NASA branch, the JSC Engineering Group felt it would be prudent to patch Endeavour’s gouged heat tile, but otherwise, the group still felt that the shuttle was safe to reenter the atmosphere.

Today the 10 shuttle and station astronauts are moving cargo and preparing for Saturday’s spacewalk, to continue assembly of the space station.

Original Source: NASA News Release

Just to remind us all that the astronauts are really quite exposed up there in orbit, a micrometeorite took a small chunk out of Endeavour’s front windshield at some point during the mission – the astronauts just noticed it. NASA officials said that the space debris impacted the shuttle’s window #2. With the impact discovered, NASA engineers are planning to study it, but they don’t think it’s a risk to astronaut safety.

Space shuttles have been beaten up by orbital debris in the past. In most cases, the impact is very small, and the impactor is absorbed by the shuttle’s external skin. In this situation, the shuttle is very well equipped with the analysis gear to really study this windshield ding if they wanted to.

As with the foam strike that carved out a slice of Endeavour’s protective heat tiles, the astronauts could use the laser and camera attached to the shuttle’s robot arm to map this micrometeorite damage in exhaustive detail. NASA engineers would then know if it’s of any risk to the astronauts.

Speaking of damage to the shuttle, NASA has decided to push back the next spacewalk for STS-118, now tentatively scheduled for Saturday. With the shuttle pulling power from the International Space Station’s electrical grid, NASA wanted the astronauts to perform a 4th and final spacewalk.

The agency is agonizing over whether or not they should have astronauts attempt to repair the gouge to the shuttle’s belly carved out by falling foam during its launch. If they do decide to proceed with repairs, two astronauts will need to be carried on the end of the shuttle’s robot arm to the underside of the shuttle. They will then try and put in exactly the right amount of heat absorbent caulking to fill the hole. If they get the wrong amount in there, they could even make the problem worse. Not to mention the risk that they could accidentally bump the fragile tiles and do even more damage.

So, get ready for more analysis before a decision gets made.

Original Source: NASA Status Report

Shuttle astronaut Rick Mastracchio and International Space Station resident Clay Anderson hurried inside today, cutting their 3rd spacewalk an hour short when Mastracchio discovered that one of his spacesuit gloves had a gash in its outer layers. Even though the rip only penetrated through two of the glove’s five layers, NASA hurried them back inside as a precaution.

Even though the damaged glove ended the spacewalkers’ mission early, they had already completed most of their tasks during their 5.5 hours in space – the mission was supposed to last 6.5 hours. They completed their primary goal, moving an antenna from a temporary position on the P6 truss over to its permanent home on the Unity module. They also moved two rail carts, and added additional antenna parts to improve station communications.

By moving this equipment off the P6 truss, the module can then be relocated from its current position atop the station over to the end of the P5 truss.

The only uncompleted task was to bring in some space exposure experiments that had been running outside the station. Not to worry, these’ll get scooped up on a future spacewalk.

Although this wraps up the three spacewalks that NASA had planned for mission STS-118, NASA is now considering how the rest of the mission will play out. With the shuttle now connected to the International Space Station’s electrical grid, it’s capable of “borrowing” power, and extending its time in orbit up to 14 days. NASA is thinking that another spacewalk may occur on Friday, but could be put off until Saturday. This task might be combined with the installation of a new camera system that’ll help analyze shuttles for damage.

Original Source: NASA Status Update

With a detailed mock up in hand of the damaged region on the shuttle Endeavour’s underside, NASA engineers have been submitting the area to rigorous tests and computer simulations. Good news. From what they can tell so far, the spot probably isn’t a risk to the safety of shuttle during its reentry, and astronauts probably won’t even need to make repairs.

To perform their experiments, engineers created a duplicate of Endeavour’s damaged section, and then put it into an arc jet. This is a room-sized blowtorch that recreates the conditions of reentry on the shuttle’s tile system. Even though the temperature on the surface of the tiles reached 1090 degrees Celsius (2,000 degrees F), the temperature on the bottom of the gouge only peaked at 170 degrees Celsius (340 degrees F). This is below the limits set by NASA.

However, even if the temperatures remain within tolerance levels, NASA would also want to avoid any lengthy and expensive repairs to the shuttle on the ground, and might get the astronauts to make the repairs. John Shannon, the chairman of the mission management team said on Tuesday that he was “cautiously optimistic” that no on-orbit repairs would be necessary.

As a point of comparison, the suitcase sized chunk of foam that dislodged, and ultimately destroyed the space shuttle Columbia weighed 750 grams (1.67 pounds), while Endeavour’s fragment is thought to be about 100 grams (3.5 ounces). Columbia’s foam strike was on the leading edge of the wing, which experiences some of the hottest temperatures of reentry, while Endeavour’s was down near the landing gear, on a region which is much cooler.

And if you really want to get to know the gouge. Check out this amazing video from NASA that has turned the damaged section into a 3-D animation. You might question their assessment of the risks, but wow, they really know the damage.

The space shuttle Endeavour reached its orbital destination today, linking up with the International Space Station. The shuttle was piloted in by commander Scott Kelly, who aligned the docking ring in Endeavour‘s cargo bay to a port on the front of the Destiny laboratory module.

Just before the arrival, Kelly stopped the shuttle about 400 metres (1,300 feet) away from the station, and then slowly back-flipped, so that astronauts on board the station could take detailed photographs of the shuttle’s wings and belly. NASA engineers will then study these images to see if there was any damage to the shuttle’s heat tile system caused during launch – a few pieces of foam were seen falling during launch, but nothing too damaging.

Once the visual inspection was completed, the two vehicles connected at 2:02 pm EDT, and the station’s residents officially welcomed the visiting astronauts aboard. Station commander Fyodor Yurchikhin rang a ship’s bell on the station signifying their arrival; one of the traditions left over from the shuttle’s nautical heritage.

The astronauts will enter the station for the first time later this afternoon, after they’ve completed checking the two spacecraft’s connection for any pressure leaks. They will also begin transferring cargo, and prepare for the upcoming spacewalks and installation of the S5 truss.

The newly equipped Station-to-Shuttle power transfer system will get its first test this afternoon as well. This system will reroute power from the station’s electrical system to the visiting shuttle. If this works properly, the shuttle mission will probably be extended from 11 days to 14, and the astronauts will perform an additional spacewalk.

Original Source: NASA News Release

Here’s another little bit of NASA bad news; let’s heap it on with the rest. Shuttle workers are trying to track down the source of an air leak on the space shuttle Endeavour that’s above acceptable limits. The problem was first discovered a few days ago, and engineers thought they’d tracked down the faulty nut. But even after tightening that nut, the cabin was still losing pressure.

This is a problem since Endeavour is supposed to blast off for the International Space Station at 7:02 pm EDT on August 7th. If they can’t trace the leak down quickly, it’ll push the mission back in an already crowded launch schedule.

If everything does go smoothly, Endeavour’s STS-118 mission will deliver cargo, spare parts and a new truss segment to the International Space Station.