Thursday, August 13, 2009

NASA Orders Extra Tank Tests On Discovery

LIVE IMAGES: The image on the left is from a live video feed in the Launch Complex 39 area at Kennedy Space Center. The image on the right is the latest still image from NASA TV. They will automatically refresh to the most up-to-the-minute image every 30 seconds.

NASA is carrying out extra inspections and tests on Discovery's external tank in an 11th-hour bid to clear the shuttle for launch, but a rollback to Kennedy Space Center's Vehicle Assembly building for repairs remains a possibility.

Discovery and seven astronauts now are tentatively scheduled for launch on Aug. 24 -- a day earlier than previously planned. A firm date is supposed to be set at an executive-level flight readiness review to be held at KSC next Tuesday.

Their mission: to haul up a huge load -- more than 30,000 pounds -- of supplies and equipment to the International Space Station. Three spacewalks are scheduled during a 13-day flight, and NASA is briefing the media today on the mission.

You can watch the briefings live here in The Flame Trench. Simply click the NASA TV box on the right side of the page to launch our NASA TV viewer. A spacewalk overview is scheduled to begin at 12:30 p.m. and the Discovery crew will hold a press conference at 2 p.m.

NASA engineers are attempting to clear two critical external tank safety issues:the potential for foam-shedding from the ribbed central part of the 15-story tank and metal brackets -- called Ice Frost Ramps -- near the top of the bullet-shaped barrel.

NASA shuttle program manager John Shannon said about 25 percent of the NASA engineering community thinks Discovery should be rolled back for additional inspections and repairs.

Here's the situation:

Thin strips of foam insulation peeled off the intertank region in the tank during launch of shuttle Endeavour last month. NASA engineers traced the problem to the failure of an adhesive that is supposed to fix the foam to a substrate primer on the aluminum lithium skin of the tank.

Nearly 200 tests done to Discovery's tank prior to its rollout to launch pad 39A showed the adhesive on its intertank is working as intended. Most of those tests were done on the back side of the tank. NASA engineers now have ordered up extra tests on the side of the tank that faces the underside of the shuttle orbiter to make certain foam won't pop off and damage shuttle heat-shield tiles. Those tests are to be conducted at the pad over the weekend.

Extra inspections also will be performed on the Ice Frost Ramps on an external tank being prepped in the Vehicle Assembly Building for a shuttle flight set for launch on Nov. 12.

The metal brackets secure pressurization lines and electrical cabling that run down the side of the tank's external. There are 34 of them on the exterior of the tank.

Large chunks of foam broke free from one of the ramps during the past two shuttle flights and three flights since late 2007. Engineers think the process used to apply foam insulation to four of the brackets might be contributing to the foam loss.
Foam in those cases is poured into a mold, cured and then manually shaped. In the future, the ramps will be built up manually.

NASA engineers performed extra x-ray inspections to the suspect ramp on Discovery's tank. But the other ramps built-up with the same process were not x-rayed before the shuttle headed to the pad because they had not shed foam in the past.

The inspections on the tank for the November flight are being conducted to increase engineering confidence and root out an potential problems with ramps built up with the pour-and-cure procedure.

However, if any problems are detected, NASA likely would roll Discovery back to the Vehicle Assembly Building so all four of the ramps made with the pour-and-cure process can be inspected. In that case, the ramps might be removed and rebuilt manually.

NASA is facing an end-of-the-month deadline to launch Discovery before standing down for the debut flight of a robotic Japanese cargo carrier on Sept. 10. Shannon said NASA would have opportunities to launch Discovery on Sept. 19 and Sept. 20 before standing down for a Russian crew exchange mission set for launch Sept. 30. The next opportunity after that would come Oct. 17. A slip to Oct. 17 would push the planned Nov. 12 launch back to Dec. 11 or Dec. 12, Shannon said.

7 comments:

Anonymous said...

I know we've hashed this before, but I still think NASA should look into leaving the cargo carrier attached to the ISS after the current mission.

It may not be rated to stay at the ISS for long periods, but what the heck. It could be used as a 'garage', or for internal storage, or something useful.

Rick Steele
Sarasota, Florida

Anonymous said...

I don't know if they will roll back for foam, but if those two tropical systems stay on projected path they will be rolling back for weather.

When selecting future launch sites, New Mexico is tropical storm free.

Microwave

Anonymous said...

Your on the right track Rick. There are three multi purpose logistics modules - MPLM's. There were three build based on what the work load was suppose to be happening before the Columbia accident. With the decrease in science that was stripped out of the budget a few years ago, you could now get by with one module. On the last shuttle flight, or maybe next to last, dedending on when they fly the AMS mission, they will indeed leave one of them at the ISS. There is a bit of work to get in into that position, mainly an upgrade of the debris sheilds. But all of that is in work.
The modules that come back, like the 17A mission getting ready to fly, are packed with all sorts of down mass "stuff." From blood and urine samples, to hardware that needs refurbished, to dirty laundry.
You will see a few missions next year with a different type of carrier - express logistics carrier (ELC) that will carry a bunch of the big spare units up to ISS to make sure it can operate past end of shuttle. Remember when the shuttle ends you lose a lot of capiblity to get big replacment units in space, and right now all your capiblity to get anything down. So you got to get those units up there before you pull the plug on shuttle.

Anonymous said...

The shuttle has rode out many tropical storm. It is the weather forecsters with their "weather wood" predictions that usally result in roll backs based on hurricane force wind predictions. KSC never saw hurricane force winds during the very active storm season a few years back, however had to roll back because of the forecast. In the weather forecasters defense, they have to make the call many days ahead because of the time it takes to get ready to roll back.

Anonymous said...

OK, what about the new Japanese freighter? Doesn't that have capability to get supplies up to the ISS?

How much cargo fits in the freighter as a percentage of how much fits in the shuttle?

I realize the Progress is very small, and I was just assuming that the Japanese vessel would naturally be made larger so as not to have redundant capability.

Microwave

Anonymous said...

No, the VAB had 120 MPH winds from either Jeanne or Frances in 2004. I remember all the panels being blown off the outer wall.

Then they did a rollout - stop - rollback - stop - rollout because TS Ernesto was supposedly headed this way, but by time the "storm" arrived it had been downgraded to Balmy Breeze Ernesto with 15 mph winds. Someone really jumped the gun on that one.

AlbertM said...

There has neever been a failure of the TPS system on the SRBs.
The TPS is painted with a special paint which increases the
tensile and shear strength. Removal of the paint on the External Tank removed this charistic of the TPS on the ET.
Put the paint back in the area of failure!