Monday, August 10, 2009

Live At KSC: Foam Trouble Could Trigger Rollback

An external tank foam-shedding problem could prompt NASA to roll shuttle Discovery back to Kennedy Space Center's assembly building for repairs, but the agency still is pressing ahead with preparations for the targeted Aug. 25 launch.

Senior NASA and contractor managers will gather Tuesday and Wednesday for a preliminary flight readiness review for Discovery, which is slated to fly seven astronauts on an International Space Station outfitting mission.

One key issue to be addressed: Significant foam loss on NASA's past two flights from metal brackets that hold liquid oxygen pressurization lines and electrical cabling on the upper exterior of the shuttle's 15-story external tank.

"I suspect there will be a good deal of discussion about this," said Kyle Herring, a spokesman for NASA's Johnson Space Center in Houston.

A recommendation to either fly Discovery as is or roll the shuttle back to the Vehicle Assembly Building for repairs will be presented at an executive-level flight readiness review on Aug. 18.

Here's the situation:

Larger-than-allowable chunks of foam insulation broke free from an ice frost ramp during the launches of Atlantis on a Hubble Space Telescope servicing mission in May and Endeavour on a station assembly mission in July.

On the Endeavour flight, chunks of foam that weighed approximately 0.044 pounds -- or about double the allowable amount -- broke free from a ramp high up on the shuttle's bullet-shaped tank.

The concern is that breakaway foam could do critical damage to vulnerable shuttle wing panels or thermal tiles, which protect the orbiter and its astronauts from extreme heat -- up to 3,000 degrees Fahrenheit -- during atmospheric reentry.

Columbia and its seven-member crew were lost in 2003 when a 1.67-pound chunk of foam broke free 81 seconds into flight, blasting a six- to 10-inch hole in its left wing. The hole went undetected during a 16-day science mission.

Hot gasses blowtorched through the hole during atmospheric reentry, leading to the disintegration of the spaceship 16 minutes before a planned landing here at KSC.

Endeavour's tank also shed an unusual amount of thin foam from a ribbed center section during its July 15 launch. NASA engineers say an adhesive failed to bond properly with a substrate primer on the aluminum lithium skin of the so-called intertank area of the giant fuel reservoir. More than 150 tests were performed on that area of Discovery's tank prior to its move to launch pad 39A last week. So that problem is not expected to be a constraint to Discovery's launch.

NASA engineers still are trying to determine the root cause of the foam loss from the ice frost ramp, which is one of 34 metal support brackets on the outside of the tank. The foam insulation applied to them is designed to smooth airflow over the brackets and prevent ice from building up on them.

The problematic ramps on the Atlantis and Endeavour flights both were manufactured using a process in which thermal insulation is poured into a mold and then left to cure. NASA engineers are considering an alternative process in which a different type of foam would be used to manually build up the ramps.

Herring said the suspect ramp on Discovery's tank has no known flaws. A special inspection technique similar to a high-tech x-ray uncovered no cracks or voids during extra testing performed prior to Discovery's move to the pad, he said.

Discovery's astronauts aim to deliver more than 30,000 pounds of supplies and equipment to the International Space Station, including a new crew sleep station, three scientific research racks and an exercise treadmill. The supplies will enable the U.S., Russia, Canada, Japan and Europe to maintain a full staff of six on the outpost.

NASA is facing a Sept. 3 deadline to launch Discovery or delay its mission until October. A robotic Japanese cargo carrier is scheduled to launch on its debut mission to the station on Sept. 10 and Russia is set to launch a crew exchange mission to the outpost around Sept. 20.

ABOUT THE IMAGE: Click to enlarge and save the NASA image of shuttle Discovery on its oceanside launch pad at Kennedy Space Center after rollout last week from the landmark Vehicle Assembly Building. You can also click the enlarged version to get an even bigger, nore detailed view. Photo credit: NASA/Troy Cryder.

9 comments:

sure said...

it is getting more and more ridiculous. first they take it out under threats of storms and a flooded crawler way. then discover foam problems. it seems the intelligent life has left.

Anonymous said...

The foam issue is a known problem that NASA engineers (who I am sure are more educated and vastly more intelligent than you) have been working on. They moved Discovery as part of normal processing while engineers continue to work the foam issue. I'm sure that if they didn't roll out and then decided the foam issue isn't that serious that you would insult them and call them stupid for not rolling out. And rollout did not take place under threat of storms. Rollout was delayed so they could let the storms pass and only AFTER the rain was miles off the coast did they move Discovery. And a wet crawlerway, like we roads, is not unique in Florida. I guess you never drive on the road after it rains.

Anonymous said...

It's amazing how the instant someone criticizes the shuttle, someone writes back with name-calling.

Please understand they have been launching the shuttle since 1982 and you'd think someone would have come up with root cause and a solution.

Excuse me for thinking.

Microwave

Anonymous said...

"Endeavour's tank also shedded an unusual amount of thin foam..."

shedded?

Todd Halvorson said...

Oops.

shed

Nice catch.

Thanks!

Todd

Anonymous said...

Look, I have to say, NASA is guilty of giving itself a serious credibility problem. They really need some help, desperately, in understanding how to deal with public opinion.

Now, listen, I know some of you really, really, really love the shuttle. I really, really, really love the space program - but hate the shuttle because it has - in Dr. Griffin's estimate - put the US space program back 15-20 years. It doesn't matter if the DoD or the Air Force or Tricky Dick Nixon or John Wayne came up with the idea, but putting that glider alongside the ET was dumb. An Apollo- or Saturn V-derivative, in hindsight for sure, would have been way better.

Now, let's look at the sequence of events. First, I don't believe the conspiracy people who think NASA is intentionally delaying. They want to launch ASAP before the hurricanes. There is no doubt. But, first we get the "unexpected" foam loss on the last one. The foam loss has been going in since the beginning of the program and was ignored forever because it hadn't caused a real problem...until Columbia. So they've had 6 1/2 years to fix this problem, since it was known to be catastrophic.

So we get foam loss the last time and they do all these tests and NASA says "We think it's OK" (a reasonable answer) and then they roll to the pad (the right move even if questions) and then they begin...to leak the potential reasons to slip. First, although they must've known about it, "NASA might slip if can't launch by Sept 3rd." What? I thought launch date was 25th? Oh, the Japanese. NASA didn't know? (They did.) Then, foam problem might force rollback. It sounds like they are figuring out the problems as they go along.

Wouldn't NASA seem way smarter if earlier in the month the press release had said, "Despite potential conflicts with the new Japanese freighter, and with lingering foam questions, NASA is rolling out to try and get a jump on hurricane season."

Instead, they look like the right hand has no clue what the left hand is doing.

I just can't wait to get these last 7 (successful) launches done with so we can start moving toward the future. A future we should have been at a decade ago.

Microwave

sure said...

so, did the foam problem occur between the VAB and the pad? or was there a foam problem while the shuttle was in the VAB and it was not noticed until it got to the pad? either way there is a problem. either poorly installed foam or poorly inspected in the VAB. unless there is some genius who can give another reason. I think they should just end this circus before more crew DIE.

Conor said...

Anon, the schedule problems that mean the Shuttle has to launch before 3rd September is down to the amount of international traffic no flying to the ISS. It's not a bad thing, and NASA did now about a possible conflict.
It's not the Shuttle that has kept the US in low Earth orbit since Apollo, but politics. I'm quite sure that NASA would like to have two or more different manned vehicles with different capabilities flying alongside each other. But the budget doesn't allow it.

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