Sunday, November 16, 2008

630p 11/15 Update: MMT briefing; KU antenna glitches; possibly lost insulation assessed


Posted: 6:30 PM, 11/15/08

By William Harwood
CBS News Space Analyst

Changes and additions:

   SR-13 (11/14/08): Shuttle Endeavour roars into orbit
   SR-14 (11/15/08): Endeavour astronauts gear up for heat shield inspection
   SR-15 (11/15/08): Heat shield inspection underway; flight controllers ask astronauts to photograph area of possible insulation loss
   SR-16 (11/15/08): MMT briefing; KU antenna glitches; lost insulation strip discussed


6:30 PM, 11/15/08, Update: Lost insulation blanket not considered serious threat; engineers implement work-arounds for KU antenna glitches 

The shuttle Endeavour is in good shape after its climb to space Friday and engineers are only working a handful of relatively minor problems, including a possibly lost strip of insulation and glitches with the shuttle's KU-band antenna, the chairman of NASA's Mission Management Team said today.

"The mission is going extremely well," said MMT Chairman LeRoy Cain. "The crew is in good shape as is Endeavour. ... There are a few very minor things that we have in work that the team is looking at but nothing of overall great significance. The space station program reported to us that the station is in good shape and the crew on board the station is ready for Endeavour and her crew to show up tomorrow."

Cain said an analysis of imagery from Endeavour's night launch Friday is not  yet complete, but poor lighting means a detailed assessment will have to wait until on-orbit inspections are completed later in the mission. The crew was told of two possible debris events late Friday, but Cain said today as far as he's concerned, only one event appears confirmed.

At roughly 33 seconds after launch, as the shuttle's three main engines were throttling back to 72 percent thrust to ease aerodynamic loads on the vehicle, a small strip of flexible reusable surface insulation, or FRSI, appeared to pull away from the orbiter's fuselage right above its left-side aft umbilical connection plate just below the left orbital maneuvering system rocket pod.

"We have one area that we're looking at from a debris standpoint," Cain said. "Just underneath the left OMS pod, in the area right above the T-0 umbilical plate, there is what we think is a narrow strip of the blanket insulation material that came loose and flew away there. ... This is not an area that is of great concern to us in terms of losing a blanket. As I said, the umbilical plate itself is an aluminum surface that is unprotected by any thermal protection system."

Just after 6 p.m. today, the astronauts took a moment to aim a camera on the shuttle's heat shield inspection boom to photograph the area. To the untrained eye, no obvious damage was apparent.

Cain said the presumably lost strip measured roughly 12 to 18 inches long, 4 inches wide and 0.3 inches thick. FRSI insulation is used in areas of the shuttle where re-entry heating does not exceed 700 degrees Fahrenheit and while engineers will carry out a thorough assessment, the loss of insulation in that area would not appear to be an issue of any consequence.

Cain mentioned two problems with the shuttle's KU-band antenna, a steerable dish antenna mounted near the front right side of the ship's payload bay that automatically finds, locks onto and tracks NASA's data relay satellites. The antenna sends and receives data, voice communications and television signals and can operate in radar mode during rendezvous operations.

In one problem, the antenna fails to maintain lock on a target satellite after getting initial pointing instructions from the shuttle's computers. Cain said flight controllers can work around the glitch by operating in what is known as GPC designate mode, in which pointing instructions are continuously sent to the antenna system. While this mode requires additional work by ground controllers, it is transparent to the shuttle's crew.

The second problem involves trouble with automatic handover between KU- and S-band communications. Again, ground controllers will manually oversee such handovers as required with no impact on the mission.

It's not yet clear what is causing the problems. If the loss-of-lock condition is located in the antenna electronics, Cain said, the KU system may not be able to operate in radar mode during Endeavour's rendezvous with the international space station Sunday. In that case, the crew will switch to a backup procedure and use the shuttle's star trackers to provide navigation data during the final stages of the rendezvous.

Cain said all shuttle crews are trained to carry out star tracker rendezvous procedures in case of radar failures.

"In my recollection, we've done at least one (star tracker rendezvous) in the space station assembly sequence, it was on STS-92 (in 2000)," Cain said. "We did exercise a radar-fail rendezvous on that mission."


Quick-Launch Web Links:

CBS News STS-126 Status Reports:

CBS News STS-126 Quick-Look Page:

NASA ISS Expeditions Page:

NASA Shuttle Web:
NASA Station Web:
Spaceflight Now:


Post a Comment
Related Posts Plugin for WordPress, Blogger...

Popular Posts