Mystery object delays Atlantis' return
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: September 19, 2006
Updated after noon news briefing; Updated at 3:45 with more wing sensor details
NASA managers today ordered the Atlantis astronauts to stop their landing preparations and to delay re-entry 24 hours to Thursday to give flight controllers additional time to assess the implications of an unusual object spotted earlier today flying below the shuttle.
The object may have shaken off the shuttle earlier today, possibly due to vibrations associated with routine pre-landing tests of the shuttle's hydraulic system and maneuvering jets. The concern is the possibility of damage to the shuttle's heat shield or some other critical component that could cause problems during re-entry.
Engineers monitoring data from sensors mounted behind the ship's carbon composite wing leading edge panels recorded eight "events" over a two-minute period earlier today. But additional analysis of the timing of the data indicates those events were associated with the known behavior of the hydraulic system during the pre-landing tests, sources said. As such, the sensors probably were not reflecting any untoward events.
"OK, we're not joking about this, but Dan (Burbank) was at window one, he looked out, he saw an object floating nearby," Jett said. "We took several pictures of it, it was fairly small. But we did get several pictures we can send down."
"Did you have a time on that?" astronaut Terry Virts radioed from mission control.
"It just happened."
Whether that object is anything of significance or related to the object that prompted the concern in the first place is not yet known. The origin of that first object is unknown, but NASA managers want to make sure whatever it is did not come from any critical systems on Atlantis, including its heat shield tiles and wing leading edge panels.
In a worst-case scenario, the crew has rudimentary repair equipment on board to fix relatively minor damage to the heat shield tiles and wing leading edge panels. The astronauts also have the capability to return to the international space station to make repairs or await rescue by another shuttle.
But those are strictly last-ditch contingency plans and Hale stressed that such speculation was extremely premature. The events today could be minor and have no impact on Atlantis' safe return.
"I feel very comfortable we'll resolve this and protect the crew's safety no matter what the outcome might be," he said. "Right now, i won't speculate any more."
Hale said the first object was noticed by a flight controller who was using one of Atlantis' cargo bay camera for Earth observation photography, a common practice when the cameras aren't needed for operational tasks.
"Today, as they were doing that, they came across a very interesting object in the field of view," Hale said. "There is a very small black object, which because we moved the camera around a couple of times we know it's not one of those camera lens artifacts, it's not a piece of lint on the lens or a reflection into the camera, which we sometimes see. But there is a very small object in that picture. It is clearly co-orbital with the space shuttle. We took a look at it and frankly there is not enough resolution ... to tell what that is. But it did get everybody's attention."
Earlier today, Jett and pilot Chris Ferguson fired up one of the shuttle's hydraulic power systems in a routine pre-entry test, moving the big elevons, or elevators, on the back of each wing through their full range of motion. They also test fired the ship's maneuvering jets in another standard pre-landing check.
"We shake the ship pretty good when we do this," Hale said. "And when we fire the reaction control system jets, some crews have commented it's like standing next to a howitzer when it goes off. So we have all this vibration going on in the shuttle. And apparently, something shook loose. I say 'apparently' because it's co-orbiting with the shuttle and the question is, what is it? Is it something very benign? ... Is it some ice, because we know ice forms on certain parts of the shuttle orbiter, is it something benign like that that we've seem before? Or is it something more critical that we should pay attention to?
"So coupling that with the fact that the weather is bad tomorrow, the MMT decided we should delay deorbit for a day and spend our time productively making sure we're comfortable with the status of the orbiter's heat shield in particular."
The astronauts were told to power up the shuttle's robot arm before going to bed so flight controllers could use its cameras to get a better view of the orbiter's payload bay and upper surfaces. Unless something obvious is seen, the astronauts likely will use the arm and a 50-foot-long sensor boom extension Wednesday to inspect the underside of Atlantis and other areas that can't otherwise be seen.
The wing leading edge sensor data was puzzling and triggered a fair amount of initial concern. The new sensors, installed in the wake of Columbia disaster, recorded a possible impact on the left wing 14 seconds after liftoff Sept. 9. A close-up inspection revealed no damage and the rest of the heat shield checked out as well. A second inspection was carried out Monday and again, Atlantis' tiles and wing leading edge panels appeared virtually pristine.
But earlier today, "we saw some eight small indications over a couple of minute period," Hale said. "To me, eight indications is not necessarily what I would expect from a micrometeoroid event. It could be some residual from the flight control system check out or the reaction control system hotfire we do. So the team is off looking at that."
Within a few hours, engineers were able to precisely time out the data, showing the sensor was responding to vibrations associated with the hydraulic system. The wing leading edge sensors have never been operational during flight control system checkout and as one source said, "we learn something new on every flight."
Sensor data aside, Hale said "the suspicion is this is something that occurred around the flight control system checkout, because it does shake the vehicle pretty good. ... I don't want to make this overly dramatic. This is something we've seen, we want to make sure its safe for us to come home and we have plans in place if it turns out the other way. But I'm not here trying to write newspaper headlines, we're just trying to bring you up to speed."
Columbia was destroyed during re-entry Feb. 1, 2003, because of a hole in its left wing leading edge that allowed super-heated gas to burn its way into the interior of the wing. The hole was caused by a piece of foam insulation that broke free during launch and hit the wing.
NASA has upgraded the shuttle's insulation system since then and installed a variety of new cameras and other sensors to make sure no heat shield damage is ever missed again.
Along with ground-based photography during launch, the Atlantis astronauts photographed the ship's external tank after reaching orbit and carried out an extensive inspection the next day to check the health of the wing leading edge panels and carbon carbon nose cap, which see the most extreme temperatures during re-entry.
Additional inspections were carried out during final approach to the space station and again, after Atlantis departed Sunday. The final inspection was in place to check for signs of impacts from space debris or micrometeoroids that might have hit the ship since the initial inspections earlier in the mission.
In all cases, the heat shield appeared in excellent condition and the Mission Management Team formally cleared Atlantis for entry. The crew was packing up for a landing Wednesday at the Kennedy Space Center when the MMT decided to delay entry for 24 hours.
The shuttle has enough supplies on board to stay in orbit until Saturday and more than enough fuel to re-rendezvous with the space station if necessary. Assuming the issue turns out to be benign, the forecast for Thursday and Friday in Florida is excellent, with the first of two Thursday opportunities on tap at 6:22 a.m. Thursday.
The official crew patch for the STS-115 mission of space shuttle Atlantis to resume orbital construction of the International Space Station.
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