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Part 4: On-board cameras promise dramatic views
Posted: December 19, 2004

Ground- and air-based shuttle imagery mark a clear improvement over what was in place for Columbia's launch. But it still isn't good enough to spot small areas of potential entry critical damage or damage to areas of the underside of the shuttle that cannot be seen from the ground.

To close that gap, NASA is installing cameras on the external tank of the shuttle, on the two solid-fuel boosters and in the recessed cavity where 17-inch propellant feed lines enter the belly of the orbiter. In addition, as soon as the shuttle reaches space, the astronauts will use a hand-held video camera to "shoot" the tank from close range before it drifts away.

A dazzling view was provided by this external tank-mounted camera flown on Atlantis' STS-112 mission in October 2002. Photo: NASA TV/Spaceflight Now
"We have added some cameras on the tank and on the solids that are primarily looking at tank and at the bottom of the vehicle for the higher impact concern areas," said Paul Hill, the lead flight director for STS-114. "From a crew perspective, they're all hands off, almost passive operations. Once we separate from the ET, we have modified the ET separation maneuver, which will pitch us around so the crew can take pictures at about half the range we used to take pictures at.

"What we're more excited about from an ET photography perspective is the umbilical well camera. Because that camera is going to give us such a good shot of the ET foam in particular that's on the orbiter side and we're going to see that at a really close range. That will give us a really good idea of how the ET insulation performed during ascent."

Within a minute or so of separation, the crew will get a full view of the tank from Columbia's flight deck.

"We would definitely be able to see if we had large pieces of foam come off," Hill said. "My expectation is, we will have really good resolution because it is a still camera instead of video, and because of the close range. Because it's a digital still camera, we'll also be able to downlink that day instead of waiting until post-flight like we would a film camera."

On board imagery will be stored and downlinked to mission control as soon as the crew sets up the shuttle's laptop computer system, along with data from new wing leading edge sensors that were added to the shuttle's wings as a post-Columbia upgrade.

Located on each wing's forward spar behind every RCC panel, the impact sensors will tell flight controllers whether anything struck the leading edges during launch. In fact, they may show engineers aspects of the shuttle they've never seen before.

The sensor system generates two types of data: Peak and detailed.

"Think about what a stereo equalizer looks like," Hill said. "You've seen these ones that, across the frequency band, as the signal bounces up and down, it leaves a hash mark. The system works kind of like that. It's recording very high rate frequency response data across the wing leading edge from all these accelerometers that are on the wing spar for every RCC panel. And it registers the peaks, the software pulls out where those little peaks are from T-0 all the way to after we've made it into orbit.

"The first thing we downlink is just the file that has all the peaks in it," Hill said. "That then tells us that we have a suspected impact somewhere and after we see that, then within an hour after the guys in the MER (mission evaluation room) see that and pick out the ones they think are potential impacts, then we put commands on board to downlink the detailed data around each one of those peaks."

Hill acknowledged that engineers worry "we're going to get data down that we don't understand, or because of the shake rattle and roll we'll get going up hill, we won't be able to interpret the data."

"What's in our favor on this is we've been flying accelerometers like this and the same data collection system in the aft compartment of the orbiter for years," he said. "Now we haven't had it on the wing leading edge and we weren't using it to detect impacts, but the hardware has been flying for some time and we have characterized a similar ascent vibe environment in the aft compartment."

In addition, the sensors have been used during impact tests at Southwest Research Institute in San Antonio, Texas, to collect actual data.

"So we have a certain amount of data on how the system will respond going up hill, we have other data to tell us what impact ought to look like," Hill said. "One thing's for sure, by the end of flight day one we'll have data on the ground and we'll know the answer to that question."

Flight Day 1 highlights (all times in Eastern; a detailed flight plan is available on the Current Mission page):

   Sat  04:11 PM...00...00...00...STS-114 Launch
   Sat  04:20 PM...00...00...09...Main engine cutoff
   Sat  05:01 PM...00...00...50...Post-insertion timeline
   Sat  06:41 PM...00...02...30...PGSC laptop computer setup
   Sat  07:06 PM...00...02...55...Remote manipulator system (RMS) powerup
   Sat  07:21 PM...00...03...10...RMS checkout
   Sat  07:46 PM...00...03...35...Elevon park
   Sat  08:06 PM...00...03...55...RMS powerdown
   Sat  09:16 PM...00...05...05...NC1 rendezvous rocket firing
   Sat  09:36 PM...00...05...25...Group B powerdown
   Sat  10:11 PM...00...06...00...Crew sleep begins
The astronauts will downlink hand-held video of the external tank shortly after reaching orbit. Hill said he expects initial, non-HDTV ground-camera ascent imagery to be available before the crew goes to sleep, as will most, if not all, of the digital still photos on board Discovery. Wing leading edge data will be downlinked late in the crew's day or during their sleep period. An imaging report based on a more detailed analysis of ground and air-based cameras should be available within 24 hours.