debris appears to fall off shuttle fuel tank
NASA via AP
In this NASA TV image from the shuttle launch, a piece of material is seen coming off Discovery's external fuel tank.
By NBC News space analyst
msnbc.com
updated 7/27/2005 1:43:33 PM ET 2005-07-27T17:43:33
ANALYSIS

Camera views from the space shuttle Discovery showed some spectacular scenes during launch — and some alarming ones as well. Pieces big and small fell away from the structure. Strange flares and shimmering auras gleamed against black space. With more than a hundred cameras and millions of megabits of visual data, we are seeing things we’ve never seen before.

In the absence of any other anomalies in the silk-smooth countdown and launch, media attention focused on these visual "funnies." But calm is called for, at least for now. The right people are already worried — the engineers on the NASA shuttle team.

It’s their job to be worried, and outside observers need only worry if the space team members fail to do so — because bitter experience has taught that unworried space workers grow complacent, make judgment errors and set up conditions for the loss of spaceships and astronauts.

A further caution: Imaging systems, by their nature, are biased and incomplete. They can only see things that are there. It is up to human beings to fill in the blanks with the things that are NOT seen, and the significantly different "big picture" that this wider perspective provides.

For example, as Discovery rocketed toward space, the external television camera near the front end of the belly tank stared back down between the tank and the fragile tiled underside of the shuttle. The Florida coastline came into view, and its roadways and airfields were laid out on what looked like a map. But suddenly on the flat background I noticed a very un-maplike visual feature. A thick black line was extending to the left from the area of the rapidly-receding launch pad. Was somebody taking a felt-tip marker to the map?

Then it hit me, and by seeing what I’d originally overlooked, the entire scene morphed from a flat map to a deep three-dimensional real-world vision. The camera’s point of view was very, very high and still climbing. The black line — already many miles long and growing visibly — was the shadow of the shuttle’s smoke trail on the ground opposite the midday sun. Only then was I able to see what had not been there on the screen — the immense depth of space between the camera and the ground so far, far below. The sudden recognition brought a thrill — and a brief bout of vertigo.

Insights from the imagery
The images from the exterior camera showed lots of other phenomena that need interpretation and perspective.

Sure, at least two pieces came off during powered flight, but neither from that camera nor from dozens of other ground-based observation points did I ever see anything remotely similar to the jaw-dropping apparition I’ll never forget seeing on that video of Columbia's Jan. 16, 2003 launch: Something bright and big flew off the upper tank, vanished behind the spaceship’s left wing, and emerged as a spray of fragments.

It was scary then, and it’s still scary to think about. And the absence of anything like it on the Discovery ascent scenes is my protection over getting too worried now. So, the flapping sheet of something coming off the tank soon after solid rocket booster separation may have been startling, but it clearly passed below Discovery’s belly with no contact. The classic hockey rule applies: "No blood, no foul."

The smaller chip off one tile on the nose gear wheel well was impressive, too — but only because, small as it was, it was still apparently registered on radar. Pending closeup views that might show a steep gouge, it looks like any of the thousand-plus other tile dings that flight experience shows are tolerable.

Shortly after the big piece came off the tank, the camera spotted a more alarming event — a bright flare emerging from behind the shuttle, probably on its aft structure. Was this a fuel tank rupture or an impact on the invisible side of the vehicle? This kind of flare had never before been seen, and it got the attention of observers both inside and outside of NASA.

This turned out to be an "ordinary" event as well, however. The flare occurred at the precise time that the shuttle ignited its auxiliary propulsion system to give a small extra boost into space. This is a fairly new procedure, and the only other shuttle flight with an external camera had seen its lens contaminated by thrusters from the solid rocket booster separation — so it couldn’t have seen the flare even if it occurred on that flight.

NASA also released images taken from ground cameras just as the shuttle cleared the launch tower, confirming eyewitness accounts of white dots coming off the nose. These weren’t feathers (although another image showed a bird actually being rammed by the ascending tank), but scraps of paper installed over the nozzles of steering thrusters to keep rainwater out.

These deliberately had been modified to tear off early, because earlier designs had held on until nearly supersonic speeds and when they ultimately tore loose, they rammed the cabin front windowsills so violently that they sometimes jammed fragments up under the outer glass layer. The addition of mini-parachutes had been announced by NASA shortly before the shuttle launch, and it was speculated at the time that they would show up almost immediately after launch as falling white dots.

Once the shuttle main engines shut down, and with the video link unbelievably still hanging in there, small particles could be noticed drifting away from the vehicle. At least two of them moved in straight lines and suddenly swerved back towards the tail.

A moment’s thought — and some back-of-the-envelope calculations — showed why this surprise should have been predictable. Even at 18,000 mph, the shuttle was still just at the upper edge of the atmosphere. With an altitude of 55 miles, it was legally not even in "outer space." The very thin air was enough, at such very high speeds, to create an aerodynamic push with the strength of a light breeze back on Earth.

The thin air also, astonishingly, manifested itself as flickering glows along the leading edge of the shuttle as it pulled off the tank. What we were seeing — what we had never seen before —was the angry glow of ionized gasses torn apart by high-speed impact with the spaceship. Such glowing plasma envelops spacecraft falling back into the atmosphere, and it should have been expected to be visible on the way up through the same air layers, but it still caught me by surprise.

The more we open our eyes, on shuttle flights and elsewhere in space, the more surprises we experience. But these results should hardly be reason for excessive worry. Keeping new eyes closed, and opting not to look, has always worried me a lot more.

James Oberg, space analyst for NBC News, spent 22 years at the Johnson Space Center as a Mission Control operator and an orbital designer.

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