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Space shuttle program manager Wayne Hale gave a press conference describing NASA’s initial assessment of external tank performance during today’s launch. The overall assessment is very favorable, both for this flight and future flights.
As NASA expected, foam was lost during launch. Five “events” were detected photographically. All events happened more than two minutes into flight, when the shuttle was at a very high altitude. For Discovery, this is good because in vacuum, the foam drifted slowly away from the tank. Even large pieces of foam lost after T+2:15 aren’t a safety hazard. The problem with foam is when it’s lost in the atmosphere, and can be turned into a high-velocity projectile by the supersonic wind surrounding the shuttle during ascent.
For future missions, the late loss of foam is considered excellent news. Apparently there were several hypothesized mechanisms for foam loss, and today’s data indicate that the primary mechanism may be something related to vacuum, which doesn’t pose a risk in future flights.
Of course, this is all preliminary information. NASA will be going over Discovery’s thermal protection system with a painstaking photographic survey, going over today’s launch photography in extensive detail, and then going back to understanding foam loss in more depth based on the new information.
In other news, I retrieved my remote cameras from the launch pad area, and everything worked! The photo above was taken by a wide-angle digital camera, unmanned at launch time, triggered by the sound of the launch. The photo below shows me servicing the camera system yesterday. The camera on the left took the photo above; the camera on the right (visible in the wide-angle shot) was a telephoto film camera, it took 36 exposures but it hasn’t been developed yet. The equipment was set up on Friday morning, and spent about 103 hours in the field, through both scrubs and the actual launch.
Discovery launched on schedule this afternoon, and is now in orbit. On Thursday, the shuttle will dock with the space station. I watched liftoff through binoculars, and the sense of time changes in unusual ways. The six seconds between main engine start and liftoff seemed to take forever, and then the launch itself seemed to pass quickly — probably because there really isn’t time to let the experience sink in. The brilliant intensity of the flame is what really caught my attention. Within a minute, the shuttle is pretty far downrange.
The sound seems like the most intense part of the experience, perhaps because photographs are everywhere, but the pounding vibration is something that can’t be captured in the same way. Even from my vantage point, three miles from the launch pad, the sound washes over everything. But since sound travels at five miles a second, the first 15 seconds of the launch are totally silent. Only at that point does the sound of main engine start arrive.
After watching liftoff in binoculars, I took a few photos and watched by eye until SRB (solid rocket booster) separation, and I went back to binoculars at that point. The sky was really clear, and I could see SRB separation better than on most of my previous launches. I was able to follow Discovery until T+5:15 in binoculars, the longest I’ve ever tracked a daytime launch. Then I looked back to the sky, and saw the cloud produced by the launch … the shuttle’s main engines burn hydrogen and oxygen, and make a lot of water vapor. In addition, there’s some acid in the clouds due to exhaust from the solid rocket boosters. Here’s what the clouds looked like from the press site:
And a view of these clouds with the Vehicle Assembly Building (the large object on the left is the back side of the countdown clock):
The space shuttle countdown is going very smoothly today. Launch is scheduled for 2:38 pm EDT. Weather is very favorable, skies are clear here at the Kennedy Space Center, and there are no technical problems. Weather forecasters are watching crosswinds at the runway at KSC that the shuttle could use in certain kinds of launch aborts, and rainshowers offshore, but neither issue is expected to present a problem. The countdown has just picked up from a planned hold at T-20 minutes. One more planned hold remains in the countdown, at T-9 minutes. In the photo I took at T-20, the launch pad is on the left side of the image.
Last night, a piece of foam apparently fell off the space shuttle’s external tank. The piece is seemingly large - about five inches long. It’s also in a seemingly dangerous place - high and on the side of the tank facing the underside of the shuttle. However, the mass of the piece is apparently small, and (according to NASA) would not have created a problem if it had broken away in flight and struck the shuttle. NASA’s main concern seems to be making sure that enough foam remains in that section to provide thermal insulation, both on the pad (to prevent ice from building up over the cryogenic propellants) and in flight (to make sure that aerodynamic heating doesn’t stress the tank). There is no indication that this problem is happening anywhere else on the tank, it appears to be a single incident. NASA managers are scheduled to meet again at 6:30 pm to review the situation.
I took the photo above while astronaut David Wolf was explaining the situation for a TV film crew. He’s pointing out the position on the tank where the foam is missing.
The countdown is proceeding on the basis that the tank is OK and can fly without repairs. If they decide that the tank must be repaired, there would be at least a 1 day delay. We’ll know more later tonight, but I probably won’t be here to provide updates until tomorrow.
Meanwhile, media photographers have been servicing remote cameras that are located near the launch pad. I spent my morning out in the hot Florida sun, half expecting that the launch would be scrubbed while I was working on cameras, but it’s still go. In the photo below, photographers Phil McAuliffe and Ron Palmisano (from NJ and CT) are working on their camera system about 2000 feet south of Discovery. These remote cameras are unmanned during the launch, the area within 3 miles of the launch pad is off-limits while the external tank is fueled, so photographers have to get them ready about 24 hours before liftoff. The cameras work by responding to the sound of the launch, and automatically taking photographs.
The shuttle launch was scrubbed again today, a couple of hours before the planned launch time. This was the second attempt at launching Discovery to the International Space Station. I took this photo at a post-scrub NASA press conference at 3 pm, where the deputy manager of the shuttle program and the launch director explained the events and what happens next. NASA usually presses the count as far as possible, since weather is unpredictable, and a clear region passing at the right time is all they need to fly. But conditions were worse than yesterday, and they decided to scrub early so ground support teams would have more time to replenish the fuel cells used to produce electricity on the shuttle in space. This is important because it increases the probability that the shuttle can stay in space for 13 days, instead of 12, and that extra time would be used to add an additional spacewalk. The next launch attempt will be Tuesday afternoon at about 2:38 pm. Since this is the 4th of July, the media will focus on that coincidence and we’ll hear lots about rockets on Independence Day. The weather forecast is 60% favorable for Tuesday, and 40% favorable for Wednesday. If it doesn’t fly by then, NASA would wait until Friday. I’ll be here through Wednesday, but need to leave that evening … but regardless of whether the shuttle launches by then or not, it’s always a fascinating experience to visit the Kennedy Space Center.
The shuttle launch was scrubbed today due to weather. Anvil clouds from storms 30 miles west of Cape Canaveral were blowing over the launch area, creating the risk of triggered lightning if the shuttle passed through these electrically charged clouds. The next launch attempt is 3:26 pm EDT tomorrow (Sunday). The weather outlook is similar - only a 40% chance of acceptable weather, with a repeat of today’s conditions considered likely. I took this photo at the time of the scrub, looking northwest from the Kennedy Space Center press site towards the approaching clouds.
The seven astronauts of mission STS-121 are currently at the launch pad boarding Discovery. The photo was taken about 12:10 pm and shows the astronauts passing the Launch Control Center on their way to the launch pad. The weather forecast has improved to 60% probability of acceptable weather, with the primary concern being anvil clouds blown east from thunderstorms over central Florida and the Gulf coast. There’s also a technical problem relating to a heater for a thruster that would be used in orbit, and it’s not clear if this could affect the launch, but there doesn’t seem to be much concern at the moment.
I’m at the Kennedy Space Center in Florida for the launch of Discovery tomorrow at 3:48 pm EDT, and took this photo at 9 pm this evening from launch pad 39-B. There’s a 60% chance that the weather will violate launch constraints. The main concern is that anvil clouds from inland thunderstorms over central Florida may be blown towards Cape Canaveral. The launch window lasts only 10 minutes, because the shuttle needs to fly while Cape Canaveral passes through the space station’s orbital plane.
