On Monday, space shuttle Atlantis is scheduled to launch STS-125, a mission to the Hubble space telescope. This is the fifth and final mission to Hubble, and is a mission that almost didn't happen. After the Columbia accident in 2003, NASA's top management decided it was too risky (no ISS lifeboat capability) and canceled it. That produced an uproar in the scientific community, and after a couple more years of study and contingency planning, the mission was resurrected, and here we are just hours from liftoff.
This mission is incredibly important, but just as much for the entire space program as for Hubble. This mission has been driving the space shuttle program's planning for 5 years now. They worked to reduce the foam shedding off the tank (which is what doomed Columbia). They created new inspection techniques to be carried out in orbit, using the robot arm, so that they'd know if they'd damaged the protective skin of the shuttle during ascent. They added sensors to the wings so they could "feel" the impact of any debris during ascent. They upgraded all of their ground cameras for launch views. They developed and tested repair techniques, to be executed by spacewalking astronauts. And they figured out a way to rescue this Atlantis crew from orbit if they deemed that it was damaged beyond repair.
Which is why space shuttle Endeavor is now sitting on the other launchpad, ready to go within a few days. It's going to sit there while Atlantis is up, and once they deem Atlantis in good shape and able to survive the fiery re-entry from orbit, Endeavor's emergency mission (officially called STS-400) will stand down and they will resume preps for what Endeavor really has next on its plate -- a mission to ISS in June.
The first 120 seconds of launch are going to be critical. During those first two minutes, any debris (such as foam coming off the tank) could hit the shuttle and punch a hole in the skin. After the first two minutes, any debris shedding doesn't matter because they are up out of the atmosphere and there's literally no air rushing by to slam the debris into the shuttle.
Now, the thing is, we won't know right away. Atlantis will probably get through those 120 seconds just fine and continue all the way to main engine cut off (MECO) 8.5 minutes after liftoff. But that's when the imagery analysis begins. Here's what to look for in the news:
1. Immediately after the shuttle reaches orbit, amateurs on the net will start looking at the footage and pointing out possible debris events. In the first two flights after Columbia (in 2005 and 2006), there was quite a bit of debris so there was a lot to talk about. But in the past 2-3 years it's been very good. We'll have this amateur data within 30 minutes after launch. Update 2:45pm: launch looked good! No debris events noted in camera replays. The first 10 seconds were exciting through when a transducer (pressure gauge) failed, creating some spurious alarms.
2. About an hour after launch there will be the post-launch news briefing, and the reporters will ask the managers what they saw. I gaurantee that the managers will say make an empty statement like "we're going to go take a look at all the data and see what we see", but you will get a sense from them whether anything jumped out at them as a problem. Update 3:21pm: managers in press briefing also saw no debris events of note!
3. The day after launch, aka Flight Day 2, the crew on orbit will do the inspections with the robot arm and will be able to see if there's any obvious damage. We'll see that inspection video coming down live so we'll see anything when they do. Update 12-May: looking good! There are some nicks in the tile but they don't think it's serious enough to trigger any actions. However, an important part of the flight control electronics failed during the launch, and while they can continue the mission for now, if they take another failure while in orbit the flight rules dictate that they must come down immediately -- like within hours. So everyone has their fingers crossed that nothing further will fail.
4. On Flight Day 3 or 4 we'll start to hear officially about any serious problems. And that is when they make the decision whether to proceed normally with the mission (capture Hubble and get to work) or whether they literally shut down the lights and start saving power so that they can survive long enough for Endeavor to get up there. Update 17-May: the "Thermal Protection System" has been officially declared fit for entry; they still have to do late inspection at the end of the mission but it's looking very good. Meanwhile there's been day after day of nail-biter spacewalks and I'm exhausted just from watching :)
I will update this post with the status of each of the 4 stages above as they are cleared.
If they end up having to rescue Atlantis, that means we will be down to just two shuttles, and NASA has said that they can't run the program with just two. They certainly wouldn't build another one, as these orbiters are 30+ year old designs and about to be retired anyway. So triggering the rescue would be the implied end of the shuttle program, forever.
Regarding the actual mission, I wrote back in September about the mission and pointed to Dr. Heidi Hammel's speech in particular. Of course, this was 7 months ago, just before the anomaly on Hubble that forced them to scrub the Oct 10th launch. The equipment to repair that latest failure is now on the shuttle and they're ready to go up and fix that too.
As I said back in September, I would encourage anyone with even a fleeting interest in science or astronomy to take the time to download and watch the entire briefing, as it is truly fantastic stuff they're talking about, and these guys do a great job of explaining it to regular people. If you don't have time to watch the entire 90-minute briefing, at least watch her 10 minutes. Links are in the post I made back in September.
Update 13-May-2009: Sadly, I see that the links to the Hammel speech in the old post no longer work. I have not been able to find the briefing on Youtube, and the repeat briefings from a couple weeks ago did not include Dr. Hammel. FORTUNATELY, I did find most of Dr. Hammel's speech incorporated into a nice 5 minute video right here. Please check it out!
Update 16-Jun-2009: And with the "Houston, wheels stop" call from the commander on May 24th, Atlantic completed her mission and everyone involved breathed a huge sigh of relief. And later that week, a Soyuz launched three men to ISS, finally bringing the space station crew up to 6 people for the first time ever. We've been anticipating the Hubble mission for 5 years, but the 6-man crew on ISS has been anticipated for nearly two decades! It didn't make headlines, because it all went so smoothly, but this is the heyday of space flight, RIGHT NOW. That last week in May, with the completion of the Hubble servicing mission and the beginning of serious science operations on the space station, represents perhaps the biggest milestone in the US manned space program since the first launch of the space shuttle in 1981. Congratulations NASA!
