Wednesday, December 8, 2010

Update for Wed, Dec 8, 2010

Well, today was quite a busy day. We did have the right conditions for the rocket launch as far as aurora is concerned, but high winds again stopped us from launching (because of the danger of the rocket going where it is not supposed to).

I am not sure if I mentioned this before, but the rocket is sitting in Andenes, Norway, nearly 1000 km to the south of where we are right now. The rocket will to an altitude close to 500 km as it passes over us, which is higher than the space shuttle's orbit. But, since the rocket is launched nearly straight up, it does not go into orbit, but just comes back to the ground. In fact, one of the very first NASA launches shot a rocket up so high (but nearly straight up) that it took 2 days to return to Earth.

So, anticipating some confusion: a "rocket" is the vehicle that gets stuff up into space. If the launch "sequence" is planned a certain way, the vehicle will be placed into orbit. This is called an orbital injection and means that the direction of the rocket motion has been turned so that it flies around the Earth (and generally keeps on doing so for a long time). When this happens, the vehicle (or spacecraft) is then called a "satellite'. Sometimes, the point is not for the spacecraft to orbit around Earth, but to go to other planets or to explore other places. In this case, it needs to be launched with enough energy for it to be able to escape Earth's gravitational pull. We'll skip the math for now, but it comes down to needing to exceed the "escape velocity", which is something like 11 km/s (or 7 miles per second -- very fast) for Earth.

This picture shows the room I am sitting in, with people staring at computer screens, trying to understand what is happening in the skies above us. This is a quiet period - when the solar wind and/or ionosphere start to heat up, so do we!! Things get a lot more intense, with lots of excitement and discussions about what we are seeing, and so on.

I think I mentioned that we follow a specific sequence each day. Work starts about 3 hours before we think we might launch and follows the sequence precisely, right down to the final countdown. Here is an idea of how it goes:

T-3:00:00 - this means "T minus 3 hours", or 3 hours before a possible launch. At this time, we launch weather baloons to start checking for winds. We also notify Air Traffic Control (ATC) that we are going ahead with a possible launch, which is one of the many safety measures we need to take. At T-3 hours, we also make sure that everyone is "on station", since we are all so spread out!! And then there are many, many other details..

T-2:00:00 - Start "horizontal checks" - at this point, the rocket is actually horizontal and inside an enclosure (we put it to bed every night...). It takes a lot to get it vertical, so some checks are made before it get elevated. Also at this time, the 1st stage rocket motor gets "armed" (they turn a lever to arm the rocket and connect firing leads), they verify that the pad is clear and then, if all is well, elevate the rocket. On one rocket campaign a few years ago, there were polar tracks around the rocket and there was some concern that we would not be able to launch because the bear would be close to the launch pad!!

T-15:00 This means "T minus 15 minutes" and is where we sit most of the time. While we sit, the engineers continue to monitor whatever they can to make sure the rocket is ok, the weather people continue to launch weather balloons, etc. Here, the scientists watch the solar wind and anything else to help decide when to "pick up the count", which is what happens when things get exciting and it looks like we might be able to launch. Once we go ahead and start counting again, this gets to be a very busy time and go through "ground station checks", road blocks get sent out to prevent people from driving close to the launch pad, we double check to make sure the pad is still clear, etc.

T-8:30 Start telemetry (or "TM"), which means to turn on the transmitters on the rocket that will send back the data during flight; turn on power and verify that instruments are operating as they should be; set final launcher settings (the final launcher setting depends on the most recent wind measurements).

T-6:30 Final experiment checks

T-5:00 Sound siren for launch clearance, arm remaining rocket motors

T-3:30 Announce science continue or hold. At this point, everyone has to decide whether to go ahead and take the count down below T-3:00, which is the final hold point. Most of the time, we have asked for the count to be picked up from T-15:00, but expect to hold at T-3:00 until we see exactly what we are looking for.

T-3:00 When we pick the count up from here, everyone is on edge and things get to be very intense. The tasks from here include making sure the people near the rocket are in the "blockhouse" (for safety), but many other things also get checked.

T-1:00 At this point, the operations controller polls all of the different parts of the team to make sure things are still working as expected. If so, everyone replies (one at a time) with a "go". If all is good else, the operations controller says "we are go for launch", which is soon followed by:

T-10 The final countdown, the classic 10-9-8-7-6-5-4-3-2-1- launch!!

One last thing, take a look at  and watch the movie of the eruption of a solar filament --- more on this later if I can, but it is a great movie from a couple days ago!!

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