Friday, December 3, 2010

update for Friday, Dec 3, 2010

Finally, we had things up and running today in the sense that the rocket is ready to go, the first day for us to finally everything in place. Unfortunately, it has been extremely windy, which would prevent us from launching for safety reasons. In addition, the solar wind was very weak and, really, there was very little aurora and we would not have launched even if we could have.

Remember, we are trying to make measurements that will help us understand what drives oxygen atoms several hundred kilometers upwards into the sky. The criteria we use to help us decide when to launch comes mostly from radar observations, using the huge radar dishes photo in the previous posting. There are other things we look for, too, like what the solar wind is doing which we can observed from a satellite in space.

The issue with winds is complicated. First, you might surprised to learn that this rocket is not guided in any way. Once it leaves the launch rail, there is nothing we can do to affect what it does or where it goes. For safety reasons, then, we have to be extremely careful about where and when to launch. With strong winds at high altitudes, there is the possibility that the rocket gets blown in exactly the wrong direction, which could become dangerous. In order to make sure that this does not happen, the team at the launch range releases weather balloons about every half hour to track the winds. These are quite large helium balloons that they can track to see where the winds blow them as they go up in altitude.

Still, even if the winds are calm at high altitudes, we have to worry about the winds at ground level, but for a completely different reason. Take a look at the sketch of the rocket below.

You can see how big the rocket is, but notice the huge fins at the bottom of the rocket, which are used to help keep the rocket pointed straight as it leaves the rail and takes off. Maybe you can imagine that, when the rocket first leaves the rail, it is not moving very fast. In that case, the fins would not have much of an effect. In fact, they would be pushed sideways by strong ground winds rather than help the rocket stay pointing upward. The result, of course, is that the rocket takes off in the wrong direction, which could be a disaster!!!

Again, this is a 4-stage rocket (can you identify the rocket motors in the drawing?) and is very long -- more than 21 meters, longer than most houses.

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