Well, very clear skies this morning and no wind to speak of!! The solar wind speed has still been fairly high (near 500 km/s) but the density is not very high (1/cc) and its magnetic field is fairly weak. Scientifically, it has been moderately interesting. The coronal hole (seen as a huge dark spot on the sun) has swept across the sun and the high speed solar wind that comes with it has just about completely passed us by. It has taken something like 4 days for that to happen and we had been hopeful that it would produce the conditions we need to launch, but no such luck, at least during the times when we had calm winds and clear skies.
The next item of interest coming our way from the sun is an "active region", or a bright spot as seen in SOHO or STEREO images. On the "STEREO BEHIND" satellite, we are already seeing increases in the density (the number of particles in the solar wind) and the magnetic field strength of the solar wind. The solar wind speed, too, is increasing. It looks like all of this is going to start to arrive at Earth around midnight on Friday night. The STEREO BEHIND satellite trails behind Earth as it orbits around the sun. The solar wind that hits Earth, in some sense, catches up to us from behind, so the behind satellite can be very useful in helping to predict solar wind effects.
It might be useful to talk about magnetic fields of planets at this point. Remember, magnetic fields always have a specific direction - this is true of any magnetic field. Also, remember that electrically charged particles cannot generally move ACROSS magnetic fields, although they can easily move ALONG a magnetic field.
So, what does this mean in space? It turns out that Earth's magnetic field is very important to life on this planet. So far, I have been talking about the solar wind, which includes most of the stuff that the sun emits. Aside from the solar wind, though, the sun sometimes emits "solar energetic particles" or SEPs. The radiation that comes with these particles could be hazardous to life on Earth if it wasn't for the fact that Earth's magnetic field prevents them from getting to the ground. In some sense, our magnetic field shields us from these particles.
Here is a movie that gives you an idea of how the magnetic field shields us from the solar wind and is pushed around by it:
And another movie showing the effect of ma
There is another effect that is important, too. Our atmosphere extends up to about 100 km in altitude, more or less, but our magnetic field reaches way out beyond this altitude and prevents the solar wind from hitting our upper atmosphere directly. If we did not have a magnetic field, the solar wind would constantly be blowing against our atmosphere and there are theories that say the solar wind would gradually drag the atmosphere away from Earth. In fact, some people believe that Mars originally had an atmosphere and a magnetic field, but that the magnetic field became very weak, letting the solar wind
drag its atmosphere away (the idea of a magnetic field becoming weaker is not so mysterious).
So, these are some reasons why our magnetic field is so important to us. There are others, too, like the fact that some birds have internal compasses and use the magnetic field to navigate when they migrate, etc.
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About Longyearbyen....
Svalbard has been explored for at least the last hundred years. Before then, there had been some visitors, but these were infrequent. Starting about a hundred years ago, scientists began to establish observing posts to study aurora. About the same time, some people began to notice that there is a lot of coal on Svalbard and began mining coal. Coal mining is still an important industry on Svalbard today. In fact, there are many signs of old mines and equipment right around Longyearbyen and there is a coal mining museum at the University. Below is a picture of Meghan, a graduate student, "inside" a mine (well, on display at the museum).
This is a picture of the monument in the center of town, highlighting how important coal mining is to this town.
Here is a picture of "downtown" Longyearbyen, taken right at noon. Yes, total darkness in the middle of the day. It's interesting, though, to see kids get out of school and walk home and play, all in total darkness. We also see people
building houses and doing all sorts of daily chores as if we had daylight. I guess we just adapt.......
2 comments:
So does that mean that you scrubbed the launch again?
yes
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