Still no luck with being able to launch the rocket. We have been seeing lots of aurora, but generally too far to the north for us to be able to reach it with the rocket. This is frustrating for us, of course. When we plan the rocket campaigns, which is something that begins 2 or 3 years in advance, one of the things we do is select a launch site. Depending on what kind of aurora we want to study (and there are many, many different types -- different colors, different shapes) we choose a site that it at the right latitude. The problem is that these things depend on how active the sun is -- which is quite complicated. More about solar activity and solar cycles later (maybe tomorrow).
More about aurora: aurora is something you see nearly all the time at high latitudes like this. In fact, there is usually a ring of aurora around the north and south poles. This is called the "auroral oval" and you can see pictures at NASA's website , taken by a satellite very high above the north pole with a camera pointed back down to Earth. You may be wondering what the auroral oval looks like in the southern hemisphere -- it turns out that you usually see the same shape and brightness in both hemispheres!
I should probably explain a bit more about this. The first point is that the auroral oval is really centered around the magnetic poles of Earth, not the geographic pole. The magnetic pole is where a compass needle points and is not in the same location at the geographic pole. Again, there are many, many different types of aurora including pulsating aurora, flickering aurora, tall rays, vortices, enhanced aurora and on and on. Each of these different types is associated with a different process that drives it - and so, each type can tell us more about the space far above it. Not surprisingly, you find these different types in different locations and at different times.
Why does aurora occur as a ring around the poles? Tough question, but the basic answer goes back to the fact that aurora is caused by electrically charged particles (electrons and ions) that fall to Earth, but that do so by flowing along magnetic field lines. Of course, in order to cause aurora, these particles have to somehow get ON those field lines. It turns out that the field lines that are anchored (to Earth) in the regions of the auroral oval provide easier access to these charged particles. Since it is easier for these particles to get attached to these field lines, more can travel down to our upper atmosphere.
Take another look at the movie from the other day, below, that shows how Earth's magnetic field shields us from the solar wind. If you look closely at the northern polar region, you can see that it shows where aurora is produced as a result of the interaction of the solar wind and our magnetic field. What you cannot see in the movie is that the size of the auroral oval depends on the energy contained in the solar wind. When the sun is very active, the solar wind carries a lot of energy to Earth and causes lots of bright aurora. Under these conditions, the auroral oval expands, delivering aurora to cities further south. These days, though, the solar activity has been very low, keeping the auroral oval small -- and keeping the aurora here too far to the north for us to be able to hit with the rocket.
One last comment - the stuff I am describing here is part of a new field of research, called space weather. The idea of space weather forecasting is to be able to predict magnetic storms -- events that carry huge amounts of energy and that can seriously damage satellites orbiting around Earth, or that drive extremely large electrical currents in our electrical power supply (destroying transformers), etc. We are now also learning that airplanes flying over the north pole (say, from the US to China) can sometimes expose passengers to higher levels of radiation than expected. This is probably not a problem for passengers (who fly occasionally), but is more of a concern for the pilots and flight attendants who make these flights on a regular basis.
Saturday, December 11, 2010
Thursday, December 9, 2010
Update for Fri, Dec 10, 2010
Well, we have now been sitting here every day since Nov 28 and still have not been able to launch the rocket. Most days, the strong winds in the vicinity of the launcher are the problem (like today!!!). Some other days, the solar wind just doesn't cooperate and we don't get aurora in the region where we can fly over it with the rocket. Patience...
The solar wind speed has been ok (near 400 km/s) but the density is not very high (1/cc) and its magnetic field is fairly weak. Scientifically, it has been moderately interesting. There is a coronal hole (seen as a huge dark spot in the middle of the sun) and we should start seeing its effects within the next day or so. We would see this as a period of much higher speeds in the solar wind. By the way, at normal solar wind speeds it takes about 4 days for the solar wind to get to Earth from the sun. This so-called High-Speed Stream would get to us about twice as fast.
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It might be useful to talk about magnetic fields of planets at this point. Remember, magnetic fields always have a particular direction - this is true of any magnetic field. Also, I should point out that electrically charged particles (i.e., particles that make up the solar wind) 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 Earth's magnetic field shields us from the solar wind and, in response, is pushed around by it -- producing aurora in the process:
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.
The solar wind speed has been ok (near 400 km/s) but the density is not very high (1/cc) and its magnetic field is fairly weak. Scientifically, it has been moderately interesting. There is a coronal hole (seen as a huge dark spot in the middle of the sun) and we should start seeing its effects within the next day or so. We would see this as a period of much higher speeds in the solar wind. By the way, at normal solar wind speeds it takes about 4 days for the solar wind to get to Earth from the sun. This so-called High-Speed Stream would get to us about twice as fast.
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It might be useful to talk about magnetic fields of planets at this point. Remember, magnetic fields always have a particular direction - this is true of any magnetic field. Also, I should point out that electrically charged particles (i.e., particles that make up the solar wind) 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 Earth's magnetic field shields us from the solar wind and, in response, is pushed around by it -- producing aurora in the process:
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.
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 Spaceweather.com 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!!
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 Spaceweather.com 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!!
Monday, December 6, 2010
Update for Mon, Dec 6, 2010
Things are starting to get interesting. Most importantly, the solar wind is improving (the energy it is delivering to Earth is increasing) which is what we need to get the aurora we are looking for. We have been seeing aurora in some of the special auroral cameras we are running quite clearly. We could see that there were several auroral arcs overhead, sort of jumping around but fairly bright. This was encouraging, but we really need to have some fairly steady conditions. Why are we so fussy? Well, it comes from the countdown. We can sit at T-15 minutes indefinitely, meaning that we can watch what is going on, discussing whether the conditions look promising, etc. and just let the rocket (and crew) sit idle. When things start to really look interesting, we ask to "pick up the count", in which case the team at the launch range begins a certain countdown sequence. This is basically a checklist of items that need to be a certain way before we can launch. I'll talk about this more later, but it includes things like confirming there are no fishing boats under the trajectory and so on.
Usually, the count will be brought down to the T-2 minute mark and held. At this point, we are generally quite fidgety, watches every instrument we can find, anticipating the launch. We can hold at T-2 minutes for about 30 minutes, after which time we have to either decide to launch or go back to T-15 minutes. If we decide to launch, the final checks in the countdown are carried out and followed by the classic 10-9-8-7-6-5-4-3-2-1-launch. So, that's why we need steady conditions in the ionosphere overhead (that is, aurora!!).
----------------------------------------------------
About aurora...
Now is a good time to say some things about aurora, sometimes called Northern Lights. First, there is no question that aurora is one of the most spectacular things you can ever see. You do see it in New Hampshire at times, when a huge magnetic storm hits, but it is generally nothing like what you see as you get nearer the magnetic poles of Earth (yes, there are "southern lights", too). The things you notice right away is that there are many shapes and colors, that things are different from day to day or even from minute to minute. Naturally they're amazing to watch but, scientifically, aurora is very important because it is part of the last step in the process of transferring energy from the solar wind to our upper atmosphere.
I should say that we already know what causes aurora, at some level. This is a bit tricky for me to explain, since I am not sure of everyone's background, but here goes.... You have no doubt heard the term "atom", which maybe you know is the building block for the stuff we are familiar with from day to day. Everything we see around us (and maybe don't see) is built up from atoms; sometimes, an atom might be attached to one or more other atoms and then we call the building blocks molecules. For example, water molecules are made up of two hydrogen atoms and one oxygen atom, which is why it is sometimes written as H2O. This gets complicated real fast, but the part that we need to deal with is not so bad. For one thing, we almost always deal with just atoms by themselves.
Well, it turns out that atoms can get excited and, when they do, they respond by giving off light. That is, if you can manage to bump an atom somehow, you can expect it to give off a brief burst of light. This, in fact, is probably happening right next to -- look up at the ceiling. Is there a fluorescent light? If so, then you have "atomic collisions" and "photon emissions" taking place right where you are. By the way, the next time your parents ask you what you learned in school today, try telling them that you studied "atomic collisions" and looked at the "photon spectra" that resulted from it. You'll probably get a very silent reaction and then they'll stop asking that question.
OK, back to aurora. From experiments that can be done in a lab, we know lots about what colors of light we can get from different atoms. We also know that the specific color that you get depends on how hard you bump an atom (how much energy gets transferred to the atoms or molecules). From some very basic measurements made in the 1960s, we know that aurora is caused by electrons or protons (originally in the solar wind) drifting along magnetic field lines. So, if you can put this all together, here is what we can learn just by looking at the colors and brightness of aurora, for example:
1. The color alone can tell you what atom is being excited (e.g., the most common color is green, which comes from oxygen atoms). There's more - from experiments on the ground, we know that oxygen atoms emit lots of different colors, depending on what energy the electrons are that collide with them. So when we see green aurora, we know that we are seeing light emitted from oxygen that is being struck by electrons with certain energies.
2. The brightness tells you how many electrons are coming down the magnetic field line (the brighter the aurora, the more electrons we have).
Well, this makes watching aurora a handy way of understanding what is going on in the space above us. There are many different colors and shapes and from simple observations from the ground, for example, we can get an idea of how much energy gets transferred to our atmosphere when a coronal hole is present on the sun (this is cool stuff)!!!
Here is a photo from a rocket campaign that we had a few years ago, in Alaska. You can even see the rockets pointing up to the sky in the bottom of the picture
----------------------------------------------------
Today's points of interest.....
Here is something you don't see in New Hampshire, a polar bear crossing sign!!
Usually, the count will be brought down to the T-2 minute mark and held. At this point, we are generally quite fidgety, watches every instrument we can find, anticipating the launch. We can hold at T-2 minutes for about 30 minutes, after which time we have to either decide to launch or go back to T-15 minutes. If we decide to launch, the final checks in the countdown are carried out and followed by the classic 10-9-8-7-6-5-4-3-2-1-launch. So, that's why we need steady conditions in the ionosphere overhead (that is, aurora!!).
----------------------------------------------------
About aurora...
Now is a good time to say some things about aurora, sometimes called Northern Lights. First, there is no question that aurora is one of the most spectacular things you can ever see. You do see it in New Hampshire at times, when a huge magnetic storm hits, but it is generally nothing like what you see as you get nearer the magnetic poles of Earth (yes, there are "southern lights", too). The things you notice right away is that there are many shapes and colors, that things are different from day to day or even from minute to minute. Naturally they're amazing to watch but, scientifically, aurora is very important because it is part of the last step in the process of transferring energy from the solar wind to our upper atmosphere.
I should say that we already know what causes aurora, at some level. This is a bit tricky for me to explain, since I am not sure of everyone's background, but here goes.... You have no doubt heard the term "atom", which maybe you know is the building block for the stuff we are familiar with from day to day. Everything we see around us (and maybe don't see) is built up from atoms; sometimes, an atom might be attached to one or more other atoms and then we call the building blocks molecules. For example, water molecules are made up of two hydrogen atoms and one oxygen atom, which is why it is sometimes written as H2O. This gets complicated real fast, but the part that we need to deal with is not so bad. For one thing, we almost always deal with just atoms by themselves.
Well, it turns out that atoms can get excited and, when they do, they respond by giving off light. That is, if you can manage to bump an atom somehow, you can expect it to give off a brief burst of light. This, in fact, is probably happening right next to -- look up at the ceiling. Is there a fluorescent light? If so, then you have "atomic collisions" and "photon emissions" taking place right where you are. By the way, the next time your parents ask you what you learned in school today, try telling them that you studied "atomic collisions" and looked at the "photon spectra" that resulted from it. You'll probably get a very silent reaction and then they'll stop asking that question.
OK, back to aurora. From experiments that can be done in a lab, we know lots about what colors of light we can get from different atoms. We also know that the specific color that you get depends on how hard you bump an atom (how much energy gets transferred to the atoms or molecules). From some very basic measurements made in the 1960s, we know that aurora is caused by electrons or protons (originally in the solar wind) drifting along magnetic field lines. So, if you can put this all together, here is what we can learn just by looking at the colors and brightness of aurora, for example:
1. The color alone can tell you what atom is being excited (e.g., the most common color is green, which comes from oxygen atoms). There's more - from experiments on the ground, we know that oxygen atoms emit lots of different colors, depending on what energy the electrons are that collide with them. So when we see green aurora, we know that we are seeing light emitted from oxygen that is being struck by electrons with certain energies.
2. The brightness tells you how many electrons are coming down the magnetic field line (the brighter the aurora, the more electrons we have).
Well, this makes watching aurora a handy way of understanding what is going on in the space above us. There are many different colors and shapes and from simple observations from the ground, for example, we can get an idea of how much energy gets transferred to our atmosphere when a coronal hole is present on the sun (this is cool stuff)!!!
Here is a photo from a rocket campaign that we had a few years ago, in Alaska. You can even see the rockets pointing up to the sky in the bottom of the picture
----------------------------------------------------
Today's points of interest.....
Here is something you don't see in New Hampshire, a polar bear crossing sign!!
Saturday, December 4, 2010
update for Dec 5
At this point, we have been trying to launch the rocket for the last several days with no luck. It has been very windy here, still, which has made things difficult, and we have not had much aurora. This morning (it is 10 PM on Saturday as I write this, but 4:00 AM on Sunday).
Let's get back to some science and, in particular, the sun. Below, I put a picture of the sun taken from the Solar Dynamica Observatory (SDO) satellite. You can look at these any time yourself at this link. As of the time I am posting this picture, it is less than an hour old!!
You can see that a lot is going on here. For us, the important things are the bright spots, so-called "active regions", and the darker spot mostly on the left side, called a "coronal hole". I'll explain why this is what we care about in a minute, but first, I need to make an important point, which is that the sun actually rotates, sort of like the Earth. I say "sort of" because it turns out that at its equator, the sun goes through a complete rotation in about 27 days; nearer its poles, the rotation takes up to 35 days!! This "differential rotation" can only be possible because the sun really is a gas, not a solid.
OK, now go here and watch some movies of the solar rotation. The point here is that, as the sun rotates, the coronal hole and active regions drift across from left to right. So, when we say that we are watching the sun, we are monitoring these things.
Next step: here is a bit of a curve ball, though. The solar wind that comes from the coronal hole and active region gets sprayed out as the sun rotates, just like water gets sprayed out of a lawn sprinkler. The effect that you get with the lawn sprinkler is a spiral shaped spray of water. Not surprisingly, the same thing happens with the sun - the solar wind is a huge spiral shaped "spray"!! This means that when we look at the sun and see something like a coronal hole, we have to keep the spiral shape in mind and realize that the solar wind from that hole will only hit us a few days later, when the images of the sun show the hole to be about 2/3 of the way across. I hope this is clear.
Ok, that's the scoop with the sun for now. Let's jump ahead to what the solar wind does to Earth's magnetic field. I already mentioned that the electrically charged particles flow along field lines to carry energy from the solar wind to our upper atmosphere. What maybe was not obvious is how dramatic this effect can be. You can get an idea of the effect by watching a "movie" of a computer simulation here. There are a bunch of movies there, grab some popcorn and poke around. These are from Prof. Jimmy Raeder at UNH.
Let's get back to some science and, in particular, the sun. Below, I put a picture of the sun taken from the Solar Dynamica Observatory (SDO) satellite. You can look at these any time yourself at this link. As of the time I am posting this picture, it is less than an hour old!!
You can see that a lot is going on here. For us, the important things are the bright spots, so-called "active regions", and the darker spot mostly on the left side, called a "coronal hole". I'll explain why this is what we care about in a minute, but first, I need to make an important point, which is that the sun actually rotates, sort of like the Earth. I say "sort of" because it turns out that at its equator, the sun goes through a complete rotation in about 27 days; nearer its poles, the rotation takes up to 35 days!! This "differential rotation" can only be possible because the sun really is a gas, not a solid.
OK, now go here and watch some movies of the solar rotation. The point here is that, as the sun rotates, the coronal hole and active regions drift across from left to right. So, when we say that we are watching the sun, we are monitoring these things.
Next step: here is a bit of a curve ball, though. The solar wind that comes from the coronal hole and active region gets sprayed out as the sun rotates, just like water gets sprayed out of a lawn sprinkler. The effect that you get with the lawn sprinkler is a spiral shaped spray of water. Not surprisingly, the same thing happens with the sun - the solar wind is a huge spiral shaped "spray"!! This means that when we look at the sun and see something like a coronal hole, we have to keep the spiral shape in mind and realize that the solar wind from that hole will only hit us a few days later, when the images of the sun show the hole to be about 2/3 of the way across. I hope this is clear.
Ok, that's the scoop with the sun for now. Let's jump ahead to what the solar wind does to Earth's magnetic field. I already mentioned that the electrically charged particles flow along field lines to carry energy from the solar wind to our upper atmosphere. What maybe was not obvious is how dramatic this effect can be. You can get an idea of the effect by watching a "movie" of a computer simulation here. There are a bunch of movies there, grab some popcorn and poke around. These are from Prof. Jimmy Raeder at UNH.
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.
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.
Wednesday, December 1, 2010
Dec 1 update
Science update: To continue with what I was saying in the previous post, we are trying to make measurements that will help us understand how aurora might provide energy that can (sort of) cause Earth's atmosphere to swell up. We are doing this by launching a rocket to a very high altitude (something like 475 km) and will measure electric and magnetic fields, as well as electrons and positive ions (charged particles from the solar wind?). Of course, we need to do this at the right time, which can be very tricky.
Here is the situation. The rocket is almost ready to be launched, sitting on a launcher located on the north coast of Norway and pointed in a northerly direction. We (the "science team") are sitting in an observatory called EISCAT, located just outside the town of Longyearbyen on Svalbard, a large island well to the north of Norway. Here, we have lots of instruments that can tell us about the ionosphere (the very upper part of the atmosphere where gobs of electrically charged particles exist). These instruments include gismos to measure Earth's magnetic field (that gets affected by changes in the ionosphere), radar to probe the ionosphere, very sensitive cameras to grab pictures of the aurora above (which tells us about where interesting things are happening in the upper atmosphere), and so on. Once we see that we have the right conditions, we will tell the folks at the rocket range to go ahead and launch - and the rocket will fly over our heads. No, we won't be able to see it, since everything is very dark here.
About where I am sitting: take a look at a map and locate Svalbard, It is very far north - Santa is our neighbor! We are staying in the town of Longyearbyen, which used to be a coal mining town, mainly for Norwegians. Coal mining on Svalbard is still an important activity here, although Longyearbyen has changed and is THE town with an airport. It also happens to be where the University Center in Svalbard is located (http://www.unis.no/). The science people from UNIS have been working very closely with us. The specific observatory that we are sitting in (right now!) is described at http://kho.unis.no/. Try to browse around that website, which describes some of the instruments located in this area. There is even a webcam there, so maybe you can spot if you look during the middle of the night. The photo gallery is neat, too, and I have copied a couple photos below:
This picture shows the two EISCAT radar dishes that measure the ionosphere overhead, as high as 500-600 miles up!!
Here is the situation. The rocket is almost ready to be launched, sitting on a launcher located on the north coast of Norway and pointed in a northerly direction. We (the "science team") are sitting in an observatory called EISCAT, located just outside the town of Longyearbyen on Svalbard, a large island well to the north of Norway. Here, we have lots of instruments that can tell us about the ionosphere (the very upper part of the atmosphere where gobs of electrically charged particles exist). These instruments include gismos to measure Earth's magnetic field (that gets affected by changes in the ionosphere), radar to probe the ionosphere, very sensitive cameras to grab pictures of the aurora above (which tells us about where interesting things are happening in the upper atmosphere), and so on. Once we see that we have the right conditions, we will tell the folks at the rocket range to go ahead and launch - and the rocket will fly over our heads. No, we won't be able to see it, since everything is very dark here.
About where I am sitting: take a look at a map and locate Svalbard, It is very far north - Santa is our neighbor! We are staying in the town of Longyearbyen, which used to be a coal mining town, mainly for Norwegians. Coal mining on Svalbard is still an important activity here, although Longyearbyen has changed and is THE town with an airport. It also happens to be where the University Center in Svalbard is located (http://www.unis.no/). The science people from UNIS have been working very closely with us. The specific observatory that we are sitting in (right now!) is described at http://kho.unis.no/. Try to browse around that website, which describes some of the instruments located in this area. There is even a webcam there, so maybe you can spot if you look during the middle of the night. The photo gallery is neat, too, and I have copied a couple photos below:
This picture shows the two EISCAT radar dishes that measure the ionosphere overhead, as high as 500-600 miles up!!
This picture shows the view we have, looking down the fjord. Actually, we don't ever see anything like this because it is completely dark 24 hours a day!
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About the rocket: putting a rocket payload together is very challenging but a lot of fun. It takes a lot of work, which is accomplished by different teams. For the kind of research we do, the usual arrangement is that NASA provides the rocket itself, the expertise to launch and to retrieve the data that gets measured. The scientists, mostly based at different universities, provide the instruments used to make the measurements. We each have a responsibility to provide various instruments, which we actually build ourselves, with the help of engineers and students. Once we have built these instruments, we deliver them to NASA (usually a few months before launch) to install them into the rocket itself (this is called integration). Some pictures might help:
This is a picture of the payload (the part of the rockets that contains the instruments). The total length of the rocket, when completely assembled, is about 60 feet. Its diameter is only about 17 inches. The payload gets carried on the very front end (top) of the rocket; instruments only take up a few of the entire rocket. Below the instruments are other "systems", like the Attitude Control System (ACS), the Telemetry System (TM) and the igniter section.
Here is a picture from the rocket range, showing the rocket as it gets ready for launch. We are using a 4-stage rocket, so 4 motors are stacked on top of each other to lift the payload where we need it to be. As the rocket motor for each stage burns out, it gets dropped and then the next stage is ignited. In preparing for launch, each stage gets slid onto the "launch rail", which is horizontal as they do so. As each subsequent stage is mounted, they get bolted together and then, finally, the payload is mounted to the motors; once this is done, the rail is elevated and aimed as it needs to be. At this time, we say we are "vertical" (although it is not quite really vertical).
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Daily activity: the routine for us generally consists of "checking in" at the start of our launch window, which starts at 2:00 in the morning. Once we have checked in, we make the trip out to the observatory, which takes about 20 minutes and is, well, interesting. Then, we sit and wait and sit and wait and sit and wait.... until the solar wind (which we monitor continuously) does what we need it to do. While we are waiting, we sit at what is called "T minus 15 minutes and holding for science". That means that all of the many daily checks regarding the rocket itself have been completed and we can launch within 15 minutes once the science team says to "go".
At some point, we expect that the solar wind will do as we hope, the ionosphere will respond accordingly and we will launch. Today, conditions were actually very poor and there is no way that we would have launched even if the rocket was ready. There were also very strong winds at the launcher, which makes things dangerous for launch -- another reason we would not have launched.
At some point, we expect that the solar wind will do as we hope, the ionosphere will respond accordingly and we will launch. Today, conditions were actually very poor and there is no way that we would have launched even if the rocket was ready. There were also very strong winds at the launcher, which makes things dangerous for launch -- another reason we would not have launched.
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