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New Solar Images Herald Better Solar Storm Tracking
Date: March 1, 2007 at 11 a.m. EST

Transcript follows of the audio teleconference

Rani Gran: Hi. Welcome to this portion of STEREO media telecon. Before we get to the news portion I just wanted to direct everybody to our multimedia page. This is the page that the speakers will be talking to during the conference. The link was provided in the media advisory but another shortcut way to get there is that you can go to and right on the front page of there, there is a link to the panorama telecon multimedia page. Just click that and you will be redirected to the multimedia page the speakers were talking to. Also, one more suggestion, if anyone is on from radio and would like to arrange an interview after this telecon please give me a call. We do have a DSN line that you can use and we will arrange that. Right now I would like to hand it over to Mike Kaiser for the rest of the introduction.

Michael Kaiser: Thanks, Rani, Mike Kaiser here. I am the STEREO project scientist here at Goddard Space Flight Center. Today we’re going to give you sort of an update on what we have been up to since the launch of STEREO, which is a little over 4 months ago now -- October 25 of last year. And we haven’t been just sitting still. We’re busy doing some things and we have some very nifty images that we think you’ll like. Before we get to that though, I thought just in case you kind of forgotten what STEREO is all about, if you go on to this multimedia page you see under presenter number one, me, you will see a couple of images. I hope these come up faster than they did yesterday. If you click on the one on the left that’s an animation and what STEREO is all about here is a thing called a coronal mass ejection. These are big powerful storms that leave the sun. They’re caused by magnetic fields on the sun breaking open and releasing a lot of hot plasma underneath, so they are storms full of electrically charged particles. They flow away from the sun at speeds of a thousand miles per second sometimes. And sometimes they hit Earth and they can push the Earth’s magnetic field back and cause an aurora and all sorts of electrical disturbances. So, of course, nobody ever died looking into an aurora but some of the other disturbances are getting to be a bit troublesome. And all spacecraft that are up there in orbit right now are full of microelectronics and very susceptible to small changes in current and voltage. So when a solar storm comes along they can get their memories reset or their power supplies wiped out. So they need to know when solar storms are coming so they can go into safe mode. Likewise, the electrical power grids on Earth--some of the long transmission lines--are susceptible to getting a little extra current induced on them by one of these big solar storms. And it can set off circuit breakers and actually knock out power systems. And the airlines are now very interested in these solar storms because they are flying polar routes up over the North Pole and when a solar storm comes, they can actually be out of radio communication which is a big “no no” with the FAA and FCC. So they like to know when a solar storm is coming so they can reroute their routes. And conceivably even astronauts, if they are on their way to Mars or the Moon outside of Earth’s protective magnetic field, could be subject to some intense radiation from some of these solar storms. Other things that are affected are like our GPS instruments. Solar storms upset the ionosphere and the radio transmissions from the GPS satellites down to the ground stations can actually produce errors in the order of a mile sometimes when there is a solar storm is in effect. So, basically, we are very interested these days in solar storms.

Now if we can click on the right hand panel I will show you what current spacecraft are able to do. This panel, which is a big movie, so it may take a while to come up. This is made by the SOHO spacecraft which has been up there in orbit for a little over ten years now. Basically this spacecraft has a telescope on board, or several telescopes called coronagraphs that make a continuous eclipse of the sun by blocking out the bright sun and so what you see is basically everything left over. You can all the stars going by and I think there’s planet Venus moving from right to left, and then you see these big puffs of smoke-like material coming out. Those are the coronal mass ejections. They’re not really smoke they’re ionized gases and you’re seeing them by reflected light. Every so often one of these actually comes out, directly at the Earth, and you see things that look all these lightning strikes going on all around and that’s actually when one of these storms hit the spacecraft and actually upset its cameras. So it’s an electrical interaction with the cameras. So, SOHO is still up there running and working just fine.

So the big question is if SOHO is doing such a fine job why do we need STEREO? And the answer is STEREO is going to make, by and large, pretty much the same measurements but we want to make them from a different place. It’s very difficult for SOHO to estimate the speed of the events that are coming right at us, because it’s like somebody standing on the other side of the room from you and blowing a smoke ring at you. You see that smoke ring expanding but trying to estimate its speed toward you and when it will arrive at you is very, very difficult. Now if you had a couple of friends off on the sides of the room looking at that same smoke ring and able to triangulate on it they could do a much better job estimating its speed and arrival time and that’s what STEREO is going to do. Eventually the spacecraft will be way off to the sides of the Earth and looking at these same storms that SOHO sees, but triangulating them from the sides, so that is what STEREO is all about. Now we aren’t there yet. We aren’t ready to make these 3-D measurements yet because the spacecraft are still too close together. Starting in about six weeks they will be three to four degrees apart as seen from the Sun and that time we’ll actually start being able to make some STEREO measurements. But up until now we’ve actually turned on all the instruments and we have some pretty interesting observations nonetheless, even though they aren’t really STEREO 3-D.

And so today we’ll give you a status of what’s happening and the main show will be Russ Howard who’s the principle investigator of the imaging instrument that makes all these nice pictures called SECCHI. He’s at Naval Research Lab and also we will have a status report on how the spacecraft itself is doing and we also have some words from our NASA headquarters program scientist. So first let’s start at APL, Johns Hopkins APL, we’re having with us today, Ed Reynolds. Now, Ed, if you click around there you’ll see he’s listed as the former project manager of the STEREO project out at APL. They built the spacecraft. They’re controlling the spacecraft and Ed was the project manager up through launch—and all the testing of the instruments and handover. And now the actual Project Manager is Ron Denissen, but, Ron could not be with us today, so Ed is sitting in one more time on STEREO and hopefully he still remembers all about STEREO. So, Ed, tell us about the launch and all the things that were done between October and now.

Ed Reynolds: Okay, thanks, Mike. Good morning. I just want to start with a real quick overview of STEREO. STEREO consists of two identical spacecraft each one of the spacecraft holds 15 instruments sensors. If you look at image 3 that’s showing the instrument placement on the behind or B observatory. Both spacecraft were launched on a single celtitude rocket with the head observatory stack on top of the behind observatory. Image 4 is showing an artist’s conception of the two spacecraft essentially minutes after their release from the launch vehicle. The key thing to point out about image 4 is that Russ Howard is going to be showing you some spectacular images. Most of those images he’s going to show you were taken from the instrument set which is located in the white area. If you look at the spacecraft on the right you kind of see a white area centered into the body this is potentially the face of the spacecraft that points toward the sun through the two year operational mission and his imagers and his coronagraphs are located in that white portion. Mission operations for STEREO takes place at a dedicated mission operation center at a facility at APL in Laurel, Maryland and that is being shown in image 5. This center is configured and staffed to operate both spacecraft simultaneously. The operation of the instrument are perform at payload operation centers that are located at Naval Research Laboratory, the University of California, Berkeley, Goddard Space Flight Center, the University of New Hampshire, the University of Minnesota, and the Paris Observatory. Moving on, I just want to talk shortly about the launch, and then I will talk about we got onto station. STEREO, last October, had a perfect launch. The early spacecraft check-out went very well for both observatories. The spacecraft separated from each other and deployed the solar panels autonomously. The initial ground contact through the deep space network went extremely well. Hours after launch we deployed the high gain antennas which allowed us to start high data rate transmissions between those spacecraft and the ground. The initial checkout of the bus, this is the first health check-up, showed that everything was performing perfectly, and the launch went so well and the propulsive maneuver shortly after launch went so well that essentially both spacecraft have enough propellant onboard to last essentially decades. The commissioning of the instruments went very well, too. A couple days after launch we deployed the S/WAVES antenna. S/WAVES is one of the four instrument suites onboard. We also deployed the impact boom. That’s that large boom that you see coming out the back of the spacecraft. And then we essentially turned on each of the 15 different instruments and did a checkout and for the most part everything went very well.

What I want to talk about next is how STEREO used the trajectory that relied on lunar gravity assist to cause the two spacecraft to escape Earth orbit and enter their operational heliocentric orbits. And the key thing to point out is that this is the first time that lunar swingbys have been used to alter the orbit of multiple spacecraft launched from a single rocket, and that shown schematically in image 6, and this technique starts with four phasing orbits. And they’re shown in the schematic, I believe it’s A1 through A4. Each of these orbits have an altitude or apogee that takes it past the moon, and each one of these orbits takes 2 weeks to complete. We went through the four phasing orbits and that’s essentially where we did the bus checkout and the instrument commissioning. On what would be the fifth orbit we start the lunar gravity assist and if you double click on instrument six you’re going to get an animation that shows it very, very well. On that fifth orbit we have lunar swingby that is denoted as F1. And F1 occurred on December 15th. And we had directed Observatory A such that it flew over the surface of the moon at an altitude of 4,550 miles. And that’s shown in the animation with the blue lines. The B spacecraft, we directed it to also swingby the moon but at a higher distance and that distance was 7300 miles above the surface. The result of these gravitational swingbys was that the Observatory A escaped Earth orbit and it now leads Earth around the Sun at a drift rate of 22 degrees per year. The B Observatory did not escape but it did get perturbed and lined itself up for a second lunar swingby denoted as F2 which occurred on January 21st of this year. And its altitude for that swingby was essentially 5,500 miles above the surface and the result of that swingby was that Observatory B escaped Earth’s orbit and it now lags Earth as it orbits around the Sun drifting away also at 22 degrees per year. At this point both spacecraft are fully operational. They are in their heliocentric orbits collecting science. And as Mike had said we are looking forward to late April to get the right geometry to start bringing down the 3-D imagery. At this point I’d like to have Russ Howard give you an overview of the imagery data that we are talking about today. Thank you.

Russ Howard: Thanks, Ed, this is Russ Howard. I’m the PI of the second instrument as Mike said. And the STEREO mission is going to be providing a new way to view this inner heliosphere--this very vast region between the Sun and Earth. And as illustrated in the images on the website we’re able to form panoramic views of this region using a set of five telescopes that image the solar environment with different magnifications, much like your camera does when you zoom in and out and move or pan your camera from side to side. But our telescopes have a fixed magnification and a fixed view.

We begin this discussion with the telescope that has the highest magnification that takes images of the solar disc in ultraviolet light at four different wavelengths corresponding to four different temperatures of the coronal plasma which is the gas surrounding the sun. You can see 3 of the 4 wavelengths in the different artificial colors in images 8, 9, and 10 on the website. These images reveal the plasma at temperatures ranging from 60 to 80,000 degrees Kelvin to over 2 million degrees Kelvin. And with that this plasma is tracing the very complex magnetic field on the sun. These images go out about 1.6 solar radii. These images that you are seeing here are the first ones taken on December 4 by the EUVI telescope which is part of the second package at the very exciting time just after the after door was opened, what we call first light.

The animation number 10 illustrates the different instrument fields of view and how they relate to each other. The reference images 11 to 16 show the individual frames of the animation. But the video is rather long so there is some streaming video links that you can click on if you would prefer to. The animation actually opens with the simulation of the spacecraft, and shows an outline of the field, and then moves to an outline of the field of views of the various telescopes, and then gives you the large view. Then it begins again at the beginning of the center, beginning with the EUVI, and I will start talking about that. What you see there is the zoomed in picture of the million degree plasma. And you see a few frames that are rotating with the solar rotation and then it pulls back to show the full disc. Then, the next few shows the next two telescopes, which are white light coronagraphs that image the corona that creates an artificial eclipse by blocking out the disc of the sun, the disc itself, and image the very faint corona around the Sun, from 1.4 to 4 solar radii, and then from 2.5 to 15 solar radii.

The patterns that you see in the white light coronagraph are the streamers that are tracing now simpler magnetic field patterns. These patterns actually extend all the way to Earth, and as the sun rotates it bathes the Earth. The Earth is being bathed by the solar wind with all this structure. The dark circles at the center of the images are the occulting discs that create this artificial eclipse. These telescopes provide a view of the sun that’s similar to that provided by SOHO for the last ten years but only out to about 1/7 of the distance to Earth. And, of course, in a few months when the separation between the two spacecraft becomes greater the viewpoints will be different than from SOHO and then the STEREO images will provide different views and will enable stereo viewing.

But the new and absolutely stunning images are obtained when we add the next two telescopes, the heliospheric imagers, and these, this is in a package that’s actually on the side of the spacecraft facing Earth. The dominating features of these two spacecraft are the zodiacal light. This is light that is produced by scattering of photospheric dust of the sunlight, by dust particles between us and the Sun. The bright vertical line that you see is Venus saturating the seeds of the pixels and you can see also the stars in the background. And the rest of the final images is a trapezoidal black area which was put in to block the light from the Earth like an occulting disc during the early part of the mission. Later on in the mission the Earth will become dim enough that it really won’t affect our images then. And the vastness of this view is illustrated in image number 16 which shows the Sun just as a little, tiny little, almost a speck in this huge, huge image. This is really the first time we’ve had such a complete view of this inner heliosphere and it enables us to track CMEs from their origin at the Sun all the way to the orbit of Earth.

And this can be seen, one that we’ve put together a sequence of a CME in the next animation number 17. And these images that you’re showing are the first we’ve really put together in this way. But they already demonstrate the capability and promise of really great things to come.

The video sequence shows two CMEs that were launched at the Sun on the 24th and 25th of January, and it tracks them all the way through the various fields of view of the different SECHHI telescopes. The very striking features in the HI2 image, the one that’s on the left of the composite, are the bands of light and dark ridges. And these are the remnants of the tail Comet McNaught that was probably the brightest comet that has come by in the last 10 or maybe even 20 years that passed by the Sun 10 days earlier than this on January 14th and now at this time on the 24th and 25th was heading away from the Sun to the lower right of the Sun. But you can see the tail caused by the cometary dust particles that are over 100 million miles away from the comet nucleus, just amazing. If you run the animation you can see the CME structure moving to the left, and can be seen well into the field of the left most image, the HI2. This particular CME was moving a little over 750 miles per second close to the sun, and decelerated to about 500 kilometers per second further away. In addition, to the optical measurements being shown here, the other STEREO instrument, like S/WAVES, observed a Type 2 burst which indicates that the CME generated a shock, and they measured it, and said it was also moving at 750 miles per second.

To travel to the Earth’s orbit takes about, at these speeds, takes about 2 to 3 days, Although we haven’t done a detailed analysis of this event we’re already surprised at how the structure has evolved as it propagated outward. And it is exactly this interaction and the joint observations of the CME and its effects that we were hoping to observe with the STEREO mission. By performing the detailed analyses of these interactions, we’ll be able to understand better what the physics is of the propagations, and then to be able to make much more accurate predictions of the impact of CMEs on space weather, and on our environment, the terrestrial environment.

There are other members of the second team, Dr. Dan Moses and Angela Salitus who are also available for questions. And, now I would to turn it over to Dr. Lika Guhathakurta who is the STEREO Program Scientist to add additional comments.

Dr. Guhathakurta : Thanks, Russ, well as you have already seen and heard from the previous presentation STEREO is using a remote and in situ instrument to characterize how the coronal mass ejections originate at the Sun and move through the heliosphere. And to provide not only a global view but also local view of the shock structure, these images are just unbelievable. To give you an example with a combination of remote imagers and in situ measurements that STEREO provides for CMEs is sort of similar to our experiences of sight and taste. Remote imaging is similar to taking pictures, for example, of an apple tree and seeing how the apples are distributed among the tree limbs, and which ones are ripe enough to fall to the ground. And STEREO remote imaging instrument SECCHI is doing just that. That EUVI telescope is actually looking at the surface of the Sun, the corona, and is looking at active regions with twisted magnetic fields and will be able to give us a sense for which of these active regions will produce a coronal mass ejection.

In situ, is kind of akin to touching and tasting the apples that were seen to fall from the tree. We have two suites, PLASTIC and IMPACT on STEREO that are providing density, speed, and embedded magnetic speeds of this material of the coronal mass ejection and solar rings, ambient solar rings. Right in the neighborhood of the spacecraft where you just saw remote sensing images from HI2. This is pretty unique, this is the first time that we have simultaneous imaging and in situ observations recorded at the same location.

STEREO will not only do ground-breaking finds with all these observations, but it is also helping NOAA with better forecasting tools for space weather. STEREO is providing what we call beacon mode data about 600 bits of highly compressed imaging and chronicle data. This data is being brought to us real time, 24 hours a day, as part of the STEREO space weather beacon that is being picked up by the NOAA dedicates stations all around the world and it’s still getting set up.

We are really excited here. This is the first time we are using instruments specifically built for obtaining 3-D information about the sun and the solar rings. We are excited about the upcoming 3-D images and to share them with the public. You’ve already heard that we haven’t really showed you the 3-D images because we don’t have them yet. But at the end of April we plan to release high quality 3-D images to museums around the country. We will also post the low resolution version of these images on the web, and put them out on NASA-TV. We have listed several companies that sell 3-D paper glasses for low cost, and some of the companies will actually send you free paper glasses if you just send a self-addressed envelope. So our goal is to distribute these images to the museum alliance and to the same organizations that distributed the 3-D images of Mars and make this unique view of the Sun and the heliosphere available to us. Rani, back to you. Rani Gran: Okay. Thank you all. I would like to turn it over to the operator for questions and answers. I just ask that…please state your name and affiliate, for, during the Q&A. Operator?

Operator: Thank you. We will now being the question and answer session. If you would like to ask a question, please press *1. You will be prompted to record your name, to withdraw your request, press *2. Once again, to ask a question, please press *1. One moment. Frank Malick of, you may ask your question.

Frank Malick of Spacenews: Thank you, this is not, it’s Spacenews, and I think for Dr. Howard. I was curious, what is the advantage of taking this early look at the Sun to kind of shakedown the instruments up until when you do get the 3-D capability, and how far are the spacecrafts right now? Are they halfway to there to that point and, I guess, can you give us a relation of where they are?

Dr. Howard: Yeah, they’re separated only by about a degree from each other at this point. So they’re really quite close to each other, but they’ll be separating from Earth at the rate of 22 degrees per year or from each other at 45 degrees per year on average, you know, that’s sort of an average figure over the whole year. So it’s only been a month, or little over a month, since the B spacecraft did its injection into the heliospheric orbit. So the second flyby of the moon, so it really hasn’t had time to develop very much separation. But, it will. I think this is orbital mechanics and so it’ll get there. So you’re asking why are we interested in the imagery at this point?

Frank Malick of Spacenews: Exactly. I’m curious about how does that either help you calibrate or make for early findings?

Dr. Howard: Well, it certainly does. Initially, early, you know, early in the mission, right now, we have, we can compare the images A & B with each other but then we can also compare them with existing instruments like the EIT instrument on SOHO, or TRACE, or the coronagraphs on SOHO, the LASCO coronagraphs. So it allows us to compare them directly, to do almost an instant calibration, a check of what our calibrations are and so it’s really quite useful. But in addition, at these very early stages, we are able to watch the development of the 3-D information, so to speak. The optimum separation for STEREO viewing is going to be when they’re…at the end of April and even beyond. But it will be very, very interesting to watch that develop.

Frank Malick of Spacenews: Thank you.

Dr. Guhathakurta: Can I add to that?

Dr. Howard: Um hmm.

Dr. Guhathakurta: I think the view that we are seeing even without the full 3-D configuration is really a very unique view, something we have not seen before. We have not seen this sweeping panoramic view which, of course, has in situationwith as well, all the way from Sun to Earth. I think even just one spacecraft observation of that is unique and we are seeing this for the first time.

Dr. Howard: That’s absolutely true that this panoramic view is absolutely unique and so we’re able even though we’re not seeing the CMEs necessarily the best way that we will coming toward Earth, the way we will when there’s some separation, we’re still seeing the evolution of this material as it goes out into interplanetary space and we’re already seeing that interaction with the solar wind so that is quite, uh, quite important, quite useful.

Dan Moses And so I may amplify it, this is a discovery, what we’ve, the view that you currently see, on the last movie you’ve seen, is a discovery. We’ve never been able to watch the progress of the CME from the Sun, from its origins, all the way out, and we did not know what would happen past something like 30 to 40 solar radii and we see that it’s different from our initial models.

Dr. Howard: And I’ll add a little bit more to that. That was Dan Moses, by the way. I’ll add a little bit more. The region that is covered by the high wand field of view, this region from about 15 to 90 solar radii is exactly the region where the coronal mass ejection must be slowing down. We know that they leave the sun at these huge speeds. A thousand to two thousand to as much as 3,000 kilometers per second, two thousand would be 3,000 miles a second. We know that they leave very, very fast but out at Earth we don’t see them that fast. And so we know that they must be decelerating, and we’re trying to understand what is the physics of that deceleration, where they’re occurring, and so this is going to show it.

Rani Gran: Operator, could we take the next question?

Operator: Sure. Mark Kauffman, Washington Post, you may ask your question.

Mark Kauffman: In terms of where you are so far, is there anything that has been a surprise to you? And also, if we could just walk back through a little bit about some of the images, 15 in particular, I guess these are the really new ones, and 17. But if you could describe what you’re seeing here in terms what might be different than what you had anticipated?

Dr. Howard: Sure. The CMEs, generally, we used to think of them in terms of a loop. Imagine--don’t forget that this is a 3 dimenstional structure that is being projected onto a plane. So we use two dimensional words to describe it; such as a loop. So they had a nice curved front much like a loop. And what we’re seeing is that it’s evolving as it’s going out. In this particular event on the 24th and 25th, that that evolved so that it looked more like two loops, sort of like the McDonald’s arches. So we have one loop evolving into two and I don’t really think it’s two. I think it’s interacting with the solar wind which is traveling at different speeds, in different regions, and so it’s being picked up and swept along just like a leaf would in a stream. And so it’s that interaction that is absolutely…we hadn’t seen that. We kind of thought, maybe we believed it, we hoped that it would be just retaining that same structure all the way out, but apparently it’s not.

Mark Kauffman: Okay, and if you could just point to the aspects of those images 14, 15, and 16, that would show what you just described, you said there were two loops.

Dr. Howard: Yeah, you have to really look at the animation number 17 to see that. And the images themselves, the ones before that, the stills from the sequence really don’t show any CME in them per se. They’re just showing you the fields of view of the instruments.

Mark Kaufmann: Oh, I see. Okay, so it’s just 17 that is…

Dr. Howard: It’s just 17 that shows that CME and if you run that, what you see in this, you can kind of see a wavy nature to this dark and white ridges and it’s that that we believe is the new thing. That’s showing this evolution.

Mark Kaufmann: Okay, and just a different question since…for some of the different reasons that you want to get this information as you folks have described earlier is there anything that you’ve seen so far that sheds particular light on or is the kind of radiation that might bathe an astronaut outside of the electromagnetic cover, or, you know, how and why auroras form? I mean, is there anything that’s evolved that far, or are we just in the early stages here?

Dr. Howard: We’re, sort of, in the early stages of the analysis, but Mike’s team can describe that a little more.

Mike Kaiser: Yeah, well, most of those things you asked we actually already sort of know. We’ve known for a long time that associated with these coronal mass ejections there are high energy particles. Those that are associated with the initial explosions at the sun and also later on when it gets to Earth. We also sort of know how the auroras work. And so what we’re trying to do with STEREO is predict when these are going to arrive, not so much determine the particular particles in them. We are going to determine when they’re going to arrive, much more accurately than has been done in the past. All these spacecraft sitting there right now do this right now like SOHO and other spacecraft can only on the average predict the arrival at Earth to like plus or minus 12 hours or so and we’re hoping to cut drastically into that down to a couple of hours.

Mike Kaufmann: Thank you.

Russ Howard: If I can…let me follow up with an uncertainty. As Mike said, we know the energetic particles, we know that the radio emission is associated with CMEs, but we don’t know exactly what that association is. And so I think what we’re going to be able to do is to be able to image exactly the site, for example on the radio emission, we are going to be able to image exactly where the radio emission is coming from. The S/WAVES instrument will be able to triangulate and give us, using the STEREO spacecraft, the two spacecraft, and we’ll be able to overlay the images, with the S/WAVES instrument and say exactly where it’s coming from. That will be a huge step.

Mike Kaiser: And that will tell us exactly where the energetic particles are being energized at that moment.

Russ Howard: And accelerated, um hmm.

Rani Gran: Operator, could we take the next question?

Operator: One moment. Danielle Fisher of (unintelligible sound) you may ask your question.

Danielle: Yes, hi, this is actually a question that was raised by a German solar scientist, one I talked to recently. He said that he is a bit worried about actually triangulating these rather tenuous coronal mass ejections especially when the spacecraft are separated much more than they are now. And I would like to know how do you want to go about this photogrammetric path? Are you doing it by hand, by eye, or is there some sophisticated type of machine up there to be employed?

Russ Howard: That is a difficult question. We haven’t done it before and so we’re kind of feeling our way, maybe. But we have two or maybe three techniques for doing this. One is to do a true three dimensional inversion. But the problem with that, much like the computer-aided tomography scans where you can get these fantastic images of a body, or the interior of your body. The problem there is that they take many, many viewpoints to generate this picture. I think the body, or the interior structure of our bodies are much more complex than the CME’s are. And so there’s hope for this. The other technique that we’re doing is to do something that we call forward modeling. And so, we use intuition maybe, scientific intuition, of what the structures are, sometimes, and we’ve built up kind of a library of structures that may be the CME is, and we will then fit these views into the various parameters associated with these models and will use the various views to define the parameters. So we have these two different approaches that we are going to take to try to solve the problem.

Mike Kaiser: If I might add, Russ, we also, I guess, plan to make use of our observations from SOHO which will continue through the STEREO period of time and that’ll actually give us three viewpoints then. The two STEREOs and SOHO in the middle of them. The more views we have, the easier it is to resolve some of these structures.

Danielle: Let me ask a follow-up. It’s about just looking at the STEREO image and image pair. At which separation of the spacecraft will we have the kind of most natural view? If you just look at the pair of images, and have the best kind of direct visual ceiling of what the CME looks like in 3D?

Russ Howard: We believe that’s on the order of five to eight degrees is that optimum separation which is not in April, but maybe more of the summertime.

Mike Kaiser: May to June. By the end of April we’re about 4 degrees apart as seen by the Sun so some of the features very close to the Sun, the little loops you’ll probably be able to see those in 3D pretty well, but the bigger features further out from the Sun, I think we have until the separation is a little larger than that.

Russ Howard: Let me just follow up a little bit. There are various types of structures that we hope to image in 3D. There are the low lying loops that you see in the ultraviolet. We’d really like to understand the structure of that and then we can compare those, the morphology of those structures with our imagery, our magneto-hydronamic models, our potential field models—these models of the magnetic field of the Sun. We’ll be able to compare the observations then absolutely directly with what they are calculating. Another type of structure are the, in the coronagraph, are the plumes, so called plumes, these are thin ray-like features that are actually at the poles of the Sun and now that we are solar minimum they are very obvious to see, and we’d like to be able to trace them down, in 3D, back to the surface. So these are very quite discrete structures. The coronal mass ejection is more complex…it’s such a huge, huge phenomenon, these other two solar features are well-defined, narrow features—you know, if you have a desk or a chair or something that you are looking in 3D, you can easily recognize that feature. And that’s what the plumes and the loops are. But the CME is a very diffuse, nebulous, almost smoke, fog, or smoke, or something like that. So it’s much more difficult to see, and you hope to be able, though, to model the outline of these events.

Rani Gran: Operator, can we take the next question?

Operator: Warren Larry, the New York Times, you may ask your question.

Warren: Thank you. Looking at this image of the CME that we have now, this movie? And I’m trying to get a better idea of how to explain this to the public. Now is this wave we see going from the Sun, does that give you an idea of the kind of power and energy of each of these CMEs or perhaps even the composition of each one in terms of what particles are coming out?

Russ Howard: Right. There’re two aspects to power or energy. One is the speed that it’s traveling, the bulk speed that it’s traveling. The other is how massive is it? And so yes, we measure the speed just by tracking it across the field, and then we measure the massiveness of it by the intensity of the structure.

Warren: I have a really quick follow up then. Will this allow us to have, for instance, some type of scale as you do for hurricanes, and so you know, a Category 1 hurricane, Category 3, as these images come to us, in terms of forecasting their effect. Will we be able to kind of scale these CMEs and have that mean something to us here on Earth?

Mike Kaiser: Actually I think our friends at NOAA, who have the responsibility for actually issuing space weather, as this is called, “warnings” already have a scale like that. This will be able to allow them do it more accurately, but the scale already exists.

Warren: Thank you.

Rani Gran: Operator? Is there another question?

Operator: At this time, we have no further questions.

Rani Gran: Alright, with that, thank everyone for calling in to the STEREO meeting telecon. If anybody wants to do follow up interviews, you can contact me, Rani Gran, and just the number, 301-286-2483. And I want to thank everybody for participating. With that, operator, I think we’re finished.

Operator: Thank you. This concludes today’s conference call, thank you for participating.

End of conference