Planetary Radio: Space Exploration, Astronomy and Science - PI Sean Solomon's MESSENGER is Orbiting Mercury!

Episode Date: March 28, 2011

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Music Music Music Music Music Music Music Music Music Music Music.com. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. Music. I'm Matt Kaplan of the Planetary Society. Join us as we celebrate the mission that has just put a spacecraft in orbit around our solar system's innermost planet. Principal Investigator Sean Solomon returns to tell us about this accomplishment and the science that's yet to come. Much, much more is in store during this week's episode, beginning with Planetary Society blogger Emily Lakdawalla. episode beginning with Planetary Society blogger Emily Lakdawalla. Emily, a couple of somewhat sad stories this week, although sad for very different reasons. Let's start with some news about Curiosity, formerly known as the Mars Science Laboratory. And still probably will be known as MSL to all of the scientists and engineers on the mission even long after it's landed. So the news this week, they're working very hard getting the rover ready for its launch late this year. All the instruments have been delivered. They're integrating them. They're doing all kinds of

testing. But having delivered the cameras, the main science cameras to the rovers, Mail and Space Science Systems was hoping to be able to deliver a slightly different version of those cameras, one that actually had a zoom capability, which would have allowed the rover to not only zoom out, zoom in, to get views of its landscape in color, but it would enable the rover to get that view in color, in 3D, in HD video. And it's got to be especially sad for MSL Mastcam co-investigator James Cameron, who is no doubt on the team for the sole purpose of getting 3D HD color video from Mars. So better luck next time for Malin Space Science Systems on getting a 3D HD color video camera onto a rover on Mars.

But the Mastcam that's on there right now is absolutely fantastic and it's going to produce the best images we've ever had from the surface of Mars. So there's really no reason to be sad at this point. Yeah, our condolences to Malin and to James Cameron, who talked about on this show, talked about how excited he was. You know, we'll have to look to folks like you to help us fake that again, I guess. Let's move on to this other story, which is only sad in that it was the end of an extremely successful mission. And that, of course, was Stardust. Yeah, this was sort of the equivalent of taking Stardust off life support, you know. So it was sad, but it had such a long and rich life.

Stardust is, of course, at the end of a long mission, especially for such a little spacecraft. It flew by an asteroid. It flew through the tail of a comet, collected samples, returned them to Earth, and then, for its last hurrah, flew past Tempel 1 again. So it visited an asteroid and two comets, had a really full mission, and was basically out of fuel at the very end. So they had to turn off the spacecraft in a neat way that would make sure that it wouldn't have radio interference with other spacecraft that were out there. But they decided to do one final act with this spacecraft to help them learn one more thing, not about the solar system, but about spacecraft. And that one more thing was to burn to depletion, burn every last molecule of fuel that they could

get through the rocket systems to try to find out if their estimates had been correct about how much fuel was left in the tanks, because there was actually some uncertainty toward the end. So they burned every last molecule. The engines burned for 146 seconds, which is not very long. It's two and a half minutes. And it's actually kind of comparable to one of the last trajectory correction maneuvers that they did. So they really were running on fumes at the end. And then they sent the last command to the spacecraft to turn off that transmitter.

And now she's in a solar orbit for forever. Even after the sun dies, it's probably still going to be in solar orbit. That's kind of a nice thought. We salute you, Stardust. And Emily, as always, we salute you. Thanks very much. Thank you, Matt. Emily is the Science and Technology Coordinator for the Planetary Society and a contributing

editor to Sky and Telescope magazine. And she'll be back next week. Here is Bill. Hey, Bill Nye the Planetary Guy here. And this week, still in the news, is the Fukushima reactor disaster, explosion, meltdown, whatever you want to call it. There's a big problem at this Japanese reactor as a result of a huge earthquake and a

huge tsunami. When you see these images from above, they're not taken from aircraft. They're taken from spacecraft. So as soon as this disaster happened, the United Nations SPDR, the United Nations Platform for Space-Based Information for Disaster Management and Emergency Response group of satellites got repositioned and re-aimed and took a bunch of pictures. These are pictures taken by Chinese satellites, European Space Agency satellites, and United States intelligence and presumed civilian satellites. And we can see what's going on on the ground with images from outer space. Now, this is a disaster. People lost their ancestors, their villages. They lost everything. But on top of that, there's this huge radiation problem and maybe even a catastrophic meltdown. And the way we're going to find out about it is by looking down from space. So it's one more reason to keep our space capability up

to snuff, to make sure we can always fly satellites, always keep an eye on things. If you told my grandfather that you could take images of Sendai, Japan with satellites from outer space, satellites from other countries around the world, he would think you were not telling the truth. But that's how we roll. That's how we fly. That's how we photograph. It's an exciting time to be able to take for granted these sorts of images. And our hearts go out to the people in Japan and everybody working to resolve this crisis. Well, thank goodness, or thank engineers and scientists, that we have these satellites. And thanks to all the taxpayers for supporting them. Meanwhile, I've got to fly. Bill Nye the Planetary Guy. You don't often hear Messenger called the Mercury Surface Space Environment Geochemistry and Ranging Spacecraft,

that long acronym does a great job of capturing the impressive range of science it began to conduct during three flybys of our solar system's first rock from the sun. A white-knuckle 15-minute engine burn finally put MESSENGER into orbit around Mercury on March 18. Now we can look forward to many, many more great images, lots of other data, and probably a few more surprises from this dynamic little planet. As principal investigator for the mission, Sean Solomon has overall responsibility for making sure we use MESSENGER to learn as much as possible.

He has already been our guest several times. I got him back on the phone just a week after orbital insertion. Sean, congratulations on this long-awaited achievement. We are all very excited for you. Thank you, Matt. It's, as you know, been a long mission so far, more than six and a half years since we launched, and orbit insertion is always a maneuver that has some risk.

And so we're relieved to be in orbit and now to be looking forward to taking measurements. Anxious-making. I don't even know if you're getting a chance to catch up on your sleep, because this is a pretty busy time, isn't it? It is. It is. After we went into orbit, we began what we call a commissioning phase, about two and a half weeks long, where we look very carefully at all the subsystems on the spacecraft and begin gingerly turning on each of the instruments.

This is the first time we have been as close to the day side of Mercury as we are now that we are in orbit. And so we're watching the temperatures on all of the spacecraft decks, the solar panels, and we're checking those against our thermal models. And everything is nominal so far. Is that concern because you, on the day side, you've got so much of that nasty sunlight reflecting back up at the spacecraft? It is, although the sunlight is only nasty if you're thinking from the perspective of feeding the spacecraft.

We make great use of the sunlight for imaging and for spectroscopy, so we very much need that sunlight. However, you're quite right that the surface of Mercury re-radiates sunlight at a rate much four times greater than that of the Earth. And so, as you know, MESSENGER shields the body of the spacecraft from the heat of the sun, which is as much as 11 times brighter at Mercury's perihelion distance than it is at 1 AU, with a sunshade that is always pointed at the sun. But we must face the planet. That's the object of study.

And the orbit, phasing of that orbit with respect to Mercury's position in its orbit around the Sun, and many aspects of the design of the spacecraft and the instruments were all solutions to a very complicated thermal problem of dealing with the heat radiated from Mercury. And by the way, I want to mention that there is a really stunning artist's conception of the spacecraft in orbit around the planet that shows off that sunshield extremely well. But it really is a beautiful picture. I don't even know if you know the one I'm talking about.

Well, there are many, and of course they all look beautiful in my eyes. And so I'm not sure which one caught your eye, but yes, our website has a number of those, and there's some quite nice ones. Well, we'll put up a link to that, and I also want to put up a link to a pretty amazing little animation. Not beautiful, just incredibly illustrative of what it took to get into orbit around this innermost planet. I mean, you already talked about six and a half years. I mean, you already talked about six and a half years. I counted, if I counted correctly, 15 times around the sun in this fascinating trajectory before you could match up with Mercury. You counted correctly, Matt.

Oh, good. We did indeed do slightly more than 15 revolutions around the sun. We had six planetary flybys after launch, one of Earth, two of Venus, three of Mercury. In between successive planetary flybys, there was a major propulsive maneuver that targeted the spacecraft toward the next flyby, so that it was really a very complicated trajectory, and my hats are off to the mission design folks who can figure out how to do that, and to our guidance and control and navigation folks who figured out how to thread that cosmic needle with such accuracy each time, because, as you can appreciate, every one of those flybys is critical to maintaining

the trajectory for the next set of events. Those guys are now real pros. Would you mention, once again, something that you brought up last time, which I don't think has gotten enough attention. Of course, we're the Planetary Society, and we like these solar sail things. Yes. That played a big part in this. It was very helpful for us.

Our guidance and control folks figured out, after we were well on our cruise trajectory, well after launch, that we could make the small corrections to our trajectory that we would otherwise use our propulsion to do by means of solar sailing. Messenger has this big sunshade that receives a lot of radiation pressure from the sun, from sunlight hitting it, and it has two big solar arrays. And the solar arrays can be articulated about one axis, and they can be tilted relative to one another. And the sunshade itself, even though it must protect the spacecraft

and the sunshade must be between the spacecraft and the sun at all times, there is a certain amount of play that we have before sunlight would illuminate directly any portion of the spacecraft. It's about plus or minus 10 degrees in yaw and pitch, using sailing terms. We can tilt the spacecraft up or down, right or left a bit. We can tilt the solar arrays to within their thermal constraints and relative to one another. Those are the three parameters that our guidance and control folks had to do the sailing. They figured this out right before the first Mercury flyby, which was in January of 2008.

And so the last correction to our trajectory that we made using our propulsion system was in 2007. And between that time and the orbit insertion maneuver last week, all of the other corrections were done with solar sailing. So it saved us propellant, it cut down on risk, and it demonstrated in the innermost solar system a technology that a lot of people have been thinking about for a long time, but we used. That's Sean Solomon, Principal Investigator for the MESSENGER mission, now orbiting Mercury. I'll be back with him in a minute. This is Planetary Radio. I'm Robert Picardo. I traveled across the galaxy as the doctor in Star Trek Voyager. Then I joined the Planetary Society to become part of the real adventure of space exploration.

The Society fights for missions that unveil the secrets of the real adventure of space exploration. The Society fights for missions that unveil the secrets of the solar system. It searches for other intelligences in the universe, and it built the first solar sail. It also shares the wonder through this radio show, its website, and other exciting projects that reach around the globe. I'm proud to be part of this greatest of all voyages, and I hope you'll consider joining us. You can learn more about the Planetary Society at our website, planetary.org slash radio, or by calling 1-800-9-WORLDS. Planetary Radio listeners who aren't yet members can join and receive a Planetary Radio t-shirt.

Our nearly 100,000 members receive the internationally acclaimed Planetary Report magazine. That's planetary.org slash radio. The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan. MESSENGER went into orbit around Mercury on March 18, after a six-and-a-half-year journey that had already taken it by that active little world three times. It has begun dipping within 200 kilometers of Mercury's surface on each pass. Sean Solomon is principal investigator for the mission.

He and his team are gearing up for the massive amount of science data that is about to flow their way. You talked about a couple of weeks. Is that when the science gets started again, and what's on the agenda? Yes, indeed. I can tell you that yesterday, Matt, all but one of the instruments were powered on. So we're well along on the commissioning part of the initial orbital operations, and all reports from the instruments are nominal. and all reports from the instruments are nominal. The engineering term for everything is beautifully along the characteristics that we expect for all of these instruments.

We won't be turning on the imaging system, which is of interest to many of your listeners, until next Monday. And the first images, as part of the commissioning effort, will be coming down on Tuesday the 29th. But we're already gathering science data. We're using the early data to evaluate instrument performance and make sure that filters and calibrations and all the details that have to be part of the data gathering are all optimized. And we're on schedule to begin what we call the mapping phase of the mission on the 4th of April. That is when we have all the instruments on, we keep them on, and we continuously gather a variety of data from Mercury from the first observatory,

the first spacecraft in orbit around the planet that we've ever had. If you do start having images to show off on the 29th, that's about the time that this program will start to be heard by our audience around the world. So that's great timing for us. Before we run out of time, would you say a word about these four so-called disciplinary groups? Sure, Matt.

We have a science team, a combination of investigators and participating scientists who were selected by NASA a few years after we launched. The number is 47. So it's a very large team. It has to be large because as the first spacecraft to orbit a planet, we wanted to have a team that spanned all of the scientific investigations that we would be carrying out, that we would be making observations from orbit for the first time on so many aspects of Mercury, from the interior to the surface to the geology to the composition of surface materials

to the exosphere to the magnetosphere to how Mercury interacted with its environment in the inner heliosphere, and how the solar wind influenced both the magnetosphere and other parts of the system, including the surface, as well as the exosphere. And so that menu of topics that cover much of planetary science demanded that we have a great breadth of expertise who could all look at Mercury with their own expert eyes, but coordinated in understanding how the many pieces of the system that the planet Mercury presents to us all interact and interrelate. So as a means to manage a team of 47, we did divide into discipline groups broadly by scientific teams. So we have a geology group and a geochemistry group and a geophysics

group and a magnetosphere and atmosphere group. But we're finding that Mercury as a planet doesn't divide its science neatly according to discipline. And we're finding that changes in the exosphere are responses to what's going on at the sun and the magnetosphere. The cumulative effects of those changes in the magnetosphere and exosphere have signatures of the surface and how we interpret color of the surface and what that tells us about geology and the composition of the rocks at the surface. And, of course, the magnetosphere of Mercury is largely defined by the internal dynamics of Mercury's core

and the generation of the magnetic field. And so the characteristics of the internal structure and the history of the magnetic field are all critical, and that comes from the realm of geophysics. And so all of these components of this very complicated and dynamic planet are interrelated. That is turning out to be great fun because it means that those of us who came into this project with a particular disciplinary expertise are finding that we have to join forces with our colleagues from other disciplines, learn the vocabulary, and learn how we each have much to teach one another about how planets work. Do you expect that that team will continue to provide surprises for us about how this planet works, and not just the planet, but the environment around it? I'm confident that we do not yet know everything that we're going to find at Mercury,

and we have certainly not sampled the range of dynamic behavior that the planet will present to us. The three flybys were really just snapshots of a set of processes that are evolving on time scales ranging from minutes to millions of years, and to imagine that we had a full sampling of what that planet can show us from three snapshots certainly can't be the situation that describes our innermost planet. Moreover, we know that a lot of the phenomena on the shortest time scales, and this is in the magnetosphere and the exosphere at Mercury, are strongly sensitive, more so than any other planet, to what the sun is doing.

And our flybys occurred at a time of extraordinary solar quiet, one of the periods of quiet at sun that we've seen in the last century. The sun is becoming more active and will continue to be more active during our orbital mission phase. So we're looking forward to entirely new examples of sun-planet interactions, and we'll be right there in a front row seat to watch as they unfold. I hope we can look over your shoulder now and then. I know we'll be able to do that publicly

on the Messenger website, but also that we'll be able to get you back here on the show to talk about some of that science and some of those discoveries. Well, I look forward to talking to you again, Matt. It's always a pleasure, and I appreciate the interest of you and your listeners in the Messenger mission. It's very exciting for the team, but it's a great pleasure to share what we find with the public and all of those who are learning that even though we haven't sent a spacecraft for a number of years to planet Mercury, it's a very interesting body that has some special lessons for our entire planetary system. And thank you and the team to, as we've been putting it here,

completing the set of classical planets that have permanent visitors from our planet. Well, we're glad to do our part, Matt, both for planetary science and for those classical astronomers who recognize the importance of Mercury.

Thank you, Sean. Sean Solomon is the Director of the Department of Terrestrial Magnetism at the Carnegie Institution of Washington. Thank you, Sean. Okay. Sean Solomon is the director of the Department of Terrestrial Magnetism at the Carnegie Institution of Washington. He's been involved with a lot of other missions and is a member of the National Academy of Sciences, past president of the American Geophysical Union. But we and probably the world now know him best as the principal investigator for MESSENGER, the Mercury Surface Space Environment Geochemistry and Ranging Probe, which is now circling that innermost planet. I'll be right back.

Do some circling around. Bruce Betts for this week's edition of What's Up. And that's just a few moments away. Bruce Betts is back on the Skype line. That's because it's time for What's Up on Planetary Radio. He's going to tell us about the night sky, and we're going to give away a Mars flag, the flag of Mars, later today. Hey, welcome back. It's really dangerous to steal those from the Martians. I know. It makes me so very angry.

Don't vaporize us, please. Anyway, what's up? Well, it's Saturn time. Let's focus on Saturn. Saturn will have its opposition on April 3rd, so the time when it is on the opposite side of the Earth from the Sun, meaning its closest point to us in this orbit. Also meaning that it rises right around sunset and sets right around dawn. So look for it in the east-southeast during the early evening, high overhead in the middle of the night, and over in the west in the pre-dawn. And as you know, if you check that out,

even with a fairly small telescope, you should be able to see the rings. You also have a good chance of spotting a little pinpoint of light that's Titan, its largest moon, second largest moon in the solar system. Also look for Spica below Saturn and brighter Arcturus about twice as far as that to its left. Predon sky, still have Venus low, extremely bright in the Predon east. All right, we move on to this week in space history. We had Comet Hale-Bopp, closest approach to the sun,

back in 1987. We also had in 1966, 45 years ago, Luna 10 became the first spacecraft to orbit the moon. We move on to Random Space Fact. Sort of Gilbert and Sullivan-like.

The space station, including its large solar arrays, spans very close to the area of a U.S. football field, American football field, which is not that, you know, on the ballpark scale of things that different than sort of the average soccer or other part of the world football field, including the end zones, by the way. Still plenty big. Yes, it is. We move on to the trivia contest. It's a little tricky because it's something that, as you found in the answers, changes with time. What spacecraft were docked with the International Space Station? And the date I specified was March 14th, 2011. How'd we do, Matt? Before we give out the answer and our winner, I want to say again,

I'm not sure that anything else has ever made me feel so much like we are now a space-faring civilization than knowing that there were five spacecraft at the International Space Station on March 14. And as you pointed out, immediately before that, six before Discovery left. Crazy busy. It's amazing. And they don't get a lot of press on a whole bunch of stuff stuck to a football field size thing with people in it. Well, our winner who got it right with five spacecraft. Now, we know a lot of folks out there, you didn't find five, and maybe you were checking out the wrong day, but we had a wild variety here, up to five, and as few as one. But our winner was Karina Kowalek. Karina Kowalek of, and I thought it was Warsaw, but it's not. It's a different city in Poland, so I apologize. It's Wrocław, and I'm sure I'm not pronouncing it correctly so I apologize doubly

but it was Karina who was among those who said there was the European ATV Johannes Kepler the cargo vessel the Japanese HTV-2 another cargo vessel the Russian Progress a third cargo vessel

and two, count them, two Soyuz capsules so quite a crowded place and just two days later them, two Soyuz capsules. So quite a crowded place. And just two days later, one of those Soyuz undocked, carrying three astronauts back to Earth. I think they should open up a drive-in diner, you know? I wonder if they have. Use the Canadarm or the Canadarm 2 to deliver burgers.

Would you like space fries with that? Yes, absolutely. Would you like to fries with that? Yes, absolutely. Would you like to station size that? Okay, too much fun. Indeed. So, Karina, you are the winner of that Mars flag, the flag of Mars, unofficial, from Metro Flags Incorporated, donated to us by those folks. You can find them at metroflags.net. Just about everything you can think of. Flags of the world

and apparently other worlds, at least one. High quality stuff. So thank you to them. And thanks, Karina. Congratulations. Congratulations. What are we giving away next time, Matt?

How about another planetary radio t-shirt? Oh, it's awesome. I love those. What was the first spacecraft to orbit the sun at the Sun-Earth L1 Lagrange point? Go to planetary.org slash radio, find out how to enter. And you will have until Monday, April 4, at 2 p.m. Pacific time to get us that answer. This is L1, so-called Lagrange, Lagrangian, or Libration Point, that is a nice gravitational party place in space between the Earth and the Sun.

It's where all the junk collects. No. That's a different place. Oh, yeah, that's in the Pacific Ocean. Sorry. Yes, that's the L23 point. I don't know why. All right, everybody, go out there, look up in the night sky and think about pottery.

Thank you and good night. He's Bruce Betts, taking another one off the wheel. He's the Director of Projects for the Planetary Society and he joins us every week here for What's Up. Phil Plait, the not-so-bad astronomer, will join us to talk about bad astronomy and more

next week on Planetary Radio, which is produced by the Planetary Society in Pasadena, California and made possible in part by a grant from the Kenneth T. and Eileen L. Norris Foundation. Clear skies! Редактор субтитров А.Семкин Корректор А.Егорова