Planetary Radio: Space Exploration, Astronomy and Science - John Anderson and the Flyby Anomaly

Episode Date: March 10, 2008

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Move over, Pioneer. Now it's the flyby anomaly on Planetary Radio. Hi, everyone. Welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan. What the heck is going on in the universe? Well, we try to answer that question every week, but this time we really mean what the heck is going on with physics, dark matter, dark energy, and spacecraft that are going faster than they're supposed to be after they fly by our Earth. We'll talk with retired celestial mechanic John Anderson

about the just-published flyby anomaly. Bill Nye the Science Guy waxes poetic about the recent lunar eclipse. Get it? And Bruce Batts will tell us what's to see in the night sky. No Q&A this week, but only because Emily Lakdawalla has a special report on the first rings ever discovered around a moon. And it's a moon of Saturn. Man, some planets get all the luck. Oh my goodness,

did you see that image of a landslide on Mars? A landslide that was underway at that very moment? Not surprisingly, it was the HiRISE camera on the Mars Reconnaissance Orbiter that got the shot, though it was just a happy accident. The image and a story are at planetary.org. Join us next week for a conversation with Hi-Rise Principal Investigator Alfred McEwen. As we prepare this week's show, Space Shuttle Endeavour is almost ready for a trip to the International Space Station. STS-123 will deliver the first piece of a Japanese-built lab and the Canadian-made robotic system known as Dexter. NASA plans a 16-day mission. Time to talk anomalies with John Anderson. That'll be right after this week's visit with Bill Nye. Bill Nye, the planetary

guy here, vice president of the Planetary Society. A couple of weeks ago, I was not in Pasadena, Planetary Society headquarters, as I am right now. I was in New York City. I was back east, as we say in North America, and I could see for only the third time in my life a lunar eclipse. Light was passing, if you will, south of our South Pole, hitting the moon and bouncing back to my eye. Now, instead of the light passing through, if I may, only a few miles or a few dozen kilometers of Earth's atmosphere, now it was passing through a curved band. It was passing through the atmosphere coming and going, if I can say. And so all the blue light that's normally in the sun's rays was scattered by molecules of the Earth's atmosphere. Scattered, distributed away from your eye, away from the surface of the moon's atmosphere, scattered, distributed away from

your eye, away from the surface of the moon, so they couldn't bounce back toward me. And so the moon was this strange and enchanting red, sort of the color of the surface of Mars, almost like wine. It was a color that you just never see the moon take on, except during a lunar eclipse. And wait, there's more. I could distinctly see a shadow on the moon, and that shadow was curved. And it was curved because it's the shadow of our own planet falling on its satellite. Now, for centuries, people believed that the Earth might not be round. Maybe it's flat or something.

But when you look at that shadow, the only shape that's only going to cast a round shadow is a sphere. The ancient Greeks knew this, and they accepted and embraced it. And yet, for some reason, we humans lost sight of it. And I hope we never lose sight of it again. You'll get your next chance to get a sight of it in 2010. I hope you're in the right place with no clouds where you can take it all in. Thanks for listening. Bill Nye, the Vice President of Planetary Society, and this is Planetary Radio.

If you've been with us a while, you've heard us talk about the Pioneer anomaly, that strange change in the acceleration of the Pioneer spacecraft that has yet to be reconciled with physics. Our guest this week, John Anderson, has worked with JPL colleague Slava Turashev on that mystery, and we'll talk with Slava again sometime soon, but John and a separate team have just announced evidence for yet another anomaly. You heard our commentator Bill Nye get understandably excited about the

flyby anomaly on last week's show. We decided to go straight to John for the story. He recently retired from the Jet Propulsion Lab, where he was a senior research scientist and the principal investigator for Celestial Mechanics on missions beginning with Mariner 5. I reached him at his home not far from JPL. John, it is great to have you back on Planetary Radio to talk about a different anomaly this time. You know, just before we went on, I googled flyby anomaly, and sure enough, it's already in the Wikipedia. But I would refer people to the article by my colleague Amir Alexander that's on the Planetary Society website, planetary.org. And of course, this is also just about to be published as we speak in physical review letters, quite prominent recognition. You told me that the BBC, darn them, beat us to you for radio. You talked to them a couple of days ago? Yeah, on Wednesday morning, I did. I spoke with BBC. All right, well, better late than never. And we are, like I said, happy to have you back to talk about this. But it's hardly new. I mean,

now it's getting the news coverage, but you actually started to become suspicious about this more than 17 years ago. Yeah, we did. It was with the first flyby of the Earth by the Galileo spacecraft, and that was on December 8th of 1990. And it wasn't very long after that we had analyzed the data, and things didn't quite add up. So there was a little group of us there at JPL that they're kind of surrounding the navigation, space navigation area. They were all very puzzled. We couldn't, as I say, we couldn't get it to add up. We couldn't quite fit the data.

So you took this, you realized, I guess, well, you know, it's probably just some error we've made in measuring velocity of the spacecraft or something like that. But did you begin to think even then that maybe there was something more mysterious going on? Well, we looked at things. I was working with Jim Campbell and Frank Jordan, who are both on this paper. It's a little team that we have actually we put together, and we were funded by JPL discretionary money by the director's office actually and we worked as a little team here in the over the about the last 18 months but there were the three of us working on this way back then

with the Galileo encounter and it took us just a little while to look at some of the things that could be obvious that we hadn't gotten quite right in our input into the fitting program. And we began to get puzzled almost immediately just a few days after that December 8th encounter that what could be going on here. We have everything in our model, and we can't quite get things to add up. When did you start to think that you'd better be watching for the next major flyby? Well, fairly soon after that, then we realized that there was another Galileo flyby just almost exactly two years later because they sync it with Revolution

of the Earth about the sun. So we got another encounter on December 8th of 92, exactly two years later, and we knew that was coming up. And almost immediately after we'd given up on trying to explain why we couldn't fit the 1990 data, we started worrying about 1992. And I know Jim Campbell got very active in making sure we had good data for it, and we worked with some of the people in the DSN, the Deep Space Network, there at JPL, and made sure we'd get some good data for the second Galileo flyby. But it didn't really pan out, did it? No, it didn't pan out.

We were surprised by that. The altitude was about 300 kilometers, and we were getting a little atmospheric drag at that. The one was about 960 kilometers, the earlier one that we puzzled about, and there was no atmospheric drag in that one. But then when we got down to about the 300 kilometer level, we started seeing the atmospheric drag, and we realized that that was going to mask this effect we're looking for. That was really, it was a velocity anomaly. So if you have any drag that's going to change the velocity, that's going to cause problems.

And we didn't anticipate that. We had to look at the data and realize that we were being affected by drag. So it didn't quite pan out. That's right. The next opportunity was NEAR, the Near Earth Asteroid Rendezvous Mission. And you had a little bit better luck with it. Yeah, we did. That one was January of 98.

That's right. So that came along about five years later. So we had to wait another five years before we got one of these. Long wait. Yeah. And, of course, we were anticipating that perhaps we'd see the anomaly again with that near flyby. And we certainly did. And there was a pretty good navigation team working on that near flyby. So we stayed coordinated with them.

working on that NEAR flyby, so we stayed coordinated with them. And sure enough, the anomaly did pop up again with NEAR, and we couldn't reconcile the orbit with the data. You got two or three more opportunities after that, I think, right? Yeah, there was a Cassini flyby. See, that was August of 99. The one that really showed it up again was fairly recent. That was a Rosetta flyby almost exactly three years ago, March 4th of 2005. And Rosetta showed it pretty clearly. And that time that was a European mission. So we had the navigation group in Europe, in Darmstadt, Germany, and they saw it.

I think they were aware that we'd had problems with the Galileo, and there was a large near effect, because that had been published in some engineering journals, and we'd gone to meetings, or at least the navigation people had gone to some meetings that do this astronautic stuff, and they'd said that there were some problems with Galileo and NIR. So I think the Rosetta people were aware of that in Europe, and sure enough, they saw an anomaly, too, and told us that it was there, and then we got the data from that and started looking at it ourselves. We'll hear more from John Anderson about the flyby anomaly when Planetary Radio continues in one minute.

Hey, hey, Bill Nye the Science Guy here. I hope you're enjoying Planetary Radio. We put a lot of work into this show and all our other great Planetary Society projects. I've been a member since the disco era. Now I'm the Society's Vice President. And you may well ask, why do we go to all this trouble? Simple. We believe in the PB&J, the passion, beauty, and joy of space exploration. You probably do too, or you wouldn't be listening.

Of course, you can do more than just listen. You can become part of the action, helping us fly solar sails, discover new planets, and search for extraterrestrial intelligence and life elsewhere in the universe. Here's how to find out more. 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. 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. First, the Pioneer Anomaly. Now, the Flyby Anomaly seems to challenge our understanding of physics.

Retired JPL senior research scientist John Anderson continues to work with a team that first noticed 17 years ago that something strange happens when spacecraft fly by our Earth. So you guys in the celestial mechanics, celestial navigation community, this was getting to be fairly common knowledge, it sounds like. It was, yeah, yeah. And we were all puzzled, and no one could solve it. And a lot of people worked on it that are experts in this area. It's a lot of expertise at JPL and there is in Europe as well. And just no team or no individual had any explanation for this or could find a

mundane effect where they needed to change something in the input and this would go away. It just didn't go away. Somebody thought to try general relativity? Well, yeah, we have that in our model. So all you have to do is just change some parameters and look at the general relativity formulation. But that's in our model. It's what we call fully relativistic,

so it's consistent with both special relativity and general relativity, and it's the general relativity that has the gravitation theory in it, and we need that. I mean, those terms are of order of v squared over c squared, where v is the velocity, velocity over the speed of light. That's where relativity comes in. And those terms are small, but they're important for the space navigation. So that was one of the possibilities, that we could tweak relativity a little bit and fit this, but that didn't work. bit and fit this, but that didn't work. Sadly, Einstein, while he may be smiling down on you for including this in the model, is not able to help much with this anomaly. When did you reach the point where you were able to say, okay, we've quantified this, we can make a projection, we can predict, based on the trajectory of an upcoming flyby, how much of this anomaly effect we're going to see?

Not very long ago. That's when we were in this phase of being funded by JPL to look into this with our little five-person team. And we did that, and we came up with this formula. It was something actually that Frank Jordan did. He was looking at could there be any pattern to these six flybys that we have, and we're seeing the anomaly in four of them. He started looking at angles, and sure enough, he found a formula which he gave to the rest of us, and we checked it out, and then we interpreted it in terms of the rotation of the Earth and came up with a proportionality constant

that depends on the rotation rate of the Earth. So we came up with an empirical formula within the last year, I would say. It wasn't over a year ago, where we can explain all of these flybys with a simple formula. And we put that in our article in PhysRev Letters. And we're saying basically to the physics community, we have this empirical formula. If you're going to be modifying anything within basic physics or fundamental physics,

you really should use this as a goal for the kind of changes you're going to make. It should satisfy this formula. But we have no explanation for it. We can't see it ourselves just why this formula works. We have no explanation for why the formula works. But it does, and remarkably well. Curiouser and curiouser. Yeah.

It's always nice when the experimentalists get out ahead of the theorists, I think. It's kind of fun. Yeah, it is. We make progress that way, you know, through technology and doing experimental work. Then the theorists kind of have to tag along and say, oh, you guys got a new result. Do you? Okay. Is the effect great enough that it's going to have to be put into these models for people who want to figure out where a spacecraft is going and how quickly it gets there? No, it's too small to worry about it from a navigation point of view.

We're going to get to the planets okay and do all our space navigation without it. It's very, very small. It's parts per million. So if you look at the orbit, it's affecting it in about the sixth decimal place, way out there. It's not critical for doing space navigation. You can leave it out. You're retired now, but it sounds like this is something that you're going to continue to work on, and your curiosity is still at a pretty high level. Yeah, that's it.

We're very curious, the team that's working on this, and we are going to keep pursuing it, and we'll try to understand the data that we have in hand a little better. This paper that's coming out this week is just our initial announcement of our results and the formula we have. And we'll keep at it with the data we have. And then as more flybys come along, I'm not quite sure when we get the next one, but it will be years, not months. And we'll continue to look at this, definitely.

John, I want to thank you and your colleagues for helping to keep things interesting and mysterious in our universe. Yeah, it's a privilege to be able to do this work. It's a lot of fun. And thanks again for joining us on Planetary Radio, where we'll continue to talk about anomalies, flyby, and the pioneer variety in future shows. Well, thank you. It was a pleasure. variety in future shows. Well, thank you. It was a pleasure. John D. Anderson, recently retired as a senior research scientist at the Jet Propulsion Laboratory, where he was often a principal investigator for celestial mechanics on a whole bunch of missions, including the one that got the flyby anomaly started, the Galileo mission to Jupiter.

The news came just a few days ago. An instrument on the Cassini spacecraft has found evidence of new rings, not circling Saturn, but Saturn's moon, Rhea. Emily Lakdawalla is the Planetary Society's Science and Technology Coordinator and the host of Q&A here on Planetary Radio. Emily, welcome to the show from Texas, I guess, combining a little business with pleasure. That's right. I'm here with my dad and my baby. Well, we won't take too much time away from this, but I'm really very happy that we can talk to you about this story about Rhea,

which you seem to be pretty happy with, too. You're really taken by this story. Yeah, I love this story because it's so easy to explain to people, even people who aren't space fans. And what I usually say to them is, you know how Saturn has rings? And they say, yeah. And I say, well, you know, it has moons, right? And they say, yeah.

And I say, well, they've just discovered that one of Saturn's moons has rings. It's the first moon ever discovered to have rings, and that really impresses people. Nobody's actually seen these. There are no images of them, or at least there are no photographs of them. No, the detection was not made with a camera. It was made with something called a magnetospheric imaging instrument, otherwise known as MIMI. MIMI counts the electrons that are flying through Saturn's magnetosphere, and it measures their energy. Mimi counts the electrons that are flying through Saturn's magnetosphere, and it measures their energy.

So usually when Cassini flies by a moon, there's this constant flow of electrons until it passes into the moon's shadow when they get cut off. But when Cassini flew by Rhea, there was this sort of slow decline in the amount of electrons as it got closer and closer to Rhea. And they think that the reason for that is because there was some kind of disk or ring system that was blocking the electrons. You're talking about this with some confidence, but can we really be confident that these are there? Well, no. Not everybody's convinced that they are there. There's really only one instrument that's made a positive detection. They have tried looking for them with the camera, but they have not seen them.

You actually found out about this story quite a while ago, and you had to sit on it for a while, didn't you? I did. It was actually mentioned briefly in one of the Cassini Significant Event Reports, which they issue weekly from the mission. And I thought that sounded awfully cool, so I wrote about it in my blog, and the first author on the paper immediately emailed me, just horrified that they'd mentioned it in the Significant Events Report. So I'd mentioned it in the significant events report.

So I quietly removed it from the blog and nobody else seemed to notice it and I sat on it until the researcher managed to get his work published in Science Magazine last week. Now it is both in your blog and in a nice story that you've written at planetary.org, which we will direct people to if they'd like to get more details about this very interesting story. We will let you get back to vacation and then I guess we'll be hearing from you with a whirlwind visit to the LPSC. That's right. Lunar and Planetary Science Conference is all next week in Houston, and I'll just be there for the first day of it. All right then. Emily Lakdawalla joins us most weeks with Q&A. Special report this week on those maybe rings of Rhea, our own 21st century cub reporter.

I'll be right back with Bruce Betts for this week's edition of What's Up. Back with us, courtesy of Skype, is Bruce Betts, the director of projects for the Planetary Society, with a what's up look at the night sky and a very interesting response to the current trivia contest. So let's dive in. Howdy. How are you? Hey there. Hi there. Ho there. Doing pretty well. Let's start talking about that night sky. In the evening sky, it's quite lovely going out in the mid-evening, and you can check out both Mars and Saturn pretty high overhead at that point.

Mars heading off towards the west and up above Orion, if you like to picture Orion as it's usually presented in constellation ways, and looking reddish and looking like a bright star, not an extremely bright star, but having its orangish-reddish color. And then farther over to the east, we have Saturn, which is rising a little after sunset right now, being just past opposition. Saturn looking yellowish and hanging out in the constellation Leo, which also, if you haven't ever tried to figure out Leo, it's a good time to do that in the early evening sky. And it's one of the few constellations that at least I can actually connect the dots and pretend to see a lion. I don't know about you. Yeah. Yeah. You know,

I just managed to do that with Orion for the first time in my life. I thought, oh my God, there's the bow. Oh, nice. Yeah, I know. That's an accomplishment. I'm moving on to Ursa Major next. You might want to move on to something else first. And the pre-dawn skies still have Venus and Jupiter spectacularly bright, but very low on the eastern horizon shortly before dawn.

Venus, the brighter of the two, and Jupiter to the upper right of Venus. And if you can really look low, down below Venus, you also may see very close by Mercury, which is much, looks like a bright star, but compared to Venus, not so much. Let's go on to this week in space history. It is the 50th anniversary of the Vanguard I launch, which we might talk about a little bit more later. That was the fourth spacecraft to be launched successfully, a

U.S. Navy spacecraft, and holds the distinction of being the oldest human-made object in space. On to random space fact! I want to talk polar progression. No, no I don't. I want to talk polar progression no no i don't i want to talk polar precession did you know you probably did matt that that the earth's pole or the earth is a whole precesses it kind of wobbles as it goes around kind of looks like a top that's spinning on a table and starts to fall and and that top the top of the top traces out a circle as it's spinning around. Well, for very different reasons, but still with the same effect, the Earth's pole precesses.

And the big precession has a period of about 26,000 years. That's about one degree in the sky, one degree every 72 years or so. So actually one degree on certainly the scale of a human lifetime. And this also means that pole stars change. So right now we've got a really groovy pole star in the northern hemisphere, Polaris, the so-called north star. But that isn't true if you go off a few hundred or a few thousand years away. And there's no bright star right now in the south giving a nice pole star. So there you go.

There's your polar procession, random space facts. Yeah, fascinating. I couldn't remember the period, but 26,000 years, not bad. Not bad. Covers most of human history. Let us go on to the trivia contest. And we asked you last time around, what was the first solar powered spacecraft? Now, I took this to mean that a spacecraft using the sun to power its electronics, basically using solar cells. Apparently, we had some diversity of

opinions. So as always, in our magnanimous way, we'll take the randomly selected person who selected either that or what else did they talk to us about, Matt? It's quite an honor, I would say, since about half the folks out there mentioned a spacecraft that never made it to orbit. Cosmos 1, the solar sail from, guess who, the Planetary Society. Yours truly, I suppose, in a sense, right? Indeed. If it had reached orbit and worked, it would have been powered in a propulsive sense by the light of the sun pushing on it. And we're still hoping for Cosmos 2 in the future to do such a thing. So I'd say we'll take either answer. And that having been said, who's our randomly selected winner who's going to win a fabulous

planetary society t-shirt you know it's jennifer barr and indeed she did she said cosmos one jennifer barr of new providence pennsylvania first time winner as far as i can tell who we're going to be sending a planetary radio t-shirt to we did get one entry and i'm sorry to say i don't remember who it was who did say deep space one the first spacecraft to actually be powered, propelled, in a sense, by solar power because it had iron in it. In a direct sense, solar electric propulsion. And you know what I probably should do? What's that? I should mention what I actually intended, which was Vanguard One.

Vanguard One, the fourth spacecraft in orbit, launched 50 years ago this week, was the first one to stick little solar cells on there and power itself using sunlight. And it's still there, the oldest piece of space junk in the sky. Amazing. Got a big orbit and therefore a stable orbit. Still up there. Congratulations to the, I think it's the Navy and to NASA this week, on the spacecraft that Khrushchev called the grapefruit, because his was so much bigger. Size matters. Yeah, but this one went farther and therefore is still up there, which I'm sure helped being

a grapefruit instead of a what, a watermelon? I don't know. How about next time? Next time, we return to the magnificent world of polar precession. What was the pole star in the north in 3000 BC, so 5,000 years ago? What was the pole star in the north? Go to planetary.org slash radio. Find out how to tell us your answer.

And you've got until March 17th, Monday, March 17th, the actual 50th anniversary of the launch of Vanguard One. To get us that entry, do it by 2 p.m. Pacific time, please. That's it. We're done. All right, everybody, go out there, look up in the night sky, and think about melting candle wax. Thank you, and good night. Well, that's Bruce Betts, the director of projects for the Planetary Society.

Who knows, it's better to light one candle than to bump your toes in the darkness, I guess. He joins us every week here for What's Up on Planetary Radio. Planetary Radio is produced by the Planetary Society in Pasadena, California. Have a great week. Thank you.