Planetary Radio: Space Exploration, Astronomy and Science - The Pioneer Anomaly: A Mystery in Deep Space

Episode Date: September 5, 2005

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A mystery in deep space, this week on Planetary Radio. Hi everyone, welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan. Why is a decades-old space traveler not where it's supposed to be? Is it just some unaccounted for quirk in Pioneer 10's design, or does our understanding of the natural laws of the universe

need to be amended? That's the question our guests are trying to answer through their investigation of the Pioneer anomaly. Later today, Bruce Betts will reveal the winners, yes, winners, of our Name the Crew Exploration Vehicle Contest, as he also reveals the night sky.

And here's a word or two about other news from around our busy solar system. Man, oh man, what a view from atop Husband Hill on Mars. Check it out at planetary.org. It was Mars rover Spirit, of course, not Opportunity, that snapped the spectacular panorama from Gusev Crater. Please pardon your befuddled host for mixing them up last week. Speaking of spectacular images, how about Neptune spinning along with its clouds and moons?

The beautiful movie can be downloaded at planetary.org. It's more proof that the aging Hubble Space Telescope can still pump out great science, even though it's down to being steered by just two gyroscopes at a time. Lastly, our hearts and thoughts go out to the hundreds of thousands left homeless by Hurricane Katrina. NASA is using its satellites and other resources to aid the recovery just getting underway. The space agency also reports only minor damage to its Louisiana facility that prepares the external tanks for the space shuttle. Here's Emily. I'll be right back with that mysterious pioneer anomaly.

Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, why don't we see more color images released from Cassini? When you compare Cassini images to those from the Mars Exploration rovers, it does seem strange that Cassini's views of Saturn and its rings are so often published in black and white. For both missions, the black and white cameras are equipped with filter wheels. To take a color picture, the camera takes one image through a red filter, one through a green filter, and one through a blue filter. The three images are then combined on a computer to produce a color view. The cameras are equipped with many other filters besides red, green, and blue, however. The rover's color vision encompasses filters

designed to tease out color differences among rocks. The filters that the rovers use most often cover wavelengths that human eyes can see, so even false color images from rover cameras look pretty realistic. But Cassini's color views are mostly taken through filters in near-infrared wavelengths, where differences in the abundance of atmospheric methane

outline the swirling patterns in Saturn's clouds. False color images made through these filters won't look much like a human view of Saturn at all. But that's not the only reason color Cassini views are rare. Stay tuned to Planetary Radio to find out more. views are rare. Stay tuned to Planetary Radio to find out more. Veteran JPL scientist John Anderson was one of the first to notice something odd about data coming back from Pioneer 10, the interplanetary probe launched in 1972. John has been investigating the so-called Pioneer anomaly for years and has now been joined by others, including his colleague at JPL, physicist Slava Turashev.

Now, with support from the Planetary Society's members, interest is rising. We got John and Slava on the phone just a few days ago for this introduction to the Pioneer Anomaly and a status report on their progress. Gentlemen, thank you very much for joining us on Planetary Radio, where we don't often get to talk about mysteries. Well, that's not true. We talk about scientific mysteries all the time. But not mysteries like this. What the heck is going on with the Pioneer Anomaly?

John Anderson? Well, we're asking the same question. We really don't understand it at all. We've got an anomaly that is clear, but we have no idea of what's causing it. So we're as puzzled as you are and really want to pursue this and see if we can get to the bottom of it. How did all this get started, John? Well, it got started because we were analyzing data for the Pioneer spacecraft. There's two of them, Pioneer 10 and Pioneer 11, and at some point, this anomalous force popped out that wasn't in our model, and we had to add a constant acceleration to the craft just to fit the Doppler data. And when you say Doppler data,

our audience knows about the Doppler effect, but how is that data telling you that basically Pioneer 10 is not where you would have expected it to be? Well, it's the same. The Doppler shift is what you hear with an ambulance or whatever when it goes by with its siren, so people are familiar with that. And we do that in radio frequencies. It's exactly the same thing. frequencies, it's exactly the same thing.

You know, the police have their radar as well and can track you with that, tell how fast you're going. John, I know you've been at JPL a long time. Your colleague, Slavo, who's also on the line, I think joined this effort investigating the Pioneer anomaly a little bit later. Slavo, why did you become part of this little project? I got involved into the study of the Pioneer anomaly because of its mystery. When I joined JPL, I realized that John was working on a very interesting problem, looking at the dynamics of the Pioneer spacecraft in the solar system. And to me, it was kind of a very simple answer

to it. I thought maybe general relativity was mismodeled. The contribution of general relativity was mismodeled into the overall modeling of the spacecraft. And so because of my background in general relativity, I thought my knowledge would help to understand that. So I joined in and I realized that general relativity essentially has nothing to do with that. Because of the simplicity of the spacecraft, one can model very precisely every detail of the spacecraft motion. And little by little, we were standing in front of the puzzle whether or not there is

a systematic force acting on the craft, and that would be some thermal radiation or some spacecraft design, or else we are dealing with something which is yet unknown. When I joined this study, I had a very limited understanding of spacecraft design. But essentially, year by year, since we joined in as a team, everybody had to develop this expertise. We are talking with people who were at the beginning of this effort. So that helps us to understand how the craft were built and how they actually behaved in space. John, once you realized years ago that something strange was going on here, did you begin to understand right away how you would need to investigate this further and that that would

involve gathering a lot of already aging data? That really didn't happen until about 1990 when I began to put together these long stretches of navigation data and see how the anomaly was behaving over many years. So I wouldn't say until 1990. Before 1990, we didn't pay much attention to it in the sense that we thought we had something important to say. But one of the big challenges of this project has not just been the theoretical, but actually getting your hands on this data going back to, what, 1972, the launch of Pioneer 10. Yeah, that's exactly right.

And it's very difficult to go back and find data that was taken 30 or more years ago. There just is no system that archives data that carefully. The data is taken for navigation. Once the mission ends, that's the end of it. There isn't really any interest in the tracking data anymore. So it's been a real challenge for us to go back and try to find the data. And Slava's actually taken the leadership role on that in trying to retrieve as much of the Pioneer data, Doppler data, as we can.

Well, let's talk about that when we come back from a quick break. Our guests are John Anderson, astronomer and senior research scientist, and Slava Turashev, physicist and research scientist. They're both at JPL, and they are leaders of a team that is trying to find out more about what is becoming known as the Pioneer Anomaly. And we will try to find out more right after this. This is Buzz Aldrin. When I walked on the moon, I knew it was just the beginning of humankind's great adventure in the solar system. That's why I'm a member of the Planetary Society, the world's largest space interest group. The Planetary Society is helping to explore Mars. We're tracking near-Earth asteroids and comets.

We sponsor the search for life on other worlds, and we're building the first ever solar sail. We didn't just build it. We attempted to put that first solar sail in orbit, and we're going to try again. You can read about all our exciting projects and get the latest space exploration news in depth at the Society's exciting and informative website, planetary.org. You can also preview our full-color magazine, The Planetary Report. It's just one of our many member benefits. Want to learn more? Call us at 1-877-PLANETS.

That's toll-free, 1-877-752-6387. The Planetary Society, exploring new worlds. Our guests are John Anderson and Slava Turashev. They are both at JPL, and they are both members of a somewhat ad hoc but very distinguished team that is looking into the Pioneer anomaly, figuring out why Pioneer 10 is not where science tells us it should be. When we left off just before the break, Slava, John was saying that you've been a big part of locating this data. First of all, I'd like to emphasize the significance of early data. We are trying to assemble the longest data arc for the two reasons. First of all, we expect that changes in the trajectory in the earlier phase of the mission would help us to eliminate or emphasize the effect of possible systematics on the spacecraft,

such as thermal radiation. And the thermal radiation on the craft is due to the power system on the spacecraft. We hope we will be able to gain enough information to either emphasize its significance or actually to eliminate its contribution. And the longest data arc will be also important because we will be able to see the temporal changes in the magnitude of the anomaly. If it's due to thermal radiation, we do expect it to be larger in the beginning of the mission, but very small at the end. Our previous analysis

showed that it's constant. This is where the puzzle comes. If it's constant, therefore, it's possibly not due to the thermal radiation, and that means it's something else. Yes, definitely, we looked through every possible location at JPL where the data might be. What we went through is to assemble a local team of experts at JPL, which helped us to read the data on the tapes and then to analyze which helped us to read the data on the tapes and then to analyze them of their significance. So now I think we almost finished the assembly, and in about a few weeks we will finish the assembly of the entire set, and that will give us enough information to address the problem. Talk about why we had never noticed this until Pioneer 10.

John? I actually looked at the Pioneers very early on in about 1969, and I realized that these were unique spacecraft. They are attitude-controlled, as we say, so that we know the direction they're pointing by spinning. It's called spin stabilization. And I looked at that and realized that this would be very good for trying to do orbital analysis and to check Newton's laws and all those kinds of things and to determine gravity fields.

So I proposed that I do that with the Pioneers, and that proposal was accepted by NASA in about 1969. So from the very beginning, I realized these were unique spacecraft. All of the JPL spacecraft that we worked with, the ones that you mentioned, are stabilized by jetting gas, by gas jets. So they're almost continuously jetting gas. Some of the more modern spacecraft, like Cassini use what we call reaction wheels, and they don't continuously jet gas, but the Voyagers did.

So the pioneers are unique in trying to do orbital analysis and finding small forces like this. Where do we go from here? You've successfully recovered a great deal of data. I take it analysis is already underway, and apparently you are inviting other scientists and engineers to become involved, and we'll be meeting soon in Switzerland. Slava?

Yes, there will be a meeting in Switzerland in the International Space Science Institute in the city of Bern in Switzerland. And we would like to open the opportunity to study the Pioneer data for other scientists. And the reason for that is that we have been very close to the data for a number of years, and we know what the data can tell us. And we would like people to be able to look at the similar data and analyze the data with us. Because it is important that different analysis, different approaches will be used, and that would only help us to find the real problem on the spacecraft, or we'll identify the mechanism

that generates that acceleration or the force that might be acting on the spacecraft or will identify the mechanism that generates that acceleration or the force that might be acting on the craft. And we hope that the international team of scientists, both from the United States and Europe, will be able to join our work in an attempt to understand the nature of the anomaly. We only have a minute or two left, gentlemen. What do you think will be the final result of this? I mean, I know it's terrible to ask a scientist to make a prediction like that.

Nevertheless, you must have some degree of hope that the Pioneer anomaly is actually going to reveal something we've never known about how our universe works. For me, if I may, there is no prosaic mechanism because if it's even the systematics on board of the spacecraft, it will be a tremendous find, because the future spacecraft that we are building now to test fundamental physics will be better. They will be more stable and more reliable into addressing the very difficult questions of universe formation and the study of the cosmological structure of our universe.

And if it's in new physics, it will be a contribution just very difficult to comprehend. John, one of the things that I think is most interesting about this anomaly, it's not that it's common knowledge yet, but people seem to be so fascinated when they find out about it. In fact, the appeal made by the Planetary Society for funds to support your work was one of the most successful the Society has ever sponsored. I even heard that some of your colleagues at JPL, when you went to them in your search for this data, were already aware of it and had it pinned up on the bulletin board. Yeah, I think you're right.

It is fascinating at all levels. You get it throughout your membership, I think, this intense interest, and we see it with professional astronomers and physicists. We see the same thing. Everybody's looking at this and saying, this is very strange and maybe we have something new here. This wouldn't be unprecedented. It's happened in the past, you know, with Newton's laws breaking down with the orbit

of Mercury, the precession of the perihelion, and we needed general relativity to explain that. So it's true, as you push with more and more accuracy, very often something will pop out that doesn't fit your current models, and you have to go back and look at the theory and change things. So I think that's the real interest here. And that may be the case that when we finally finish our analysis, we'll conclude there is no mundane mechanism that we or anybody else can think of, and it must be new physics. Of course, that would be extremely exciting,

but we'd also be very lucky if the pioneers happen to turn up something like that. It's unlikely. So on the other hand, we're very conservative and say, well, we'll probably just understand some new navigation effect when we finish, and that will be very important for future spacecraft, as Slava said, but we won't really make any impact here on fundamental physics. That's the conservative approach, and I think we have to keep that mindset. We don't want to get overly excited here.

We need to do this very carefully and proceed very carefully. Well, one way or another, let's hope that this mystery is solved, whether it's mundane or something that changes the physics textbooks. But, gentlemen, I hope that we can check back with you again, perhaps after that conference in Bern, Switzerland. Good luck solving that mystery. Well, thank you very much. Yeah, we'll look forward to talking with you again.

Thank you. John Anderson is an astronomer and senior research scientist at JPL, and his colleague there is Slava Turashev, who is a physicist and research scientist. They are part of a fascinating team working on a fascinating challenge, and that is the Pioneer Anomaly. And you can learn more at planetary.org, where we will have links up right where you may be listening to this radio show so that you can learn more about this mystery from Pioneer 10.

We're going to go to a bit more information from Emily, and when we come back, it'll be time for Bruce Betts and this week's edition of What's Up. I'm Emily Lakdawalla, back with Q&A. Why are there fewer color Cassini images being released than there are for the rovers? Again, to take a color picture, the cameras actually have to combine three pictures, one each through red, green, and blue filters. With the rovers, this is tremendously easy to do. The rovers are highly stable camera platforms. The camera stays absolutely still as it switches between filters. The set of three images always shows exactly the

same view on Mars. It's just as easy for the rover scientists to show a color view as it is for them to show a black and white view. But the same is not true of Cassini. Cassini is always in motion. Between filter changes, Cassini's camera moves, changing the distance to its target. Parallax can make a moon appear to shift against Saturn in the background. And everything that Cassini's camera moves, changing the distance to its target. Parallax can make a moon appear to shift against Saturn in the background. And everything that Cassini photographs is moving, too. The little moon's orbit and spin and Saturn's clouds swirl. As a result, no two views that Cassini takes look quite the same, and three sequential images can't automatically be combined into a color picture. It takes human intervention and time,

which are precious commodities to a busy science team involved in the exploration of Saturn. Fortunately, there are many amateur image processors out there who are all too happy to take the necessary time, and they have produced some stunning views. Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio.

Hey, Bruce Betts is here. He's the Director of Projects for the Planetary Society. He joins us each week just about this time in Planetary Radio for What's Up. So, what's up, Bruce? Balloons and trees and birds and the sky. The sky. The sky. Let's talk about the sky. We've got planets up.

If you look after sunset in the west, you will still see Jupiter and Venus looking incredibly bright. After they're coming only a little over a degree apart on September 1st, they are separating. Venus is getting a little higher in the sky after sunset and Jupiter a little lower. But in the next few weeks, you should still be able to catch Jupiter and certainly Venus for several weeks looking extremely bright. You will also see Mars looking very bright, rising around 1030 in the east, looking very orangish, almost as bright as the brightest star in the sky right now, but dimmer than Jupiter and Venus, but with that spiffy orangish reddish tint. Have you seen that recently? Absolutely, yeah. And boy, is it orange. This is maybe a week ago when it was coming up at about 11.

Unmistakable. And I haven't taken the telescope out yet to look at Mars, but Jupiter was great. Yeah, if people have small telescopes or big ones, take a look at Jupiter and Venus and eventually Mars. Saturn is also barely up in the pre-dawn sky, low in the east. And so that's another thing to look at. But it'll be getting much better over the coming months as it gets higher. Again, let's go on to this week in space history. Viking Lander 2 was launched 30 years ago in 1975. And Mars Global Surveyor arrived at Mars eight years ago.

Oh, my God. Eight years? 1997. What is amazing about this is not that it got there eight years ago, but that it's been working. Still working. Still working and still working beautifully, returning wonderful data on the red planet. So, very, very cool mission. Time flies when you're having fun and getting good data.

It is. We've got a bunch of, still have five working missions at Mars. On to a human space update. The Progress resupply craft that's docked to the International Space Station on September 7th will be, after having its mouth shoved full of trash and other things, it will be shoved away from the space station and will burn up over the Pacific Ocean. And then the following day, they will launch a new Progress supply ship, these very reliable unmanned spacecraft that are resupplying Sergei Krikalev

and John Phillips on board the International Space Station. That's going to come up again later, isn't it? Oh, it is. It's almost a theme. On to Random Space Fact! Speaking of the International Space Station and Sergei Krikalev, on August 16th, he eclipsed Sergei Avdeyev's record of 747 days in space.

Sergei Krikalev currently up there. Every day he's up there is another day on the record for the longest time in space. He's spent almost two years of his life in space. Incredible. And, you know, I don't know how old he is, but I've got to think that that's probably at least 5% or so of his total life. 5% weightless in space. That's amazing. I'd settle for a tenth of a percent.

Okay. Can we arrange that? I hope so. All right. Would you please? Yeah, maybe we can find a way. If only we had a good spacecraft to send you out to the moon. Oh, yeah.

Let's talk about that. Hey, that brings us to our trivia contest. We asked you to make us laugh, make a funny about what we should call the first crew exploration vehicle, the CEV, the spacecraft being developed by NASA, first for low Earth orbit, but then to take us out beyond, perhaps to the moon or beyond. And how'd we do, Matt? We asked people to get funny, and we extended the deadline, and they did. It's good that we did. And we've never made people wait so long to find out who our winner is for a contest. But it was worth it because we got a bunch more really good ones.

You know, I'm sorry. We just don't have time to mention everybody. So be proud. Be glad. You gave us your support. Put it on your blog, whatever you want, if you don't hear it today. But know that we appreciate you. We had so many good ones, though. We figured we got to do better than just one winner, right? So we do have a second runner-up. Can we start with that?

Now, the second runner-up is actually the winner of the Best Kiss-Up Prize. Congratulations. And it is one of our regulars, makes us smile almost every week. Torsten Zimmer out there in Germany. Here's his kiss-up prize, and you'll know why when you hear it. He based it on our names. Not just you and me, but Emily. Excellent. Emily, exploration module including landing yacht.

Matt, moderately acceptable transportation tool. And Bruce, and I think you got the best one, bargain rocket, uniquely cost efficient. I really am. I am uniquely cost efficient. Few people realize that. Thank you for noticing. And congratulations on the second runner-up. No prizes, but our gratitude for being such a great kiss-up.

Now, first runner-up. First runner-up. Remember, the first runner-up, if the winner is unable to fulfill their obligations in any way, the first runner-up will probably not either. Congratulations, Sandy. Sandy Oakstead. Sandy, who was the random winner of the regular trivia contest just, I don't know, two, three weeks ago, something like that.

Here it is. Here it is. Sandy's new name that we will suggest to NASA for the CEV, the Crudabaker. Nice. Beep, beep. Beep, beep. The Crudabaker. I love it. I love Crudabaker. Nice. Beep, beep. Beep, beep. The Crudabaker. I love it.

I love Crudabaker. Put a little horn in it? Yeah, Crudabaker. Perfect. You know, in space, no one can hear you honk. Ah, ah, ah, ah, ah, ah, ah, ah, ah, ah, ah. You want to hear the real winner. That's actually why there are no geese in space.

Turns out. There had to be a reason. Yeah, yeah. We've wondered that for a long time. I do. I want to hear the winner. Well, here it is. It's another acronym.

It came to us from Dwayne Deal. Dwayne, congratulations. You're our big winner. Rochester, Minnesota. Now, you've got to hear the whole thing. All right. Because it's not funny until the very end. Okay.

I won't laugh. The acronym is ALICE. Oh, wait. You promised. I'm sorry. Astronaut Lift and Interspace Craft for Exploration. No, it's not funny. It's actually not a bad name.

Astronaut Lift and Interspace Craft for Exploration. When they are ready to take off, the captain would say, To the moon, Alice! Bam! Now? Now you can laugh. That's funny. Now, for those of you too young to know about it, look up the Honeymooners and Jackie Gleason.

You can probably find one online. But for us old guys, that's pretty damn funny. That is. That is. And it supports exploration beyond low Earth orbit. And, Dwayne, you're going to be getting not just a Planetary Radio T-shirt, but a poster. What, a solar sail poster, I think? Great.

So congratulations and thank you. Thank you very much. Back to a somewhat more normal trivia contest where you don't have to make us laugh, although we really enjoy it. We don't mind. As of September 7, 2005, how manyly Ships have visited the International Space Station? These are the robotically controlled spacecraft that resupply the space station. How many have visited the International Space Station as of September 7th? So that includes the one that's there right now, will be burned up in the ocean,

but not the one scheduled to launch on September 8th. Go to planetary.org slash radio, find out how to enter our contest and compete for the glorious Planetary Radio t-shirt. And get those entries to us by Monday, September 12th at 2 p.m. Pacific. Monday the 12th at 2 p.m. Pacific. And we promise we'll make sure that you're in that random drawing among all the correct answers for this brand new trivia contest. They're really going to have to pull their little Google thinking caps on tight this time because I don't think this will be that easy to find. I could be wrong. Well, we'll find out.

We'd prefer that you do it by first principles or go to Kazakhstan to the launch site to try to look at a number of scorch marks or something like that. But if you must, look on the web. We're all done. All right, everybody, go out there. Look up at the night sky and think about darkness. Ooh, darkness. Thank you.

Good night. Well, I think it's Bruce Betts. I can't see him. It's too dark. But he is the director of projects for the Planetary Society, and he joins us every week here on What's Up. Hello, darkness, my old friend. Planetary Radio is produced by the Planetary Society

in Pasadena, California. And here's an interplanetary welcome to our newest radio affiliate, CHON-FM in Whitehorse, Yukon, Canada. Thanks for joining us. Have a great week.