NASA plans to launch a spacecraft Saturday bound for a group of asteroids known as the fossils of our solar system. WAMC's Jim Levulis spoke with Dr. Tom Statler, program scientist for the Lucy Mission, about the undertaking.
Statler: Well, we're really excited to be sending Lucy off on this mission to the Trojan asteroids. It's a 12-year voyage to eight different asteroids with one spacecraft. It's never been done, and we're going places no one has ever seen. The Trojan asteroids are leftover raw materials from the formation of the outer planets, Jupiter, Saturn, Uranus, and Neptune. And they share an orbit around the sun with the planet Jupiter, but they're not at all close to Jupiter. They're sort of 1/6 of a lap ahead and 1/6 of a lap behind. So our spacecraft is going out as far as even farther than the distance of Jupiter. But we're not going to Jupiter. We’re going in two totally different directions.
Levulis: And NASA refers to these asteroids as the fossils of our solar system. What gives them that distinction?
Statler: Well, for one thing, they are four and a half billion years old. They are bits of the original material that condensed after the formation of sun and they did not get incorporated into planets. Like I said, they’re leftovers. And so they're fossils in that way. But they're also fossils because of where they are. They're in these special orbits that orbit along with Jupiter. And we're still working on understanding how that happened. The best evidence is that the reason they're there is because of a really sudden rearrangement of the planets early on in our solar system’s history. It looks like Jupiter, Saturn, Uranus, and Neptune, at the beginning of our solar system were much closer to the sun than they are now. And because of their gravitational interaction with each other, there was an instability and they suddenly rearranged themselves into the configuration we've got today. And a side effect of that was to trap leftover bits from all over the outer solar system into these groups. So if that's right, when Lucy gets there, we're going to find a wide variety of very different asteroids that came from different places in our early solar system.
Levulis: And so what in particular will the Lucy spacecraft and the Lucy mission be measuring, looking for as it studies those asteroids?
Statler: Well, the spacecraft is going to be flying by each of these asteroids at a speed of around four to six miles per second. And that's because there's no way we could possibly carry enough fuel to actually slow down and stop or land or do anything like that. So we have a suite of instruments on the spacecraft. There is a high-resolution telescopic black and white camera to show us the basic geology and details of craters and cliffs and whatever else is there. We've got another camera that is registering multiple colors and spectra in detail to figure out the detailed reflectivity of the surface that tells us what minerals are there, what compounds, tells us about chemical composition. And then we've got another instrument that is like a remote no touch thermometer to measure the temperatures of the surfaces, that's going to give us a hint into what the consistency of the surface is. Is it dusty? Is it gravelly? Is it rocky? Is it solid rock? And then we'll use the radios on the spacecraft to very, very precisely measure the change in the Doppler shift as the spacecraft flies by, and that's going to tell us the gravity of these asteroids, allowing us to measure the mass. So we're basically figuring out the basic vital statistics of each of these asteroids as we go by.
Levulis: And how might all that information help us better understand how our solar system formed and perhaps even our life started on earth?
Statler: Well, the important thing we've come to understand is that none of the planets formed in isolation. You know, it's easy to think that the earth is here and Jupiter is impossibly far away and couldn't have had any influence over what was happening on Earth. But we understand that that's really not the case. All the planets were forming at around the same time and developing at the same time. And so what was happening in the outer solar system affected what was happening on the Earth. For example, this rearrangement of the orbits that I mentioned, that may have sent a huge number of asteroids into the inner solar system that might have impacted the earth in large numbers, impacted the moon. Some of this might have been responsible for the huge numbers of craters that we see on the moon. And we also know that there are a lot of asteroids that are very abundant in ices, in water ice and other kinds of icy materials, and also in carbon varying materials. And so it's possible that what was happening in the outer solar system had some influence on how Earth acquired its water, how Earth acquired the carbon-based compounds that might may have set the stage for the emergence of life. I wouldn't go so far as to say that the Trojan asteroids are going to tell us about what happened on Earth. But it's all part of this big picture that we're trying to figure out scientifically.
Levulis: That's fascinating. How did the mission come to me named Lucy? That's an interesting name.
Statler: It’s a great story. So Lucy is not an acronym for anything. Strangely enough with NASA where everything is an acronym. Lucy is named after the Lucy fossil. It's the fossil of one of the earliest human ancestors known that was discovered in Ethiopia in 1974 by Donald Johanson and his team, and that fossil really revolutionized our understanding of the development of the human species. And we're expecting that in a similar way, the Lucy mission is going to revolutionize our understanding about the evolution the development of our solar system and our planets. The other angle on that is, why is it Lucy and not Agnes or something else? Donald Johanson’s team when they were excavating the site in Ethiopia, this is in 1974, they had a lot of tapes, and they were playing Sergeant Pepper's Lonely Hearts Club Band. And people really liked Lucy in the sky with diamonds. So somebody in the team said, hey, let's name the fossil Lucy, as the name stuck, so the fossil has been named Lucy ever since. And that's why the mission is named Lucy.
Levulis: Sometimes the idea just presents itself right there. How can people follow Lucy on its mission?
Statler: In any number of ways, so you can always go to nasa.gov/Lucy for the latest news and on social media on Twitter and Facebook. The handle is #LucyMission.
Levulis: And then finally, Tom, I was looking over your bio, and I noted that you have an asteroid named in your honor. How did that come about?
Statler: I do. Well you know, at the beginning, there were very, very few asteroids and they were very hard to discover. So the prerogative to suggest a name for an asteroid lies with the discoverer of the asteroid. That person can suggest a name to the International Astronomical Union for approval. And when asteroids were hard to discover, it was very important to name asteroids after things that were quite important. There are a lot of asteroids being discovered now. And so I had the privilege having made a contribution to asteroid science before my NASA career when I was a professor doing research, having made a contribution my colleagues in the asteroid field were really wonderful to nominate me to have an asteroid named after me. It's a wonderful honor. There are lots of asteroids. And I think in the future, there will be opportunities for many, many prominent people in all kinds of fields, not just science, to have asteroids named after them.
Levulis: And if I have my information correct, that is asteroid 9536 that is named in your honor.
Statler: It is 9536 and I'll shout out to my asteroid neighbor, Mike Nolan, my good friend who is asteroid 9537.
