Launched in December 2014, the asteroid explorer Hayabusa 2 is now cruising in outer space as scheduled. It will arrive at the asteroid 1999 JU3 in 2018, the same year that NASA’s OSIRIS-REx is due to arrive at the asteroid Bennu. Both the Japanese and American explorers are attempting to unlock the mystery of the birth of the solar system. We interviewed the principal investigator of the OSIRIS-REx mission, which is now in preparation for launch, scheduled a year from now.
* This article was published on September 4, 2015.
Going after organic material
— What is the purpose of OSIRIS-REx?
OSIRIS-REx will drop its capsule to Earth, but will not land (courtesy of NASA/Goddard/University of Arizona)
OSIRIS-REx is an asteroid sample return mission. The purpose is to send a robotic spacecraft to a near-Earth asteroid called Bennu. We will spend almost one year mapping the asteroid, looking at the minerals, the geology and the physics of its surface, and then we will select a site and send our spacecraft down for a “touch and go.” We will collect a sample, and then leave the asteroid’s surface and return the material to Earth for scientific analysis.
We will launch OSIRIS-REx in September 2016. The spacecraft will come back to Earth one year later for an Earth gravity assist – that is, using the gravity of the Earth to change the trajectory of the spacecraft – and then reach the asteroid in August 2018. The plan right now is to get the sample in October 2019, 14 months after we arrive at the asteroid. But the spacecraft won’t leave the asteroid until March 2021, coming back to Earth in September 2023. It’s a very long journey – same as Hayabusa 2, only the capsule comes back and the spacecraft stays in orbit around the sun. So maybe we can send it on another mission, to another asteroid or something.
— How will you collect the sample?
Collecting the sample using TAGSAM (courtesy of NASA/Goddard/University of Arizona)
TAGSAM under development (courtesy of Lockheed Martin)
We have a device we call TAGSAM – the Touch-and-Go Sample Acquisition Mechanism. The head is a filter that’s about 30 cm in diameter – like an air filter. It’s on the end of a robotic arm, which also carries three bottles of nitrogen gas. We put the head out in front of the spacecraft, the filter touches the surface – just a very short contact. And it’s like a vacuum cleaner – we send the gas down, it swirls around, and then we suck it up through the filter, which catches the soil. It’s like we’re vacuum cleaning the surface of the asteroid. We can do it three times if we have to, but hopefully we just have to do it once, because I worry a lot about what will happen when we hit the asteroid – the properties of the surface are uncertain.
So we take our sample, we open up the return capsule, we put the sample in, remove the head, and then close it. A camera watches and makes sure that everything is lined up properly. And if we get enough of a sample, then we just come home. The science requirement is a 60-gram sample.
- Playing Tag With an Asteroid
- NASA animation with a step-by-step illustration of the OSIRIS-REx mission’s sample-collection plan.
— Why did you choose Bennu?
We chose Bennu as the target because its orbit is very close to Earth, so the energy needed to get there and bring a sample home was low compared to many other asteroids. We also chose it because its surface looks like it has a lot of carbon, and we’re very interested in organic molecules. Maybe asteroids led to the origin of life on Earth, so we want to understand the organic chemistry of these asteroids, which are ancient pieces from the early history of the solar system. One of objectives of this mission is solving the mystery of the solar system’s birth. So it’s a combination of engineering – the asteroid is easy to get to – and science, which requires organic material.
The biggest challenge: touchdown
— What is the most challenging thing about the mission?
Asteroid Bennu imaged by radar (left) and shape model (courtesy of NASA/JPL-Caltech (left), NASA/NSF/Cornell/Nolan)
The most challenging thing is touching the asteroid to get the sample, because we don’t understand the nature of the soil on the asteroid. Asteroid Bennu is very small – only 500 meters across. To most telescopes, that’s just one point of light. We have radio telescope data from the Arecibo Observatory in Puerto Rico, and we were able to get a radar map, but that’s not really a picture. We know the shape of the asteroid from the radar data, but… we don’t know if it’s like quicksand? Is it very hard? Is it slippery? Is it dangerous? The radio map doesn’t give us this kind of important information for touching the asteroid. So the first thing I worry about is, is it really going to be difficult, or is it going to be like we imagine? Will our design work well? We’ll know that in August 2018, when we get the spacecraft’s camera close enough to take a picture.
We watched the Hayabusa mission very carefully, and something happened when they touched the asteroid. We don’t know what happened, and so we wonder why Hayabusa had problems when it touched the asteroid Itokawa. We’ve tried to think of everything that might go wrong, and to make sure our spacecraft is strong and can survive, but still, you are flying a spacecraft into an asteroid that you don’t understand very well. Even touching the asteroid is a science experiment. So, obviously, the engineering is a challenge, but the harder challenge is other things.
— What are those things?
The harder challenge is keeping up the team morale. Even though I’m a professor at a university, NASA put me in charge of the mission, and I have control of the science and also the budget and the schedule. My team consists of 450 people. I have to make sure they are happy and healthy, because it’s a stressful job; make sure they have the resources they need to do their work; and make sure they understand how valuable they are. So the job really is managing a very large team of people with very different skills and personalities, and keeping everybody focused on the mission’s success. The engineering is hard, but the really hard part is the big team.
OSIRIS-REx is a partnership between the University of Arizona, which is an academic institution, NASA, which is a government agency, and Lockheed Martin, which is a private company – very different cultures. So that is the biggest challenge.
I started in 2004, and sample analysis will be done in 2025. Making this mission succeed will take 21 years of my life. So I have to think about the whole story from beginning to end. And I will definitely make it a success.
— What are your hopes for OSIRIS-REx?
OSIRIS-REx (courtesy of NASA/Goddard/University of Arizona)
I have many hopes for OSIRIS-REx. First, I hope we are successful, that everything works well: the Atlas V rocket gets us into space, the spacecraft gets to the asteroid. We want it to be interesting, but also safe to get a sample from the surface. And then of course I hope that Bennu has many secrets about the early solar system, and that we bring back a sample that is a scientific treasure that many people can study for generations. We hope the asteroid is exciting, but not too exciting – because it may be too challenging.
— What’s the current state of development of OSIRIS-REx?
We are one year from launch. The spacecraft is almost completely built. The hardware – the flight system – is coming along very well, and we are now installing scientific instruments on the spacecraft. So we will leave Colorado, where Lockheed Martin is located, and go to Cape Canaveral, Florida in May 2016, and make the final preparation for launch in September.
Making the most of Hayabusa’s results
— What is the influence of the first Hayabusa?
Itokawa imaged by Hayabusa
Hayabusa was a great mission – an amazing accomplishment. I was very excited to see the data come back from the Hayabusa mission. We started OSIRIS-REx in 2004; we got the first pictures of Itokawa in 2005. So when we were first designing the mission, we had no pictures of Itokawa, and we thought we were going to get a sample like from the moon, which is very fine powder. We were still going to go with the vacuum, but we thought we would be designing a vacuum for fine dust. And then we saw Itokawa, and we said, “Oh my God, that’s what a small asteroid looks like?” It was so strange and different than anything we had ever imagined, because it was lots of big boulders and no fine particles, and a strange shape, like two big boulders touching each other. And then the Muses-C region, which is where the smallest particles were, had gravel – rocks one or two centimeters in size. And so we decided we needed to design to grab gravel and bigger rocks, because there was probably no fine dust on the surface of the asteroid.
We have telescope data on Bennu. Bennu is bigger than Itokawa, and it’s shaped like a sphere, while Itokawa is more like a peanut. And Bennu also looks smoother. Its surface is smoother, and the grains look like they’re smaller, maybe less than a centimeter on average. So I told my team, “Design the spacecraft to go to Itokawa.” I think Itokawa is more rugged than Bennu, so if we can design a mission that will get a sample from Itokawa, then we should be able to get a sample from Bennu. We’ve used Itokawa as our “design case.” We’ve designed the mission for Itokawa, and we think Bennu’s environment may be a little more gentle in comparison.
And then we also saw the challenge of touching the asteroid, because they had some problems when they tried to get the sample – the spacecraft was damaged when it contacted the asteroid’s surface. We have studied what happened to Hayabusa, and how can we make sure OSIRIS-REx survives the same kind of event. So the Hayabusa mission was really valuable to us. And of course the sample from Itokawa came back, and we are now thinking about everything we’ve learned about the asteroid from the sample. There were small dust particles that came back, and that is helping us plan our sample science for OSIRIS-REx as well. So Hayabusa was a great mission.
— What do you think about the Hayabusa 2 mission?
I think it’s a very bold mission, because they want to get three samples, and, as I said, I worry about getting just one sample. So to go for three is bold. And they also have a bomb that will explode and dig a crater on the surface of the asteroid. That’s a very challenging experiment. By coincidence, the Hayabusa 2 and OSIRIS-REx operations are happening at the same time. They launched in 2014, we launch in 2016, but they both arrive in 2018. It takes them four years to get to the asteroid, it takes us two years to get to our asteroid, and then it takes them two years to come home and it takes us four years to come home. It’s a very interesting coincidence in many ways. We want to make good use of the opportunity.
“We’re much stronger if we help each other”
— What are your plans for promoting cooperation with Hayabusa 2?
OSIRIS-REx probe nearing asteroid Bennu (courtesy of NASA/Goddard/University of Arizona)
There’s an agreement between NASA and JAXA that says NASA will get part of the Hayabusa 2 sample and JAXA will get part of the OSIRIS-REx sample. So we are talking to each other about collaboration between the science teams. The timing is really great because we will be at the two asteroids at the same time, so we can really talk to each other and share personnel. We will have some Japanese scientists in Tucson, Arizona, and we’ll have some of our scientists here in Japan helping each other explore. It is important to exchange information while we are operating our spacecraft.
The plan is for Hayabusa 2 to get the first sample in, I think, October 2018. That’s about one year before we go for our sample, so I want to know what happens to Hayabusa 2 when they touch the asteroid. This is the biggest unknown and the biggest danger for OSIRIS-REx, so we really want to understand what the surface is like when you touch it. You know, it could be so soft that you just sink, or it could be so hard that you bounce off. So we really want to know what the soil is like on the asteroid surface, and then we have a year to study before OSIRIS-REx goes and gets its sample. This is very valuable to OSIRIS-REx. It’s very good for reducing the risk for our mission, so I’m very grateful.
On the other hand, one of the areas where we can help Hayabusa 2 is software. We have spent a lot of time and money developing software that can create a three-dimensional image of the asteroid. We have offered to share the software and our people who work on it with the Hayabusa 2 team, so that we can help them with the shape model and with the navigation around the asteroid. We are talking with JAXA about all of these areas. We’re much stronger if we help each other, and share lessons learned and ideas about how to make the mission safe.
— So it sounds like collaboration can produce great synergies.
Hayabusa 2 will collect samples from an artificial crater (courtesy of Akihiro Ikeshita)
We really have an opportunity to come up with one sample-science plan to study both types of materials. For example, Hayabusa 2 wants three samples, and we want one. We kind of look at it like it’s really four samples of asteroid. And so if parts of 1999 JU3 look like parts of Bennu, and Hayabusa 2 gets that sample, then we probably won’t go to that spot on Bennu. We’ll pick something that looks different from the Hayabusa 2 area, so that we can get diversity of material. We can make sample collection more valuable by working together to pick the four sites, three from JU3 and one from Bennu.
I’m very good friends with the people who are working on Hayabusa 2. I look at us as pioneers. Hayabusa 2 and OSIRIS-REx are both pioneers studying asteroids, and we have the same will toward studying asteroids. The science is very similar. And by studying two asteroids, the science is increased maybe four times, because not only do you get two samples, but you get to compare the samples to each other and learn why they are different, and how they are the same. So the science becomes more powerful because of the diversity of material.
Space is the best place for exploration
— What is your research specialty in planetary science? How did you become interested in it?
I studied meteorites for most of my career. My interest started when I was a college student in 1993, and I got a research grant to study the search for extraterrestrial intelligence – in other words, aliens that have technology. We were using radio to see if we could find another planet where there were intelligent people with technology. We didn’t find anything, but it got me thinking about who else it out there. Are there other planets? Is there life on these planets? And is that life intelligent and does it have technology? That really was exciting to me. I wanted to learn how life started, and how common it is. So I decided I needed to understand the origin of our solar system. How did the Earth form? Why does the Earth have oceans? Why does the Earth have life? And that led me to meteorite science, because meteorites are pieces from the early solar system.
— Were you interested in space as a child?
I always wanted to be an explorer. I wanted to go someplace where nobody had ever been before, like climb a mountain or go to the bottom of the ocean, or something like that. But on Earth there are not very many places left to discover. That’s what made me interested in outer space, because that’s where there’s still a lot of places to explore. I don’t get to go personally, but I can build a robot and send it, and that’s kind of like a part of me that is going. So it was really the desire to be an explorer that led me to think about outer space as the best place for exploration.
“Each mission will keep building on the one that came before it”
— What is the attraction of exploration?
Comet 67p/Churyumov-Gerasimenko imaged by Rosetta (courtesy of ESA/Rosetta/Navcam)
Exploration is being the first to see a new world, when you go somewhere nobody has ever been before and it’s beautiful. We saw the pictures from Rosetta, the European Space Agency mission. That comet is amazing, and unlike anything we ever imagined. Every time we go to a new world we are surprised and in awe of the beauty and the diversity of the solar system. And there are so many places to explore. The Earth is so tiny compared to the vastness of even our solar system, and the solar system is so tiny compared to the galaxy. It’s just almost incomprehensible what a tiny piece of the universe we are, yet we are so special because we can think, and we can build machines, and we can ask questions about all these things. Only mankind has always had a great curiosity about an unknown world.
— What are your expectations for the Japanese planetary mission?
I have many Japanese colleagues from meteorite science and from planetary science, and they’re the best in the world. I think the Japanese have a very excellent space program. Our Japanese colleagues should be very proud of the vision of the leaders here. I heard that after Hayabusa 2, they may go to Phobos or Deimos, one of the moons of Mars. This would be an amazing mission, and a very important mission for science. I really am impressed by the technology that has been developed in Japan, and with that technology, picking this challenge makes sense. JAXA has clearly developed excellent capabilities for asteroids, so it’s a perfect combination to do Mars exploration by going to one of its moons and bringing a sample back. I’m hopeful that maybe we can be a partner, or contribute to this great mission.
What’s really important, I think, is that you have a continuous set of opportunities, because the missions are so challenging. As I said, it’s hard to manage a big team, but once you have a team that has succeeded, the chance of the next project succeeding is so much higher if you can put them to work right away: “Okay, you just finished Hayabusa 2, now go to Deimos and get a sample.” If you just said, “We’ve got Hayabusa 2, now we’re not going to do anything for ten years,” you’re going to have to almost go back to the beginning and learn again how you did it. So I think the plan right now looks very promising, that each mission will keep building on the people and technology of the one that came before it. That is the real key to success, I think.
Dr. Dante S. Lauretta
Principal Investigator, NASA Asteroid Explorer OSIRIS-REx
Professor of planetary science at the University of Arizona’s Lunar and Planetary Laboratory
Dr. Lauretta began his studies at the University of Arizona, receiving a B.S. in Math and Physics and a B.A. in Oriental Studies in 1993. In 2001, after earning a Ph.D. in Earth and Planetary Sciences from Washington University in St. Louis, he joined the faculty of the Lunar and Planetary Laboratory. Dr. Lauretta was selected as a Kavli Fellow of the National Academy of Sciences in 2008, and received the Antarctica Service Medal of the United States of America in 2010, for his service as a member of the 2002-03 Antarctic Search for Meteorites. He is an expert in the analysis of extraterrestrial materials, including lunar samples, meteorites and comet particles.
[September 4, 2015 ]