Planetary Radio: Space Exploration, Astronomy and Science - Return From Ryugu: The Hayabusa2 Leader on His Mission’s Success

Episode Date: March 17, 2021

Hayabusa2 project manager Yuichi Tsuda and his team learned a lot from Hayabusa1, Japan’s troubled-though-successful mission that returned a sample from asteroid Itokawa. Now they are celebrating the recovery of a much larger sample from a different world: asteroid Ryugu. Dr. Tsuda joins Mat Kaplan for a fascinating, exclusive conversation about the mission’s 5-billion-kilometer journey and the great science to come. There’s more to discover at https://www.planetary.org/planetary-radio/yuichi-tsuda-hayabusa2See omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

Five billion kilometers to Earth, this week on Planetary Radio. Welcome, I'm Matt Kaplan of the Planetary Society, with more of the human adventure across our solar system and beyond. Some of you got that science fiction reference, right? We're not talking about oldie but goodie British sci-fi films. Our topic is the gloriously successful asteroid sample return accomplished by Hayabusa 2, the Japanese mission that is now voyaging to two other asteroids. Hayabusa 2 project manager Yuichi Tsuda is here to tell us about his spacecraft and the great science it has enabled.

Then we'll travel even further across the void to Saturn for the answer to this week's space trivia contest, courtesy of Bruce Betts. Bruce will also give us another what's up review of the night sky. I can't feel much better than I do when I see fresh wheel tracks on the red planet. So I'm a happy Mars camper looking at this week's edition of The Downlink. It's topped by an image taken by the Perseverance rover of its own mark on Mars. Just below are these headlines, beginning with a big sigh of relief. The 30-year-old Hubble Space Telescope is back in full operation after a software glitch put it in safe mode for a few days.

Hang on, old friend. The JWST is coming soon. Speaking of old friends, NASA's SOFIA observatory, the big infrared telescope carried by a 747, has discovered carbon in a comet. If you're going to have carbon-based lifeforms, you probably need several good helpings of element number six, and there seems to be plenty out there. Northrop Grumman will be developing the small two-stage rocket that will carry samples of Mars back to Earth. The NASA contract is another step in the sample return process begun by Perseverance. Want more? You'll find it every week at planetary.org

slash downlink. There are only a few days left to become part of the Planetary Society's 2021 Virtual Day of Action. Chief Advocate Casey Dreyer needs everyone on board before the online training session on March 28th. You can learn more at planetary.org slash dayofaction. Back to those 5 billion kilometers. That's roughly how far Hayabusa 2 had to travel to reach Ryugu and return. It was only when it had almost reached the asteroid that Yuichi Tsuda and his team saw

how difficult sample return would be. Almost all of Ryugu is covered with boulders, big ones that could seriously damage the spacecraft as it approached. This was just one of the challenges met as Hayabusa 2 managed to grab not one but two samples from the surface. It also dropped similarly successful mini-rovers, including one built by Germany and France. And as you're about to hear, it blew its own 18-meter-wide crater in Ryugu so that it could look below that messy surface. There was plenty of reason for celebration when, after six years in space, the probe finally sent its sample return capsule streaking through Earth's atmosphere to the Australian outback.

And it's not done yet, so neither is Yuichi. He joined me a few days ago from JAXA, the Japanese space agency. Dr. Tsuda, congratulations. I say that on behalf of myself, all the members of the Planetary Society, and all the listeners to this show. It has been absolutely wonderful to see the tremendous success of the Hayabusa2 mission, and welcome to Planetary Radio. Yeah, thank you for inviting me to this radio, and yeah, the Hayabusa2 is a really great success, even for us. I'm very proud of that.

You should be. Six years, 5 billion kilometers out there to the asteroid and back. Where were you on December 6th of last year, 2020, when the sample return capsules streaked across the sky and came to rest in the Australian outback. Were you in Australia? Unfortunately, no. I wanted to be there, but I was actually in the Sagamihara Space Operations Center. That's a control room of the spacecraft located in the center of Japan.

So I was controlling the spacecraft. So that spacecraft worked perfectly to the end to separate the reentry capsule precisely to Australia. And also after that, the spacecraft had to continue the flight to an extended mission. So I have to be in the control room to take care of the spacecraft itself. Obviously, someone had to stay at home and drive the spacecraft. But I know that there was a very excited reaction when you learned that the sample return capsule had arrived on the ground in one piece. That must have been absolutely thrilling.

Yes, yes, exactly. That must have been absolutely thrilling. Yes, yes, exactly. So when I saw the fireball in the sky of Australia, actually through the internet, the time was exact. Within one second of the era, also the direction was perfect. For us, Hayabusa 2 team,

it was a time we physically viewed the appearance of the spacecraft. And before that, we just watched the status of Haibusa 2 through the telemetry and data displayed on the computer. So like a virtual, at that moment, we could watch physically the spacecraft. That's a wonderful moment also for me and the team. Almost as exciting as being there in the Australian outback, I'm sure. It was a perfect ending to an essentially perfect mission. The capsule came back, I read, in excellent condition.

Was it in better condition than you expected? Yes, the capsule's condition was perfect and almost as expected. We found the landed capsule actually a few hours after the landing. Then after that, we brought the capsule back to the facility and opened it immediately. Everything was as planned and the condition of the capsule back to the facility and opened it immediately. Everything was as planned, and the condition of the capsule was very clean. We could not almost imagine that that capsule traveled more than 5 billion kilometers in the interplanetary field. Very, very clean, like new.

Truly amazing. I did just read that as we speak, the capsule may be put on display in a museum there in Japan so that the members of the public can see it. Is that still happening? Yes, we are planning that. In a few days from now,

we are going to display that to the public. But we are still to display that to the public. But we are still watching the condition of the situation of the COVID-19. We will decide soon. But in the Hayabusa 1 era in 2010, we did the same things. We displayed the returned sample to public and at that time many, many people came to see the capsule from all over Japan. That was surprising for me, like the space science community, that so many people are interested in space missions. in space missions. I'm not a bit surprised because we at the Planetary Society know how the public is often extremely excited to be able to participate in these successes.

Speaking of participating in these successes, I saw an image on the Hayabusa2 website of those two micro SD cards that contain the names and messages of members of the Planetary Society and many, many other people, and that apparently they came back in good condition and you're able to read the data off of those? Oh, yes, yes, yeah. So I have to thank the Planetary Society to collaborate with us. There are many names and messages in the micro SD card contained in the Venture Capsule. And that was already opened and the data was retrieved. To tell the truth, I was expecting some errors because of the cosmic radiation effect. Sure.

But in reality, what we confirmed was that there was no error. So that all the names and the message are contained as it was installed six years ago. And it works like a time capsule. So many of you may already forget what you put as a message to the SD card, but you will be able to remember soon. I look forward to looking up my own message. I know my name was carried by Hayabusa2 to the asteroid and back. Oh, you also did that. Oh, yes, absolutely. Well, I'm a member of the society for one thing, but I wouldn't have missed the opportunity. There were some other messages, messages of congratulations. And I promise we're going to of leaders of space agencies around the world.

And there is a colleague of yours, Dante Loretta. I know you know Dante well. He's been a guest of ours on Planetary Radio several times. And of course, he is the principal investigator for OSIRIS-REx, the other asteroid sample return mission out there. If you'll indulge me, I'd like to play that message that he sent to congratulate you and your team. Here it is. It's very brief. I'm incredibly proud of the accomplishments of the Hayabusa2 team. This mission has been groundbreaking in so many areas. Exploration of asteroid Yugu has shed new light on our understanding of the formation of our solar system and the properties and future of near-Earth asteroids. I'm particularly proud of our ongoing collaboration where we have worked together to understand

both asteroid Bennu and asteroid Yugu, interpret the results in terms of understanding the history of our planet, why Earth is a habitable world, and how the origin of life occurred here. And I'm particularly excited to get those Hayabusa 2 samples into our laboratories to perform detailed investigations and further our understanding of the properties of asteroid Yugu, and looking forward to comparing those to the properties of asteroid Yugu, and looking forward to comparing those to the samples from asteroid Bennu in just a few short years. Congratulations again on a historic, amazing accomplishment. Everybody here has been

cheering for you and rooting for you, and we're very proud of the amazing sample return from asteroid Yugu. Ganbatte kuduzai. So Dante Loretta, leader of the OSIRIS-REx mission, he has talked on our program a number of times about this collaboration between your team with Hayabusa2 and his. I think this is an important component of both missions. Do you feel that way? Yes, yes, sure. Yeah, Dante is a good friend of mine for around 10 years. And we have been discussing how to do the exploration of the unexplored asteroids,

both from engineering point of view and also from the scientific point of view. And we have been sharing the same type of problems and same type of difficulties for a long time. So for me, he is a very long time official friend. Because of this type of collaboration, both missions are mutually stimulated and motivated. I sometimes explain to JAXA's upper level or to the government that, hey, OREX is doing it this way, so we have to be more smart.

And in that way, we can propose more challenging things or sometimes more budget. Oh, that's good. Dante has also told me how much his team was able to learn from Hayabusa 1 because of the information that was shared there. And I know that you have also talked about, you know, that mission, which was also successful. In fact, there is a news item just recently about some science that has come from the sample returned by Hayabusa 1. But it was a troubled mission. Did you learn a lot? Did it help sample returned by Hayabusa 1. But it was a troubled mission. Did you learn a lot?

Did it help prepare you for Hayabusa 2? Yes, yes. Actually, I learned a lot. My career as a space engineer started from the Hayabusa 1. Hayabusa 1 was launched in 2003. At that time, I joined the JAXAA and I joined the Hayabusa-1 team. Since then, the Hayabusa-1 faced many many troubles and the landing was not perfectly successful but just faintly retrieved the samples of asteroid Itokawa. After that, the spacecraft lost the communication

for a few tens of days. Very fortunately, we could re-establish the communication. The fuel was lost after that because of the leakage in the pipe. using the another other backup strategy then we could finally bring the spacecraft back to earth and each moment this has one team worked very hard to solve the problem and i watched the way the team was solving the problem not always depending on the pre-planned way, but sometimes the team solved the problem in a totally different way using the equipment that was not expected to be used for that specific function. And in that way, we could finally bring the spacecraft back to the Earth. From that experience, we learned a lot. And for the Hayabusa2 mission, I am the lead of the engineering of the spacecraft.

So I tried to reflect all the lessons learned from Hayabusa1. I didn't want to experience again the bad experience of the Haibusa 1. So in that sense, the Haibusa 1 was a good teacher for the Haibusa 2. It is a very inspiring story. Really, success grabbed from the jaws of defeat, as we might say. I don't know if you had heard this story. It came out just a couple of days before our conversation that this one tiny bit of dust, and it was given the name Amazon because apparently it looks like the continent of South America, has been revealed to contain water and organics. What an amazing science result to get from this spacecraft that almost didn't make

it back to Earth. Actually, I haven't noticed about that news. I'm glad to tell you about it. Yeah, thanks. Yeah, but sometimes earlier than that news, there was, I think, another research finding the clue of water in the sample of Itokawa. Yeah, the surprising thing is that the Haibusa 1 returned 10 years ago. And after 10 years, the research is still continuing. Yes. So the return sample is really a treasure for scientists. Like a sample of the Moon by Apollo missions, the research continues for several decades. Equipment on ground evolved time by time.

So once we got the sample from the other celestial body, then we can make a research with the latest instruments on ground accessed by many worldwide scientists and they can do their own research in their own labs that's the important things it's also a great lesson considering the much larger sample that has now been returned by Hayabusa2, which I'm sure will be delivering the same sort of science for many, many years to come. Before we talk more about the sample return, I hope that you can talk a little bit about the science that Hayabusa 2 conducted at Ryugu even before, I mean, while it was at the asteroid still. What did we learn about the asteroid even before that journey back to Earth began? First of all, before we arrive at the Ryugu, only thing we know is from the light spot observed through the ground-based telescope.

And that's the only information we have to plan the mission. After we arrived at Ryugu, we were surprised that the shape is so odd. It looks like a top shape, what we call top shape. Actually, the top shape is the popular shape among the asteroid scientists. For example, the Bennu, which is a target of the Oryx mission, was known to have the top shape from the radar observation. But for Ryugu, we didn't have such a radar observation due to the geometrical constraints between Earth and Ryugu. So we are surprised that Ryugu is also a top shape. Just by chance, we became the first mankind to visit the top shape just before the OREC mission. Yes, yes.

Yeah, the next thing we are surprised is that the surface of Ryugu was bumpy and covered with numerous rocks all over the globe. We thought that there was no safe place to land the spacecraft. Again, much like Bennu. Yeah, yeah. So that terrain feature is also found in Bennu. In that sense, we share the same headache, both in Bennu and Lidu. Because of that, we had to completely change our strategy to make a successful landing. We delayed our original schedule by four months to change the strategy and make a more fine observation of the asteroids and to reprogram the spacecraft to do the more precise landing. There were many difficulties and for me, after we succeeded in that,

I thought that's the best experience for me from the other engineers. Finally, we succeeded in landing to the surface of the asteroid with the landing accuracy of one meter. So, you know, the asteroid itself is 3,000 million kilometers away from the Earth. So with that distance, one meter accuracy landing. So that's more than satisfactory. Oh, I think it's quite satisfactory, yes. Yes, yes. That's Hayabusa 2 project manager Yuichi Tsuda.

He has more to share, including a brief look ahead toward a Japanese mission to the moons of Mars. Stay with us. Space exploration doesn't just happen. In a democracy where you're competing against other priorities and resources, In a democracy where you're competing against other priorities and resources, we need to maintain a constant engagement in the political process to ensure the types of missions we want to see in the future. I'm Casey Dreyer. I'm the chief advocate here at the Planetary Society. I'm asking you to consider making a donation to our program of space policy and advocacy that works every single day to promote your values in space science and exploration to the people who make the decisions in our democracy. Your donations keep us independent, keep us engaged, and keep us effective. Go to planetary.org slash take action. That's planetary.org

slash take action. Thank you. Can I explain the whole history within the... Sure. The proximity of the Shamburyugu? A brief history would be great. Just briefly. Okay. So after the first landing was successful, that was February 2019. One and a half months later,

we did new challenges, which was to dig a hole or make an artificial crater on the surface of an asteroid by the kinetic impacting. For that, we developed the Nobel device called the Small Carrion Impactor, and that was very successful and finally we could make the 18 meter diameter and the three meter depth big hole on the surface of asteroid and through that we could obtain the the subsurface information not only the surface information but also the subsurface information of the asteroid or the internal structure of the asteroid. After that, one thing we wanted to do is bring the subsurface material back to Earth. So for that purpose, we attempted to do the second touchdown about three months later. And there was actually a huge discussion

whether we should do the second touchdown or not. But after the thorough discussion and the technical and scientific investigations, we decided to do that. On July 11th, in 2019, we did the second touchdown. And that was also very successful. And at that time, the landing accuracy was as small as 60 centimeters.

So we expected to get the subsurface material. So after that, we returned to the Earth. We already opened contents of the capsule and we already confirmed that the samples from two sites are included in the samples. So I hope we can say something about the component ingredient of Ryugu soon. of Viagoo soon. Absolutely, yes. And as you said, laboratories around the world looking forward to getting portions of that sample. Before you go on to that, though,

I have to mention this amazing image. We have a copy of it on the Planetary Society website that was taken, I read, about three seconds after Hayabusa 2 fired that impactor for the small carry-on impactor experiment at the surface of Ryugu. And you can actually see the material being blown off of the surface of the asteroid. It is truly one of the most amazing images I've ever seen come from elsewhere in the solar system. Yeah, it's really a dynamic image or dynamic movie. Yeah.

We also surprised that that kind of very drastic reaction occurs. Actually, we had the worst case scenario and the best case scenario in the and the always we are based, we try to be based on the worst case scenario. And in that case, we expected to have like one meter or two meter crater was generated. But in reality, what we found is that more than 18 meter diameter and the huge ejecta was blown up in the air to as high as like 40 meter or so. So it's a very drastic response. You made quite an impression, quite an impact on asteroid Ryugu, one might say. We will get to the samples, but I also want to mention these passengers that you were carrying on Hayabusa 2 that you also delivered to Ryugu.

In particular, that little lander called Mascot that was built by the DLR, the German space agency, in collaboration with JAXA and CNES, the French agency. And that resulted in even more stunning images from right there at the surface of the asteroid. I hope that people will either visit our website or yours and we'll provide these URLs, the web addresses, on this week's show page at planetary.org slash radio. But you must have been pleased by the success of Mascot and the other little spacecraft that you carried. Yeah, we had three Japanese robots called Minerva 2 and also the Mascot lander by the German and the French partners. They are all successful. As you said, the images and there are other science data, but especially images are very exciting to see. Stunning.

It's the scenery just in front of the robot on the surface. So the resolution of that image is less than one millimeter. And it's a color image. meter. And it's a color image. It's just wonderful to see the scenery of the outer celestial body. It's a new world. It really is. Literally. Okay. Those samples. Are they making, are portions of the sample now in laboratories in Japan? And have they started to make their way across the world? laboratories in Japan and have they started to make their way across the world? Yes. So after we opened the container of the capsule, then we first measured the weight of the sample, which the mass of the samples and which was 5.4 gram. Our criteria or mission requirement was 0.1 gram. requirement was 0.1 gram. So compared to that, 54 times heavier than that.

Very good return on investment. More than satisfactory. Yes, yes. We have three chambers, chamber A, B, C, and chamber A contained the sample from the first touchdown, and chamber C contained the samples from the second touchdown. And chamber B was open between touchdown number one and number two. And we confirmed, we saw some very fine grains in the chamber B. So that's also, that will be also interesting to investigate. Now in the curation facility in Sagamihara, we are picking up each sample from the chamber one by one. Each grain sizes from less than one millimeter to up to one centimeter. So one centimeter sample looks like a stone. So we are now making a

catalog of what we got. And soon, in early summer, we will start to analyze the compounds of the material. So what we call the initial analysis. And through that, we want to confirm how much, especially carbon-related material and also the water-related material are contained in that sample. Because for 45-second emission, carbon and water is the theme of our science. The scientists, I'm sure, cannot wait to get these particles into their spectrometers and start to look for these organics, which, because I know this was a carbonaceous asteroid, largely consisting of carbon compounds in water. It's a cliche to say so, but we are talking here, aren't we, about the building blocks of life. Yes, yes. We are focusing on the organic compounds, also the hydraulic minerals. We already estimated from the

in-situ observation in Ryugu that the sample is estimated to contain some organic material and also the hydraulic minerals. But we did not know exactly what type of compounds we have, especially for the molecular number of the organic compounds, if we have a very large molecular number, that means that material is composed of a series of carbon atoms. Very complex molecules. Very long chain of the carbon atoms. That's right, that's right.

So the complex molecules can be related to life easier. So through investigating that way, we may know how complicated material exists in the universe outside Earth. So important. I'm thinking because also, while we have all the meteorites that have covered the surface of Earth for billions of years, these are exactly the sorts of complex molecules and volatile compounds, which don't last more than, in some cases, minutes or hours or days or weeks in a meteorite that hits Earth. And isn't this part of why it's so important to pick up these pristine samples from asteroids and bring them home? That's right. So all the meteoroids came through the atmospheric reentries. So at least the surface information was buried or changed due to the very high temperature. information was buried or changed due to the very high temperature. Also, because the meteorites stay very long on the surface of the Earth,

so the contents should be changed. But the direct sample from the asteroid, the sample itself is contained within the very tightly sealed chamber in the reentry capsule. The contents inside the capsule has never experienced the Earth's atmosphere, even though the capsule itself experienced the reentry. And the contents were directly transported to the curation facility, which are clean and the environment is controlled and isolated from the Earth's environment. So now we have a very pure pristine material as it was in space. That's important scientifically. So really the best part of the mission may be yet to come because it will come from the science that is performed using these samples.

And as we mentioned earlier, Hayabusa2's work is not done either. Where is it headed now? And is the spacecraft in good condition for the years ahead and its next targets? in good condition for the years ahead and its next targets. Yes. After the capsule was separated to head to Earth, the main spacecraft diverted from the reentry corridor and flew away from Earth again. Now, as a mission extension, or we can say it's a bonus mission, we are aiming at visiting two new asteroids.

One is named 2001 CC21 and another is 1998 KY26. Those two are new to humankind and also very scientifically interesting. The first target, 2001 CC21, we will do the flyby in 2026, five years from now. For the 1998 KY26, we will arrive there, rendezvous there, in 2031, 10 years from now. And the spacecraft condition is currently very healthy.

And the fuel left aboard the spacecraft is more than 50%. Excellent. Which means that we can do the similar type of travel as a round-trip mission to Ryugu to the new targets. So we want to make full use of it to pursue extra science. target. So we want to make full use of it to pursue extra science. 2031, as we have heard many times on this program, exploring the solar system requires a great deal of patience. That's right, that's right. 10 years is short for space engineering and space science. At least

we have to think like that. I also read that these other asteroids, which Hayabusa 2 will visit, they play a part in another area of research, which I know is important to you and is important to a lot of us who live here on Earth, and that is planetary defense.

Is that element of the mission an important one to everyone on the Hayabusa2 team? Yes, that's right. The planetary defense is actually also a small part of our mission objective in the Hayabusa2 mission, the original Hayabusa2 mission. Hivesat-2 mission, the original Hivesat-2 mission. But for the extended mission, we put the planetary defense as one of the big pillars of our objectives. Because we are going to visit two asteroids, the first one, 2160-21, we will do the first flyby, which is going to be a very precise, controlled, very close flyby, which means that if we can do the same strategy, we'll be able to hit impact the asteroid. But instead of that, we will try to fly the spacecraft very close to the asteroid.

So it's like an impact experiment of the spacecraft. So from the engineering point of view of the planetary defense, the orbit deflection is one of the key technologies to be studied to avoid the impact of the asteroid to the earth. So this technology is expected to connect to that future technology. And also the second target, 9091 ky26, that's really an interesting asteroid. Its size is only around 30 meters, so it's very small. And the rotation period is as fast as 10 minutes. So it's a very fast-rotating asteroid. Many of these asteroids exist around the Earth's orbit. And sometimes they come into the Earth's atmosphere once in a million years or once in 10 million years and make

a vast disaster. So that kind of very small and fast-rotating asteroids are the good target to investigate scientifically to know more about the target of the planetary defense. Another very important

step as we learn how to defend our planet in, you know, ways that the dinosaurs weren't able to. It is good to hear that it has this element as well. Before we close our conversation, I hope that you can say something about another very exciting mission, which is coming up from JAXA, and that is the Martian Moons Exploration, or MMX mission, to Phobos and Deimos, launching, I believe, in 2024.

Aren't these, in a way, also asteroid missions? Because I know the thinking is that those two moons, once upon a time, were asteroids. Yes, yes, yeah. The MMS is scheduled, planned to be launched in 2024 and explore the Martian moons. The mission was originally inspired by the Hayabusa 2 mission. So actually, I was one of the proposer of that mission initially. The Phobos is about 10 times larger than Ryugu. So the environment is a little bit different from the asteroid. And also the Phobos

is trapped in the Mars gravity. So the spacecraft has to first go to Mars orbit and then reach Phobos. And in the return phase, we have to leave Phobos and then escape from the Mars gravity and then return to the Earth. So it's more complicated with the bigger propulsion systems. And the strategies are a little bit, actually very different from the HyperSat-2 mission. But we know how to deal with the sample return mission. And after we arrive at the targeted celestial body, then we can apply our technology to land or access to the surface of the bodies. So in that sense, the MMX is strongly based on the technical heritage of Hayabusa2. I am very personally looking forward to that.

And from my perspective, I hope this, like a descendant of Hayabusa 2, will do well in its mission. That would be a descendant to be very proud of. And with those samples returned from Phobos, which is the target for sample return, I know, it is just possible that we will be getting back a sample from Mars itself, isn't it? I mean, because there is material from Mars that has ended up on Phobos. MMX could be a Mars sample return mission. Yes, yes. Yeah. So going to Mars surface, it's very challenging. NASA is already been doing so, but returning the sample from Mars is even difficult. Yes. But yeah, as you said, that some of the particles or samples of Mars may exist in the surface of the Phobos.

And that's something we are aiming at by the Phobos sample return. Dr. Tsuda, you have painted a very bright picture of the future, both for Hayabusa 2 and MMX. And we know that JAXA has many other plans underway. But of course, our purpose here is largely to congratulate you again on the tremendous success of this mission that you have led as the project manager. Thank you so much for spending this time with us today to tell us about Hayabusa2 and best of success to you and your team and JAXA with all of these great plans for the future. Yeah, my pleasure. Thank you very much.

I'm very happy to introduce about the Hayabusa2 to the public and the world and also in the U.S. Thank you very much for this opportunity. Yuichi Tsuda leads the Hayabusa2 team that has successfully returned material from asteroid Ryugu. I think I need to apologize before we turn to What's Up. By the time I discovered a problem with my audio track, it was too late to re-record this week's segment with Bruce. Maybe you can pretend I'm talking to you in a Zoom session?

On second thought, I'd hate to subject you to another one of those. Hey, it's time for What's Up on Planetary Radio. So, the chief scientist of the Planetary Society is here. He's here every week to tell us about the night sky and bring us a contest and random space facts. There's just so, so much. Welcome back. Thank you. Joy will just so, so much. Welcome back. Thank you. Joy will be had.

By all. Well, most people. Almost all. There's a couple of people over there in the corner who look kind of sad. Hey, over there, cheer up. Bruce is here. Hey, I'm here. And hey, night sky, still cool after all these years and millennia.

And, well, you get the idea evening sky uh still got mars and aldebaran and taurus looking very similar like twins in the southern southwestern sky pretty high up and mars will be to the upper right of aldebaran in the early evening or mid evening. And they are similar in brightness, similar in color. On the 19th, they will be near the moon as well. And in the few days after that, they'll be at their closest point together, about seven degrees. That's that's about 14 moon diameters for those playing the home game. And in the pre-dawn sky, getting higher all the time are Jupiter and Saturn. Jupiter looking super bright, Saturn looking yellowish up above it. And they are low

in the east, very low in the pre-dawn. We'll be getting higher over coming months. Have to admit they're getting higher. They're getting higher. I just saw a Ringo Starr interview by Stephen Colbert. I did too! It was so cool! Wasn't that great? He looks like he's much younger than us. He looks like he's about, maybe not much younger than you actually, but a lot younger than me. He looks good.

He does, yeah. He's the Ringo man. On to this week in space history. It was 10 years ago that MESSENGER went into orbit around Mercury, the first Mercury orbiter. Going back further to 1965, this week the first spacewalk occurred by Alexei Leonov of the Soviet Union. And moving forward to a dark day that was hidden from much of the world for a long time, in 1980, 50 workers died at the Soviet launch pad in a rocket explosion.

On to random space fact. Not the way the Beatles would do it, but not bad. Not good, not Beatles. Maybe Wings. Maybe Wings would do it. I would love to speculate with you on this, but I think we'll need a different podcast. So instead, I will tell you about something you've been hearing about, Hayabusa 2. They had what they called a solar sail mode.

I don't know if you know it, Matt, but I'm kind of into solar sailing. A little. It wasn't a solar sail, but they used solar radiation pressure, this push of light used by solar sails for propulsion. They used it to help control the spacecraft orientation during several months of the mission and were able to use just one reaction wheel to change the orientation of the spacecraft on one axis rather than having to use all of them. It was designed in part using lessons learned from their solar sail mission, ICAROS. I did not know this. Had I known, I might have brought it up with Dr. Tsuda, but I'm very glad that you have. He published papers talking about it. All right, we move on to the trivia question I asked you. Of the spacecraft which used Venus for a gravity assist maneuver, you, of the spacecraft which used Venus for a gravity assist maneuver, which went farthest out in the solar system? How'd we do, Matt? A moderate but very nice response this time around. And we

got this poem, which is really quite impressive, from Gene Lewin in the state of Washington. And so I'm going to let him answer the question, and you can confirm. In order to travel to planets afar and sometimes out of our galaxy's hood, the assistance of forces provided by mass are used and results are quite good. Approaching a planet, and sometimes the sun, can serve as a way to change speed and adjust the velocity to such a point that lets us get to the place that we need. Cassini employed this racket, we know, and traveled furthest of those on this list. Even Serena, the noted queen of the court in doubles, needed a Venus assist. Surprise ending. Didn't see it coming.

No, neither did I. i was reading it uh gene hey congratulations and thank you is he correct is it cassini it is indeed cassini multiple spacecraft have used venus for gravity assist cassini went the farthest out all the way to saturn our winner and he's the first time winner winner, once again, Ben Drout, who said, yep, Cassini performed two gravity-assist flybys, Venus, just a Venus, and then those others, Earth and Jupiter. Ben, who is in Dubuque, Des Moines, Davenport, Mousetail Town, Mason City, Keokuk, Ames, Clear Lake, ought to give Iowa a try. I'm not saying which of those he lives in, but it's one of those. Congratulations, Ben. We are going to send you that copy of The Lion of Mars by the award-winning children's author Jennifer Holm.

It's a terrific book for young adults. And we'll throw in a Planetary Society rubber asteroid as well. Darren Ritchie, he says, we're full of music today. Well, a cheer anyway. Give me a V, give me a V, give me an E, give me a J. What does it spell? Saturn. Yes, the initials were often used to describe the seemingly crazy orbital mechanics maneuvers used to fly by planets to get out there to Saturn. From Laura Dodd in California, Northern California, now I wonder if Cassini also traveled the greatest number of miles during its mission

to and around and around Saturn, which I doubt. Wouldn't Voyager 1 have an edge just for traveling for so many years? Oh, yeah. Voyager 1 and Voyager 1 have an edge just for traveling for so many years? Oh, yeah. Voyager 1 and Voyager 2. All the friends in Sweden, although I understand the principle, it always fascinates me that going the, quote, wrong way, unquote, first makes the best journey, makes for the best journey. And finally, from our poet laureate, Dave Fairchild, when our Galileo went to Jupiter

to play, it got a gravity assist from Venus on the way. Cassini said, that's good for you, but I can do better. I'm headed out to Saturn, where I'll be the new pace setter. Thank you all. Here's a question for you for next time. What was the Hayabusa 2 small carry-on impactor's projectile made of? This is the SCI. There are more than one projectile on Hayabusa 2, or there were.

So pay attention. Small Carry-On Impactors Projectile. What was it made of? Go to planetary.org slash radio contest. And I did come across this in my research, but it did not come up in the conversation with Dr. Tsuda. So go for it, folks. You have until the 24th. That's March 24th, Wednesday at 8 a.m. Pacific time. And you know what I discovered? We have a lot of great books piling up at the office. And so, I mean, these

are great, great space books. And I think we're going to give away a series of these, beginning with this extra copy we got, one we gave away some time ago, by Wade Roosh, a great science writer, called Extraterrestrials from MIT Press. It's a fun little book. It goes through the various answers people have given to that question from Enrico Fermi. Where is everybody? through the various answers people have given to that question from Enrico Fermi, where is everybody? It can be yours if you were chosen by random.org and hit us with the right answer for this one. Keep those cards and letters coming. Well, no, we don't need cards and letters,

but if you want to send us a nice card, why not? I think we're done. All right, everybody, go out there, look up in the night sky, and think about what object in the solar system you'd like to hit with a two kilometer per second projectile thank you good night it's that asteroid out there that has my hometown's name on it i want to hit it with what you say two kilometers a second i think i want to hit it about 400 years before it impacts. Will that do? That should do. Depending on how big it is, we'll have to look into your hometown. It's a good-sized town. That's Bruce Betts, the chief scientist in the Planetary Society,

who is here every week for What's Up. I'm back in full voice. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by its members throughout the world. Mark Hilverda is our associate producer. Josh Doyle composed our theme, which is arranged and performed

by Peter Schlosser at Astra.