NASA's Curious Universe - Asteroid Hunting

Episode Date: October 19, 2020

NASA's OSIRIS-REx spacecraft will attempt a daring feat: to briefly reach out its mechanical arm and grab a sample from an asteroid’s surface. Dante Lauretta, Heather Enos, and Ron Mink introduce you to NASA’s asteroid hunter and what this sample return mission means for us here on Earth.

Osiris Rex is a grand adventure of exploration in deep space. We built a robotic spacecraft and we launched it off the Earth and we sent it to a near-Earth asteroid named Benu. This is NASA's curious universe. Our universe is a wild and wonderful place. I'm Patty Boyd and in this podcast, NASA is your tour guide. NASA has sent a robotic spacecraft billions of kilometers from Earth to do something we've known.

never done before. Collect a sample of an asteroid. In this episode, we're exploring asteroid Benu, the target of our Osiris Rex mission. October 20th, 2020 is the culmination of an enormous amount of work by thousands of people all around the planet. We are getting ready to send our spacecraft down to the surface of asteroid Benu to collect our sample. That's Dante Loretta.

He's the principal investigator on the Osiris Rex mission. He's been with the team since the very beginning, 2004, preparing for this exact moment. Our goal is to get the treasure off the surface of that asteroid. We're scientists and we're geologists, and our treasure is in the form of rocks. But these aren't just any rocks. These are very special rocks. These are rocks that are older than the Earth that date from the formation of the solar system, and they hold clues to why the Earth is a habitable planet.

why we have oceans here, and maybe why the origin of life occurred. So we have the amazing objective of bringing those rocks back to the surface of the Earth so we can get them into our laboratories and study them in great detail. It's the first time an American spacecraft will attempt to collect a sample of an asteroid and deliver it to Earth. Scientists hope Osiris Rex will bring back the largest cache of dirt from space in half a century. Like moonsoil, from the Apollo era that scientists are still analyzing in their labs today, soil from Benu will be preserved for decades to come.

Future generations will have a chance to analyze it, people not yet born, using techniques not yet invented, answering questions we don't even know to ask yet. And scientists like Dante can't wait to get their hands on these samples. Studying asteroids is important for a few key reasons. One is they are the oldest geological samples from the formation of the solar system. Literally the oldest rocks that formed around the sun are found in asteroids. So what would NASA want with a bunch of old rocks? While analyzing those ancient rocks will help scientists understand the early solar system

in a way that studying Earth rocks can't. Those rocks don't exist on the surface of the Earth because the Earth is a very active geologic body, geologic body, it's got volcanoes, it's got rain, it's got erosion, it's got plate tectonics. So these rocks and the asteroids, they're over four and a half billion years old. There's nothing that old on the surface of the Earth. Benu is a deep space time capsule, a leftover fragment from the tumultuous formation of the solar system. It's been well preserved in the vacuum of space for billions of years.

Some of the mineral fragments inside Benu could be older than the solar system. These microscopic grains of dust could be the same ones that spewed from dying stars and eventually coalesced to make the sun and its planets nearly 4.6 billion years ago. Benu's makeup excites scientists.

It's thought to be rich in organic molecules which are the building blocks of life on Earth. And it's got the ingredients of another very important molecule locked inside its minerals. And you'll probably be surprised, but it's water. Water in space is incredibly valuable for a couple of reasons. Primarily, you can break it apart and make liquid hydrogen and liquid oxygen, and that is one of the most powerful rocket fuels that we know of.

The presence of water ingredients on Benu means that one day we may be able to use asteroids like space gas stations. You could have a space crassion. that's using liquid hydrogen and liquid oxygen, and then it could stop at Benu and get refueled, or you could bring that fuel back even to around the moon or near-Earth orbit, and you could use it to refuel vehicles there. Studying Ben-U will also help scientists understand the hazards of near-Earth asteroids.

Benu is also what's called potentially hazardous, which means it has a reasonably high probability of impacting the Earth in the future, creating a widespread natural disaster. And I don't want anybody to panic because the impact would be not for at least 150 years, but still, it's something I feel as a species we should be studying.

Benu is one of the most potentially hazardous near-Earth objects currently known. It's as wide as the Empire State Building in New York City is tall. And it has about a 1 in 2,700 chance of impacting Earth sometime between the years 2175 and 2199. Our ability to make a detailed study of the asteroid now helps us prepare for the future,

should Benu stay on a course towards Earth in the next century. It's kind of a gift to the future to go out and characterize this object because it's likely that some point in the future, maybe within the next hundred years, some group of people are going to have to figure out how to deflect this asteroid and prevent it from impacting the Earth. There's a lot of information locked up in the rocks and dirt on Beno's surface. But before scientists on the ground get the opportunity to study those samples, Osiris Rex has to collect them.

The spacecraft launched in 2016 from NASA's Kennedy Space Center in Florida with this goal in mind. Go Alice. Go Centaur. Go Osiris Rex. Everyone is Go. Standing by for launch? And liftoff of Osiris Rex. Its seven-year mission to boldly go to the asteroid venue and back.

Since launch day, Osiris Rex has had its eye set on asteroid Benu. For two years, it's made its way to the asteroid and has been in orbit ever since, circling the asteroid and mapping its surface in great detail, all in preparation for October 20th, the day it will attempt to grab a sample from the surface. On the ground, Osiris Rex engineers like Ron Mink have been preparing too. As a systems engineer, part of my job is to identify the bad things that could happen and to prepare for them. And so I'm thinking about risk all the time. Now, Benu, the asteroid, hasn't been very compliant with what we need at surface to be.

We first saw the asteroid in August of 2018. And that was one of the most exciting days of my life. Something I'd been planning for well over a decade was finally coming into focus. Literally, I could see the target. And then the asteroid got more and more resolved, and I just had this sinking feeling in my stomach because the surface looked really rough, rugged, and rocky,

and not what we were expecting. Our sample collector, we need to have, you know, particles that aren't much more than an inch in size to be collected. And there aren't very many places on Benu that have grains that small. And so we think we found the sweetest spot on the asteroid, and we're going to go there. But Benu may not want to give up her secrets. That's probably my biggest concern. We've done everything we can, but that's part of exploration.

Space exploration means being vulnerable. and sometimes trying things that no one has tried before. The Osiris Rex team has done everything they can to prep the spacecraft for its sample collection. They've even gone through rehearsals for the big day. Finding the right spot, one that's clear of boulders, is key. It wasn't easy, but the team found such a spot. They called it Nightingale.

It's a 52-foot-wide, relatively clear area inside a crater, a rare sighting on Baneu. And if Nightingale doesn't work out, the mission team picked a backup site, dubbed Aspre, where they can try for the second and final time to pick up a sample. These sites have the most evidence for fine-grained material on the asteroid and give Osiris Rex the best shot at collecting a sample. After years of hard work, the big day is here. If Osiris Rex succeeds in its mission,

scientists will get the opportunity to unlock secrets of the earth. early solar system. Even though the talented team is prepared beyond question, in space there's always a risk that things might not go according to plan. Even though we found a nice spot where we think there's lots of material that we can collect a sample from, there's still some pretty big rocks around that site. The biggest one I call Mount Doom, it's about 10 meters tall and it's just off to the east of the crater, and we absolutely do not want to fly into that.

We don't know what's going to happen when the spacecraft touches the asteroid surface. One of the things that might happen is it might tip over and start to move in another direction, and then it fires its engines to leave the asteroid surface. It could fly right into Mount Doom if it did that, if it tipped over too much. If the team can safely capture samples from Ben-U, there's a huge payoff. For Dante and the team, there's a lot riding on this moment. It's the culmination of many years of hard work for an entire team. On sample collection day, the stakes are high.

We are getting ready to send our spacecraft down to the surface of asteroid venue to collect our sample. As you can imagine, there's a lot of excitement, there's a lot of anxiety, and there's a lot of nervousness to make sure everything goes according to plan. I've been working on this program since 2004. Almost 17 years of my career has been focused on this one day to make sure everything goes according to plan. We have fought through everything that could go wrong on that day, and we've done our best as the team of engineers and scientists and managers to make sure we've mitigated all known risks.

That doesn't mean that things can't go wrong still. Because there's always the unknown nature of the asteroid surface and what's going to happen when we make contact. On the day of the sample collection, Osiris Rex will go through a series of carefully choreographed moves to prepare to secure rocks and soil from the surface of Benu. Osiris Rex was designed with these steps in mind. So Osiris Rex is a robotic spacecraft,

and it is designed to operate around an asteroid and eventually go down to the surface to collect those rocks. So there's some very special features about the spacecraft that allow us to do that. Osiris Rex has a number of science instruments on board that will do things like map the surface of Benu and provide information about the minerals it finds there. It's also got cameras and sensors to help it navigate and an arm that will collect rocks and dirt from the asteroid surface.

Even though Osiris Rex has the right tools to get the job done, sample collection can be pretty tricky. We need to get onto the surface into a parking spot-sized space with our spacecraft in order to collect a sample. And when you're doing that from 200 million miles away, it takes a lot of practice. That's Heather Enos. She's the deputy principal investigator for the mission

and will walk you through the steps of Osiris Rex's sample collection, a process called TAG. So TAG is touch and touch. and go. And what we mean by that is literally we are reaching out with the arm of our device, and we are touching and going. We don't land on Benu. We actually literally kiss the surface with the end of the arm. We're kissing the surface for about somewhere between six and 16 seconds, so it's a really, you know, after all of these years, it really all happens in less than 20 seconds. But leading up to that moment, Heather and the team will observe as Osiris Rex swoops closer and closer to the asteroid's surface, preparing to make contact.

The day of tag, it's about a four-and-a-half-hour sequence, we call it, and we will leave orbit. Currently, we're in a safe home orbit, we call it, around Benu. And we will command the spacecraft to get out of its orbit and start to slowly descend onto the surface of Benu. The spacecraft is going to fire its thrusters and leave orbit and very slowly approach the surface of Benu, taking images along the way. Osiris Rex will use those images and compare them to an existing catalog of the site. This helps the spacecraft make sure it's headed in the right direction. The whole time, Osiris Rex is going through the steps on its own. There's no one controlling Osiris Rex in real time from the ground.

All of this is preloaded, autonomous, and so once we hit Go, everything becomes autonomous. We're going to send up a set of commands that basically tell the spacecraft what to do from leaving orbit until leaving the surface. So it's on all automated commands. We don't have a joystick or an Xbox controller here on the ground to tell the spacecraft what to do, because there's going to be at about a 15 to 20 minute delay in our signal, so we can't talk to the spacecraft in real time that way. It's all pre-planned. Osiris Rex is fully autonomous.

It begins to descend closer to the asteroid's surface. At that point, we're about 125 meters from the surface, and that's our first opportunity to do our position and velocity checking and to make sure that our trajectory is, is on target. So then we would continue to go down a little bit slower, even yet. And then we do another check, which we call match point. And that will be at about 40 meters above the surface.

And then we have the, what we call our tag sam arm, touch and go arm, that is then deployed. And we slowly descend to the surface. Osiris Rex will aim to collect at least 60 grams of dirt and rocks, equal to a about 30 sugar packets. It does that by stirring up the asteroid surface. Think about a reverse vacuum cleaner. We actually use a gas bottle, a very high purity nitrogen,

to blow down on the surface in order to get the soil to move and to be agitated, because otherwise, with no gravity, things don't move around, and so we're forcing movement by blowing it down with the high purity nitrogen. It's a very clean, pristine gas, so we're not contaminating the surface with any. we've brought along. After stirring up the surface, the samples will float up into a chamber. Once Osiris Rex successfully secures them, the spacecraft will slowly drift away from Benu until it reaches a safe distance, and it will stay there until its departure in March 2021, preparing for its return back to Earth. When Osiris Rex reaches Earth in 2023, it will drop

the capsule with the samples packed inside into Utah's West Desmercans. where scientists will be waiting to collect it. We really refer to it as the mission that keeps on giving, and the reason that we call it that is we're bringing back this precious material back to Earth, and it's going to then be analyzed in laboratories at the macroscopic scale that we cannot do remotely. And getting these samples back to Earth will be a huge deal. It could literally change what we know about the history of our solar system.

That's why the data. day of tag will be an emotional one for the whole team. To get here, it really has taken a lot of time and a lot of people's passion and a lot of sacrifice. So you become personally attached to the spacecraft. It becomes human. The instruments become human. And it's not just a team after this many years of sharing this hard work and sacrifices and common passion with your team. It really becomes your family. You know, we hear a lot about the planets, you know, Mars and Venus and Mercury, there have been, you know, fabulous missions to all those objects and there, you know, some pretty incredible science and some incredible pictures.

But what I love about asteroids and comets is that each one of them is their own unique, small world. And there are, you know, literally tens of thousands or depending how small you want to look at, millions of them in the solar system that we can explore. And so, you know, I look at Benu as not just a base rocker, the flotsam left over from this formation of the solar system, but rather a unique world all of its own that has its own beauty and its own secrets.

And also in the case of Benu, it's its own dangers. Osiris Rex, it's an extension of me in so many ways, it's hard to explain. And it sends chills down your spine because you're like, wow, we are an amazing species. The human beings built this, this robot, and we sent it out on this seven-year billion kilometer journey to go get this material so that we could study it in our laboratories.

Cyrus Rex is all about inspiring the next generation of scientists and engineers and leaders to go after something big, whether in space exploration or in any field that you're passionate about, you can make it happen, and when it does happen, it makes your whole life worthwhile. This is NASA's Curious Universe. The Curious Universe team includes Maddie Arnold, Michaela Sosby, Margo Wall, and Vicki Woodburn. Our executive producer is Katie Atkinson. Special thanks to Rylent Heggy, Ronnie Gras, Nancy Neil Jones, Lonnie Sheckman,

and the University of Arizona. You can follow Osiris Rex as it completes its tag attempt in real time. Go to www.n.org. slash Osiris Rex. If you liked this episode, please let us know by leaving us a review, tweeting about the show at NASA, and sharing this episode with a friend. Still curious about NASA?

You can send us questions about this episode or a previous one, and we'll try to track down the answers. You can email a voice recording or send a written note to NASA-curious Universe at mail.nassah.org. Go to nassah.gov slash curiousuniverse for more information.