LIVE - "10 minutes about OSIRIS-REx mission "
Uploaded on October 9, 2018
LIVE - "10 minutes about OSIRIS-REx mission "
2018-10-09 - For World Space Week, we will present you "10 minutes about OSIRIS-REx mission " with CSA expert Tim Haltigin. (Credit: Canadian Space Agency)
Tim Haltigin: Good afternoon, everybody and welcome to 10 minutes with the CSA. This is a series of online virtual seminars where we get to share with you some of the fun collaborations and projects that we're working on, here, at the Canadian Space Agency.
So, my name is Tim Haltigin and I am the Senior Mission Scientist in planetary exploration at the CSA, and today I want to spend a bit of time with you talking about a mission we're working on that is going to take us on a journey through the history of the solar system. So, this is 10 minutes on OSIRIS-REx.
Now, to set the stage a little bit let's wind back the clock by a couple of years to September the 8th, 2016. We were sitting under a beautiful, perfect, near cloudless sky and just past 7:00 pm at Cape Canaveral in Florida, watching an Atlas V, 411 rocket blast off, carrying with it a spacecraft about the size of an SUV, that is going to allow us to virtually go back in time by four and a half billion years, to help us unravel some of the mysteries of the earliest history of the solar system. So, this was this OSIRIS-REx spacecraft that went on its way.
Now, OSIRIS-REx is a collaboration that is led by NASA, that has a mission of going to an asteroid named Bennu; imaging it; taking various measurements of it; collecting a sample of it and bringing that sample back to Earth so that we could study it here, in laboratories.
Now, the reason this is so awesome is that asteroids; you can think of them almost like a cosmic time capsule - these are the leftover remnants that went into build the planets. And so essentially, what happened is that this is material that has locked-in the chemistry of the early solar system and really hasn’t changed over the last several billion years. And so, if you're able to go and grab a piece of an asteroid and bring it back, essentially, what you're doing is you're going back in time by four billion years, to understand the chemistry of the early solar system and what the materials were really like that went into forming the planets. And so, this is a mission that really is going to help us understand how the Earth was formed in the first place.
Now, since its launch the spacecraft has had quite an adventure. It has been chasing asteroid Bennu through space and its first year after launch went around the sun and started to approach the Earth again, and actually flew underneath the Earth, under Antarctica and got a gravity assist that helped shape its trajectory and put it on a path towards Bennu. Since then, it has still been chasing Bennu and it has travelled almost two billion kilometres since it left.
And what is particularly exciting for us is that we're only six weeks away from arrival. So, at the beginning of December of 2018 the science team gets to start its proximity operations, or its real science mission, and so we're getting really, really pumped, getting ready to do this.
Now, I know this sounds -- you know, easy enough; hey, you just launch a spacecraft and you go and chase an asteroid and go grab a piece of it. But obviously, it's not that simple. We've got an awful lot of work ahead of us, in the next couple of years, in getting ready to figure out where we can collect the sample from. And one of the most important things you need to do is understand the shape of the asteroid very, very well, to make sure that you can locate somewhere where you can bring the spacecraft in safely, deliver it and collect a sample.
Now, Canada's role on the mission is that we have contributed an instrument called the OSIRIS-REx laser altimeter - or OLA. And you can think of it sort of like a 3D scanner that is going to map the asteroid. We're going to shoot lasers that -- and map it and get a very high precision map of the topography. And so, as we get closer and closer to the asteroid, into about seven kilometres and down to about 225 meters away, we're going to be using OLA to fire laser pulses out and measure the shape and create a shape model and understand the topography of the surface of the asteroid extremely, extremely well.
Now, the way this works is kind of like a radar, but instead of using a radio wave it uses light. And so, using laser transmitters inside of OLA we shoot a pulse out that bounces off the surface of the asteroid and comes back to the instrument. And what you do is measure very precisely the time it takes for that laser pulse to go out, bounce off the surface and come back. And if you can measure the time accurately, essentially, what you have done is you have measured a distance between the spacecraft and the asteroid.
Now, imagine doing this at two different locations on the asteroid - you would get two points. Imagine if you took 10 different points around the asteroid. You could see how the shape model starts to build in complexity.
Now, imagine shooting it, say, at a hundred different locations, or even a thousand different locations. You start building up this data that is going to help you recreate the shape of the asteroid's surface. Now, imagine doing it a million times, or even more than that. OLA is going to take over one billion individual laser shots and we're going to know the surface of this asteroid - that is 500 metres across; we're going to know one measurement every seven centimetres across the entire globe, and so we're going to understand this perhaps better than any shape we have understood in the solar system ever.
And then we wait. We're actually in the wrong place in space to come home right away and so we have to wait for almost a full year before we can start the return cruise, and then it's two years to get home. So, in September of 2023 there's going to be a canister about this big landing in the Utah desert with some very, very precious cargo inside. And it is exactly this cargo, these samples, that we are so excited about getting and being able to analyse.
Now, as much as OSIRIS-REx is a mission about understanding our past, this is very much a mission for the future as well. Because as we have learned with sample return missions, this -- it's sort of the gift that keeps on giving. You can think about the Apollo missions, for example, which brought back samples from the Moon in the late 1960s and early 1970s. Even today, almost 50 years later, we're still making brand new discoveries.
So, imagine what we're going to be able to do with these? What is the world going to be like in 2030? Or in 2040? In 2050? I mean, we will be able to ask questions that we just don't know how to ask yet, and we're going to be able to answer them with technology that just flat out doesn’t exist.
And so, that's one of the reasons I'm so proud to be working on this mission is that it's really paving the careers for generations of scientists, in the sense that it is our job, as a mission team, to go and get those samples and bring them back to Earth, but for any of the young people and students who might be watching today, it is very much your job to be ready to work on them.
So, with that I will say thank you and I'm just so excited about this mission. We're six weeks away from starting. You can follow the adventure along on the mission website, on the Canadian Space Agency website, on our Facebook page, our Instagram feed, and our various social media platforms.
So, now, I guess we will take some questions from online.
Okay; so, the first question we've received is: Why did you choose asteroid Bennu? Well, that is an excellent question. Right now we know of approximately half a million asteroids and so obviously, down-selecting from half a million to one was a bit of challenge. But there are a number of criteria that went into the decision-making. First, out of those 500,000 or so asteroids we're aware of there's only a certain proportion of which that we can get a spacecraft to, that have the right orbit that we can reach.
Now, of those, there's even a smaller percentage where we can get a spacecraft there and back. Of those, there are only a certain number that are of the right size, that we're interested in. If asteroids are too small they actually spin really, really quickly, and the faster they spin the more difficult and the more dangerous it is to try to place a spacecraft in contact with it. And so, Bennu is about 500 metres across and rotates once every 4.3 hours, which is safe for our spacecraft engineers to plan a trajectory to go and touch it.
So, asteroids that we can get a spacecraft to; asteroids we can get a spacecraft back from; large enough. And of those there were only five that had the composition that we were particularly interested in studying and of those five Bennu is one of the asteroids that we have characterized extremely well using instruments on Earth. And one of the objectives of the mission is to compare how well we can measure asteroids from the Earth, versus how we measure them while we're right there, at the asteroid. So, we ended up with Bennu as our final choice.
Okay. Next: When will Canada get its sample portion? Well, that's a great question - thanks for asking. So, in return for its contribution of OLA, Canada actually gets a portion of the sample that comes back. Now, this is the first time that Canada has ownership of any astromaterials from a sample return mission, which is why we are really excited, in Canada, about this.
Now, the spacecraft or the Earth return capsule comes back in 2023, in September. It will then be then be transported to the Johnson Space Center in Houston, where it will be -- the sample will be examined in what is called its preliminary examination, and that will go on for at least six months. So in early to mid-2024 we can expect that the Canadian portion will be subsampled and brought home to Canada for Canadian scientists, for generations, to study.
Okay. So, let's move on, then, and we will take a question from Instagram. What kind of information do you intend to get by mapping the surface of an asteroid? So, this is really the OLA science question. With OLA -- as we mentioned, it is obviously -- we need to understand the shape of the asteroid extremely well in order to collect a sample from it. So, the sample head that is at the end of the arm only has about 15 degrees of movement on it, and so, when you're coming in to take a sample, essentially, what you have to do is you have to come in perfectly square to the surface, and if you don't understand the shape of the asteroid, it's sort of a 30-centimetre scale - you're running the risk of not being able to collect a sample in the first place.
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