Asteroid in near-Earth orbit - sampling mission for building blocks of life
Did organic molecules get to Earth from asteroids? OSIRIS is NASA's mission to collect a sample from an asteroid in a near-Earth orbit. The asteroid is half a kilometre in diameter and hence has no gravity. To get the sample, the mission will 'kiss' the asteroid. The sample will be tested to determine whether if it contains the building blocks of life. The mission will be launched in 2011,will arrive in 2013, spend a year there, then return in 2017.
Michael Drake: I'm principal investigator on a mission called OSIRIS which is an acronym but is also an ancient mythological god of Egypt responsible for delivering agriculture to the Nile delta. We're going to a near-Earth object that originated actually in the main belt. We want to go to a near-Earth object because they're relatively easy to get to compared to going out to beyond Mars to between Mars and Jupiter where the main belt of asteroids are.
What we want to do is relate it, amongst other things, to the life issue. Earth went through a phase which we call a magma ocean phase where the planet was completely molten to at least 1,000 kilometres, and this probably actually happened repeatedly as the planet grew. Any organic material that was there would have been sterilised, would have been broken down to pure carbon.
There is no good understanding of how life got started on Earth. One possibility is those individual carbon atoms somehow became self-assembled into more complex organic materials here on Earth. But we know that the universe is actually replete with organic molecules, and organic-rich asteroids exist and there's a very good probability that the organic material that ultimately led to the origin of life came in after the Earth cooled and oceans had formed from space in the form of chunks of organic-rich asteroids.
So we want to go and return a pristine piece of an organic-rich asteroid and get a sense of what the building blocks for the origin of life might be. We don't know what we're going to find, that's the nature of exploration obviously. We're going to launch in 2011, get there in 2013, spend about a year at the asteroid, at some point, when we understand the asteroid well enough, go down and sample it, and then come home. We get home in 2017 and return to Utah where the Genesis solar wind samples and the Stardust comet samples landed, and hopefully we have a nice soft landing on Earth. Then we'll disseminate samples around the world to qualified scientists, including many of the fine scientists in Australia who are my friends.
Robyn Williams: And of course this mission will be unmanned.
Michael Drake: Yes, this is a robotic mission. Human spaceflight is extraordinarily expensive. Putting humans in harm's way is not something you do lightly. There's a silly debate that goes on about human versus robotic spaceflight. The reality is they compliment each other. There are some things humans do much better than anything else. For example, we still have the best computers (namely our brains) that exist on the planet, and we can make real-time decisions in response to what we observe. On the other hand, we can't go in very hostile environments but robots can, and if you think about it here on Earth we use robots all the time as an extension of ourselves.
So this is a robotic mission. At some point it might be paving the way for humans, astronauts, to go to such an object. Maybe there are resources there-water or the organic material-that might be useful in a trip on to Mars, which is one of the ambitions of the American space program. I think that personally that's quite a long way off. It's technically a very hard thing to do. We don't know how to keep astronauts alive right now all the way to Mars. But one of the things we will have on our OSIRIS asteroid sample return mission is an undergraduate student-built experiment, and it's related to the question of; could we use asteroids somehow that come close to Earth and then go out to Mars and then back to Earth to, in a sense, hitch a ride to Mars with astronauts?
And when I say 'hitch a ride', we might land on them and bury ourselves in the soil, the 'regolith' as it's called, to shield ourselves from nasty radiation coming from the Sun and from the galaxy. Maybe we just shield ourselves from the Sun by hiding behind it all the way to Mars. But we're going to actually have undergraduate students here in the US build a radiation sensor that we'll bring back to Earth and figure out what the total dosage you would get if you were a human going out to roughly the orbit of Mars and coming back to Earth on a mission, in this case, that would last a total of six years.
Robyn Williams: How big is the asteroid?
Michael Drake: It's only a little over a half a kilometre in diameter, it's quite small. That poses some interesting problems in terms of how you get down to it because it effectively has no gravity, so you can't land on it in the normal sense. We have figured out a way to basically 'kiss' it, get our sample and come back off it again with a technique that we think will work. It's a little like a pogo stick, is the best way to think about it. We're quite confident that the sampling mechanism we have is going to work. We tested here at 1 G on Earth, we're actually going to test it in a vacuum at 1 G and we're going to test it in air in a parabolic flying aeroplane that simulates zero-G for a short period of time to make sure it's all going to work as best we can in the environment at the asteroid itself.
Robyn Williams: Well, we'll find out in ten years time. Quite extraordinary that this university seems to break all records when it comes to scientific papers and results, as measured by Pasadena. What's the figure?
Michael Drake: We've been sufficiently successful that when it comes to exploring the solar system, the amount of competed money, the money that you have to compete for, coming through the University of Arizona to explore the solar system (and it flows through the Jet Propulsion Laboratory) is larger than all other universities in the nation combined. I was quite astonished when I saw that number myself. And interestingly, up the road from us at Arizona State University, 100 miles north...Arizona State is number three in the nation. So the state of Arizona has done rather well its solar system exploration.
- Michael Drake
- Department of Planetary Sciences
University of Arizona
Tucson Arizona USA
- Robyn Williams
- David Fisher