August 17, 2011
NASA Spacecraft To Visit Asteroid
NASA has announced that it is planning to send a spacecraft to a distant asteroid in five years to gather samples of what could be the building blocks of all life on Earth.
The OSIRIS-REx spacecraft, if all goes well, will intercept asteroid 1999 RQ36, orbit it for one year, and then reach out a robotic arm, touch the surface and grab up a handful of dirt and then return to Earth with the precious sample."We call it "Ëtouch and go'," said principal investigator Michael Drake of the University of Arizona. "OSIRIS-REx will approach the surface at 0.1 m/sec (only 0.2 mph, less than a tenth of walking pace) and, without landing, stretch out its arm equipped with a sample collector. We'll simply agitate the asteroid's surface with ultra-pure nitrogen to stir up material for capture."
Based on previous observations of 1999 RQ36 from ground-based telescopes, scientists believe the asteroid is rich in carbon-based compounds. NASA's hope is that some materials brought back from the asteroid can shed light on life's origin on Earth.
Some scientists also believe Earth's surface was sterilized soon after the planet was formed 4.5 billion years ago. Planetoids and other debris left over from the creation of other planets pummeled Earth, turning into a cratered wasteland. The tremendous kinetic energy from the collisions heated Earth to the boiling point.
"Earth at 'time zero' had a steam atmosphere that was wrung out to make a boiling hot ocean," said Drake. "Imagine standing on a lava lake in Hawaii, but it's a planet-wide, 600 mile deep lake. You and everything else, including any organics and any one-celled organisms, would be converted to carbon dioxide and water. Gone."
In this scenario, an infusion of organic materials from elsewhere might be required to create life on Earth. The building blocks for life on Earth may have come, at least in part, from asteroids.
The mission will also serve another purpose. Astronomers have been searching for ways to divert near-earth objects (NEOs) from smashing into the planet. Until now, that feat has only been able to be accomplished in the movies, such as in the films Armageddon and Deep Impact.
A program is underway at the European Space Agency (ESA) to learn more about how Earth can be defended from the potential impacts of asteroids. ESA's Project Don Quixote is expected to begin a year earlier than the OSIRIS-REx mission, and will involve a couple of spacecraft in a test to determine whether near-earth objects can be diverted.
The OSIRIS-REx mission will also help NASA learn how to navigate close to asteroids, preparing them for the day they will be able to land a craft on one.
Upon reaching 1999 RQ36 sometime in 2019, the spacecraft's cameras and instruments will spend a year studying and photographing the asteroid and measure its surface topography, composition, and thermal emissions. Its radio will provide mass and gravity field maps. The information gathered will help scientists get a better understanding of the asteroid and also help the team select a suitable spot to grab a sample.
The mission has other implications as well. Asteroid 1999 RQ36 is the Near-Earth Object "Most Likely to Succeed" in impacting our planet. Of all near-earth objects in space, 1999 RQ36 has a 1/1800 chance of hitting Earth by the 22nd century.
"We're the first species that can mitigate asteroid extinction," said Drake. "With enough information, we can project the orbit of a threatening asteroid."
If researchers can track the precise path of 1999 RQ36, as well as other NEOs, they can devise a way to nudge the object out of a collision course with Earth. "If you simply pushed your finger into the surface, you'd fly off into space, disappear, and never come back!"
NASA plans to offer near-live coverage of the operations, but the real action begins when the sample comes back in 2023, said Drake.
Image Caption: Conceptual image of OSIRIS-REx. Credit: NASA/Goddard/University of Arizona
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