NEW YORK • For the next two years, Nasa's robotic spacecraft will be chasing down an asteroid near Earth in the hopes of scooping up some of the most primordial bits of the solar system.
Osiris-Rex's mission is simple: Fly to an asteroid, grab some of the rock and bring it back to Earth, where scientists will study the pristine ingredients that went into the making of the solar system, including possibly the building blocks of life.
"What was that beginning organic material like?" the director of Nasa's planetary science division, Dr James Green, wondered. "That's what's really exciting... This is what we want."
The details are a bit more complicated.
The spacecraft is sitting on top of an Atlas 5 rocket at Cape Canaveral, Florida, ready for its launch tomorrow on a seven- year mission.
Osiris-Rex - a shortening of Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer - will be aiming to get close to the asteroid Bennu.
Discovered in 1999, Bennu is a carbon-rich, almost black asteroid. Data from Nasa's Spitzer Space Telescope and radar measurements by ground- based radio telescopes suggest it is a "rubble pile" with pebbles about 1.3cm wide on the surface.
Scientists believe it is a conglomeration of leftovers, largely unchanged in the last 4.5 billion years. "It's a time capsule from the earliest stages of solar system formation," said Dr Dante Lauretta, a professor of planetary science and cosmochemistry at the University of Arizona, the mission's main investigator.
Osiris-Rex will survey Bennu for more than a year to select the site where it will grab the sample of rock. In July 2020, it is to descend slowly and bounce off the surface like a pogo stick at a gentle pace. A sampling head, which looks like a car engine's air filter, will shoot a burst of nitrogen to kick up dirt and small rocks during the three to five seconds it is in contact with the surface.
After departing Bennu in 2021, Osiris-Rex will pass by Earth in September 2023, dropping off a capsule with the samples that will land in a Utah desert.
A Japanese mission, Hayabusa 2, will similarly collect samples from another carbon-rich asteroid.
Dr Lauretta said he was particularly interested in gleaning information about organic molecules such as amino acids, the building blocks of proteins that are known to float in outer space. One question is whether Bennu contains higher concentrations of the 20 amino acids used by forms of life on Earth compared with dozens of others not found in living organisms.
Scientists also hope that waterlogged minerals in the sample could tell whether the water in Earth's oceans came from asteroids like Bennu.
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