Within the next five years, the U.S. space agency NASA plans to launch a robotic rendezvous mission to a nearby asteroid to retrieve rock samples scientists hope can shed new light on the formation of the solar system and the building blocks of life on Earth. The mission also has another purpose: to learn more about the asteroid which is on a collision course with Earth.
The asteroid, named 1999 RQ36, orbits the Sun every one-and-a-half years and crosses Earth’s orbit each September.
Experts say the 575-meter-wide asteroid is on track eventually to collide with Earth, sometime in the year 2182, with potentially devastating results. But those same experts are quick to add that such a collision is unlikely to happen.
Well before 2182, they believe, scientists will have devised a plan to deflect the huge rock into a new and harmless orbit.
Michael Drake, director of the University of Arizona’s Lunar and Planetary Laboratory in Tucson, is principal investigator of NASA’s OSIRIS-REx asteroid mission, now set to be launched in 2016.
The unmanned spacecraft will rendezvous with the asteroid and use a suite of specialized cameras and infrared spectrometers to provide scientists with a wealth of data about the giant space rock.
Drake says astronomers and engineers are already studying the best ways to nudge 1999 RQ36 out of Earth’s path.
“There are strategies such as putting a large Mylar sail, maybe say a half mile [about 800 meters] across its surface - that in itself is an interesting engineering challenge - and using photons from the Sun to sail it away much like a sailboat works on the ocean.”
Drake says another strategy for moving the asteroid into a safer orbit would be to paint one side of the dark rock white. That would change the amount of sunlight it reflects, leading to a difference in the solar photon pressure on each side and a change in the asteroid’s course.
Researchers also hope the mission will answer some fundamental questions about life on Earth.
A little more than a year after observing 1999 RQ36, the OSIRIS-Rex space probe will move in close over a period of weeks and will extend a mechanical probe to collect dust from the surface of the asteroid, which Drake says is likely to be rich in clues to the origins of life on Earth.
Asteroids are the rocky remains from the formation of the solar system some 4.6 billion years ago, and Drake says 1999 RQ36 contains an abundance of amino acids, or protein building blocks, in addition to pristine organic materials not found anywhere on Earth.
Drake says scientists believe the organic materials they expect to find on the asteroid are similar to those that bombarded the Earth after it cooled down enough for liquid oceans to form:
“We don’t see any of [the material] in our meteoric collections to date probably because the material is too fragile to survive through the Earth’s atmosphere," he said. "That doesn’t mean individual molecules didn’t get through. But we’re not recognizing them because even if they are falling today, their signal would be swamped by all of the life around us. We’d never detect it.”
Because there’s no gravity on the asteroid, Drake says the spacecraft will synchronize its movements with the massive rock as it moves to within a few meters. It will collect dust samples by “kissing” the surface with a spring-loaded extension arm that will bounce on the surface every five seconds, kicking up the dust with puffs of nitrogen gas and gathering them into a small chamber.
Scientists hope to collect between 60 grams and two kilograms of dust, which will be stored in a sample collection capsule attached to the OSIRIS-Rex space probe. The probe will then bring the capsule back toward Earth, arriving in 2023. When it nears the planet, it will jettison the capsule, whose heat shield will protect it during its fiery re-entry into earth’s atmosphere. A parachute will slow the capsule down and land it safely at a recovery site in Utah.
Drake says the organic material from the asteroid will be studied by scientists all over the world for many years to come.
“For example, the Apollo [lunar rock] samples collected between 1969 and 1972 are being studied today," said Drake. "And in many cases by people who weren’t even born at that time using scientific instruments that weren’t even designed or conceived of at that time, and asking questions we don’t know how to ask at that time simply because we didn’t know enough to ask the questions. And so it’s a legacy that drives science literally for generations.”
In an earlier version of this story we incorrectly reported the name of investigator Michael Drake as William Drake. VOA regrets the error.