NASA’s asteroid sample retrieval spacecraft is ready for launch. OSIRIS-REx is an ambitious mission to the asteroid Bennu, a mountain-sized “near-Earth object” that scientists believe holds the secrets of the solar system’s origins. Today, September 8, at 7:05 p.m. EDT (weather permitting), it will launch into space and begin a two-year journey to Bennu. The mission team will eventually choose the most scientifically interesting spot on the asteroid and direct the spacecraft to make contact and take a physical sample. It will return to Earth in 2023 and eject the sample capsule, which will parachute down to Utah’s west desert.
The science objectives of OSIRIS-REx are right there in its name: Spelled out, it is the Origins Spectral Interpretation Resource Identification Security-Regolith Explorer. The vehicle carries a payload of five scientific instruments and a sample collection arm called the Touch-and-Go Sample Acquisition Mechanism (TAGSAM) to help it accomplish each of the key words or phrases in its name. Each instrument and its purpose is explained below.
1. ORIGINS: BRINGING A TIME CAPSULE FROM THE BIRTH OF THE SOLAR SYSTEM BACK TO EARTH
“This is really what drives our program,” Dante Lauretta, the principal investigator of the mission, said on Tuesday, September 6 at a press conference held at Cape Canaveral, where OSIRIS-REx will launch from. “We’re going to asteroid Bennu because it is a time capsule from the earliest stages of solar system formation, back when our planetary system was spread across as dust grains in a swirling cloud around our growing proto-star.” Bodies accumulated in the cloud, many getting water ice and organic material—key compounds that led to the habitability of Earth and the origin of life. Bennu is one such body. By taking a hopefully carbon-rich sample of the asteroid and bringing it home, planetary scientists will be able to study in a laboratory setting a pristine cache of the building blocks of Earth.
Lauretta describes sample return as being the forefront of planetary exploration. If Bennu is a time traveler from the distant past, sample return is time travel to the distant future. As new laboratory techniques and technologies are developed, they can be applied to the samples. Scientists today will be able to study the samples at the parts-per-million level. Fifty years from now? Who knows what technology will have been developed. To appreciate how massive an advance might be in store, consider that 50 years ago, computers were only just being introduced to the field of geology. Now we can study the composition of many bodies in the solar system.
2. SPECTRAL INTERPRETATION: ANALYZING BENNU’S COMPOSITION
Since Bennu’s discovery in 1999, scientists have used the best telescopes on Earth and in space to study the asteroid. As such, they have an extraordinary data set from which to work, and believe they have a pretty good handle on the asteroid’s composition. The spacecraft, up close and personal with the asteroid, will use its spectrometers and cameras to provide “ground truth” to the distant observations of telescopes. Scientists will be able to see how well their predictions matched reality. What they got correct will have confirmation; what they got wrong can be used to refine their models. All of this can then be applied to thousands of other objects in the solar system.
3. RESOURCE IDENTIFICATION: EYEING FUTURE MINING OPERATIONS
Lauretta tells mental_floss that when OSIRIS-REx was first conceived, resource identification was “cool science fiction.” The idea of going to asteroids and mining them for material was the sort of thing people in some Jetsons-like future would be able to do, but not us. Today, however, companies are lining up for the chance to begin celestial mining operations. OSIRIS-REx will be pioneering the technologies and capabilities necessary to provide detailed global analysis of an asteroid’s surface. They will be able to focus on composition and mineralogy with an eye toward identifying regions of interest. It will be, in other words, creating the sorts of prospecting maps once seen in the Old West—only this time for an off-world ore-rush.
4. SECURITY: STUDYING BENNU’S TRAJECTORY TO AVOID POTENTIAL ASTEROID COLLISIONS
Earth’s orbit around the Sun is startlingly perilous. Bennu, to name only one near-Earth object, has small-but-not-small-enough chance of colliding with this planet in the 22nd century. (The odds are 1 in 2700, which is about the same as your odds of dying by exposure to smoke or fire. That’s a pretty terrifying figure when you consider the destruction and damage that such an asteroid impact might cause, and that people die in house fires all the time.)
Scientists will use the data returned from OSIRIS-REx to study something called the Yarkovsky Effect. As asteroids go about their orbit, they absorb energy from the Sun and emit that energy as heat. That emission essentially acts as a small, natural asteroid thruster, and changes an asteroid’s trajectory over time. In the seven years that scientists have known about the existence of Bennu, the Yarkovsky Effect alone has changed the asteroid’s position by about 100 miles. If they can get a grip on the phenomenon and its causes and effects, they can apply it not only to Bennu but also to thousands of objects throughout the solar system. If something bad is coming, we can know about it—and perhaps find a way to stop it.
5.REGOLITH EXPLORER: UNDERSTANDING HOW SURFACE PARTICLES BEHAVE IN MICROGRAVITY
Regolith is the blanket of dust and gravel on the surface of many celestial bodies. Scientists don’t quite understand random mechanics in a microgravity environment. Even if Bennu’s sample collection arm was unsuccessful, “By the act of putting our [Touch-And-Go Sample Acquisition Mechanism] device on the surface of the asteroid to collect the sample, in and of itself we are performing a fantastic science experiment,” says Lauretta.
The science begins in 2018. The journey begins today.
September 8, 2016 – 8:00am