5 Goals of the OSIRIS-REx Mission to the Asteroid 'Bennu'

NASA Goddard Space Flight Center
NASA Goddard Space Flight Center

After almost two years in space, NASA's groundbreaking spacecraft OSIRIS-REx is now on its final approach to its target—the asteroid Bennu, a mountain-sized, near-Earth object that scientists believe holds the secrets to the origins of the solar system.

When it reaches Bennu on December 3, 2018, it will match the asteroid's speed as it orbits the Sun (63,000 mph), and fly in formation with it for the next couple of years as it maps and surveys the surface. Then, on July 4, 2020, OSIRIS-REx will reach out to Bennu with a robotic arm, scoop up a sample from the surface, and store it in a capsule. The next year, the craft begins heading back to Earth, where in 2023 it will eject the sample-containing capsule over the Utah desert for retrieval.

It's the first time in history this kind of sample retrieval has ever been attempted, and scientists are pretty excited about it. The mission objectives of OSIRIS-REx are embedded in its name: the Origins Spectral Interpretation Resource Identification Security-Regolith Explorer. The craft has five scientific instruments tasked with carrying out these objectives. Let's break it all down.

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 in 2016, shortly before the spacecraft was launched from Cape Canaveral. "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 described 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, scientists in coming years can use them to analyze the samples with far more sophistication than we're capable of today. 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 here on Earth. 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 told 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 pioneer 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 is only one of several near-Earth objects that have a small-but-not-impossible 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 a 12-year period, the Yarkovsky Effect changed Bennu's position by more than 115 miles. If researchers can better understand the causes and effects of the phenomenon, they can apply that knowledge not only to Bennu but also to thousands of objects throughout the solar system. If some object is headed our way, we can know about it sooner—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 is unsuccessful—it can make three attempts—Lauretta said the effort alone pushes the boundaries of research: "By the act of putting our device on the surface of the asteroid to collect the sample, in and of itself we are performing a fantastic science experiment."

Editor's note: This story originally ran in 2016 and was updated in August 2018.

How to See the Full Sturgeon Moon on Thursday

Brook Mitchell, Stringer/Getty Images
Brook Mitchell, Stringer/Getty Images

The full moon of every month has a special nickname. Some—like September's harvest moon, December's cold moon, and May's flower moon—have obvious connections to their seasons, while other names are harder to decode. August's sturgeon moon is an example of the latter. It may not be the prettiest lunar title in The Old Farmer's Almanac, but that doesn't mean the event itself on August 15, 2019 won't be a spectacular sight to behold.

What is a Full Sturgeon Moon?

The first (and normally the only) full moon that occurs in August is called a sturgeon moon. The name may have originated with Native American tribes living around the Great Lakes in the Midwest and Lake Champlain in New England. These bodies of water contain lake sturgeon, a species of freshwater fish that grows up to 6.5 feet in length and can live 55 years or longer. August's full moon was dubbed the sturgeon moon to reflect its harvesting season. This full moon is sometimes called the green corn moon, the grain moon, and the blackberry moon for similar reasons.

When to See the Full Sturgeon Moon

On Thursday, August 15, the full sturgeon moon will be highly visible around sunrise and sunset. The satellite will be 99.9 percent illuminated by the sun when it sets Thursday morning at 5:57 a.m EDT—just nine minutes before dawn. On the West Coast, the setting moon will coincide perfectly with the rising sun at 6:15 a.m. PDT.

If you aren't interested in getting out of bed early to catch the sturgeon moon, wait until Thursday evening to look to the horizon. Twenty-seven minutes after sunset, the full moon will rise on the East Coast at 8:21 p.m. EDT. On the West Coast it rises at 8:10 p.m. PDT, 30 minutes after the sun sets.

The moon generally looks bigger and brighter when it's near the horizon, so twilight and dawn are ideal times to catch the spectacle. But it's worth taking another peek at the sky closer to midnight Thursday night; the Perseid meteor shower is currently active, and though the light of the moon may wash them out, you're most likely to spot a shooting star in the late night and early morning hours.

A Full Harvest Moon Is Coming in September

suerob/iStock via Getty Images
suerob/iStock via Getty Images

The Old Farmer's Almanac lists a special name for every month's full moon, from January's wolf moon to December's cold moon. Even if you're just a casual astronomy fan, you've likely heard the name of September's full moon. The harvest moon is the full moon that falls closest to the fall equinox, and it's associated with festivals celebrating the arrival of autumn. Here's what you need to know before catching the event this year.

What is a harvest moon?

You may have heard that the harvest moon is special because it appears larger and darker in the night sky. This may be true depending on what time of night you look at it, but these features are not unique to the harvest moon.

Throughout the year, the moon rises on average 50 minutes later each night than it did the night before. This window shrinks in the days surrounding the fall equinox. In mid-latitudes, the moon will rise over the horizon only 25 minutes to 30 minutes later night after night. This means the moonrise will occur around sunset several evenings in a row.

So what does this mean for the harvest moon? If you're already watching the sunset and you catch the moonrise at the same time, it will appear bigger than usual thanks to something called the moon illusion. It may also take on an orange-y hue because you're gazing at it through the thick filter of the Earth's atmosphere, which absorbs blue light and projects red light. So if you've only seen the full harvest moon around sunset, you may think it always looks especially big and orange, while in reality, any full moon will look that way when it's just above the horizon.

When to See the Harvest Moon

This year, the harvest moon will be visible the night of Saturday, September 14—about a week before the fall equinox on September 23. The moon will reach its fullest state at 12:33 a.m. ET—but if you're still convinced it's not a true harvest moon without that pumpkin-orange color, you can look for it at moonrise at 7:33 p.m. on September 13.

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