NASA’s OSIRIS-REx spacecraft captured this image of the asteroid Bennu on Dec. 12, 2018. The asteroid can be a water-rich target space for the miners.
The near-Earth asteroid Bennu would have the space for the miners to make their case to skeptical investors.
New observations from NASA’s OSIRIS-REx spacecraft suggest that the 1,650-meter wide (500 meters) Bennu ports much accessible water, an important resource that prospective asteroid miners target.
Water can be split into its constituent hydrogen and oxygen, the main components of rocket fuel. These things can then be sold against an off-Earth “gas stations”, where spacecraft can refuel on the go, mining advocates have emphasized.
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“For an asteroid miner, Bennu is pay dirt,” OSIRIS-REx principal investigator Dante she now, from the University of Arizona, told Space.com. “That is exactly the kind of goal that we want to go ahead and process [for] a fuel depot that people aiming for the first profitable asteroid to mine.”
The study of Bennu close-up
The $800 million OSIRIS-REx mission launched in September 2016 and slipped into orbit around Bennu on Dec. 31 of last year. This last event was an epic performance: Bennu is the smallest object ever to be circled by a spaceship.
OSIRIS-REx is making valuable observations of Bennu job, but a lot of the mission of the science data to be collected here on Earth. If all goes according to plan, the probe will snag a sample of Bennu material in July 2020, then deliver those things to the Earth in a special return capsule arrival in September 2023.
The main goal of the mission is to learn more about the solar system, the beginning and the better understanding of the role that dark, carbon-rich asteroids such as Bennu may have played in the life originated on Earth. This role is suspected to be of interest; scientists believe that asteroids may have delivered much of our planet water, as well as many of the complex organic molecules — the building blocks of life as we know it.
But OSIRIS-REx has a number of subsidiary objectives, as indicated by the full name: “the Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer.” The “security” bit refers to information that can help humanity to better deal with potentially dangerous space rocks, a large category that counts Bennu as a member. And “resource identification” is a nod to the nascent asteroid-mining industry, which needs to know which stones to go after.
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In December, the OSIRIS-REx team announced the detection of hydrated clay minerals on Bennu’s surface. The finding indicated that water was probably abundant in the interior of Bennu parent asteroid long ago, the scientists said at the time. (Members of the Team think Bennu is a pile of debris, consisting of pieces of that shattered asteroid, which is about 62 miles or 100 kilometers wide. Bennu may harbor the fragments of the impactor.)
The new results, that she now, and his colleagues announced today (March 19), confirm and extend a recent discovery: OSIRIS-REx is now spotted on the clear signature of the iron-oxide mineral magnetite on Bennu’s surface.
Magnetite is usually an indication of a very intense hydrothermal activity,” she now said.
He and the mission of the team is still not nailed down the origin of this activity. But the main theory states that the Bennu parent asteroid formed, far away from the newborn sun, with large amounts of water, ice and organic, along with rocky and metallic material. Some radioactive elements, such as aluminium-26, got sucked, and the heat thrown by this stuff probably melted many of which are native ice.
“Water had probably circulated through the interior of the asteroid, such as a hydrothermal system on Earth, and changed the originally anhydrous rocky material, the formation of this clay,” she now said. The flow also “likely changed the metal to produce iron oxides such as magnetite.”
This probably happened very early, he added, within the first 10 million years or so of solar system existence.
To be clear: The water that we’re talking about it on the day Bennu is not stand-alone and pure; it is locked up in that clay, in the form of hydroxyl groups (one oxygen atom and one hydrogen atom connected to each other). But it is probably accessible: Hydroxyl can be baked out of clay, the generation of water vapour, asteroid-mining advocates say.
Photo of Bennu shape
The magnetite is just one of the many discoveries she now and his colleagues today in seven papers, which were published in the journals Nature, Nature, Astronomy, Nature Geoscience and Nature Communications. The team also discussed the results during a press conference today at the 50th Lunar and Planetary Science Conference (LPSC) in The Woodlands, Texas.
For example, OSIRIS-REx observations suggest that Bennu the rotation speed accelerating, probably due to the reradiation of solar energy as a heat — something that is known as the Yarkovsky-O’keefe-Radzievskii-Paddack (YORP) effect. It currently takes Bennu approximately 4.3 hours to complete one rotation; if this spin speedup keeps on going, that rotation period will be cut in half in 1.5 million years), she now said.
The team is also determined Bennu’s bulk density to be about 72.3 lbs. per cubic foot (1,190 kilograms per cubic meter) and the asteroid is the interior of the approximately 50 percent open space. Both of these numbers indicate that Bennu is a pile of rubble instead of a solid block of stone, the scientists said.
And then there is the asteroid surface. By counting the craters, the team has estimated that Bennu formed between 100 million and 1 billion years ago, probably after a giant collision in the main asteroid belt between Mars and Jupiter. (Bennu moving to a near-Earth orbit happened quite recently; these paths tend to be stable for only 10 million years or so, the mission, the members of the team said, due to the gravitational encounters with the Earth and other rocky planets.)
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The abundance of the visible craters may force a rethink about how asteroids such as Bennu and Ryugu, the japanese space probe Hayabusa2 is now engaged with up close, have their eye-catching diamond shapes. The leading explanation posits that this form is the result of a rapid spin, allowing loose asteroid material to migrate to the equatorial regions. But such a migration would be expected to bury the many craters, so maybe there is something else going on.
“We are actively re-evaluation of that model,” she now said.
The team also found that, on average, Bennu reflects only 4.4 percent of the sunlight, which makes the asteroid one of the darkest objects in the solar system. But Bennu is far from uniform; in combination with a very dark spots, sports are much brighter regions, of which a number of reflections from 15 percent to 20 percent.
And in a real shocker, OSIRIS-REx observed particles streaming from Bennu’s surface multiple times in January and February, and that means the space rock is one of only a dozen or so known “active asteroids.” It is unclear what the cause of this activity, but the team is keen to investigate, she now said.
No other spacecraft has ever witnessed such an asteroid activity up close, he added.
Example-collecting, it can be more difficult than expected
Bennu the surface of diversity also manifests as rocky robustness, which has surprised the mission team. Radar images by the large, ground-based dishes, such as the Arecibo observatory in Puerto Rico had revealed just a boulder with a width of between 33 feet and 66 feet (10 to 20 meters). These data, and the presumption of a spin-induced equatorial migration of material, the OSIRIS-REx researchers reason to think Bennu is pretty smooth, at least at low latitudes.
“Everything was self-consistent and put a lot of centimeter-scale particles, probably concentrated in the equator,” she now said. “And I was really envisioning a kind of beach that went all the way around the asteroid in the equatorial regions.”
But the reality is very different from this prediction. OSIRIS-REx has spotted more than 200 boulders in the 33-66-foot size of the range so far, and the largest boulder-free patches, the probe has found to date to measure between 16.5 metres and 66 metres (5 to 20 m) wide, the new paper reported.
That is a problem, because the mission design calls for OSIRIS-REx to grab and an example of a rock-free patch of at least 165 feet (50 meters) in diameter.
“We have an upgrade of the autonomous guidance system on the spacecraft, so it can be a lot smarter and lead us in that smaller region,” she now said.
The team will also collect many other high-resolution images of the landing than previously expected, he added.
She now said that he is confident that the team will do all the work, although the sample is collected may have to be pushed back a bit as a result. But the team has some leeway; the sampling operation can be carried out as at the end of October 2020 no significant impact on the mission timeline, she now added.
The OSIRIS-REx team takes the heart of the success of Hayabusa2, which took samples from the rugged Ryugu last month. And she now and a number of colleagues a trip to Japan in April to get information and advice from Hayabusa2 members of the team, especially about how Ryugu surface behaved during the sampling sortie, ” he said.
“That is still our greatest uncertainty — what is the nature of this material, in the environment of microgravity?” She now said. “What forces are holding it together, and how to respond when a spaceship blows in and then fires thrusters to back away from it?”
The Hayabusa2 team, by the way, unveiled a series of new results today, and in three articles in Science magazine and on the LPSC. The Japanese mission has determined that the 3,000 feet wide (900 m) Ryugu is likely to be relatively dry, but it is carbon-rich and diamond-shaped such as Bennu.
Ryugu may be drier, because it has lived in the inner solar system more than Bennu, or has swung closer to the sun on the different jobs, she now said.
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“You haven’t seen nothing yet”
The new OSIRIS-REx results come from the observations during the probe of the approach Bennu last summer and fall, and its early days in orbit around the space rock. There is much more to come, as the science team analyzes the more detailed information and images.
For example, OSIRIS-REx is not confirmed by the presence of organic materials on Bennu’s surface, but the probe hasn’t really had a chance to look yet. The observations to be able to do the trick will be conducted in seven or eight weeks from now, if everything goes according to plan, she now said.
“The science is really starting to accelerate,” he said. “You haven’t seen nothing yet.”
And we may have to wait a few years for the most exciting results. Hayabusa2 is the sample is scheduled to land on Earth in December 2020, and the OSIRIS-REx not touch down until almost three years later.
“This is really exciting,” she now said. “You can learn a lot by bringing a sample back from an asteroid, but we are going to learn exponentially more by bringing samples back from these two asteroids, which initially looked very similar to each other, can still be related to each other, but have a different history.”
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Original story on Space.com.