Scientists said they got more material than expected from the Osiris-Rex mission during its seven-year journey to the asteroid Bennu.
A first glimpse of the jackpot from a seven-year mission to bring back bits of an asteroid was unveiled on Wednesday.
NASA officials in Houston displayed images of salt-and-pepper chunks of rock and particles of dark space dust that were brought back to Earth from the asteroid, Bennu, and described initial scientific observations about the material. The mission, Osiris-Rex, concluded in September when a capsule containing the collection of asteroid samples re-entered through the Earth’s atmosphere and was recovered in the Utah desert.
As technicians pried into the external container, they found that some of the material leaked out. Scientists were able to perform a quick analysis that revealed some early findings.
The asteroid bits included waterlogged clay minerals. Their presence could help solve how Earth became a water planet. Asteroids similar to Bennu may have crashed into Earth, filling our oceans.
“The reason that Earth is a habitable world, that we have oceans and lakes and rivers and rain, is because these clay minerals like the ones we’re seeing from Bennu, landed on Earth four billion years ago,” Dante Lauretta, a professor of planetary sciences at the University of Arizona who serves as the mission’s principal investigator, said during a NASA event on Wednesday.
The materials also contained sulfur, a crucial element for many geological transformations in rocks. “It determines how quickly things melt and it is also critical for biology,” said Dr. Lauretta, who displayed microscopic images and 3-D visualizations of the material. The scientists also found magnetite, an iron oxide mineral that can play an important role as a catalyst in organic chemical reactions.
“We’re looking at the kinds of minerals that may have played a central role in the origin of life on Earth,” Dr. Lauretta said.
The asteroid is also chock-full of carbon, the key element in the building blocks for life. One sample contained 4.7 percent carbon by weight.
“We picked the right asteroid,” said Daniel Glavin, a NASA astrobiologist working on the mission. “And not only that, we brought back the right sample. This stuff is an astrobiologist’s dream.”
The NASA mission that brought back the samples was named Osiris-Rex — a shortening of Origins, Spectral Interpretation, Resource Identification and Security, Regolith Explorer. It concluded on Sept. 24 when a capsule containing the bits of Bennu landed under a parachute in the Utah desert. From there, the capsule was taken to the Johnson Space Center in Houston. When technicians there removed the lid of the canister with the sample collecting instrument, they found dark powder and sand-size particles.
“And already this is scientific treasure,” Dr. Lauretta said.
While providing a quick, early look at what’s inside, that material has also slowed the work to get into the main compartment of the sample-collecting tool.
“The only problem is a great problem, and that’s we’ve found a lot more sample than we were anticipating” before even getting to the main part of the collecting instrument, said Francis McCubbin, the astromaterials curator at the Johnson Space Center. “We need to very meticulously and carefully collect every grain. It’s taking us a little longer to get inside, but the view so far is amazing.”
For Maritza Montoya, one of the technicians meticulously gathering the samples, that meant using a spatula to push the powder into small piles, then scooping them up with a tiny dust pan. “It is literally a mini dust pan,” Ms. Montoya said.
In all, that leakage provided 1.5 grams of powder and particles.
“You can see that they have a metallic luster to them,” Ms. Montoya said. “So when you shine light, they sparkle back and reflect that light.”
When the sample collector was flipped over, larger chunks were revealed including rocks that had prevented a seal from shutting completely.
“There’s a whole treasure chest of extraterrestrial material,” Dr. Lauretta said.
The scientists as yet do not know how much material they have. After a few more weeks of disassembling the apparatus, they expect to be able to weigh it. While the spacecraft was still at Bennu, the engineers performed a maneuver that provided a rough estimate — 8.8 ounces. The hope was that Osiris-Rex would bring back at least 2.1 ounces.
Scientists plan to compare the Bennu samples with what a Japanese spacecraft, Hayabusa2, brought back from a similar asteroid, Ryugu, although scientists can already see differences. Ryugu, for instance, contains less water.
Bennu, discovered in 1999, is a carbon-rich asteroid that is almost black in color. It is about 1,600 feet wide. That compares to the Empire State Building, which is 1,454 feet tall including the antenna at the top. The carbon-rich materials are intriguing because asteroids like Bennu might have seeded Earth with the building blocks for life.
Osiris-Rex launched in 2016 and arrived at Bennu a couple of years later, making observations at a distance. From those remote findings, it identified carbonate minerals in the asteroid, which typically form in environments that include both hot water and carbon dioxide. That suggests that the larger object that Bennu was once part of possessed hot springs or some other sort of extensive hydrothermal system. If that is the case, then it is possible for there to be liquid water that has been trapped in pores in the minerals for several billion years.
“We might actually have samples of the asteroidal water directly,” Dr. Lauretta said.
In October 2020, Osiris-Rex pogo-sticked off the asteroid using its sampling tool, which looks like an automobile air filter at the end of a robotic arm, to pick up the rock samples. A burst of nitrogen gas knocked up rocks and dust into the collection filter, and then Osiris-Rex slowly backed away without landing on Bennu.
A flap on the collection tool was jammed open, and the collected rock and dirt started escaping back into space. Mission managers decided to stow the sample as quickly as they could. In May 2021, the spacecraft started heading back to Earth.
With the samples on the surface, researchers will measure the ratio of hydrogen to deuterium, a heavier form of hydrogen, and see if that ratio matches what is found in Earth’s oceans. Scientists had once thought comets provided the water, but the hydrogen-to-deuterium ratio of most comets is different from Earth’s.
Scientists will also look for amino acids, the building blocks of proteins that have been found in meteorites that have fallen to Earth.
But meteorites sitting on Earth are quickly contaminated. “Microorganisms immediately colonize them,” Dr. Lauretta said. “
With the Bennu sample, scientists will be able, for the first time, to look at the amino acids used in living things from a pristine asteroid.
The samples could also help shed light on why all life on Earth uses only one of the two mirror forms of amino acids and other complex organic molecules. If Bennu contains more of the mirror form used by life, that suggests the cosmos pushed the odds toward that. Otherwise, it may have been some other factor, or just pure chance.
The Osiris-Rex research could also help protect Earth in the future.
Bennu is categorized as a near-Earth asteroid, and scientists say there is a 1-in-1,750 chance it could slam into Earth during a series of very close passes between 2175 and 2199.
Bennu is not large enough to cause planet-wide extinctions. But it would be catastrophic at the point of impact.
While the mission has concluded, the spacecraft’s journey is not over yet. After releasing the return sample capsule, the main spacecraft swerved away from a collision with Earth and is now headed toward Apophis, a 1,000-foot-wide asteroid that will fly within 20,000 miles of Earth in 2029. Soon after that close approach, the spacecraft, now renamed Osiris-Apex — short for Origins, Spectral Interpretation, Resource Identification and Security-Apophis Explorer — will enter orbit around Apophis.
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