NASA sample shows asteroid Bennu could have come from small ocean world

NASA's first asteroid sample is the most pristine sample of its kind. Now, back on Earth, the sample from asteroid Bennu has already delivered surprising findings about the early solar system and where the asteroid might have come from. 

After a seven-year journey to asteroid Bennu and back, NASA's OSIRIS-REx spacecraft dropped off its sample of rocks and dirt collected from the primitive asteroid last year in the desert of Utah. It took a while to remove the lid from the sample canister carefully, but even the first bits of the asteroid from the lid were carbon-rich, an essential element for all life on Earth. 


Scientists with NASA's OSIRIS-REx Sample Analysis Team published their early findings on the Bennu sample. They say they found organic compounds. The sample also contained the surprising finding of magnesium-sodium phosphate, which the spacecraft imaging team could not see through spectra data on the asteroid. OSIRIS-REx spent several years mapping the asteroid before the touch-and-go maneuver to collect the sample. 

A tiny fraction of the asteroid Bennu sample returned by NASA’s OSIRIS-REx mission, shown in microscope images. The top-left pane shows a dark Bennu particle, about a millimeter long, with an outer crust of bright phosphate. The other three panels sh

University of Central Florida astronomy and physics professor Humberto Campins served on the OSIRIS-REX science team during the OSIRIS-REx mission and said the team expected to find hydrated minerals or minerals that reacted with water.

"But the magnesium sodium phosphates are the result of a hydration process … indicative of a very complex fluid, reactions or chemical reactions in the parent of Bennu," said Campins, who was not involved in the new study. "We still don't understand. The detailed study of this will tell us a lot more about what was going on in the parent."

This image shows four views of asteroid Bennu along with a corresponding global mosaic. The images were taken on Dec. 2, 2018, by the OSIRIS-REx spacecraft’s PolyCam camera. (Image: NASA/Goddard/University of Arizona)

The findings indicated that Bennu's parent world was possibly one with water. 


"The presence and state of phosphates, along with other elements and compounds on Bennu, suggest a watery past for the asteroid," said Dante Lauretta, co-lead author of the paper and principal investigator for OSIRIS-REx at the University of Arizona, Tucson. "Bennu potentially could have once been part of a wetter world. Although, this hypothesis requires further investigation."

Just the beginning of Bennu surprises

The latest findings are more proof that the OSRIS-REx team picked the right asteroid to bring a piece back to Earth. According to NASA, the sample analysis team finds something new each week.  

The discoveries from Bennu will soon be a global science initiative. Dozens of labs in the U.S. and worldwide are set to receive parts of the Bennu samples from NASA’s Johnson Space Center.

Campins said to expect much more research and discoveries to come from the sample now that it’s on Earth.

"This is going to be a very interesting few years," Campins said. "It's starting to give us a different look, a different data set, to try to understand the most primitive material in the solar system, which are probably linked to the origin of water on Earth, probably linked to the origin of organic molecules on Earth, which was a major motivator for this mission."

Astromaterials processor Mari Montoya and OSIRIS-REx curation team members set the TAGSAM (Touch and Go Sample Acquisition Mechanism) down in the canister glovebox after removing it from the canister base and flipping it over. (Credit: NASA)

Having a pristine sample of an asteroid created 4.5 billion years ago unaltered by Earth's atmosphere or other contamination will help scientists answer critical questions about how life on Earth formed. 

Campins said it's possible Bennu can help answer the crucial question of what was the "step between the most complex organic molecule and the first living cell." 

The spacecraft is operating under a new name and a new mission. The new OSIRIS-APEX mission will study the asteroid Apophis when it flies by Earth in 2029. This encounter will be close enough that we can see the asteroid from Earth without the help of a telescope. 

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