Are humans the aliens? NASA finds all of life's key ingredients in asteroid Bennu sample

Samples from asteroid Bennu have delivered remarkable insights into the origins of Earth’s water, the organic molecules that may have seeded life here and elsewhere, and the fundamental materials and building blocks of our planet and solar system. 

All of this was discovered in just 4 ounces of dust and rock, carefully gathered by NASA’s OSIRIS-REx mission in 2023.

Relics of the early solar system 

Michelle Thompson, an associate professor of earth, atmospheric, and planetary sciences at Purdue University, was among the first nine lead investigators on the OSIRIS-REx science team to examine Bennu’s samples. 

Thompson and her colleagues had 72 hours to perform initial measurements and analyses, drawing on her expertise in how off-world bodies and their chemistry respond to space environments. 

The discoveries shed light on how Earth and the solar system formed and whether life’s building blocks arrived via asteroids.

“Asteroids are relics of the early solar system,” Thompson said. “They’re like time capsules. We can use them to examine the origin of our solar system and to open a window to the origin of life on Earth.”

Bringing Bennu sample to Earth

NASA’s OSIRIS-REx is the agency’s first mission to retrieve samples from an asteroid and return them to Earth.

The mission is focused on analyzing solar system building blocks and exploring resources that might enable future deep-space missions. 

After more than a decade of planning and collaboration among hundreds of team members, OSIRIS-REx successfully returned 4.29 ounces (121.6 grams) of Bennu’s material – exceeding its goal of 60 grams. 

Once-in-a-lifetime experience

The asteroid samples provide scientists with a rare, pristine look at asteroid dust and rock unaltered by Earth’s atmosphere.

“This is a truly once-in-a-lifetime – maybe a once-in-several-lifetimes – experience,” Thompson said. “OSIRIS-REx was selected in 2011, the year I started graduate school, and launched in 2016, the year I finished my PhD.” 

“It reached Bennu in 2018, the year I came to Purdue. And now I am one of the first humans to get to study it. Bennu is a treasure trove of information; this is literally the project of my career.”

Pristine samples from asteroid Bennu 

Although pieces of asteroids sometimes land on Earth naturally as meteorites, the fiery journey through Earth’s atmosphere often damages or contaminates them. 

By bringing Bennu’s samples home inside a protective capsule, scientists can examine them in a virtually unaltered state.

This clarity allows for more precise evaluations of organic compounds, isotopes, and minerals that could explain the origins of water on Earth and the formation of life.

Organic molecules in Bennu samples

Bennu is a carbonaceous asteroid, rich in carbon and other elements crucial to life’s chemistry. The Bennu samples reveal key details about organic molecules that are essential to life’s development.

“Looking at the organic molecules from Bennu, we are getting an understanding of what kinds of molecules could have seeded life on early Earth,” Thompson noted.

“We won’t find life itself, but we’re looking at the building blocks that could have eventually evolved into life.”

Ammonia is crucial for life

Scientists found incredibly large amounts of ammonia in the Bennu samples.

Ammonia is important for life because it can combine with formaldehyde, which was also found in the samples, to create complex molecules like amino acids when the conditions are right.

When amino acids join together into long chains, they form proteins, which are essential for almost every function in living things.

Bennu comes from a water planet

The presence of elements like phosphate, sulfate, and other salt minerals in Bennu’s dust points to an environment conducive to forming vital biomolecules. 

“Together with our international partner teams, we have been able to detect a large proportion of the minerals that are formed when salty, liquid water – known as brine – evaporates more and more and the minerals are precipitated in the order of their solubility,” explains Dr. Sheri Singerling, who manages the Schwiete Cosmo Lab.

Professor Frank Brenker of Goethe University Frankfurt noted that other teams have found various precursors of biomolecules such as numerous amino acids in the Bennu samples.

“This means that Bennu’s parent body had some known building blocks for biomolecules, water and – at least for a certain time – energy to keep the water liquid,” explained Professor Brenker.

Similar brines have been detected or suggested across the solar system, including at the dwarf planet Ceres and Saturn’s moon Enceladus.

Mystery of Earth’s water

The samples also had traces of minerals containing water. Understanding how asteroids can deliver these resources offers vital context about how Earth’s water might have arrived. 

“The scientific community doesn’t have a definitive understanding of how Earth got all its water,” Thompson said. 

“Looking at how much water is part of these minerals in the samples from Bennu gives us a clue about how much water was out in the solar system when the planets were forming.”

“How much material was available that could have been delivered through impacts – not just organic material, but water and minerals as well.”

Why does any of this matter?

Scientists around the world are now parsing the Bennu samples to deepen our knowledge of planetary science.

The experts are analyzing mineral content, studying stable isotopes for clues about the solar system’s formation, and testing hypotheses about how organic compounds travel between celestial bodies. 

The final goal is to piece together a clearer picture of how life-supporting environments arise and persist. Although the newly returned samples measure just a few ounces, their significance is immense.

Panspermia suggests that life, or the essential building blocks of life, could be distributed throughout the universe via meteoroids, asteroids, comets, or even space dust.

Is that what happened here on Earth? Is humanity the ultimate result of an asteroid colliding with our planet billions of years ago?

By continuing to analyze this pristine material from asteroid Bennu, we may just learn the answer to that question sooner rather than later.

Video Credit: NASA Goddard Space Flight Center

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