Mysterious Unknown Material NASA Just Brought to Earth from Asteroid Bennu Puzzles Scientists

Bennu is thought to be the most dangerous known rock in the solar system, with some predicting that it could hit the Earth in the next 300 years. That’s the main reason why we want to find out more about it.

On September 24, 2023, NASA’s OSIRIS-REx spacecraft delivered a sample of rocks and dust from asteroid Bennu, a near-Earth object that is about 500 meters wide and orbits the Sun every 1.2 years. The sample capsule parachuted into the Utah desert, where scientists eagerly awaited to examine its contents. But what they found inside was not what they expected: a mysterious unknown material that could hold clues to the origin of life on Earth.

OSIRIS-REx stands for Origins, Spectral Interpretation, Resource Identification, and Security – Regolith Explorer. The main goal of the mission, which we reported on here, was to collect and return a sample of at least 60 grams (2 ounces) of pristine material from Bennu’s surface, thought to be rich in organic molecules and hydrated minerals that date back to the early stages of the solar system. These materials could help scientists understand how planets formed and how life began, as well as improve our knowledge of asteroids that could pose a threat to Earth.

The spacecraft launched in 2016 and arrived at Bennu in 2018. It spent two years mapping the asteroid’s surface and selecting a suitable landing site, with the help of stereo imaging experts such as Dr. Sir Brian May, the legendary guitarist of Queen and an astrophysicist. The chosen site was named Nightingale, a relatively smooth and flat area surrounded by boulders.

On October 20, 2020, OSIRIS-REx performed a daring maneuver called Touch-And-Go (TAG), in which it briefly touched the surface of Bennu and fired a burst of nitrogen gas to stir up and collect some regolith (loose rocks and dust). The spacecraft then backed away and stowed the sample collector head with the sample inside a capsule for safe return to Earth.

However, the mission team soon realized that the collector head had captured more material than expected, so much so that some particles were escaping through small gaps in the lid. The team decided to expedite the stowage process and minimize any further loss of material. They also canceled a planned maneuver to measure the mass of the sample, as it could pose a risk of spilling more material.

The sample capsule was released by the spacecraft on September 24, 2023, as it flew by Earth at a speed of over 40,000 kilometers per hour (25,000 miles per hour). The capsule entered the atmosphere and deployed a heat shield and parachutes to slow down its descent. It landed safely at the Utah Test and Training Range, where recovery teams retrieved it and transported it to NASA’s Johnson Space Center in Houston, Texas.

There, scientists opened the capsule and were amazed by what they saw: a dark powder and sand-sized particles that covered the avionics deck of the science canister. They also noticed some larger chunks of material that looked different from anything they had seen on Bennu before. They were shiny, metallic, and had an irregular shape.

Now, University of Arizona planetary science and cosmochemistry specialist Professor Dante Lauretta has disclosed that the retrieved fragments from the 3-billion-year-old asteroid Bennu, located on the outer lid of the sample capsule, showcase a distinctive composition abundant in carbon and organic molecules. These particles, distinguished by their dark color, are composed of centimeter- and millimeter-sized “hummocky boulders” displaying a unique “cauliflower-like texture.”

As noted above, despite the successful material collection on Bennu’s surface, an unforeseen problem emerged when particles began leaking from the sample collector’s head. Professor Lauretta linked this issue to a 1.3-inch (3.5 cm) stone obstructing a small flap, enabling the material to escape into the lid.

Ongoing technical difficulties arise from two malfunctioning fasteners, impeding the ability to access most of the 70.3-gram sample within the head. Technicians are utilizing tweezers to extract small rocks through a partially open flap.

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Initial spectroscopic analysis, which examines light reflections to identify material composition, revealed a prevalent blue spectral signature. This mysterious tint implies a potential higher water content than initially anticipated, with more comprehensive insights expected during a forthcoming spring scientific meeting.

The material’s enigmatic nature is further emphasized by its significant concentrations of magnesium, sodium, and phosphorus, leaving Professor Lauretta puzzled and saying, “It’s a head-scratcher right now. What is this material?”

To find out more about this mysterious unknown material, the scientists will perform various tests and analyses on the sample over the next few months. They will also distribute portions of the sample to other laboratories around the world for further study. The OSIRIS-REx mission has already achieved its primary objective of returning a sample from an asteroid, but it may have also brought back something unexpected: a puzzle that could reveal new secrets about our solar system’s history.

Sources: 1, 2, 3, 4, 5