The OSIRIS-REx spacecraft returned triumphantly to Earth in 2023 after accumulating 4.3 ounces (121.6 grams) of treasured grains of mud and rock from the asteroid Bennu in 2020. Whereas that pattern return was an unimaginable feat of engineering, its arrival on Earth was only the start of the scientific journey. 

On Jan. 29, NASA held a press convention to announce findings by two groups learning the Bennu samples. Detailed in two Nature papers launched the identical day, the grains reveal that Bennu held a wealth of amino acids, together with 14 of the 20 that make up organic proteins – the fabric that makes up dwelling issues. Whereas none of those discoveries counts as life in itself, they’re the molecules that life makes use of to construct itself. Their existence closely strengthens the idea that such supplies had been delivered to Earth by asteroids akin to Bennu. 

Scientists additionally revealed the invention of clays and brines, substances that solely happen with the sluggish evaporation of water. This informs the historical past of water within the photo voltaic system, and particularly the interaction of water and the molecules wanted for all times. 

Nicky Fox, affiliate administrator of the Science Mission Directorate at NASA Headquarters, stated in a press launch that, “Asteroids present a time capsule into our house planet’s historical past, and Bennu’s samples are pivotal in our understanding of what substances in our photo voltaic system existed earlier than life began on Earth.”

A prelude to life

Bennu, like different asteroids, gives a window into the early photo voltaic system. For scientists, these house rocks are pristine environments, untouched by the difficult cycles of climate, water, rock, and extra that happen on planets and moons. They will reveal the supplies current within the photo voltaic system’s early days, and a simplified historical past of how these supplies got here to be. 

Along with the 14 organic amino acids, the samples from Bennu additionally contained 19 extra non-biological amino acids, in addition to the 5 nucleobases that make up RNA and DNA. The workforce additionally discovered a shocking quantity of ammonia, which reacts with formaldehyde, additionally current on Bennu, to create many amino acids, giving a neat image of how the abundance of supplies got here to be. The wealth of advanced chemistry, together with the chemical parts vital for all times, make the Bennu samples a strong software for investigating how life arose.

“Knowledge from OSIRIS-REx provides main brushstrokes to an image of a photo voltaic system teeming with the potential for all times,” stated Dworkin. “Why we, to date, solely see life on Earth and never elsewhere — that’s the actually tantalizing query.”

One other main discovery from the Bennu samples had been briny supplies that kind as water evaporates. Asteroids like Bennu’s mother or father physique most likely fashioned immediately from the buildup of icy rocks. In some unspecified time in the future, that ice will need to have melted, as water is critical to kind most of the supplies discovered on Bennu. However the brines present that the water additionally then evaporated. Maybe counterintuitively, this lack of water was additionally vital: It was solely because the water disappeared that a few of the chemistry grew to become attainable to create the supplies that someday could be integrated by life.

A cautious investigation

None of this evaluation would have been attainable and not using a sample-return mission — or if the samples been compromised. OSIRIS-REx had the difficult activity of eradicating samples from Bennu and transporting them to Earth. However scientists had a special however equally difficult activity as soon as they arrived: not letting Earth’s ambiance have an effect on that point capsule of house rock. 

Tim McCoy, curator of meteorites on the Smithsonian Pure Historical past Museum in Washington, D.C., and lead writer of one of many Nature papers launched right this moment, identified that particularly when learning the historical past of water, any contamination of water vapor would have rendered their research unattainable. The historical past of water within the photo voltaic system is knowable solely due to the cautious curation of the asteroid samples. 

The samples had been faraway from the spacecraft’s return meeting in a clear glove field, with no publicity to exterior air. The pattern container was pumped filled with nitrogen, an inert fuel. The samples at the moment are divided between a bevy of establishments, partially to acknowledge the worldwide effort that went into the mission, and partly in order that no single accident can destroy all of the samples. 

The Apollo lunar missions likewise returned a wealth of samples. Due to their cautious preservation, scientists are nonetheless capable of experiment on lunar samples, regardless of the 50-plus years because the finish of Apollo. 

Jason Dworkin, OSIRIS-REx undertaking scientist, identified that almost all of the Bennu pattern continues to be unexplored. With the identical cautious curation because the Apollo samples, scientists will be capable of unearth new discoveries for many years to come back. 

“The clues we’re in search of are so minuscule and so simply destroyed or altered from publicity to Earth’s atmosphere,” stated Danny Glavin, one of many co-authors. “That’s why a few of these new discoveries wouldn’t be attainable and not using a sample-return mission, meticulous contamination-control measures, and cautious curation and storage of this treasured materials from Bennu.”

Left-handed life

Out of any nice scientific discovery come not simply solutions, however extra questions. One of many largest questions provided by the Bennu samples entails the “handedness” of molecules. Many molecules are chiral, that means their form can take considered one of two mirrored kinds, left-handed or right-handed. Life as we all know it vastly prefers left-handed molecules, and has developed to make use of and produce them. Scientists don’t know why, however have postulated that an over-abundance of left-handed molecules on early Earth might need given rise to this choice. 

However Bennu’s samples had an equal abundance of left- and right-handed molecules. If Bennu is certainly consultant of the asteroids that delivered the substances for all times, then the query of why life prefers lefties continues to be a thriller.