A final flyby for asteroid Bennu and 5 other top space and science stories this week

Welcome to Wonder Theory, your weekly space and science digest.

In a matter of days, robots achieved milestones across our solar system as researchers here on Earth uncovered windows into the early days of humanity. These contrasting advancements amaze us here at the CNN Space and Science team, especially because they happen so often.

Learning how our ancestors created cave art and engraved prehistoric stone maps transforms these early humans from unrelatable figures to relatives with common ground.

Similarly, the robotic investigators we send to planets and asteroids, those rocky time capsules of the last 4.5 billion years, uncover the past of the solar system. Fueling our curiosity, these insights share not only where we came from, but what had transpired long before humans walked across Earth.

Here are some of the astonishing explorations and discoveries from this week.

Across the universe

The OSIRIS-REx spacecraft has been in an orbital dance with the near-Earth asteroid Bennu since arriving in December 2018 — but that meet and greet is about to come to an end. The spacecraft completed a final flyby of the asteroid on Wednesday, coming as close as 2.1 miles to Bennu’s surface.

This artist's concept shows the flight path of NASA's OSIRIS-REx spacecraft during its final flyby of asteroid Bennu.

The spacecraft is now drifting away from its companion of two-and-a-half years and will depart for Earth on May 10.

Bennu and OSIRIS-REx had a close encounter on October 20, 2020, when the spacecraft briefly touched down on the surface of the asteroid and backed away. This allowed the spacecraft’s sampling arm to collect 2 ounces of material from Bennu that will be returned to Earth in September 2023. The sample could shed more light on the formation of the solar system and how elements like water may have been delivered to early Earth by impacts from asteroids.

The images captured by OSIRIS-REx on its final run will reveal the aftermath of the sample collection event in October, which was a messy affair. Expect to see those images, and how much Bennu’s surface was altered by the rendezvous, next week.

A long time ago…

Ancient cave painters may have purposely sacrificed their ability to breathe in order to create history-making artwork.

New research analyzing cave paintings from 14,000 to 40,000 years ago in Spain and France has shown that many of these works of art can be found in deep, narrow passages of cave systems.

The Upper Paleolithic artists would have needed artificial light to see as they worked. Fire would have diminished the available oxygen, causing hypoxia — releasing dopamine and causing hallucinations, according to the study.

The researchers believe this was a conscious decision that helped the artists connect with the world around them and their beliefs — including the cosmos and the underworld.

The wonder

Another week, another rover selfie on Mars — but this one is even more historic. The Perseverance rover snapped a selfie with the newly independent Ingenuity helicopter, which is sitting in the middle of a Martian air field and preparing for the first powered, controlled flight on another planet.