OSIRIS-Rex Mission and the Secrets of Creation or Destruction

This Sunday, June 30th, we celebrate the International Asteroid Daya day to raise awareness about the risks of a catastrophic asteroid impact and what we can do to prevent this from happening or at least minimize the damage. It is also a time to discuss the importance of studying these space rocks, not only to protect our planet, but also to learn more about the Universe that surrounds us, the origins of the Solar System. And if there is a space mission where we can learn a little about all this, it is the OSIRIS-REx mission that visited Bennu, a 500-meter asteroid that can help us unravel the secrets of creation, or destruction.

OSIRIS-REx was an ambitious NASA mission that traveled millions of kilometers to collect samples from one of the most dangerous asteroids for our planet, bringing back to Earth a true scientific treasure. The information collected by the probe promises to revolutionize our understanding of the formation of the Solar System and perhaps even the origin of life.

Discovered in September 1999, Bennu was extensively studied during its approach that year. Early analyses showed that it is a primitive asteroid, rich in carbon, one of the basic elements for life as we know it. Scientists believe that Bennu is a remnant from the time when the Solar System was forming, and that it preserves, virtually intact, complex organic molecules, such as amino acids, which are the building blocks of proteins and, therefore, of the creation of life!

But Bennu isn’t just a fascinating object of study; it also poses a potential future risk to Earth. The asteroid currently passes about 300,000 miles (480,000 kilometers) from Earth’s orbit. That’s a relatively safe distance, but it won’t be that way forever.

It turns out that Bennu's orbit varies by about 284 meters each year due to a phenomenon called the Yarkovski Effect. It may not seem like much, but if it accumulates over the years and is combined with gravitational disturbances, this could put Bennu on a collision course with our planet. Studies show that, starting at the end of the next century, the asteroid should begin a series of 157 close approaches to Earth with real possibilities of impact. Very small chances, it's true, but enough for Bennu, with its 500 meters in diameter, to be considered one of the most dangerous asteroids for our planet. If it were to hit Earth, it would have the energy equivalent to 100,000 atomic bombs. Yet another excellent reason to learn more about this menacing cosmic traveler.

And that's where our protagonist, the OSIRIS-REx probe, comes into this story! Launched in September 2016, the NASA probe traveled for two years until it encountered Bennu in December 2018. Upon approaching, the spacecraft wasted no time and, using its state-of-the-art scientific instruments, began mapping the asteroid's surface in detail, searching for the ideal location to collect samples.

But Bennu had a little surprise in store for this first encounter. Scientists had already suspected that it was a “rubble pile” asteroid, that is, formed by the gravitational regrouping of debris from an asteroid destroyed by an impact. However, images from OSIRIS-REx revealed that Bennu’s surface was much more rugged than expected, full of rocks and boulders, which made it difficult to find a safe landing site.

After months of complex analysis and calculations, the mission team finally chose the ideal location for sample collection: a relatively flat crater called Nightingale, which, in addition to offering a less risky landing, appeared to contain carbon-rich material.

In October 2020, OSIRIS-REx performed a spectacular controlled descent maneuver, approaching the surface of Bennu with the lightness of a bird. Using a robotic arm equipped with a special collection system, the probe “kissed” the asteroid, releasing a jet of nitrogen that lifted dust and small fragments from the surface. This material was captured by the probe, providing a valuable cosmic gift for scientists here on Earth.

With its precious cargo on board, OSIRIS-REx bid farewell to Bennu in May 2021 and began a two-year journey home. In September 2023, the capsule containing the samples separated from the spacecraft and made a triumphant entry into Earth's atmosphere, landing safely in the Utah desert in the United States.

The opening of the capsule was a moment of great anticipation for the scientific community. And the wait was worth it! Preliminary analyses of the samples revealed the presence of water, rare minerals and complex organic molecules, including amino acids, compounds essential for life!

The discovery reinforces the theory that, in the distant past, asteroids like Bennu may have brought to Earth, in addition to water, the basic ingredients for the emergence of life. Interestingly, the asteroid that today poses a deadly threat may hold the key to explaining the origins of life on our planet.

During just over two years in orbit around Bennu, the OSIRIS-REx Mission captured images of the asteroid's surface in unprecedented detail. In addition to collecting samples, it also mapped its physical and chemical properties and recorded spectacular moments in which Bennu loses material to space due to its high rotation. These achievements will certainly help us learn a little more about our origins and protect our planet. All of this is in line with the goals of Asteroid Day. But OSIRIS-REx also has other curious connections with this global movement to raise awareness about asteroids.

Brian May, guitarist for Queen and one of the founders of Asteroid Day, is also an astrophysicist and was part of the OSIRIS-REx mission team. Another interesting fact is that, during its approach to Earth, after sending us the capsule with the samples from Bennu, the probe deviated from Earth and adjusted its trajectory to encounter, in 2029, the asteroid Apophis, one of the most feared by humanity.

With all this, the OSIRIS-REx mission reminds us that science and exploration are essential to unlocking the mysteries of the cosmos and ensuring humanity’s future. Who would have thought that a pile of space debris like Bennu could simultaneously hold the precious secrets of creation and the terrifying portents of destruction?