Bennu is an asteroid that originated from the debris of a primordial world destroyed approximately 4.6 billion years ago. Scientists believe Bennu coalesced around 1–2 billion years ago from this rubble. It likely formed in the main asteroid belt between Jupiter and Mars before gradually drifting closer to Earth. Bennu approaches Earth every six years, coming within 186,000 miles at its closest point.  

The asteroid was named Bennu in 2013 after a young boy won a NASA-sponsored naming contest. The name references an ancient Egyptian deity. Bennu is considered relatively small; it measures about one-third of a mile wide at its equator. For comparison, Mercury, the smallest planet in the solar system, is approximately 3,000 miles across. Bennu is only slightly wider than the height of the Empire State Building.  

There is no possibility for life on Bennu, as it lacks atmospheric pressure and experiences extreme temperatures. However, on September 6, 2016, NASA launched its first asteroid sampling mission, OSIRIS-REx. The spacecraft successfully collected a sample from Bennu on October 20, 2020, and returned it to Earth in September 2023.  

Analysis of the sample has led to a groundbreaking discovery. Scientists found that Bennu contains a variety of rich minerals, along with carbon and nitrogen compounds. More notably, the sample includes fundamental components of DNA—amino acids and nucleo-bases. It contains 14 of the 20 amino acids essential for life on Earth, as well as all four ring-shaped molecules that make up DNA: adenine, guanine, cytosine, and thymine.  

Although these compounds do not indicate the presence of life, they support the theory that asteroids may have delivered the fundamental building blocks necessary for life on Earth. This discovery has also sparked further questions about whether similar processes could have occurred elsewhere in the universe.