As reported in the Oct. 22 Briefing, NASA has confirmed that the OSIRIS-REx spacecraft has collected more than enough sample material from the Bennu asteroid for the purpose of the mission.
The latest developments in the mission show that perhaps it was a little “too successful,” in that it collected so much material that it appeared that larger clumps of the sample had lodged in the lid of the sample collector head, allowing smaller particles to slowly escape. The NASA team immediately changed plans to stow the collector head in the Sample Return Capsule, which will keep the material safe on its return journey to Earth.
“Bennu continues to surprise us with great science and also throwing a few curveballs,” said Thomas Zurbuchen, NASA’s associate administrator for science at the agency’s headquarters in Washington. “And although we may have to move more quickly to stow the sample, it’s not a bad problem to have. We are so excited to see what appears to be an abundant sample that will inspire science for decades beyond this historic moment.”
Of all the asteroids in all of the solar systems in all the galaxies, mankind landed on Bennu; how was Bennu chosen? NASA narrowed down the choices by looking at the following criteria: Starting with over 500,000 asteroids in orbit, 7,000 were near-Earth orbits; out of those, only 192 had optimal orbits for a sample return; out of those, 26 had a diameter greater than 200 meters, and of those, 5 were carbon-rich, and then Bennu was selected. The asteroid is more “diamond-” or octahedron-shaped than spherical, and it’s more than 208 million miles (334,928,372 km) from Earth.
The size of the asteroid is crucial because the smaller the asteroid, the faster it spins. Bennu rotates on its axis about every four hours, which made a landing feasible. And, it makes the landing all that more remarkable, because the spacecraft would have to spin along with the asteroid (“geosynchronous”) in order to land.
It’s also one of the oldest objects within a near-Earth orbit, dated to about 4.6 billion years old, and some of the inner core may actually be older than that. Meteorites can be studied, but they’re contaminated as they make their way through Earth’s atmosphere.
Asteroids in general are also very rich in mineral deposits and other resources. As mankind develops new technologies to unlock these resources, asteroids could become fueling stations or “stepping stones” in our progress outward into the Solar System.
RT reported on Oct. 21 that Bennu offers a treasure-trove of scientific data—it showed the presence of water, and its surface is littered with carbon-bearing organic material. NASA scientists anticipate that “this organic material may point to the development of primitive biology across the universe.”
NASA has produced a 3D terrain model and its short video, “Tour of Asteroid Bennu,” can be viewed at https://www.youtube.com/watch?v=QunVAWABQSc. The name “Bennu” refers to an ancient Egyptian god who was self-created, and had a role in the creation of the Universe. He was also linked with the Sun and rebirth, and may have been the original inspiration of the legend of the phoenix.
A short video “ASTEROIDS Size Comparison,” by MetaBallStudios, showing the comparative sizes of some of the most notable asteroids, can be found at https://www.youtube.com/watch?v=bSkPNMjRRio. Bennu (525 m) is slightly larger than Apophis (370 m).
