Why is the asteroid ejecting bean particles in space?

The asteroid, which is being studied by NASA’s OSIRIS-REx, shows some surprising activity on its surface, and scientists are beginning to understand what may be causing it.

When NASA’s OSIRIS-REx spacecraft Asteroid (101955) reached Bennu, mission scientists knew that their spacecraft was orbiting something special. Not only was the boulder-strewn asteroid shaped like a rough diamond, its surface was cracking with activity, blowing small pieces of rock into space. Now, after more than a year and a half with Benue, they are beginning to better understand these dynamic particle-rejection phenomena.

A compendium of studies in a special edition of the Journal of Geophysical Research: Asteroids and the planetary home on these cryptic particles. Studies have given a detailed overview of how these particles function in space, as possible clues as to how they are extracted, and even how their trajectory is used to estimate Benue’s weak gravitational field. Can be done for

Usually, we consider asteroids, not comets, to be active. Comets are made of ice, rock, and dust. As those ions are heated by the Sun, the surface of the comet nucleus, a spark of vapor from dust and chunks is lost in space, and forms a long dusty tail. On the other hand, asteroids are primarily composed of rock and dust (and perhaps a small amount of ice), but it turns out that some of these space rocks can also be surprisingly lively.

“We thought Beanu was a wild card discovery in a boulder-covered surface asteroid, but these particle events certainly surprised us,” said Dante Lauretta, OSIRIS-REX’s lead investigator and a professor at the University of Arizona. “We have spent the last year investigating the active surface of Benue, and it provides us with a remarkable opportunity to expand our knowledge of how active asteroids behave.”

The OSIRIS-REX (short for Origins, Spectral Interpretation, Resource Identification, and Security-Resolith Explorer) camera was repeatedly projected into space, a mile (565) during a January 2019 asteroid survey. Meter). ) Is detailed at its equator.

A study led by Steve Chesley, senior research scientist at NASA’s Jet Propulsion Laboratory in Southern California, found that most of these pebble-shaped pieces, which typically measure around a quarter-inch (7 millimeters), were found. Benu was pulled back. Under asteroid’s weak gravity after a short hop, it sometimes returns to space even after hitting the surface. Others took longer to return to the surface, remaining in orbit for some days and 16 revolutions. And some were cast out with enough oomph to completely avoid Beenu’s messengers.

Using the data collected by NASA’s OSIRIS-REx mission, this animation shows the trajectory of rock particles after the asteroid (101955) was ejected from the surface of Benue. Credit: m. Brozovic / NASA / JPL-Caltech / University of Arizona

By tracking the travel of hundreds of emitted particles, Chesley and his colleagues were also able to better understand whether the particles could launch from the surface of the bean. Particle sizes are expected for thermal fracturing (such as the asteroid’s surface being repeatedly heated and cooled during rotting), but also match the locations of the modeled impact of meteorites at locations of ejection events. Eats (small rocks hitting the surface of Bienu) orbits the Sun). It could also be a combination of these events, added Chesley. But for a definitive answer, more comments are required.

While there are many scientific questions in their existence, the particles also served as high-fidelity investigations of Bennu’s gravitational field. Several particles were orbiting Beanu, which is very close to the OSIRIS-REx spacecraft, and therefore their trajectories were highly sensitive to the irregular gravity of Benue. This allowed researchers to estimate Bennu’s gravity even more accurately with instruments from OSIRIS-REX.

“The particles were an unexpected gift to the science of science in Benue because they allowed us to see small changes in the asteroid’s gravitational field that we might not have been aware of otherwise,” Chesley said.

On average, only one or two particles are extracted per day, and because they are in an atmosphere with very low gravity, most are moving slowly. As such, they pose little threat to OSIRIS-REx, which will attempt to touch down on the asteroid on 20 October to scoop surface material, which may also include particles removed before it returns to the surface .

If all goes according to plan, the spacecraft will return to Earth in September 2023 with a cache of bennu for scientists to study further.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland provides overall mission management, systems engineering, and security and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona in Tucson is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation plan and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and Canatex Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REX is the third mission of NASA’s New Frontiers program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

For more information about NASA’s OSIRIS-REx, visit:



News media contact

Ian J. O’Neill / DC Eggle
Jet Propulsion Laboratory, Pasadena, California.
818-354-2649 / 818-393-9011
[email protected] / [email protected]