Click, crackle, pop! The “hopping” of dust on asteroids could influence how these small bodies migrate through space.
New images of the Bennu and Ryugu asteroids have helped shed light on the new findings, which could explain the pathways these space rocks take as they orbit the sun and sometimes drift away near Earth.
“The more fine-grained material, or regolith, these asteroids lose, the faster they migrate,” said lead author Hsiang-Wen (Sean) Hsu, a researcher at the University of Colorado Boulder’s Atmospheric and Space Physics Laboratory. . in a report. (opens in a new tab)
Some “curious” photos captured at Bennu, as the scientists called it, sparked discussion. These came courtesy of an asteroid-sampling mission known as OSIRIS-REx and showed the surface to look like sandpaper, defying scientists’ expectations of candy. Similar images came from another recently studied asteroid called Ryugu, explored by a Japanese spacecraft known as Hayabusa2.
Related: Dramatic Sampling Shows Asteroid Bennu Has Nothing To Do With Scientists’ Expectations
Hsu and co-lead author Xu Wang, a research associate at LASP, led a team creating computer simulations and lab experiments to better explain the imagery of these two worlds.
“Forces akin to static electricity can blast the smallest specks of dust, some no larger than a single bacterium, out of the asteroid and into space, leaving only larger rocks behind,” says the press release. The same process may even be at play in places like Saturn’s rings, another place filled with tiny, airless worlds.
Asteroids constantly spin worlds and because they are so small, the sunlight falling on their surface varies greatly. A small region can flash rapidly between sunlight and shade and stretch surface rocks until they crack.
Even dust grains are affected, as they are flung through space by a process called electrostatic lofting. Sunlight on regolith eventually accumulates negative charges on individual dust particles.
When enough charge builds up, the particles move away from each other like two repelling magnets, at speeds sometimes exceeding 30 km/h.
“No one had ever considered this process on the surface of an asteroid before,” Wang said.
The simulations seem to show the most effect of dust explosions on smaller asteroids, as these tiny worlds have comparatively weaker gravity. On smaller worlds, similar in size to Ryugu, regolith can be lost to space over eons.
This loss not only creates the boulder-strewn landscape seen on Bennu and Ryugu, but given enough time, an asteroid could lose a lot of its dust. A “cleaner” surface is more exposed to the effects of solar radiation, which can push the orbit in a different direction given enough time.
Although the effects are still poorly understood, scientists hope to gain more information with NASA’s upcoming Double Asteroid Redirection Test (DART) which will visit two other asteroids of similar scale to Ryugu and Bennu. DART will arrive at the system, called Didymos, in September and slam into the smallest rock to perform an asteroid impact test.
A story based on the research was published July 11 in Nature Astronomy (opens in a new tab).