Tiny asteroids like Bennu or Ryugu are dust-free. Scientists have long wondered why. Now it turns out that our sun and the violent solar storms could have something to do with it.
Asteroids are weird. Some are made of rock while others are made of ice (themis), sometimes rotating and sometimes simply tumbling (toutatis), and they can be from tens of kilometers wide to a few centimeters. And scientists have spent years trying to understand these anomalies in asteroids and the cause behind them because they might reveal something important to us. And it seems that scientists have come across such a thing. Smaller asteroids like Bennu and Ryugu share one very intriguing property – they are all dust-free. And scientists have found that this feature is caused by various solar activities, including solar storms.
It might seem a little odd to think that a solar storm can clear asteroids of dust and understand its importance for us, but rest assured it will reveal information that may be useful to us. Scientists only recently learned about this phenomenon after the Hayabusa2 and OSIRIS-REx spacecraft visited the two asteroids and found that their surface is not as smooth as that of large asteroids like Vesta. The bodies of these smaller asteroids looked like a rocky canyon, with small rocks heaped everywhere and not a speck of dust to hold them together.
Dustless asteroids issue important solar storm warning
A new study published in the Nature journal highlights that smaller asteroids shed the dust on their surface due to a process known as electrostatic repulsion. Simply put, electrostatic repulsion means that two particles of the same charge repel each other. And the study found that in the case of the smaller asteroids, this is caused by the sun’s ultraviolet radiation. So when these rays fall on the dust, the dust loses electrons from its atomic structure and once charged, they shoot off the asteroid and plunge into empty space.
But why is this phenomenon only visible in smaller asteroids? The answer is simple. Due to the smaller size, the asteroids have a weaker gravitational pull and are unable to balance the repulsion of similar charges.
And what does it have to do with us? Well, solar storms carry similar radiations. And if we know that this is the effect that solar radiation can have on the dust particles, the guess is that the same can happen with the small instruments in the satellites spinning in Earth’s upper orbit. While they don’t run the risk of being catapulted into space, zapping from UV rays can impair their function by charging the instruments. Some of these satellites are used for critical communications and security purposes, and the slightest change in the readings of these instruments can be very problematic.
This information will help scientists not only better understand the asteroids, but also think of better ways to protect satellites from solar storms.