Solar wind may help detect Earth-bound space rocks

Changes in streams of plasma and particles spewing from the Sun, called solar wind, may help detect potentially dangerous space rocks that are headed toward Earth, a new study has found.
The findings could help identify smaller near-Earth objects - such as the Chelyabinsk meteor that exploded over Russia in 2013 - before they blast through Earth's atmosphere, according to study co-author Hanying Wei, a researcher in earth, planetary and space sciences at the University of California at Los Angeles (UCLA).
Smaller space rocks and ultrafine dust often trail the massive near-Earth objects that circle the Sun.
Even if the main asteroid never comes close to the planet, Earth's gravitational pull can peel the smaller orbitals off and bring them directly toward the planet.

These smaller impacts won't destroy the Earth, but they batter the planet every few decades and can still be incredibly damaging, said study co-author Hairong Lai, a space physicist at UCLA.
When meteoroids randomly collide with the medium-size rocky bodies in the dust cloud around an asteroid, even tiny particles can pulverise the much larger objects, creating an ultrafine haze of dust.

The researchers wondered whether the presence of this fine dust, a byproduct of these catastrophic collisions, could help identify asteroids with large amounts of debris as well as the smaller near-Earth objects trailing them.
Photons ping the surface of the fine dust particles, knocking off electrons and leaving the dust positively charged, Wei said.

As a result, the stream of particles spewing from the Sun, called solar wind, interacts with the charged dust and creates a spike in the magnetic field.
Several spacecraft in the solar system have onboard magnetometers that can detect these magnetic signatures of collision.
By using data from multiple spacecraft on the size and scale of the magnetic field perturbations, along with previously derived data on the speed and characteristics of known interstellar bodies, the team can calculate the size and shape of a trailing debris cloud.
These asteroids circle the Sun year after year, the researchers can map how the debris trail changes over time. From there, existing simulations can reveal whether Earth is in the path of rocky debris, Lai told 'Live Science'.

The team has already found that Asteroid 138175, which circles the Sun roughly every 368 days, may have tens of thousands of small but deadly objects in its orbit that may pose a threat to Earth.
In contrast, Asteroid 308635, which circles the Sun every 455 days, does not carry much rocky debris in its wake.