Monitoring Elusive Collisions In Space
April 24, 2013

UCLA Scientists Devise New Method To Locate Incoming Meteoroid Debris

April Flowers for - Your Universe Online

Asteroids and other objects in our solar system collide often, but researchers are not always able to detect or track such impacts from Earth. This means that we are sometimes caught unaware by the "rogue debris" created by the impacts.

New research from the University of California, Los Angeles, has devised a method to monitor these types of collisions in interplanetary space. The team used a new method to determine the mass of magnetic clouds that result from the impacts. Nearly 30 years of observations of such collisions went into the findings published online in the journal Meteoritics and Planetary Science. The study could help researchers have a better understanding of how to locate incoming meteoroid debris that could endanger the Earth.

"The passage by the Earth earlier this year of the small asteroid 2012 DA14 and the explosion the same week of an even smaller asteroid in the atmosphere above central Russia remind us that while space is mostly empty, the objects that are orbiting the sun do occasionally collide with other orbiting bodies, and the energy released in such collisions can be catastrophic to the bodies involved," said Christopher T. Russell, a professor in UCLA's Department of Earth and Space Sciences.

"We have found a way by which we can monitor such collisions in space by identifying the magnetic signature produced in these collisions," he said. "While the colliding objects may be only tens to hundreds of feet across, the resulting magnetic signature can be hundreds of thousands of miles in width and be carried outward from the sun by the solar wind for millions of miles."

The new method for finding the mass of collision-produced magnetic clouds that contain fine, electrically charged dust was devised by Hairong Lai, a graduate student in Russell's laboratory.

"We have used multiple spacecraft encounters with these magnetized clouds to determine their dimensions," said Lai, the lead author of the research. "Then we calculate the magnetic force applied to the dust, which balances the sun's gravitational force, allowing us to weigh the fine component of the debris created by the collision. These dust clouds weigh from about 10,000 to 1 million tons – very similar in mass to the asteroids the Earth recently encountered over Russia and over Australia."

The team applied the technique of monitoring the debris cloud of collisions to material co-orbiting with the asteroid designated 2201 Oljato, which was first associated with collisions near Venus in the 1980s. Oljato made successive passes by Venus in 1980, 1983, 1986, when NASA's Pioneer Venus spacecraft was in orbit around the planet.

The Venus Express mission from the European Space Agency (ESA) entered orbit in 2006 and resumed monitoring the collisions. The collision rates have dropped dramatically in the sector where impacts with material in Oljato's orbit can be detected. The rates in other sectors, however, remain unchanged.

"The collisions have destroyed both the impactors and their targets in this longitude sector, demonstrating that meteor streams can be quite dynamic," said Hairong, who presented research last week at the third Planetary Defense Conference of the International Academy of Astronautics. "They can be created by collisions and also destroyed by collisions."

Because asteroids whose positions are currently known by scientists are all potential producers of smaller meteoroids that can change orbits more rapidly, tracking becomes more difficult. The new method makes the tracking much easier.