Last month, an international team of astronomers tracked asteroid 2012 TC4 as it passed near our planet. The exercise was envisioned as a test of global response capabilities in the event of a dangerous asteroid flying towards our planet.
TC4 was assumed to be harmless but its size and orbit were not well understood. Now astronomers have been able to reduce the uncertainty significantly. It was estimated to be between 10 and 30 meters (30 and 100 feet) across and has now been confirmed to be 15 meters (50 feet) long and 8 meters (25 feet) wide. Thanks to the sophisticated optical and radio wave observations, the astronomers also refined its orbit estimation showing that TC4 is absolutely harmless.
"The high-quality observations from optical and radar telescopes have enabled us to rule out any future impacts between the Earth and 2012 TC4," Davide Farnocchia from NASA’s Center for Near-Earth Object Studies, who led the orbit determination effort, said in a statement. "These observations also help us understand subtle effects such as solar radiation pressure that can gently nudge the orbit of small asteroids."
TC4 reached the closest point to Earth on October 12, when it flew about 43,780 kilometers (27,200 miles) above our heads. But the observational campaign started early in the summer, conducted by researchers from the US, Russia, Canada, Italy, Germany, Colombia, Israel, Japan, South Africa, and the Netherlands.
"This campaign was an excellent test of a real threat case. I learned that in many cases we are already well-prepared; communication and the openness of the community was fantastic," Detlef Koschny, co-manager of the near-Earth object (NEO) segment of the European Space Agency's Space Situational Awareness program, added.
"The 2012 TC4 campaign was a superb opportunity for researchers to demonstrate willingness and readiness to participate in serious international cooperation in addressing the potential hazard to Earth posed by NEOs," said Boris Shustov, science director for the Institute of Astronomy at the Russian Academy of Sciences.
It wasn’t just ground-based facilities that pitched in. Astronomers also used space telescopes to understand TC4 better. The network of telescopes was also used to estimate how quickly the object was rotating. The team was surprised to see that it was spinning fast, about once every 12 minutes, but it was also tumbling.
"The rotational campaign was a true international effort. We had astronomers from several countries working together as one team to study TC4's tumbling behavior," said Eileen Ryan, director of the Magdalena Ridge Observatory, which tracked the asteroid for two months.
The danger from asteroids is remote but extremely serious, so, luckily, we are now better prepared than before this campaign begun.