How Did We Not See the Russian Asteroid Coming?
Over a hundred people are injured after a meteor or meteors reportedly exploded over Chelyabinsk, Russia this morning. Although there are no confirmed deaths, the full extent of the situation is still being assessed.
Chelyabinsk is a city of about a million people, located just to the east of the Ural Mountains. This morning, several people captured video of a bright trail streaking across the sky, followed by a saturatingly bright light. Although some people say that the lights were caused by a meteor shower, others believe that it was a single meteor that cut across the sky and exploded in the atmosphere.
Accounts of injuries vary, but it appears that anywhere between one hundred and four hundred people were injured, most of them by glass from shattering windows. (Reuters is saying 400.) The explosion shook the buildings, and it seems as though the 6000-square-foot roof of a Zinc Plant collapsed. Some people say that fragments of the meteor rained down on the town. Given that it was one of the biggest meteors to hit Earth in possibly a century, why didn’t we see it coming?
For answers, we turned to NASA’s Amy Mainzer, a scientist who works with the space agency’s Near Earth Objects (NEO) program, and one of the main researchers on the NEOWISE satellite project to map NEOs in the sky.
We are quickly learning a lot about the Russian fireball. It was pretty small - only about 15 m and about 7000 tonnes - and that’s why it wasn’t detected. This object wasn’t seen earlier because it was really faint, and it might not have been visible to observers in the night sky. Most of the survey efforts have been very successful in finding the largest asteroids (about 90% of the near-Earth objects larger than 1 km in diameter have been found), but there is still a lot of work to be done with finding and tracking the smaller objects.
Though it seemed enormous, the meteorite that struck Russia was relatively small. It’s likely that objects like this could hit again without warning, simply because right now our satellite systems are combing the skies for truly deadly objects that could wipe out a country or even a continent.
Still, added, Mainzer:
NASA is studying ways to improve the survey capabilities; an example of a prototype new system is the NEOWISE project that I worked on, which used an infrared telescope to discover and characterize NEOs. But the program has been expanded in budget by about a factor of 3 in the last couple of years, so that’s good.
One way that NEOWISE was helpful was that it could measure objects that appear dark to other telescopes. Often we judge the size of asteroids and meteors by measuring how bright and reflective they are. The problem is that some large objects are actually quite dark and very little light bounces off them. Using an infrared telescope like the one on NEOWISE helps us identify even these cloaked objects that might be invisible to other devices.
Images via AP