Our solar system is chock full of asteroids - millions of them. While most are contained within the asteroid belt that lies between Mars and Jupiter, these rocks can be found pretty much anywhere in the solar system. Many scientists believe that the majority of asteroids are composed of material left over from the formation of the solar system, so they represent an exciting opportunity to understand our history. NASA's OSIRIS-Rex mission to collect a sample of one of these bodies and return it to Earth will launch in 2016 and the agency has also targeted exploring an asteroid as the next step for our human spaceflight program. But, some of these asteroids could also pose a risk to the Earth and a new report released this week concludes that NASA is not doing enough to find them.
The US Congress has charged the agency with finding at least 90% of near-Earth asteroids over 140 meters by 2020, but NASA's own inspector general charges that they are not on track to complete this task. Among the factors he cites are insufficient personnel, insufficient funding, and a lack of a specific plan. This, after NASA has already increased its asteroid-hunting budget tenfold to $40 million per year.
Finding near-Earth asteroids is not an easy task by any stretch. Although large enough to cause considerable damage here on Earth, a 140-meter asteroid is tiny in the vastness of space. Compared to objects like stars and planets, asteroids appear to be moving very quickly across the sky and their irregular shape and often-dark surfaces means that their brightness is very low and often unpredictable. The smaller you go, the tougher the job gets: NASA has already found over 90% of asteroids larger than a kilometer in size.
Do any of these rocks pose a risk to Earth? Happily, the answer is no. That doesn't mean that no rocks will hit the Earth, we're stuck everyday hundreds of times, but these objects are small enough that they will simply burn up in our atmosphere as shooting stars. NASA classifies the risk posed by asteroids on a scale of 0-10, where 0 is no chance of collision or the object too small to matter and 10 is an event certain to happen that will destroy civilization on Earth. Every object currently classified is a 0. We've never found an object with a rating higher than 1 and all of those objects were eventually reduced to a 0 once we understood their size and trajectory better.
So, what will NASA do in response to this report? In a statement released regarding the report, John Grunsfeld, the agency's associate administrator for science, concurred with some of the report's conclusions and emphasized that they would be taking steps to remedy them as quickly as possible. Until they do, we will just have to hope that an important one doesn't escape our detection!
You can read the full report here.