Here’s How This New NASA Telescope Will Hunt Down Dangerous Asteroids – SlashGear

Spotting asteroids is challenging for several reasons. Firstly, there is the matter of size. Asteroids over a kilometer in size do exist and are usually relatively easy to see because they are so big, while small asteroids of under 100 meters across don’t pose a risk as they would burn up in Earth’s atmosphere. But those asteroids in the middle range, from 100 meters to 1,000 meters across, could cause huge damage if they hit the planet but are difficult to detect.

Another reason it’s hard to spot threats is that they can come from different directions, so we need to be looking across the whole sky to spot them. As well as asteroids, which typically originate in the asteroid belt, there is also the issue of comets. These contain ice as opposed to rock, and typically originate from the Oort cloud, which makes their paths hard to predict.

A dedicated telescope like NEO Surveyor will be able to detect two-thirds of asteroids that are larger than 140 meters across as well as be able to observe more comets to determine how much of a threat these might be.

Finally, asteroids can be made of different sorts of rock and so can be lighter or darker. The lighter asteroids reflect more light and are easier to see, while the darker ones are even harder to spot. That’s why NEO Surveyor looks in the infrared, so it can see the heat given off by the asteroids instead of relying on visible light. As the asteroids get closer to the sun they heat up, and this heat makes them visible in the infrared.