in the early 21st century impact prediction usually doesn't work. almost all of the asteroids that hit earth are a surprise. nasa wants to get better at impact prediction by building more powerful telescopes. a big new telescope, made for searching, is being built in northern chile called the lsst. it is very big and will take years to build. it should be ready by 2023. when it is ready the powerful telescope should be a lot better at seeing small asteroids.