For the first time, two rovers from Earth have reportedly landed on an asteroid not from Earth. The Japanese Space Agency JAXA says it recently made history by putting the unmanned exploration robots on the asteroid's surface. First, the mission, it's cost is estimated at $150 million. It launched in December of 2014 and finally got near the asteroid this summer and it's Japan's second mission of this kind.
The last one to a different asteroid was able to bring some samples back to Earth but it had some technical failures with it's rover. The asteroid itself is more than 100 million miles away from Earth and Japan's goals this time around included getting detailed information about the rock's surface, using explosives to gather material from just beneath that surface and then bringing samples back to Earth by the end of 2020. A total of three rovers will be used to do all this. The vehicles themselves aren't particularly big. The spacecraft that got them there is about the size of a large refrigerator. So the rovers it carried are smaller than that.
These vehicles don't drive over the rock surface like an interplanetary dune buggy. Rather they hop jumping almost as high as 50 feet at a time.
The asteroid they're on is just over a half a mile wide. Scientists think it's rich in water and organic materials and that the samples they get from it will help advance their knowledge of solar system's start-up. If everything goes according to plan, JAXA says this will be the first sample return mission to this type of asteroid. NASA has a similar mission in it's planning but that one isn't due back to Earth until the year 2023.