Why Japan is landing hopping robots on an asteroid

Japan has landed two hopping robots onto asteroid Ryugu as part of the Hayabusa2 mission. It's Japan's second mission to an asteroid, where it plans to return some samples of Ryugu to Earth by the early 2020s. So that scientists can study the samples with more sophisticated instruments and hopefuly uncover some of the biggest scientific mysteries of all. Following is a transcript of the video.

On September 21, Japan’s space agency made history. It became the first country to land not one, but two rovers onto an asteroid. Already, the unmanned rovers have sent back the first images while on the surface. And no, so far it’s looking like there are no alien cities on its surface. But this mission, called Hayabusa2, could ultimately help solve one of the grandest scientific mysteries of all: Where did life on Earth come from?

Scientists have been studying asteroids for years. NASA, for example, landed its N.E.A.R Shoemaker spacecraft on asteroid Eros in 2001. But its Japan’s space agency that is the first to deploy a pair of rovers to explore an asteroid’s surface. Japan launched the Hayabusa2 mission in December, 2014. So, it has already been about 3.5 years in the making.

The spacecraft rendezvoused with its target in June 2018. Snapping a series of pictures that revealed the asteroid’s shape. The asteroid of choice was 162173 Ryugu, or Ryugu for short. In Japanese it refers to a magical, underwater Dragon Palace. Now, the asteroid flies through space, around the sun ever 16 months. Conveniently between the orbits of Earth and Mars.

Making it an ideal target for the mission. Which, if all goes according to plan, will return a sample of the asteroid to Earth by the early 2020s. As the spacecraft flew closer to the asteroid’s surface, it prepared to deploy its first two unmanned rovers. But these guys aren’t your typical space rover. They’re slightly bigger than the size of a large iPhone. Measuring just 7 by 18 centimeters. And they won’t be driving around on the asteroid’s surface. They’ll be hopping.

Yup, you heard that right. Hopping. Japan designed the rovers with a spinning cylinder inside that gives it the power to hop about a few meters at a time. This reduces the risk of getting stuck on the rocky, uneven surface. But it doesn’t come without it’s own risk. Asteroids are relatively small and therefore have a weak gravitational pull. And even by asteroid standards, Ryugu is tiny. It’s less than a kilometer across, making it no larger than a few city blocks. So, if the rovers hop too high, they could potentially go flying off into space. But so far, the mission looks good.

The rovers have already achieved their first hop. Now, this may be the first time Japan has landed on an asteroid but it won’t be the last. These two rovers are just the first of four that Japan aims to land on Ryugu. The other two rovers are scheduled to land within the next year. In the process, Japan hopes to collect and return a sample of Ryugu to Earth. So that scientists can study it in more detail, looking for traces of water and organic material. If it turns out that asteroids like Ryugu contain similar material that we see on Earth it would be strong evidence for the idea that life on Earth first came from an asteroids billions of years ago. But this is a mystery that we can only answer if we study asteroids directly.

Join the conversation about this story »