字幕表 動画を再生する 英語字幕をプリント In 2020, NASA’s OSIRIS-Rex mission landed a probe on Bennu, an asteroid about half a kilometer wide. Weighing in at a whopping 77.6 million metric tons, it’s safe to say Bennu could wreak some pretty serious havoc if it collided with Earth. But that’s just one reason why we’re probing its composition. Bennu may be more than 4.5 billion years old, so getting to analyze samples from its surface could tell us so much about our early planet, solar system, galaxy, and universe, stuff like where did Earth’s water originally come from? Subscribe to Seeker and watch our recent Elements video all about research into water-rich asteroids for more.