이 에피소드에 관해
The solar system provides some handy “parking spots” for spacecraft. They’re steady locations for watching Earth, the Sun, or the rest of the universe. They’re called Lagrange points. They’re small regions in space where the gravity of two bodies is balanced. An object can stay at a Lagrange point with little effort. Space agencies take advantage of that gravitational quirk by placing probes there. For any two astronomical objects, such as Earth and the Sun, there are five Lagrange points. But some of them are more useful than others. The point known as L2 has been especially popular. It’s a million miles on the opposite side of Earth from the Sun. Normally, a spacecraft at that distance would move a little slower than Earth and fall behind it. But at L2 it can stay in place – almost. Over time, the craft would slowly drift away. So instead, it orbits that point – keeping it locked in position. From L2, a space telescope has a clear view of the universe, unobstructed by Earth itself. But it stays close enough to Earth to remain in easy contact. So more than a dozen space telescopes have settled in there, including the James Webb telescope. When a telescope’s job is done, it fires its thrusters to leave L2 so it won’t interfere with ongoing missions. For the past year, L2 also served as a parking spot for a pair of probes bound for Mars. We’ll have more about that tomorrow.
Script by Damond Benningfield
