To The Moon ... And Lagrange Points?

GUY RAZ, host:

One of the options from the Augustine report was to carry out experiments in deep space - at places called Lagrange points. But what are they? And more importantly, where are they?

To find out, there was only one place to go, the National Air and Space Museum here in Washington.

So I'm here at the museum now. And to my left is a scale model of the Apollo lunar module, the craft that actually landed on the moon. And to my right is George Sonneborn. He is an astronomer at NASA's Goddard Space Flight Center.

And you're here to talk with us about Lagrange points. What are Lagrange points?

Dr. GEORGE SONNEBORN (Astronomer, NASA's Goddard Space Flight Center): Joseph Lagrange was a mathematician and physicist in the 18 century. So this is around the time of the American Revolution. And he discovered that an object could orbit in space and stay stationery relative to the Earth.

RAZ: Hmm.

Dr. SONNEBORN: And it wasn't discovered until the 1900s that his mathematical prediction was actually correct.

RAZ: So if we were to imagine it, it would be sort of like an invisible bubble?

Dr. SONNEBORN: In the case of the Earth and the sun system, the Earth's gravity and the sun's gravity balance each other so that an object would orbit the sun at exactly the same rate that the Earth does. So from the Earth, it looks like it's at a fixed location in space, even though it's really orbiting the sun.

RAZ: So how many of these Lagrange points are there?

Dr. SONNEBORN: There are a total of five Lagrangian points. One, just in front of the Earth toward the sun; there's one opposite the Earth away from the sun. The third Lagrangian point is on the opposite side of the sun at around the same distance as the Earth is, but on the opposite side. And then there are two that are off 60 degrees in front of and behind the Earth and its orbit.

In terms of space, there isn't much there. But there a fair number of satellites both at the inner Lagrangian point to study the sun, and there are several satellites, at least three right now that are operating at L2, the outer Lagrangian point to study space.

RAZ: So now, the Augustine report is recommending that NASA consider sending a manned mission to one of these Lagrange points. But what would a manned mission give us here on Earth versus just sending up a satellite?

Dr. SONNEBORN: I mean, this could be a staging point for going elsewhere because this is a relatively stable point in space. You could have a servicing platform. There's - you could do a lot more there than you could right now. I mean, it's been limited by resources.

RAZ: How long would it take to get to the closest point?

Dr. SONNEBORN: A direct launch to one of the Lagrangian points takes about three months to get there.

RAZ: Oh, so it's far.

Dr. SONNEBORN: It's a million miles away from the Earth.

RAZ: This all sounds really a sort of '60s science fiction to me.

Dr. SONNEBORN: Well, it's actually interesting. You mention science fiction. There's been a lot of books written over the years about civilizations that would leave the Earth at some point in the future and have new colonies that would be built and set up at these Lagrangian points.

RAZ: Like the Death Star...

Dr. SONNEBORN: Yeah. Yeah.

RAZ: ...exploding in the Lagrangian point.

Dr. SONNEBORN: Yeah. Yeah. Yeah.

RAZ: Pretty cool.

Astronomer George Sonneborn works at the Goddard Space Flight Center in Maryland. He joined me here at the Air and Space Museum in Washington, D.C. And now, I've got to run back to the studio.

Thanks for being with me.

Dr. SONNEBORN: Okay, you're welcome. Thank you. Transcript provided by NPR, Copyright National Public Radio.