Crazy Engineering: Starshade/Coronagraph

Astronomers now know that virtually every star in the night sky has at least one planet orbiting around it. And they believe that many of these planets could harbor life.

Here's the problem.

The planets are orbiting extremely bright stars sometimes billions of times brighter than the reflection off the planet. But if you could block just the light from the star all of a sudden you can study the planet in more detail.

Let's go figure how to block a star's light on this episode of Crazy Engineering.

(Music)

Alright. We're here with Nick Siegler in this very fun looking lab. Ah Nick, can you tell us a little bit about where we are?

Mike, we're in JPL's Starshade Lab.

What exactly is a starshade used for?

Mike, there are two techniques that NASA is advancing to look for life on exoplanets. The

starshade, basically, is a large shade that is flown outside of a telescope with the intention of blocking the light from the star. So then we can see the planet's light skirt the shade and capture it by the telescope.

Ok, so this is much like I'm looking up at the sun and I want to see a bird or a airplane. I put my hand up to block the sun's light. But we have to do it on a much larger scale for a star.

The starshade itself is tens of meters in diameter. That's the size of a baseball diamond.

(Sound effect)

Just about how far away from the telescope would it have to fly?

It's tens of thousands of miles. You can fit four Earths between the telescope and the shade.

It's got its own propulsion system. It literally its own spacecraft.

How do we get it up to space? That's the engineering challenge. Is how do we get something that has to deploy to tens of thousands of meters in diameter that can sit on a rocket.

So now our engineers have some up with a technique based on the ancient practices of origami.

Sounds difficult.

How do you know that's going to work?

Well, we do what we always do.

We start small and we work our way up.

So we started in this case with something a few inches in size. Then we built something a meter in diameter and we matured it up to two meters and now, we finally got up to five meters. The one that flies in space is going to be 10's of meters.

Ok, so you're using origami to make this really large starshade, a fun mechanical engineering project, but you mentioned that NASA actually is investing in two different technologies.

What's the second technology?

That one is called the coronagraph.

The coronagraph.

Can we take a look at that one?

Let's go.

(Sound effect)

Okay Nick. This is obviously a lot different from the last lab we were in. We're in bunny suits. We're trying to be super clean.

Can you tell us where we are right now?

Mike, we are in JPL's High Contrast Imaging Testbed Lab. This is where we test the next generation of space coronagraphs. Behind us, is one of our vacuum chambers where we simulate the environment of space.

What's the big different in approaches here?

With the starshade, we saw the blocker was way outside of the telescope.

Now as another approach, we're going to take that huge blocker and shrink it down to the size of something that can fit in between your fingers.

This way, you can fit on the backend of a telescope.

This particular mask is the size of a pinhead.

All of that starlight has to be focused right onto that little pinhead.

You want to make sure that focused light from the star hits the sweet spot of the mask.

So, it's critical that we have a mechanism to control the focused light.

Alright, so we saw the starshade and now the coronagraph. They're both crazy in their own ways and it's a lot of really great engineering.

So, what's the end game? What do we hope to accomplish?

Mike, we're trying to develop technology to be able to look for life on other planets. The hard part is blocking the light from the star. Once we do that, we have other technologies that are more mature and would be in a better position to look for evidence of life.

Nick thank you so much for showing us both of these approaches and both your laboratories. We really got a sense of a contrast between the different approaches.

Hope you guys out there had a lot of fun learning about it and check back soon for some more Crazy Engineering.

For more information on exoplanet research: http://exep.jpl.nasa.gov/