The world's biggest digital camera is almost ready to be installed on its telescope

MARY LOUISE KELLY, HOST:

The world's largest digital camera is nearly complete. Scientists expect exciting discoveries once the 3.2 billion-pixel camera is paired with its telescope. NPR's science correspondent Joe Palca recently visited the lab where the camera was built.

JOE PALCA, BYLINE: The camera is being built at the Department of Energy-funded SLAC National Accelerator Laboratory in Palo Alto, Calif. This camera is huge. It weighs three tons, and it's two stories tall. When I visited earlier this month, it was lying horizontal on a large steel platform.

AARON ROODMAN: The lens cover is still on, so we can't look in the business end.

PALCA: Aaron Roodman is the camera program lead. We're inside a high-ceiling clean room, wearing Tyvek hoods, jumpsuits and booties, and latex gloves to avoid contaminating the equipment inside the camera. Sitting on its side, the camera body looks to me a bit like a jet engine.

ROODMAN: So you want to go up on the - should we go up on the platform to take a closer look?

PALCA: We clamber up the half-dozen metal steps to the platform. We're now just inches away from the camera body - so close I could touch it. Roodman says, don't.

ROODMAN: It's OK if you did, but let's try not to.

PALCA: Oh, OK.

ROODMAN: Yeah. Let's not...

PALCA: Well, you know, every kid wants to touch it.

ROODMAN: I know. Let's try not touching it. I think nothing would happen if you did...

PALCA: OK.

ROODMAN: ...But just a good practice not to.

PALCA: Roodman's caution is understandable. If I spent $168 million for a camera, I wouldn't want people messing with it either. And there's nothing quite like this camera. There are custom-built lenses, filters, bespoke electronics, a giant shutter and special refrigeration to keep the equipment cool, all packed into the cylindrical camera body.

ROODMAN: In this configuration, it is just - it just looks jam-packed, but seeing everything together like this is fantastic.

PALCA: The Vera Rubin Observatory in Chile, where the camera is headed, is also unique. Its telescope is designed to see a large chunk of the sky at a time, so it needs a huge camera to capture the images. Each night, the camera is expected to generate 20 terabytes of data.

ROODMAN: Right now, we're scheduled to ship the camera to Chile in April.

PALCA: This should be a time of elation for people working on this project. The camera's nearly finished. The telescope is also nearly complete, and Roodman and his colleagues are pretty upbeat. But there's a problem nobody thought of when the telescope was conceived - communications satellites, thousands already in orbit, many more to come. To the naked eye, they're usually invisible. But to the telescope camera, they're bright objects.

ROODMAN: They're going to be anywhere from a medium nuisance to a major nuisance. It's not a good development for us at all.

PALCA: You can write a computer program that will digitally eliminate the satellites. But because the Vera Rubin telescope sees such a large chunk of the sky at once and there are so many satellites, it will be hard to remove them all. Tony Tyson is chief scientist for the new observatory. He says it was designed to find what Tyson calls things that go bump in the night - objects that are not there one night, but appear a day or so later. These could be exploding stars or stellar collisions or something entirely new to science. The satellites could make this a problem. Tyson says, when the telescope sees something unusual like that, it will alert other telescopes to look at that part of the sky so whatever went bump in the night can be studied in depth.

TONY TYSON: I think that we're going to have a very big background of false events - of bogus alerts. That's what worries me most.

PALCA: Things that the software misidentifies as new, but are really just a reflection from a satellite. A false tip will send other telescopes off on a wild goose chase. Tyson says some companies, such as Starlink, have agreed to take steps to mitigate the problem, such as using less reflective material in their satellites. Other companies haven't been as accommodating. Tyson says they won't know for sure how big a nuisance these satellites are until they install the camera in the telescope and start looking at the sky. Joe Palca, NPR News.

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