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How NASA's Webb telescope gets its packed schedule


Imagine a bunch of kids unwrapping a fancy new toy on Christmas morning that everyone wants to play with. How did the parents decide which kid gets to put their hands on it first? Well, if that toy were a $10 billion space telescope and the kids were astronomers from all over the world, then Dr. Christine Chen would be one of the parents who figures out who gets to play with it. She's been working on the James Webb Space Telescope since 2008, and now that it's out in the universe, she manages the team sorting through proposals from scientists who want to use it for research. Dr. Chen, welcome to ALL THINGS CONSIDERED.


SHAPIRO: OK. So how many people actually want to play with this toy? Like, how many proposals is your team sorting through?

CHEN: Oh, my gosh. So we've had one proposal call so far. And I think the response to that was about 1,200 proposals.


CHEN: And that's the second largest number of proposals we've ever gotten, even for Hubble.

SHAPIRO: Well, because your group has experience from Hubble, there's a process in place. How do you decide whose research gets to the top of the pile?

CHEN: So lots of people from all over the world come with their best ideas for what they think would be great science to do. And the review process is a dual anonymous peer review system. So that means that not only do members of the community submit proposals, but members of the community also review them. When the proposals are reviewed, there are three criteria to determine how they rank. One is how the program will contribute to our understanding of a particular subfield in astronomy. Criteria two is if there's broader impact beyond that individual subfield. And then the third criteria is whether or not you really need JWST because if you don't, then you should probably use a different facility.

SHAPIRO: OK. So about 1,200 people submitted research proposals in this first round. What percentage got accepted?

CHEN: About 25% of proposals were accepted. We actually anticipate, you know, it'll become more competitive with time because now that James Webb Space Telescope is in space and people are seeing, like, how well it's working, more and more people are just getting more and more excited. So we expect more and more proposals.

SHAPIRO: Oh, it's proven to work.

CHEN: Exactly, yes.

SHAPIRO: I'm guessing that some of these projects are long-term and involved, while others might require just an hour or a day of the telescope's time. How does that factor into the considerations?

CHEN: So the vast majority of the proposals just take a year to execute. So they might be observations of something really cool that just happened, like a supernova in a galaxy. Or someone wants to look at an extrasolar planet as it goes in front of its host star. And so those observations are limited to just one cycle. But you're absolutely right that there are some projects for which people need to monitor targets to see if their behavior changes over time. And in those cases, they can actually ask for what are called multi-cycle observations. So they can ask for time in the cycle that the proposal calls for, the one after it and the one after that - so up to three cycles at a time.

SHAPIRO: So after the research proposals have been greenlit, who handles Webb's schedule? Like, is there a Google calendar or daily planner? Like, does the telescope have a personal assistant?

CHEN: Yeah, that is a super-complex problem. So there's two major constraints for scheduling observations. One is, like, timing. When are they available to the telescope? - because sometimes you're looking for a particular thing to happen. So, for example, with those transiting exoplanets, you might be waiting for the planet to go right in front of its host star. And people have measured their orbits very precisely, so they know exactly when that's going to happen to, like, the nearest minute. Constraint No. 2 is data volume. The data recorder that's on James Webb Space Telescope - it has a, you know, somewhat limited capacity compared to all of the cameras and the spectrographs around the telescope. And so people have to be really careful so that you don't overflow the recorder and you can return everyone's observations down.

SHAPIRO: Dr. Christine Chen is an associate astronomer at the Space Telescope Science Institute. Thanks for talking with us.

CHEN: Thank you.

(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.

Ari Shapiro has been one of the hosts of All Things Considered, NPR's award-winning afternoon newsmagazine, since 2015. During his first two years on the program, listenership to All Things Considered grew at an unprecedented rate, with more people tuning in during a typical quarter-hour than any other program on the radio.
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