NASA's newest telescope has a top secret past

The new Nancy Grace Roman space telescope is slated to launch this weekend. It was originally built for the National Reconnaissance Office as a spy satellite, but was never launched. Instead, NRO gave it to NASA about 15 years ago. After some major modifications, it’s set to begin its five-year mission peering at new supernovas, distant galaxies and planets orbiting stars outside our solar system. It should help scientists get a better understanding of the mysterious force known as dark energy – which will tell us about the fate of the universe. If you liked this episode, check out Regina’s reporting demystifying the mysterious red dots http://lnk.to/C0Cpam spotted by the James Webb Space Telescope. Interested in more space news? Email us your question at [email protected] mailto:[email protected]. Support public media with NPR+ and enjoy perks for over 25 podcasts like this one. This show’s perks include sponsor-free listening. Learn more at plus.npr.org http://plus.npr.org. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

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  You're listening to Short Wave from NPR.

• 0:22Speaker 01

  Hey, Short Wavers. Regina Barber here. Get ready, because we're about to get an entirely new window into the universe. The Nancy Grace Roman Space Telescope, called Roman by its friends, is scheduled to launch at the end of August. So we called up an old friend of Short Wave, former NPR science correspondent, Joe Palca, to talk about it. Hey, Joe.

• 0:42Speaker 02

  Hey, Gina.

• 0:42Speaker 01

  So I hear that astronomers are stoked about this thing. I mean, I am.

• 0:46Speaker 02

  Yeah, stoked is a pretty good way to put it.

• 0:49Speaker 03

  If it delivers on what we think, it will be the best thing ever.

• 0:53Speaker 02

  Yeah, that's a version of stoked. That's Daniel Skolnick of Duke University, one of the scientists who'll be using Roman data to unlock the mysteries of the universe.

• 1:03Speaker 01

  OK, so, Joe, what have you been learning about the Roman Telescope?

• 1:06Speaker 02

  Oh, lots of stuff. To start off, it was named after a woman you maybe never heard of. I hadn't. She was NASA's chief astronomer back in the 60s and 70s, Nancy Grace Roman. And she gets credit for getting the Hubble Space Telescope from an idea to a reality. But one of the most unusual things I learned is that this Roman telescope wasn't originally built to look at the heavens. It was designed to be a spy satellite.

• 1:36Speaker 01

  I am looking forward to hearing all about how that happened. Today on the show, a preview of the Roman Telescope mission and its curious origins. You're listening to Short Wave, the science podcast from NPR.

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• 3:16Speaker 01

  So, Joe, I'm really intrigued by this, like, spy satellite lore. How does a spy satellite become a space-based, like, telescope observatory?

• 3:25Speaker 02

  Yeah, well, some of the details are murky because it involves the National Reconnaissance Office. And that's an agency of the government that manages surveillance assets. And the office was once so secretive, the government didn't even admit it existed.

• 3:39Speaker 01

  Wow.

• 3:40Speaker 02

  So the story goes, every 10 years, astronomers put together a list of their top priorities for the coming decade. And in the 2010 decadal survey, astronomers agreed they wanted a telescope that could look for more examples of type 1A supernovas. These are a particular type of exploding star.

• 3:59Speaker 01

  Yeah, so astronomers love these type 1A supernovas, these exploding stars, because they all seem to have the same brightness. So if you, like, catch one and it appears, and you measure its brightness, you can tell how far away it is. They're called standard candles. It's kind of like if you had a candle next to you and the exact same candle down the street, the candle down the street is going to be dimmer. But how much dimmer is actually just due to that distance?

• 4:22Speaker 02

  Yeah, so I call it a cosmological yardstick.

• 4:25Speaker 01

  Yeah.

• 4:25Speaker 02

  Yeah, it's a great tool. But anyway, that was what the 2011 Nobel Prize went for, and it was for using these standard candles to discover dark energy, a force that explains why the universe is expanding and accelerating when gravity suggests it should be slowing down or even contracting.

• 4:43Speaker 01

  Yeah.

• 4:43Speaker 02

  Anyway, going back to Dan, that astronomer or cosmologist we heard from earlier, he said, one day, 15 years ago, when NASA was in the midst of planning to build this telescope to look for more of these supernovas, the agency got a call.

• 4:58Speaker 03

  The National Reconnaissance Office reached out to NASA, saying, we have this amazing satellite sitting in a hangar that we're not using. And what do you guys think about, instead of pointing downwards, we point upwards and you guys use it?

• 5:12Speaker 01

  I love this so much. So like, instead of spying on Earth, we're using it to spy on alien worlds.

• 5:17Speaker 02

  Right. And so it never actually got into space, and it was sitting in a garage, essentially, in Rochester, New York, until NASA got hold of it.

• 5:25Speaker 01

  Nice. Well, how much did NASA have to modify it?

• 5:28Speaker 02

  Well, there were a lot of modifications, but some of the key bits, like the main mirror for collecting light, that was already built.

• 5:34Speaker 01

  Right, OK, so it has a mirror. What else does this telescope have going on for it? Like, what instruments does it use to collect this data?

• 5:41Speaker 02

  Well, there's two main instruments. One is called a coronagraph. And Roman's coronagraph essentially cancels out the light from a star and allows a camera to see a much fainter object, like a planet orbiting nearby. It's a technology that's never been flown in space before, so it'll be interesting to see if it works and how well.

• 5:59Speaker 01

  I remember using Hubble Space Telescope images in grad school, and I had to manually do this, to just cancel out, you know, light from something really bright to see the dimmer things in the image.

• 6:09Speaker 02

  Yeah. And the other main instrument that'll be used quite a lot is the Wide Field Instrument, which is basically a 300-megapixel infrared camera for taking pictures of these huge numbers of stars that the telescope will see with each image.

• 6:23Speaker 01

  Right, OK, so to that end, if the main mirror is about the size of the Hubble's main mirror, what can Roman do that Hubble just can't? I mean, other than being, like, newer?

• 6:33Speaker 02

  Yeah, no, newer is always good. But it has a much wider field of view, so it can see a much broader swath of the sky. And Julie McHenry says there's another key difference. Julie is Roman's project scientist, and at a recent news conference, she said that one of the observations the telescope will make is a survey of all the stars in the Milky Way galaxy.

• 6:55Speaker 06

  Roman has broadly the same sensitivity and sharpness of vision as Hubble, but we survey the sky much faster. So that one month of observations to survey our Milky Way galaxy would take about a century with Hubble.

• 7:10Speaker 01

  This is so amazing. Surveys are so important to astronomy. This is great.

• 7:15Speaker 02

  Without a survey telescope, you just couldn't do that. And even the newer James Webb Space Telescope, it has a bigger mirror, but it has a much smaller field of view, so it only looks at a small patch of sky at a time.

• 7:26Speaker 01

  Yeah, so getting the same amount of data from either of these telescopes would take longer than the lifespans of them being in space.

• 7:35Speaker 02

  Yeah, this is a telescope that was built to do surveys.

• 7:38Speaker 01

  Right.

• 7:38Speaker 02

  So it takes broad pictures of the sky instead of focusing on one or two objects. And Julie says that meant rethinking how the telescope would be used.

• 7:47Speaker 06

  Our model isn't the traditional astronomers write proposals and get time on the telescope and go off and do a thing. I mean, we do that as well, but that's not the primary way to use Roman. So what we did over the last few years was to work with the scientific community all over the world and ask them for their ideas on how we should use Roman.

• 8:09Speaker 02

  And what they came up with is several surveys that will collect data over months or years that scientists will all get equal access to.

• 8:17Speaker 01

  And they can just, like, download it from their website. This was kind of similar to Hubble. There was a lot of archival data, and people got degrees from that data.

• 8:25Speaker 02

  Yeah, anybody can get it. And when I say anybody, Julie McHenry says, yeah, really, anybody.

• 8:30Speaker 06

  You can be a teacher in a high school in Kentucky, and your students have the opportunity to see Roman data. New Roman data, new Roman discoveries at the same time as a professor in Princeton.

• 8:44Speaker 01

  So cool.

• 8:45Speaker 02

  Some of these surveys are what are called time domain surveys, which means they look at the same patch of sky over and over. And if you're wanting to find type 1A supernovas, you have to keep checking the same patch of sky because you don't know when an exploding star is going to appear.

• 9:01Speaker 01

  Yeah. So you, so you look at these images, you know, separated by hours or, or weeks, and you look for things that aren't in the earlier images, like if something popped up.

• 9:09Speaker 02

  Yeah, exactly. They say, things that go bump in the night. I like that.

• 9:13Speaker 01

  Yeah. So do you have an idea of how many type 1A supernova, these, these special exploding stars, how many they might find?

• 9:21Speaker 02

  Right. I asked Dan, that researcher from Duke we heard from earlier, and he said he expects it'll be in the thousands.

• 9:26Speaker 01

  Yeah.

• 9:27Speaker 02

  And he says finding them will help scientists better understand how fast the universe is expanding and could confirm or discredit the current model of the entire universe that scientists currently reference.

• 9:39Speaker 03

  In the last few years, there have been measurements saying that model might be wrong. And that's something that Roman will absolutely nail. Roman will just hit really hard.

• 9:49Speaker 01

  I, I, I cannot wait. Okay. So in addition to finding more of these supernovae, like, what else do astronomers hope to learn from the surveys that Roman will be doing?

• 10:00Speaker 02

  Well, one of the surveys is designed to look for galaxies and galaxy clusters.

• 10:04Speaker 01

  Oh, that's my bread and butter.

• 10:07Speaker 02

  The distribution of these should reveal important information about the nature of dark matter and how it interacts with these giant objects. But they're also hunting for exoplanets.

• 10:18Speaker 01

  Exoplanets, the planets that orbit distant stars, you know, not planets in our solar system, but orbiting some other star that isn't our sun.

• 10:25Speaker 02

  Right. And there are several techniques for doing this. The most common one that people may have heard of is using something called transits, where light dims when a planet passes in front of the star.

• 10:35Speaker 01

  Yeah.

• 10:36Speaker 02

  But that only works if the planet's orbit causes it to pass in front of the star as we see it from Earth.

• 10:42Speaker 01

  Yeah. It's super important, like the angle you're looking at this planet because it's, it's eclipsing the star, basically.

• 10:48Speaker 02

  Right. But Roman is going to use a different technique called microlensing, which involves measuring the deflection of light from a star when a closer star with orbiting planets passes in front of it. The technique was famously described by Albert Einstein in a 1936 paper, although he thought this would never be a useful thing because it would be too hard to measure. But Scott Goudy helped prove him wrong. Scott is an astronomer who co-developed this thing called gravitational microlensing technique. Since Roman will be looking at hundreds of millions of stars, the expectation is they'll see tens of thousands of these microlensing events.

• 11:28Speaker 07

  We're looking for planets that are just completely undetectable by any other method, including planets that are, you know, at the center of our galaxy and planets that are very analogous to our own solar system planets like Jupiter, Saturn, Uranus, and Neptune.

• 11:43Speaker 01

  I think it's fascinating that, like, the curvature of space and it bending can help us find planets. Like, this is so sci-fi to me, you know, like, microlensing was something I learned in grad school, not related to planets. So this is so cool. Okay.

• 11:59Speaker 02

  Yeah. And it's pretty interesting that you can use the same telescope to do such different kinds of surveys, one looking for exoplanets and the other looking for supernovas. And basically, they have the same observational needs. But Scott told me there are some slight differences in the way the surveys are conducting, depending on what you're looking for, maybe the frequency with which you survey the same patch of sky. And that has led to what he describes as some friendly tension between astronomers who are interested in exoplanets and those who are interested in finding supernovae.

• 12:30Speaker 01

  Oh, yeah. I can see that.

• 12:32Speaker 07

  Then it gets into these very existential questions, like, which science is more interesting? Exoplanets or measuring the equation of state of the universe, which of course, there's no way to actually objectively answer that question.

• 12:45Speaker 01

  I mean, I kind of agree with him. It's really hard. I do not want to be in one of those camps. I'm not.

• 12:49Speaker 02

  No. Well, I'm definitely not. So don't point at me.

• 12:53Speaker 01

  Okay. So neither of us are going to join that, like, debate. But Joe, is there a particular area of astronomy that you're excited about that's going to come out of this telescope?

• 13:04Speaker 02

  What I like are the things that we don't know what to get excited about. No one knew what the Hubble telescope would find when it started looking at an empty patch of sky for 100 hours. And suddenly, the deep field surveys revealed that the sky was anything but empty. It was filled with galaxies.

• 13:20Speaker 01

  Yep.

• 13:20Speaker 02

  And now the James Webb Space Telescope has found what they're calling little red dots. And no one is sure what the heck those are. There was a paper earlier this month in Nature saying these might actually be an entirely new class of celestial objects.

• 13:34Speaker 01

  Yeah. The little red dots have been like everywhere in astronomy. I just did a story in a past episode about these, these little red dots and how they could be this, like, new, maybe black hole star. We'll link to that in our show notes in case anyone else wants to hear about it.

• 13:47Speaker 02

  Well, I'm just saying that I want to call them Joe Dots.

• 13:54Speaker 02

  That's a memorable name.

• 13:56Speaker 01

  Sounds like a, like a donut hole and like a cup of Joe. It's just breakfast.

• 14:01Speaker 02

  Joe Dots. Come on.

• 14:03Speaker 01

  So how soon will we be seeing results from these surveys Roman is doing? Like, this, these new celestial objects, we don't even know we're going to find.

• 14:09Speaker 02

  Right. Well, it, it's going to take Roman about 100 days after it leaves Earth to cruise to this L2 Lagrange point, which is a spot where it can go into a stable orbit. It's about a million miles from Earth. And then, of course, they start the surveys and, and these take a while. So there may be a while before we get the full results from Roman, but the first dribs should trickle in probably three or four months after launch.

• 14:35Speaker 01

  Joe, thank you so much for bringing us the sneak peek of the Roman telescope and we're excited to have you back when there's data.

• 14:42Speaker 02

  Yeah, exactly. Hope so.

• 14:46Speaker 01

  This episode was produced by Burley McCoy and edited by our showrunner Rebecca Ramirez. It was fact checked by Tyler Jones and the audio engineer was Jimmy Keely. I'm Regina Barber. Thank you for listening to Short Wave from NPR.

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