transcript

Speaker 1:
[00:03] Hi, I'm Ira Flatow, and you're listening to Science Friday. In early April, all eyes were on the moon, right, with the lunar flyby of the Artemis space mission, and they got an unprecedented view of the lunar far side. But researchers are working to put eyes on the far side of the moon in another way, by delivering a tiny radio telescope there. It's called LuSEE-Night, and joining me to talk about it is Anže Slosar, Science Lead for the mission. Welcome to Science Friday.

Speaker 2:
[00:34] Hello, thank you very much.

Speaker 1:
[00:36] Anže, describe this little radio telescope for me, if you will.

Speaker 2:
[00:41] Okay, so we're putting like a small pathfinder radio telescope called LuSEE-Night on the lunar far side. And really, it's a pathfinder. It's the simplest thing you can imagine that could receive radio signals from the outer space. So, people have been dreaming about putting a radio telescope on the moon because the moon has a special property. Then, on the far side of the moon, you at the same time shield it from the Earth and shield it from the Sun. And that's supposed to make it one of the best observatories for the radio frequency observations in the entire solar system. Okay? And especially so at the very low frequencies, where basically observations from the ground are very, very difficult. If you go below 50 megahertz, observations from the ground, basically, it's like looking up from the bottom of the swing pool. Everything is blurred. It's a total mess.

Speaker 1:
[01:30] So I should not be picturing this big giant Arecibo-type radio dish. We're talking about a demonstration project, a little project, right?

Speaker 2:
[01:39] Yeah, it's a little project. It's basically calling a telescope. In some sense, it's a misnomer, right? It has essentially four antennas, the four stink antennas like your portable radio. It's really more kind of radio receiver. It's like FM receiver you have at home, but kind of slightly at slightly lower frequency and can kind of see all the frequencies at the same time. So it will make very, very blurry pictures of the sky that we can then reconstruct to then turn into kind of like a low resolution map of how the sky looks like at these frequencies. However, having said that, it will be the first time in the history of humanity we're actually able to make any maps at this very, very low frequency.

Speaker 1:
[02:19] Now there's been talk that it can see something called the Dark Ages signal. What is that?

Speaker 2:
[02:26] Yeah, so Dark Ages signal is something very exciting. I would call it like a Platonic ideal or something where the field is going towards, something that we want to see in, I would say, 50 years. So LuSEE-Night will not see it, but it's a pathfinder for seeing Dark Ages. So Dark Ages refers to this particular epoch in the evolution universe, where kind of this initial hot plasma, this soup of protons and electrons and so on, has kind of cooled down enough that we have just neutral hydrogen and nothing more. And because it's so early that we have no stars, no stars have already turned on, this is a very, very pristine universe, right? Which we can explain just using fundamental physics like general relativity, atomic physics, thermodynamics, stuff like that. We can make extreme precise predictions. Because once the stars turn on and you get galaxies and planets and so on, the universe becomes a very complicated place. It's like weather. But before it starts on, if you could measure that epoch, you could really make some really fundamental measurements of the universe. Now, unfortunately, as I said, LuSEE-Night will not see dark ages because they are kind of foregrounds which are much brighter than this thing from our own galaxy and other galaxy shining. But it will kind of enable us to basically demonstrate that the far side of the moon is really as good as a place to make observations that people think it is, right? People have been thinking it's the best place to make these measurements, but nobody has actually done it.

Speaker 1:
[03:57] Is this sort of seen as a way to pave the way for future radio telescopes on the far side of the moon?

Speaker 2:
[04:04] For sure. Basically, LuSEE-Night, it's a pathfinder and we're really thinking about where to go next. The natural way is to build up so-called interferometers, where you put many individual elements of a radio telescope and combine those signals so they start acting like a big dish. However, you eat the elephant in small pieces, so that's why we start to swap the pie finder. If it works, you will learn a lot about how to make these observations, how to survive the lunar night, how to operate the telescope, what the big problems are. But there are still fundamental unknowns, like maybe they are micrometriotes, maybe the moon has a weak ionosphere that is going to make our relation difficult. You know, LuSEE-Night will try to understand and thus pave the way for bigger instruments in the future.

Speaker 1:
[04:53] Are you hoping to be able to see these dark age signals or not?

Speaker 2:
[04:57] With LuSEE-Night, I don't think we will be able to see a dark age signal unless something really surprising happens. Having said that, because this is such an unexplored part of the radiofrequency spectrum, maybe there will be other surprises, you know. There are people who think maybe the cause of microarray background is very bright at these very low frequencies. Maybe there is new dark matter physics or some new other fundamental physics that will produce kind of interesting new spectral lines or features in the maps or in frequency space. You know, there are very, very, very few parts of modern science where kind of things are unknown at this level of precision, okay? So that's what makes it really exciting.

Speaker 1:
[05:40] That is sounding exciting. So how do you get to the far side of the moon?

Speaker 2:
[05:45] So we get to the far side of the moon on board of a Lander, which is paid by Eclipse. Eclipse is the NASA commercial lunar payload services. Basically, it's a way for NASA to develop like an ecosystem of private sector providers that can take you to the moon and land you there. And basically we can have like DHL to the moon. And we are one of the early landers from this program. We will be on the Blue Ghost 2. You might remember a Blue Ghost 1 successfully landed on the lunar near side last year. It was the first successful landing by a private sector company on the moon. And that's why it makes us very, very hopeful because we will be essentially using the same lander, but on the lunar far side. Landing is essentially autonomous. So in principle, it's not that difficult whether you're on this side or the other side. One thing is that because you're outside of the wreck, the field of view from the ground, you have to rely on the relay satellite that kind of bounces the signals from the earth. So you can actually communicate back to earth, and this adds clearly a layer of complexity. But we'll see. Fingers crossed we'll land and our instrument works.

Speaker 1:
[06:57] What's the timeline on this?

Speaker 2:
[07:01] We're still talking about launch being slated for the end of 2026. It might get delayed. Nobody knows. In space business things often get delayed. But I think, no, I can't wait to get there and see it.

Speaker 1:
[07:16] Well the Chinese were the first to land a vessel on the far side and return samples. You're looking to be the first to put a telescope there. Yeah.

Speaker 2:
[07:27] So there will be many, many firsts in this mission. It will be the first US mission to land on the far side. It will be the first private sector mission to land on the far side. It will be the first functioning radio telescope on the far side. Chinese also had an instrument that unfortunately didn't work very well and we're trying to kind of not repeat similar mistakes. It will be the first commercial instrument trying to survive the lunar night, which is very difficult, right? So moon is extremely difficult to survive both day and night because during the day it's very, very hot and during the night it's very, very cold. And so you have to design for two very different thermal environments.

Speaker 1:
[08:05] Well, I have a practical question for you. If it's on the far side of the moon and the moon is always facing away from the earth, how do you get your signals back to earth?

Speaker 2:
[08:16] So there is a satellite that circles around the moon. And if it's far away, it can be simultaneously in the view of your instrument, the far side and the earth. But mostly, when it's on the far side, it talks to our LuSEE-Night, and when it goes around, it talks to the ground and this allows us to transfer our data back. But this, for example, puts an interesting level of complexity because the total amount of volume you can transfer, it's quite low. We hope to transfer about six gigabytes of data for every lunar cycle, 28 days. And so, one could almost email this data around.

Speaker 1:
[09:02] I'm fascinated about how you got this idea. How did this project get started? Where did the idea come from?

Speaker 2:
[09:10] This is a very interesting project. It started about six or seven years ago, and it went from the top level of echelons of administrations trying to get DOE and NASA to work together for various reasons that are kind of lost in the midst of time. But it was like, at some point, essentially, I received a call asking me, do you want to take part in a project to put radio telescopes on the moon? And I said, why not? Like, this sounds like a very exciting opportunity.

Speaker 1:
[09:44] So they just called you up and said, we've got a spot for you to put your project on. You want to go?

Speaker 2:
[09:51] Yeah. Well, there was no project time. People just said, do you think interesting science could be had by putting radio telescopes on the lunar far side? And at the time, we were kind of thinking about putting a large telescope on the ground for kind of related science. But this sounded like there was fun thing. And basically, there was a spot, and it's time to go. So I said yes, and I never thought I would be doing like a space mission in my life, but this is how science goes.

Speaker 1:
[10:20] Are there other astronomers who were annoyed that you got to skip to the front of the line?

Speaker 2:
[10:26] I mean, partly yes, because normally this project starts with the community processes, these big surveys where community comes together and decide what are the next big step. So if you want to start a new project, you have to start going around your colleagues, lobbying, trying to convince them why they should be doing something. And this takes time and effort. Well, this came out of nowhere. But frankly speaking, it's also a relatively small project. It's not like big flagship projects that DOE often does. For me personally, the fact that it's small, it's been kind of really like a boon. I feel like a postdoc again. Like it's such a simple system. I can understand everything and I can go and really kind of develop low level things without having to fight bureaucracy. But having said that, for somebody who has spent their career doing stuff on the ground, like the psychology of sending something to the moon is just insane, right? It's just very difficult, this idea. Now you're done, you're going to put it in the box and you're not allowed to touch it anymore. And if you messed up, well, you messed up. It's too late now, right? That's been new and kind of very, very difficult.

Speaker 1:
[11:40] Well, you're the pioneer. You're the pioneer in this, right?

Speaker 2:
[11:44] We're the pioneers.

Speaker 1:
[11:45] Well, I wish you great luck and please stay in touch because we'd like to know when this blasts off and we'll keep track of it, okay?

Speaker 2:
[11:52] Okay. Thank you very much for having me.

Speaker 1:
[11:54] You're welcome. Anže Slosar is science lead for the LuSEE-Night project. He's based at Brookhaven National Laboratory out there on Long Island. Thanks for listening. And you know, we're always looking for your ideas. Give us a call on the listener line 877-4-SCI-FRI. That's 877-4-SCI-FRI. This episode was produced by Charles Berquist. I'm Ira Flatow. We'll see you soon.

Speaker 3:
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