#412: Cosmic Queries: A Voyage to Voyager & Defending Astronauts Beyond Earth

Hi there, thanks for joining us on a Q and A edition of Space Nuts. I'm Andrew Dunkley, your host once again. Thanks for joining us and good to have your company on this edition. We're answering some questions about light in space. This one comes from Lee's asked a very interesting question. I've never actually thought about this particular concept, but it's a question that I think is worth answering for sure, That's why we included it. Fenton wants to know about shielding astronauts in the outer reaches of the Solar System, and he's got an idea on how to do that. Robert wants to talk about things we learned from the Moon and what if our moon wasn't the same as the Moon is now, would our learnings be different. That's a really interesting question. And Duncan wants to talk about ice giants and why are they ice giants? Why don't we call them something else? That's all coming up shortly on this edition of Space Nuts ten nine ignition Space Nuts or three two Space Nurse as when I we bought it. Bill's good. Once again, we welcome the one and only Fred. What's an astronomer? At Tello? Fred? Hello and how have you been since we lost I haven't moved from this seat you all that time? Well, it's I can see you glued to your chair there very much. So shall we get straight into it and answer some questions from our audience? We will, it is that's what we're here for. This first one, Fred comes from Lee. He lives in New York City. He's asking how much light is in space? You'll qualify that question. For example, if you were to visit Voyager one where Voyager one is today, would you be able to see it? Would you see just a silhouette? Would you be able to make out details and colors if there are any colors on it? What about if you and voyage were midway between the Sun and Alpha Centauri. Can we know a reasonably accurate answer or is it pure speculation? Thanks love the show. Lee from New York, I've never thought about that. I mean, we take for granted light on Earth because we're illuminated by the Sun, but it's a bit different in other parts of the Solar System and the universe in general. So yeah, if we could just go snap, we're out there next to Voyager one, could we actually see it? Is it illuminated in any way. Is it being illuminated by something? What would it be like? The answer is yes, you'd see it. And so we're talking really now about the sensitivity of the human eye, because with a camera, you know, with the long exposure settings and things, you'd be able to see in great detail. But thinking about the human eye. So I used to work, as you know, signing Spring Observatory. I spent many hours outside at night. There. It is a place that is truly dark. There's no interference from street lights. There are a few blobs of light on the horizon, but nothing that affects the pristine darkness of the night sky. And on a starry night, with the sun not in the sky, you can see quite clearly. There's enough light from the stars themselves to let you see where you're going, let you walk around and be quite confident that you're not going to fall off the mountain, as I nearly did one night when it was cloudy. I went out without my torch and thought, oh yea'll see by the stars. But fortunately, unfortunately the cloud had come in. I could see anything, and I nearly fell off the mountain. I didn't in the end, but a long drop three. Yes it is. Yes, it's quite a long drop anyway, if you you know, normally on the starry nights, you will see by the light of the stars. Now, where Voyager is Voyager one, I just looked it up. It is at a distance from the Sun in astronomical units, which is one hundred and sixty three astronomical units. That's one hundred and sixty three times the number of times the distance between the Earth and the Sun. So that's one hundred and fifty million kilometers. Multiply that by one hundred and sixty three and you will get what do you get? So I was looking for eighty kilometers, but it's not there. I'll have to do the numbers anyway, it doesn't matter. The main thing is its distance is twenty two point five y five light hours away. That's how long it takes the signal to get from Voyager to Earth. It's almost a day. It's almost a light day away. So at that distance from the Sun one hundred and sixty odd astronomical units, there's still significant light coming from the Sun. Not to mention Venus and you know, Jupiter, the other planets, mostly the Sun. Though you're being illuminated by the sun, so that's certainly opposite as compared with just being illuminated by the starry sky, which is what I was just talking about. So you'd see it really clearly. You wouldn't have any problem making it out, assuming you I was dark adapted, so it's fairly bright out there. We talked about the sensitivity of the human eye, as you referred to how small amount of a light can we see as human beings. I think there were some experiments let me think it one photon or one yes, that's right. We might have talked about this. There were experiments done that showed that the human eye is capable of detecting single photons. It was under special circumstances, but that is just extraordinary when you think that the human eye can also cope with broad daylight. That's the amazing thing about the human eye. It can. You know, it's quite happy to see light at one brightness and then a light that's only a million as bright if I deal with that, and that's a combination of what's called retinal bleaching and the iris of your eye opening and closing. It's all those things come together to give you this unbelievably versatile and sensitive tool with which we can look at the surroundings. Whether it's the rock face I'm looking at now, because that's what about yea it consists of, or whether it's you know, the night sky where you're looking at faint objects in the sky. It's quite amazing. So even if you win deeper into space, way beyond our solar system, you you would probably still see objects that you were near. There be enough light from the stars. The Milky Way is bright. It would it would you know, even if, as as Lee says, if even if you were halfway between the Sun and Alpha Centauri, you'd still see it because of the ambient light that's coming from from the stars. Yeah, and you'd still see color because that's well, yeah, it's dark enough, it might turn into the grays, which happened. Yeah, and I think that's likely. I think I don't think you would see color. You would. You would where it is now, there's enough light coming from the Sun that you'd see color. But I think when you got further out you would start to just see the you know, the as you said that that feed that's sort of pale gray appearance where you look at very low low light levels, indeed where the color cells aren't recept Mmm, they got LEI the answer of questions yes to all of the above, basically question excellent question. All Right, let's move on. This is from Fenton. Yeah, hello Fred and Andrew. This is Fenter contacting from Saint Paul, Minnesota in the US. I sort of have a different type of astrophysical question for you, and this is on how to shield astronauts from radiation outside of the Van Allen I was curious if you know of any pending technologies that would allow this of this choice would some people would say is lead? But I can think of several reasons why this is not a good idea. How about a miniature down Allen Belt which could surround a spacecraft? How does that sound? How could this become a reality? Thank you very much. I hope you liked the question. I now thanks vent and Venton always has these intriguing thoughts. I've noticed in the times that we've heard from him. Maybe we should start by explaining what the Van Allen Belt is. For those of us who just can't remember, like me, it's sort the Van Allen Belt, so that basically the the you know, the magnetic shielding around the Earth, which is caused by the magnetism of the Earth. It's caused by the fact that we've got an iron core and basically it's in two parts. It's solid and liquid, so it acts like a dynamo. It's rotating, and that gives us this exactly the protection that Fenton is talking about. I was going to refer I'm a bit annoyed. Actually lost it. There is a very nice article on it's actually on the BBC's website, their Sky at Night website. There's a lovely article on exactly this here I found it. I hadn't lost it. How astronauts can hide from radiational mars and it goes into the exactly the problem that Fenton's talking about. How do you present how do you prevent astronauts basically becoming irradiated and over time it's basically lethal because of the cosmic radiation that's coming down through space and it does sell damage in your body and it can actually trigger cancer. So the whole study of this is sorry, the thrust of this article BBC Sky at Night Magazine is to discuss how you might protect astronauts from the radiation and that's not just on Mars but en route. Okay, the solution that Fenton has suggested is covered in a paragraph. I'm going to read it because we've quoted where the sources for example. All right, let me go back up with prograph. One method of helping astronauts to avoid the radiation on Mars is active shielding. For example, superconducting electromagnets could be used to create a powerful magnetic field to deflect the incoming charged radiation particles away, just as the Earth's field does. That's the Lanele belt. The problem is that such solutions can demand a lot of power to run, and the technology is a long way from being fully developed. An easier alternative is passive shielding, simply placing a thick bulk of shielding material between the crew habitat and the sky. And then they go on to consider different materials. Aluminium aka aluminum, the metal that spacecraft are constructed from, is actually a pretty bad radiation shield and they say, when hit by an energetic cosmic ray, is atoms can shatter and fly onwards to create even more radiation particles and Martian soil the regulith which if you're on Mars, you might think about digging a hole there. It's got the same problem, but it's actually abundant, and so you could use that to dig a pole. If you put the two to three meter layer on top of your habitat, then you'll get some protection. But the thing that surprised me Andrew is once again it comes from this same article. Hydrogen is the best shielding material as it's light atoms. Yeah, it's light atoms, and by light I mean not heavy. Its light atoms don't create as much secondary radiation, and so tanks of rocket fuel or water which is rich in hydrogen, placed over crew quarters could double up as effective radiation shields. I've heard that before that one way of protecting your spacecraft as it flies to Mars is put it in a tank of water. It's the last thing you'd expect to do, but water is a good childing material. And they also point out the alternative of hydrogen rich plastics like polyethylene, could be used to cement regular grains together this is on Mars and improve their shielding effect. So if you want to read more about this, it's an article that originally appeared in the August twenty two issue of BBC Sky at Night magazine and it covers pretty well amost the ideas that have been that have been suggested for this radiation issue. It's one that's got to you know, it's going to find an answer soon because put all, Elon and his starship is getting nearer to thinking about going to Mars. I don't think it's ever going to happen, but that's uh, that's something he'll definitely be thinking about. Yes, indeed, he's too busy dealing with the Australian government at the moment. Indeed, that's right, some of the content on Twitter that the government wants to get rid of simply because of its volatility. But anyway, that's a different story. But there's plenty of water on Mars, so maybe maybe creating those water barriers is probably the simplest thing to do. You've already got the material there, if you've if you've landed in the right spot where you've got whatever, that's the question. Yes, indeed, well done, Fent, and you actually happened across some of the answers to in asking your question. Uh, this is based out's Andrew and here with Professor Fred Watson. Three four space nuts. Now Fred our next question comes from Robert. Hi, guys, love your show. Sorry for the long question, but feel free to paraphrase or shorten it. Our moon is heavily created and has given us a lot of insight into the history of the Solar System and perhaps how the planet's formed. But what if we had a moon like the icy moon Europa or the shrouded in Hayes Titan, both of which don't show immediate evidence of cratering. Would our theory about how the planets developed would be different? What other insights about our Solar System would be missing or would we be missing? And lastly, would we have spent or would we have sent people to land on such moons? I e? Would they be more dangerous for astronauts? Cheers Robert in Vienna, Austria. Wow, I don't think we've had a question from Vienna before, have we? Lovely to hear from you, Robert. I think I think Robert might have been in touch once before. It's here from Vienna. Yeah, I was in Vienna at the beginning of last year and I think I think we got something around about the same time. And I was at the u ND when I was the copyhoss beating Anyway, that's another issue. What if we had Yeah, it's a really interesting question. What would we not know about the Solar System if our moon was basically one that had been resurfaced in recent years, Because that's what makes us surface smooth. That's how we recognize the fact that the universe sorry that the It's how we recognize the age of a surface is by how many creators it's got the oldest, the older the surface, the more craters it has. And so the moon's south southern region, which is heavily created, as is the backside, tell us that early on in the Solar System's history it was very wild and wily place, with things charging about all over and causing these craters. Now, if we had a moon that was like Europa that had you know, I see guysers on it, that basically covered up the craters, would we have known about that? My guess is yes we would, because we'd see other bodies within the Solar System, like you know, other moons, like places like Series, the biggest of the asteroids, the dwarf planet that dominates the asteroid belt, that's heavily created. Parts of Pluto are heavily created Mi Mas one of Saturn's moon. His moons is heavily created too, so we'd know about it by looking at other objects, even if our own moon was smoothly surfaced. It's but the Roberts last point on this, would we have sent people to land on such a moon? I think I don't know. That's a really good question. I mean, we have sent people to land on our moon as it stands, with an ancient surface. In fact, where they landed were more recent than the heavily created surfaces, because there were, principally in the Maria the basalt planes. So maybe that suggests that we would have landed people on Europa as well, because I think we probably, Yeah, we probably would because it would have a solid surface, there'd be places, because it would be so close to us, we'd be able to examine and find the right landing points. Might be a bit more difficult with a moon that shrouded in gas. Yeah, yeah, that's right, and especially a place like Tyson. I still think we'd have done it. Actually, I think, you know, the JFKs promised to put past lots on the moon would have still held good even if it had been a very different place. If it had been like EO. It might have been a different story where you know you've got the most volcanically active body in the entire Solar system with stuff going off all over the place. I think we might have been a bit more reluctant to land on EO. Yes, possibly, so it would be interesting to have something different. But then if we'd always if we'd always had an ice moon, we probably would have caught a question from Robert asking if we had a rocky moon. Now would interpretation of the formattage and planets if there was a rocky moon next us instead of an im Yes, in an alternative universe, Robert, you would have flipped your question. But to hear from you, hope it all is well in Austria. Our final question for this episode comes from Duncan. Hello, Duncan here from Weymouth in the UK. Again, of course just looking, was just doing some reading and I noticed that Uranus and Neptune are often referred to as ice giants. Now, given that ice is basically just sort of like a rock form of water or CO two or whatever else, but basically just the solid form of it, why are they not just called rock giants? Why do we make the definition of ice rather than just calling them rock It just seems odd because the little planets in the Inner Solar System are referred to as rocky planets, So given that they're also apparently rocky, why are they not called rocky giants? Okay, thank you boy, thanks. Duncan appreciate your questions as always. Yeah, why do we call them ice giants just for the sake of the exercise, because there's gas giants and ice giants, Yeah, except one is a subset of the other. And so all four of the outer planets Jupiter, Saturn, Neptune, sorry, Uranus and Neptune, they're all gas giants because they have high mass, you know, much more in the case of Jupiter, certainly than our own planet. They've got the giants that big, they've got high mass, and they don't have a visible surface, which is why they call gas giants, because all we see is a gassy envelope. Just to go to the last of Duncans questions there, we wouldn't call the inner planet's rocky giants because not giants. They're kind of normal planet size. You know. If you think of the Earth as being your standard planet, then Mercury Venus and Mars are similar in size, all smaller venuses about the same size, but Mercury and Mars, of course are smaller. So it's only when you compare with the size of Earth that you'd start talking about giants because they are much much bigger than Earth. And so that's the gas giants. So why are Urinous and Neptune called ice giants? Horse They have hazes of ice in their atmosphere. So, and that's the trick. It's not a solid surface, it's not rock. It's a haze. It's kind of like a dust of ice which permeates their atmosphere, and it's water ice in fact, mostly So that's why they called ice giants, because unlike Saturn and Jupiter, which don't have these hazes, the outer the rocky rocky sorry, the two outer planets Uranus and Neptune do they have ice hazes in their atmosphere, hence the name. Okay, because the last episode we learned there wasn't much water in Jupiter. That's right, in the two outer I guess giants. Yeah, it sounds like there is. Is that why they're a different color? Yes, yes, I think that's right there. And also their atmospheric constituents are different. They don't have the same belt structure that Saturn and Jupiter do. It may be that that's because any belts that exist are much lower in the atmosphere and so you don't see them. Yeah. I mean there's there's a strong body of advocacy within the space fraternity to get get more spacecraft out to Uranus and Neptune, because they're the two planets about which we know least and it will be good to know more. Yeah. Well, if you sit down in snow for long enough, your rainus turns into our ice. I couldn't help it. Sorry, Yeah, which is why we call it Urinus. Yeah, it's just a joke. You've got to tell you to Yes, I blame Johannes Border, who is the person who chose the name. It's fine in German. Is nothing wrong than ruins, all the jokes, all right. So, yes, they're ice giants for a very good reason, Duncan, because they've got ice in them in the atmosphere. But technically speaking, they are in fact gas giants. But yes, differentiate them because of their substantially different atmospheres. There you are, thanks Duncan. Great to hear from you. Great to hear from everybody. Thanks for sending in your questions. Don't forget. You can see in questions via our website, spacenuts podcast dot com, space nuts dot io, and all you have to do is click on the various links on the right hand side send us your question. That's audio questions only, or you can send us text and audio questions via the AMA tab up the top. It's your choice. Don't forget to tell us who you are and where you're from and have a look around. While you're on our website. Will join our media social media platforms Facebook, Instagram, YouTube, or you can subscribe just by pressing the subscribe button below, which, yes, it's down there somewhere I don't know, one of those places. Fred has always Thank you so much, pleasure and you see you, Sue. Okay, Fred Wat's an astronomer at large. We'll catch him on the next episode of Space Nuts. We might catch you then as well, because not to you today, didn't even call in sick. I need a note and from me Andrew dot Thanks very much for your company. We'll see you again soon on the next episode of Space Nuts. Bye bye. You'll be listening to the Space Narts podcast available at Apple Podcasts, Spotify, iHeartRadio, or your favorite podcast player. You can also stream on demand at fights dot com. This has been another quality podcast production from fights dot com.