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

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Hi there, thanks for joining us
on a Q and A edition of Space

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Nuts. I'm Andrew Dunkley, your
host once again. Thanks for joining us

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and good to have your company on
this edition. We're answering some questions about

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light in space. This one comes
from Lee's asked a very interesting question.

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I've never actually thought about this particular
concept, but it's a question that I

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think is worth answering for sure,
That's why we included it. Fenton wants

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to know about shielding astronauts in the
outer reaches of the Solar System, and

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he's got an idea on how to
do that. Robert wants to talk about

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things we learned from the Moon and
what if our moon wasn't the same as

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the Moon is now, would our
learnings be different. That's a really interesting

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question. And Duncan wants to talk
about ice giants and why are they ice

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giants? Why don't we call them
something else? That's all coming up shortly

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on this edition of Space Nuts ten
nine ignition Space Nuts or three two Space

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Nurse as when I we bought it. Bill's good. Once again, we

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welcome the one and only Fred.
What's an astronomer? At Tello? Fred?

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Hello and how have you been since
we lost I haven't moved from this

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seat you all that time? Well, it's I can see you glued to

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your chair there very much. So
shall we get straight into it and answer

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some questions from our audience? We
will, it is that's what we're here

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for. This first one, Fred
comes from Lee. He lives in New

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York City. He's asking how much
light is in space? You'll qualify that

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question. For example, if you
were to visit Voyager one where Voyager one

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is today, would you be able
to see it? Would you see just

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a silhouette? Would you be able
to make out details and colors if there

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are any colors on it? What
about if you and voyage were midway between

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the Sun and Alpha Centauri. Can
we know a reasonably accurate answer or is

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it pure speculation? Thanks love the
show. Lee from New York, I've

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never thought about that. I mean, we take for granted light on Earth

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because we're illuminated by the Sun,
but it's a bit different in other parts

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of the Solar System and the universe
in general. So yeah, if we

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could just go snap, we're out
there next to Voyager one, could we

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actually see it? Is it illuminated
in any way. Is it being illuminated

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by something? What would it be
like? The answer is yes, you'd

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see it. And so we're talking
really now about the sensitivity of the human

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eye, because with a camera,
you know, with the long exposure settings

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and things, you'd be able to
see in great detail. But thinking about

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the human eye. So I used
to work, as you know, signing

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Spring Observatory. I spent many hours
outside at night. There. It is

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a place that is truly dark.
There's no interference from street lights. There

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are a few blobs of light on
the horizon, but nothing that affects the

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pristine darkness of the night sky.
And on a starry night, with the

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sun not in the sky, you
can see quite clearly. There's enough light

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from the stars themselves to let you
see where you're going, let you walk

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around and be quite confident that you're
not going to fall off the mountain,

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as I nearly did one night when
it was cloudy. I went out without

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my torch and thought, oh yea'll
see by the stars. But fortunately,

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unfortunately the cloud had come in.
I could see anything, and I nearly

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fell off the mountain. I didn't
in the end, but a long drop

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three. Yes it is. Yes, it's quite a long drop anyway,

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if you you know, normally on
the starry nights, you will see by

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the light of the stars. Now, where Voyager is Voyager one, I

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just looked it up. It is
at a distance from the Sun in astronomical

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units, which is one hundred and
sixty three astronomical units. That's one hundred

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and sixty three times the number of
times the distance between the Earth and the

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Sun. So that's one hundred and
fifty million kilometers. Multiply that by one

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hundred and sixty three and you will
get what do you get? So I

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was looking for eighty kilometers, but
it's not there. I'll have to do

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the numbers anyway, it doesn't matter. The main thing is its distance is

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twenty two point five y five light
hours away. That's how long it takes

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the signal to get from Voyager to
Earth. It's almost a day. It's

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almost a light day away. So
at that distance from the Sun one hundred

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and sixty odd astronomical units, there's
still significant light coming from the Sun.

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Not to mention Venus and you know, Jupiter, the other planets, mostly

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the Sun. Though you're being illuminated
by the sun, so that's certainly opposite

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as compared with just being illuminated by
the starry sky, which is what I

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was just talking about. So you'd
see it really clearly. You wouldn't have

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any problem making it out, assuming
you I was dark adapted, so it's

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fairly bright out there. We talked
about the sensitivity of the human eye,

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as you referred to how small amount
of a light can we see as human

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beings. I think there were some
experiments let me think it one photon or

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one yes, that's right. We
might have talked about this. There were

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experiments done that showed that the human
eye is capable of detecting single photons.

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It was under special circumstances, but
that is just extraordinary when you think that

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the human eye can also cope with
broad daylight. That's the amazing thing about

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the human eye. It can.
You know, it's quite happy to see

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light at one brightness and then a
light that's only a million as bright if

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I deal with that, and that's
a combination of what's called retinal bleaching and

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the iris of your eye opening and
closing. It's all those things come together

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to give you this unbelievably versatile and
sensitive tool with which we can look at

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the surroundings. Whether it's the rock
face I'm looking at now, because that's

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what about yea it consists of,
or whether it's you know, the night

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sky where you're looking at faint objects
in the sky. It's quite amazing.

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So even if you win deeper into
space, way beyond our solar system,

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you you would probably still see objects
that you were near. There be enough

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light from the stars. The Milky
Way is bright. It would it would

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you know, even if, as
as Lee says, if even if you

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were halfway between the Sun and Alpha
Centauri, you'd still see it because of

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the ambient light that's coming from from
the stars. Yeah, and you'd still

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see color because that's well, yeah, it's dark enough, it might turn

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into the grays, which happened.
Yeah, and I think that's likely.

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I think I don't think you would
see color. You would. You would

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where it is now, there's enough
light coming from the Sun that you'd see

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color. But I think when you
got further out you would start to just

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see the you know, the as
you said that that feed that's sort of

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pale gray appearance where you look at
very low low light levels, indeed where

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the color cells aren't recept Mmm,
they got LEI the answer of questions yes

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to all of the above, basically
question excellent question. All Right, let's

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move on. This is from Fenton. Yeah, hello Fred and Andrew.

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This is Fenter contacting from Saint Paul, Minnesota in the US. I sort

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of have a different type of astrophysical
question for you, and this is on

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how to shield astronauts from radiation outside
of the Van Allen I was curious if

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you know of any pending technologies that
would allow this of this choice would some

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people would say is lead? But
I can think of several reasons why this

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is not a good idea. How
about a miniature down Allen Belt which could

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surround a spacecraft? How does that
sound? How could this become a reality?

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Thank you very much. I hope
you liked the question. I now

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thanks vent and Venton always has these
intriguing thoughts. I've noticed in the times

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that we've heard from him. Maybe
we should start by explaining what the Van

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Allen Belt is. For those of
us who just can't remember, like me,

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it's sort the Van Allen Belt,
so that basically the the you know,

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the magnetic shielding around the Earth,
which is caused by the magnetism of

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the Earth. It's caused by the
fact that we've got an iron core and

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basically it's in two parts. It's
solid and liquid, so it acts like

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a dynamo. It's rotating, and
that gives us this exactly the protection that

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Fenton is talking about. I was
going to refer I'm a bit annoyed.

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Actually lost it. There is a
very nice article on it's actually on the

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BBC's website, their Sky at Night
website. There's a lovely article on exactly

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this here I found it. I
hadn't lost it. How astronauts can hide

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from radiational mars and it goes into
the exactly the problem that Fenton's talking about.

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How do you present how do you
prevent astronauts basically becoming irradiated and over

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time it's basically lethal because of the
cosmic radiation that's coming down through space and

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it does sell damage in your body
and it can actually trigger cancer. So

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the whole study of this is sorry, the thrust of this article BBC Sky

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at Night Magazine is to discuss how
you might protect astronauts from the radiation and

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that's not just on Mars but en
route. Okay, the solution that Fenton

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has suggested is covered in a paragraph. I'm going to read it because we've

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quoted where the sources for example.
All right, let me go back up

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with prograph. One method of helping
astronauts to avoid the radiation on Mars is

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active shielding. For example, superconducting
electromagnets could be used to create a powerful

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magnetic field to deflect the incoming charged
radiation particles away, just as the Earth's

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field does. That's the Lanele belt. The problem is that such solutions can

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demand a lot of power to run, and the technology is a long way

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from being fully developed. An easier
alternative is passive shielding, simply placing a

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thick bulk of shielding material between the
crew habitat and the sky. And then

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they go on to consider different materials. Aluminium aka aluminum, the metal that

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spacecraft are constructed from, is actually
a pretty bad radiation shield and they say,

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when hit by an energetic cosmic ray, is atoms can shatter and fly

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onwards to create even more radiation particles
and Martian soil the regulith which if you're

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on Mars, you might think about
digging a hole there. It's got the

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same problem, but it's actually abundant, and so you could use that to

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dig a pole. If you put
the two to three meter layer on top

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of your habitat, then you'll get
some protection. But the thing that surprised

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me Andrew is once again it comes
from this same article. Hydrogen is the

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best shielding material as it's light atoms. Yeah, it's light atoms, and

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by light I mean not heavy.
Its light atoms don't create as much secondary

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radiation, and so tanks of rocket
fuel or water which is rich in hydrogen,

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placed over crew quarters could double up
as effective radiation shields. I've heard

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that before that one way of protecting
your spacecraft as it flies to Mars is

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put it in a tank of water. It's the last thing you'd expect to

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do, but water is a good
childing material. And they also point out

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the alternative of hydrogen rich plastics like
polyethylene, could be used to cement regular

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grains together this is on Mars and
improve their shielding effect. So if you

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want to read more about this,
it's an article that originally appeared in the

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August twenty two issue of BBC Sky
at Night magazine and it covers pretty well

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amost the ideas that have been that
have been suggested for this radiation issue.

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It's one that's got to you know, it's going to find an answer soon

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because put all, Elon and his
starship is getting nearer to thinking about going

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to Mars. I don't think it's
ever going to happen, but that's uh,

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that's something he'll definitely be thinking about. Yes, indeed, he's too

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busy dealing with the Australian government at
the moment. Indeed, that's right,

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some of the content on Twitter that
the government wants to get rid of simply

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because of its volatility. But anyway, that's a different story. But there's

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plenty of water on Mars, so
maybe maybe creating those water barriers is probably

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the simplest thing to do. You've
already got the material there, if you've

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if you've landed in the right spot
where you've got whatever, that's the question.

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Yes, indeed, well done,
Fent, and you actually happened across

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some of the answers to in asking
your question. Uh, this is based

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out's Andrew and here with Professor Fred
Watson. Three four space nuts. Now

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Fred our next question comes from Robert. Hi, guys, love your show.

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Sorry for the long question, but
feel free to paraphrase or shorten it.

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Our moon is heavily created and has
given us a lot of insight into

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the history of the Solar System and
perhaps how the planet's formed. But what

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if we had a moon like the
icy moon Europa or the shrouded in Hayes

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Titan, both of which don't show
immediate evidence of cratering. Would our theory

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about how the planets developed would be
different? What other insights about our Solar

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System would be missing or would we
be missing? And lastly, would we

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have spent or would we have sent
people to land on such moons? I

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e? Would they be more dangerous
for astronauts? Cheers Robert in Vienna,

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Austria. Wow, I don't think
we've had a question from Vienna before,

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have we? Lovely to hear from
you, Robert. I think I think

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Robert might have been in touch once
before. It's here from Vienna. Yeah,

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I was in Vienna at the beginning
of last year and I think I

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think we got something around about the
same time. And I was at the

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u ND when I was the copyhoss
beating Anyway, that's another issue. What

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if we had Yeah, it's a
really interesting question. What would we not

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know about the Solar System if our
moon was basically one that had been resurfaced

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in recent years, Because that's what
makes us surface smooth. That's how we

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recognize the fact that the universe sorry
that the It's how we recognize the age

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of a surface is by how many
creators it's got the oldest, the older

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the surface, the more craters it
has. And so the moon's south southern

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region, which is heavily created,
as is the backside, tell us that

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early on in the Solar System's history
it was very wild and wily place,

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with things charging about all over and
causing these craters. Now, if we

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had a moon that was like Europa
that had you know, I see guysers

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on it, that basically covered up
the craters, would we have known about

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that? My guess is yes we
would, because we'd see other bodies within

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the Solar System, like you know, other moons, like places like Series,

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the biggest of the asteroids, the
dwarf planet that dominates the asteroid belt,

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that's heavily created. Parts of Pluto
are heavily created Mi Mas one of

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Saturn's moon. His moons is heavily
created too, so we'd know about it

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by looking at other objects, even
if our own moon was smoothly surfaced.

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It's but the Roberts last point on
this, would we have sent people to

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land on such a moon? I
think I don't know. That's a really

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good question. I mean, we
have sent people to land on our moon

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as it stands, with an ancient
surface. In fact, where they landed

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were more recent than the heavily created
surfaces, because there were, principally in

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the Maria the basalt planes. So
maybe that suggests that we would have landed

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people on Europa as well, because
I think we probably, Yeah, we

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probably would because it would have a
solid surface, there'd be places, because

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it would be so close to us, we'd be able to examine and find

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the right landing points. Might be
a bit more difficult with a moon that

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shrouded in gas. Yeah, yeah, that's right, and especially a place

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like Tyson. I still think we'd
have done it. Actually, I think,

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you know, the JFKs promised to
put past lots on the moon would

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have still held good even if it
had been a very different place. If

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it had been like EO. It
might have been a different story where you

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know you've got the most volcanically active
body in the entire Solar system with stuff

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going off all over the place.
I think we might have been a bit

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more reluctant to land on EO.
Yes, possibly, so it would be

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interesting to have something different. But
then if we'd always if we'd always had

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an ice moon, we probably would
have caught a question from Robert asking if

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we had a rocky moon. Now
would interpretation of the formattage and planets if

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there was a rocky moon next us
instead of an im Yes, in an

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alternative universe, Robert, you would
have flipped your question. But to hear

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from you, hope it all is
well in Austria. Our final question for

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this episode comes from Duncan. Hello, Duncan here from Weymouth in the UK.

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Again, of course just looking,
was just doing some reading and I

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noticed that Uranus and Neptune are often
referred to as ice giants. Now,

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given that ice is basically just sort
of like a rock form of water or

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CO two or whatever else, but
basically just the solid form of it,

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why are they not just called rock
giants? Why do we make the definition

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of ice rather than just calling them
rock It just seems odd because the little

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planets in the Inner Solar System are
referred to as rocky planets, So given

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that they're also apparently rocky, why
are they not called rocky giants? Okay,

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00:21:02.319 --> 00:21:07.519
thank you boy, thanks. Duncan
appreciate your questions as always. Yeah,

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why do we call them ice giants
just for the sake of the exercise,

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because there's gas giants and ice giants, Yeah, except one is a

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subset of the other. And so
all four of the outer planets Jupiter,

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Saturn, Neptune, sorry, Uranus
and Neptune, they're all gas giants because

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they have high mass, you know, much more in the case of Jupiter,

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certainly than our own planet. They've
got the giants that big, they've

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got high mass, and they don't
have a visible surface, which is why

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they call gas giants, because all
we see is a gassy envelope. Just

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to go to the last of Duncans
questions there, we wouldn't call the inner

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00:21:57.200 --> 00:22:02.759
planet's rocky giants because not giants.
They're kind of normal planet size. You

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know. If you think of the
Earth as being your standard planet, then

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Mercury Venus and Mars are similar in
size, all smaller venuses about the same

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size, but Mercury and Mars,
of course are smaller. So it's only

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when you compare with the size of
Earth that you'd start talking about giants because

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they are much much bigger than Earth. And so that's the gas giants.

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So why are Urinous and Neptune called
ice giants? Horse They have hazes of

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ice in their atmosphere. So,
and that's the trick. It's not a

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solid surface, it's not rock.
It's a haze. It's kind of like

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a dust of ice which permeates their
atmosphere, and it's water ice in fact,

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mostly So that's why they called ice
giants, because unlike Saturn and Jupiter,

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which don't have these hazes, the
outer the rocky rocky sorry, the

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00:23:03.440 --> 00:23:07.519
two outer planets Uranus and Neptune do
they have ice hazes in their atmosphere,

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hence the name. Okay, because
the last episode we learned there wasn't much

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water in Jupiter. That's right,
in the two outer I guess giants.

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Yeah, it sounds like there is. Is that why they're a different color?

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Yes, yes, I think that's
right there. And also their atmospheric

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constituents are different. They don't have
the same belt structure that Saturn and Jupiter

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00:23:33.400 --> 00:23:37.960
do. It may be that that's
because any belts that exist are much lower

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00:23:38.000 --> 00:23:42.599
in the atmosphere and so you don't
see them. Yeah. I mean there's

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there's a strong body of advocacy within
the space fraternity to get get more spacecraft

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out to Uranus and Neptune, because
they're the two planets about which we know

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00:24:00.160 --> 00:24:06.000
least and it will be good to
know more. Yeah. Well, if

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you sit down in snow for long
enough, your rainus turns into our ice.

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I couldn't help it. Sorry,
Yeah, which is why we call

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00:24:17.279 --> 00:24:23.559
it Urinus. Yeah, it's just
a joke. You've got to tell you

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00:24:23.920 --> 00:24:30.240
to Yes, I blame Johannes Border, who is the person who chose the

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00:24:30.319 --> 00:24:37.319
name. It's fine in German.
Is nothing wrong than ruins, all the

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00:24:37.400 --> 00:24:41.880
jokes, all right. So,
yes, they're ice giants for a very

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00:24:41.880 --> 00:24:45.559
good reason, Duncan, because they've
got ice in them in the atmosphere.

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But technically speaking, they are in
fact gas giants. But yes, differentiate

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00:24:49.640 --> 00:24:55.440
them because of their substantially different atmospheres. There you are, thanks Duncan.

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Great to hear from you. Great
to hear from everybody. Thanks for sending

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00:24:57.400 --> 00:25:00.519
in your questions. Don't forget.
You can see in questions via our website,

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00:25:00.519 --> 00:25:04.680
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dot io, and all you have

280
00:25:04.799 --> 00:25:08.000
to do is click on the various
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281
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282
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button below, which, yes,
it's down there somewhere I don't know,

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00:25:33.160 --> 00:25:37.599
one of those places. Fred has
always Thank you so much, pleasure and

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00:25:37.759 --> 00:25:41.559
you see you, Sue. Okay, Fred Wat's an astronomer at large.

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We'll catch him on the next episode
of Space Nuts. We might catch you

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00:25:45.559 --> 00:25:51.279
then as well, because not to
you today, didn't even call in sick.

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00:25:51.400 --> 00:25:53.960
I need a note and from me
Andrew dot Thanks very much for your

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company. We'll see you again soon
on the next episode of Space Nuts.

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