Hi there, thanks for joining us on Space Nuts, Q and A.
My name is Andrew Dunkley, your host. It's great to have your company,
and we thank our audience for sending in questions. We've got some new
ones the other day, so we're going to try and knock off a few
of those in this episode. Viano has got in touch with us this week.
He's asking questions about planets and photographing planets and missions to distant planets that
we might be able to take a look at, but will there be problems
if we want to send back images. We've got a question from Brady,
could a moon have a moon? That is? That's a good question,
let's look into that. And Scott is asking about the star system HDF one
one zero zero six seven. I'm sure you know it well. We'll find
out all about it this week on Space Nuts. Fifteen second in channel ten
nine ignition seek one space nuts or three two space notes as when I re
bought it. Neil's good and joining us to tackle all of those questions with
most insightful answers. Professor Fred what's an astronomer at large? Hello Fred,
Hello Andrew. Hopefully this will be Q and A rather than Q and not
A, which is always the risk. You know, it is a bit.
But you know, even when we get questions we can't answer, which
we've actually received while we've been talking today, we really chase them up if
we can, so never never be discouraged. We we do. We'd love
to get your questions, and I will tell you how to do that at
the end. Let's go to our first question, Fred, And this one,
as I said, comes from Viano. Hey, guys, from Flo
in Italy. So I have a two questions for you. The first one
is related to the break To project with old us that they want to reach
comoch entiality with the sort of solar sale at around one speed of light,
which I think it means more or less one another kiln we just per second.
I worked within the other cameras and I know how difficult it is to
find the right time configuration the optical alensis focused and so on, and I
was thinking that maybe it will not be possible to take a clear picture of
a planet if you're moving so fast in front of What do you think about
that? The second question is related to the planet ORBITA. So can you
please explain me what is that? Defines the distance between the planet and stand
so for sure there must be a sort of gravity equilibrium, but I cannot
understand why they are not in order considering the mass or the envolumements, so
there must be something else. And so, guys, I started listening to
you because of to learn us on English. I'm pretty sure if my English
is not so rude or in books, but based ont the looking at this
guy, I love this US now and I think it is great great,
So thank you guys, my mate, Thanks Fiano. I'm a little bit
disturbed that you think we're going to be helpful with your English, but now
I'm really pleased that you said us a question. Your English is actually very
good, and indeed we understood perfectly what you were asking us. But thanks
for sending in a question. It's greatly appreciated. And having been in Florence
fairly recently, what an amazing place you live in, a beautiful part of
the world. I happen to be there at All Saints Weekend, which is
a four day public holiday, and there were thousands and thousands and thousands of
people there. It was almost impossible to move through the city square and see
all the sites just everyone flocked to Florence that weekend, big religious holiday.
But what an amazing place. Yes, and beautiful part of Italy too.
It's yeah, just extraordinary around there. Now he mentioned the Breakthrough project.
This is the plan to send micro spacecraft on a flyby of Alpha Centauri,
the planets of Centaury B. Is it? And they they won't be able
to stop. I remember it's talking about that. So let's just sort of
review what Breakthrough is about and then try and answer Viano's questions as to whether
or not we'd be able to send back a photo or two. This is
actually a great question, and I think there's quite a lot of subtlety to
it. So it's a Breakthrough starshot and that project was initiated by Uri Milna,
billionaire who set up the Breakthrough Foundation in order to study the possibilities of
using light sales, laser driven light sales to accelerate a spacecraft which might only
weigh less than a kilogram, you know, it's tiny stuff. We're talking
about to a speed which would allow you to reach Proxima Centaury, the nearest
of the Alpha Centauri system, a dwarf red dwarf star within a you know,
within a reasonable number of years. And so yeah, if you accelerate
it to a third of the speed of light one hundred thousand kilometers per seconds,
as Fianna says, then you're probably going to take I mean alone for
acceleration and deceleration, you're probably going to take less than twenty years to get
your four light years away. And that then you but then you faced with
the issue and it probably wouldn't be just one spacecraft. I think it will
be a little flotilla of sail driven spacecraft which would fly along the laser line
accelerated. Sorry, there's the people are people are complaining about our rooster Andrew.
They think he's they think he's a cockrel. He's not. He's a
dog with a stupid voice. And he does that when someone turns up.
He does even when not when somebody turns up, he just does it because
it just doesn't occur. Well, look, I've counseled him the nature of
little terriers or little terrors, whichever way you want to look at anyway,
So yeah, you whizz through the proximate centaury system and he does have planets
one hundred thousand kilometers per second, you've got cameras that are supposed to be
able to photograph planets. You want to photograph them in enough detail that you
can actually see what's going on on their surface. That is an incredibly difficult
problem. The nearest thing I can draw up parallel to, which was very
successful was New Horizons fly by the Poluto system back in twenty fifteen. Is
that right? Fourteenth of July twenty fifteen. I think that was it?
Let me check brains, Yeah, you check that, and the actually I
might have the fourteen might be something else, because my recollection is that the
fly by velocity the fourteen was the fourteenth of July twenty fifteen. There you
go, that's got it right, yeh. Check. Check the other figure
for me, though, Andrew, because I think, if I remember rightly,
the fly by velocity was fourteen kilometers per Second's yeah, I haven't got
that, but I will look it up now, okay, just to make
sure. So, and that was an amazing feat of engineering. Twenty three
kilometers per second, okay, twenty three, So I'm mixing up the fourteen
of the day. Yeah, twenty three kilometers per second. That are you
sure that was the fly by velocity. That sounds more like the maximum velocity.
Well, hang on, I'll keep looking. Yeah, I think it.
I think it was the fastest spacecraft ever launched because at one point in
its trajectory probably new horizons flew within twelve and a half thousand kilometers of Pluto
at a relative velocity of eleven kilometers eleven Okay, that sounds more like it.
Yes, eleven kilometers per second. It's a very small percentage of one
hundred thousand kilometers per second, which is what the fly by speed will be
for any breakthrough space shot star shot initiatives. But it was highly successful what
they had to do because you can't control this in real time, Andrew,
because you've got you know, I can't remember what the time delay was,
but it was minutes out to get the signal out there, and this thing
flashes by. So they had a pre arranged sequence of shots the camera angles
to get not just Pluto as if as they flew by, but Pluto's moons,
all of them, including the biggest one care on they did. They
did fantastic planning and built into the engineering of this so that when you know,
the spacecraft got within x thousand kilometers of Pluto. This sequence started and
it was executed perfectly. It was just a choreographed set of imagery. And
of course, I guess we're all familiar with the dramatic pictures that were returned
six hours be time delay six hours. There you go. Yeah, so
thank you. I'm glad. It's a long time ago. What's that it's
nine years ago since all the Gift talks I talked about about one hundred times,
I think, so I knew the numbers. But receding in the past
anyway. So the issue that that Vianna raises, we have a different set
of circumstances here. We've got these tiny little machines which have cameras on board
pointing hopefully in the right direction. You've got a four and a half year
time lag back to Earth, so there's no chance whatsoever of pointing the thing.
It has to all be done robostically. So you can have sensors on
board that will look for the brightest object in the field of view and basically
point your camera towards it. But one hundred thousand kilometers per second, there
are also what we call relativistic effects. The geometry of space changes, so
you're not just taking you know, saying that well, we know where these
things are, we can point the camera at them. You've got to take
into account the fact that space is distorted by the relative velocity one hundred thousand
kilometers per second, third of the speed of light, which will change the
directions of the things that you're looking in. It basically squash squashes the stars
forward in your field of view in that relativistic effect. So all those phenomena
and I think, you know, if the animal's amazing doubts about whether this
is feasible, I think is right on the money, because I think it
is so difficult to do. We don't even know whether the technology would work
to get us there in that length of time. But it's a very interesting
problem and it's one that needs to have interesting answers. Indeed, I mean
buried and play. Other effects like the distance of the planet from the stars,
exposure times. Yeah, there's so many other factors that need to be
back and I'm sure the scientists involved would take that into account, but there's
certain things they won't be able to control. And when you're talking robotics,
once they're on their way, that's it. You're not really going to be
able to do much once they get too far away to to take those photographs
and transmit them back. You just just going to sit and wait and hope
and pray that it all works and then four and a half years less you
get your pictures. But yeah, and it's just your lucky blob. Yeah.
Now, the other bit of question was about the orbits of planets,
and it is. It's a great it's you know why planet's in a particular
orbit. There's the orbit is basically dictated very much by the distance the two
go completely together. In fact, the mass of the object itself is of
less important. For example, you know, if you're in Earth orbit,
if you're at four hundred kilometers, you've got to have a certain velocity to
stay in orbit, whether you're a cube SAT or whether you are the International
Space Station much more massive than a cube SAT. So it's all about the
orbital velocity and the distance from the Sun. That's what dictates basically where planets
stay. They've obviously formed there at those distances. We think the gas giants
are gas giants because they're beyond the frost line, so that they grew big
as they accumulated ice and that made them, you know, give them the
possibility of accumulating still more material to gas around them. I hope that answers
the question beyond Bianna. Thanks very much and so good to hear from you,
and hope all is well in Florence. This is Space Nuts Andrew Dunkley
with Professor Fred Watson Space Buds. Now, Fred, we've got a text
question that's come in from Brady. Hello from the great state of Florida,
with a great view of all the launches here, are you lucky Duck?
I was wondering if a moon could have a moon also, would that be
called a moon? Moon? Love listing to you all every week, Brady.
Thanks Brady, very jealous of where you are. I'd love to be
able to sit and watch a few launches from Florida. What a mesmerizing place.
I've been lucky enough to visit there and found it all very extraordinary.
Could a moon have a moon? Fred? Just a footnote to that.
I'll be there in about three weeks, and yes you will. By the
time this episode's out of me, you're probably already. But moon of the
moon, Yes, such an object will be defined as a sub satellite,
so satellites are moons. It satellites the technical term that we use nowadays.
People think of them as artificial satellites, but actually the word means the satellite
of a planet, something going around a planet. A sub satellite will be
something going around a satellite, And the the answer is yes, it could.
Theoretically, you could have a sub satellite, you could have a moon
of a moon, but the odds are that they're quite rare. And the
reason for that is that we know of none in the Solar System. Of
all the two or three hundred moons that we know in the Solar System,
I can't remember the exact number now, none of them have a sub satellite.
None of them have a moon. So that is probably because theory suggests
that, and this would depend on what the planet was like the planet that
these things are going around. It's the tidal effects of the planet that are
probably what would disturb or what has disturbed any possible sub satellites in the Solar
System. So what I'm saying is in the Solar System at least, the
reason why we don't find moons of moons is because of the gravitational pull of
the planets themselves. These actually make the would make it unstable, so you
lose the moon of the moon. The moon itself might stay there, but
this other moon going around it might be too unstable. And it's all of
it just because of the tidal effects, that's the gravitational pulling effects of the
planet itself. But that might not always be the case. It's the case
in the Solar System, but it might not always be the case. And
there is at least one basically one planet, which is Kepler sixteen twenty five
B, which which could in theory have a satellite, and in theory could
have a sub satellite. So that's just because of the gravitational you know,
distribution between the parent star which is Kepler one six two five and the planet
Kepler one six two five B. That's that's one suggestion. But as far
as we know, there are any in the Solar system, Okay, So
for it to happen, the circumstances have to be exactly right, exactly that's
right, to be a bit special. The answer to your question for two
hundred and ninety three moons in the Solar system, Oh there you go,
two ninety three. Thank you, at last count, At last count,
thanks Brady. I like your name better moon Moon. That works for the
moon. Yes, this is space Nuts. Andrew Dunkley here with Professor Fred
Watson. Three four Space Nuts. Now we've got a question from Scott Hey.
This has Scott from Oregon. I recently became aware of HD eleven zero
zero six seven system because apparently it has six exo planets that are orbiting in
like a I I think, perfect mathematical arrangement or something. But my real
question is really about like it's a part of a triple star system, and
at least according to the information I found, the companion planet is it's actually
a companion binary star system is thirteen thousand, four undred astronomical units from the
primary star. And I'm just kind of curious, is why when something is
that paraway, is it kind of considered still like a triple star syst.
I just assumed the you know, we're I mean, that seems like a
really far distance for them to still be kind of considered together. So I'm
just go curious start how they caind of categorize these things. Thanks, thank
you, Scott. That is a great question a triple star system, but
he's questioning distance and whether or not. It could actually be that. Yeah,
that's how far is too far for a binary slash triple star system.
That's look at again. This is a great question, and it's it's really
all about gravitational what we call gravitational binding. So that's star HD sixty seven
is gravitationally bound to this spectroscopic binary system, which is called HD eleven zero
one zero six. Now you know that eleven double zero sixty seven is interesting
because of these six planets which are in a lovely orbital resonance with each other.
It's at a distance of one hundred and five light years. But Scott's
question isn't really about the planet. There's the star and its planets. It's
about this companion binary system. What do we mean by a spectroscopic binary system?
A binary system is two stars orbiting around the common center of gravity,
usually called the Barry center. If it's spectroscopic, it means we can't see
them as two separate stars. We can see them as a single star in
any telescope. But we know it's two stars because the spectroscope of the spectrograph
reveals by the Doppler effect that there are two sets of barcodes which are moving
relative to one another as the stars orbits each other. So it's by using
the spectroscope that we know that there is a pair of stars there rather than
just a single one, whereas HG double one double zero sixty seven itself is
said to be part of this as a triple star system. So Scott quotes,
and I haven't actually verified this, but I'm sure he's right. Thirteen
four hundred astronomical units of separation between them. Now, that's about a quarter
of a light year. A light year is about sixty three three hundred astronomical
units, or what's an astronomical unit distance from the Earth to the Sun one
hundred and fifty million kilometers. So an astronomical unit is a unit we use
within the Solar system. Tend to use light years beyond the Solar system,
but for a triple star system, that is quite a long way off.
Thirteen thousand and four audio astronomical units. As I said, it's roughly a
quarter of a light year. I'm going to throw in a coincidence here,
Andrew that you probably don't know about, but the number of astronomical units in
a light year is, as I said, about sixty three thousand, three
hundred is very very similar to the number of inches in a mile, which
is about sixty three thousand and three. Right. Wow, it's a nice
coincidence that we can't use anymore because we're electric here, well anyway, except
they can use it in America they can, yes, But so what means
what defines it as these two are the binary and the star itself HD eleven
zeros or A sixty seven, what makes it a triple star system. It's
because they are gravitationally bound. The movement of the two relative to each other
tell you that they are in orbits around their common center of gravity. And
so once again that's detected spectroscopically and probably actually also by the Gaya astrometry spacecraft,
which can measure the positions of stars very very accurately. Indeed, so
I think that is why it's termed a triple system rather than just two stars
that have to be near each other. It's because they've got movements that suggest
that they're gravitationally bound to each other. They are dancing. They're dancing what
a lot of the most book, Yes, yeah, well a dance like
me. One of them is going to fall over real quick indeed, so
there you ask God. Hopefully that will appease you at least answer your question.
We've got one without notice, and I know you love those Fred.
This comes from a Facebook user listener, Dean A. Fellas. A question
for you, how does Hubble maintain a steady image of targets while in orbit?
It's stabilized, and what stabilizes it are gyroscopes, which are an absolutely
vital part of the mechanism that operates Hubble, and in fact it's why Hubble's
lifetime will eventually be limited because the gyroscopes did fail. I think they need
three. I think they can just about manage with two, but they need
three to work properly. Back in the day, two thousand, probably two
thousand and eleven ish thereabouts, trying to think when the yeah, I think
twenty eleven was when the last Hubble mission, Hubble repair mission went up,
and it was to repair or to replace gyroscopes. That was in the last
year or so of the Space Shuttle, because the Space Shuttle was the only
vehicle then available that could reach the orbit of the of the Hubble Space Station
sorry Hubble space Telescope at six hundred kilometers, so it's gyroscopes which have failed.
They're still working pretty well as far as I know, but maybe again
they will fail and that will bring the mission to an end, because you
want me to point the telescope, Yes, exactly, And that was twenty
twenty three, I think when Yeah, No, it was a while further
further back than that. I remember us talking about those gyro failures. Wasn't
that long ago? There might have been other ones, could have been been
since that mission. I mean, Hubble's been up there at it for a
very long time. Things don't last for four years. Yeah, it's incredible,
isn't it. Of course there are going to be new telescopes like James
web in Action and the new one that he says set up, and of
course we talked about one Lancy Grace Roman Times, yeah, which is also
going to be launched in a few years. So plenty more going up there
to continue the work. But yeah, thanks for the question. Lovely to
hear from your dean, And if you do have questions for us, please
send them to us via our website, space nuts podcast dot comspacenuts dot io
and send it to us simply by clicking on the relative button you can click
on the AMA tab where you can send us audio or text questions, or
on the right hand side this this weird green button that says send us your
questions. When you hover over it, it turns purple. Yeah. I
don't know, but you can send us your question there as long as you've
got a device with a microphone. All good, and don't forget to tell
us who you are and where you're from, and we'll do our best to
give you an answer. Fred. That's the end of another episode. Thank
you, sir, pleasure, good questions and great stuff. Keep them coming
in, folks. It's great to Yeah, all right, Fred, catching
next week. Thank you, Professor Fred Watson Astrong at Large. And thanks
to Hue in the studio who were funneled through a couple of late questions that
we managed to well. We put one on the back burner and we tackled
the other. And from me Andrew Unkley, thanks for joining us. Catch
you on the very next episode of Space Nuts. Bye bye. You'll be
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