#402: Pergola Projections & Proxima Possibilities: Solar Shields and Exoplanetary Expeditions

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Hi there, Andrew Dunkley here.
Thanks for joining us on Space Nuts QDA.

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This is the separated second half of
what used to be a big podcast,

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but we've decided to break it up
because of audience feedback mainly, and

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that enables people to absorb the show
smaller chunks, which seems to be much

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more palatable for most. So we'll
carry on with this and see how it

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goes. Coming up on this episode, we're going to be answering questions about

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Planet nine. We'll also be chasing
up Rusty's solar pagola. Remember we talked

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about that a few weeks ago.
Well, Rusty's come up with a follow

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up idea and David's got a what
if question for us, which I've had

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to do some research on because I
honestly couldn't answer it until I did some

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homework. And I hope Fred's got
some homework too, but he might have

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a better idea than I have,
and a bit of homework as well.

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Following up questions from Wayn and Wayne
asked us about supernova supernov's causing gravitational waves,

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yes or no, and how insight
is able to triangulate impact points of

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things hitting the planet's surface. Lee
wanted to know about that, So we'll

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be doing all of that in this
episode of Space Nuts Q and A right

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now for fifteen seconds. Guidance is
Internal ten nine Ignition, Space Nuts NI

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four three two Space Nuts. As
I reported, Bill's good and joining us

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again is Professor Fred Watson, Astronomer
at Large. It's a coincidence spread that

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we're both still wearing the same shirts
as we did in the last episode.

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I mean, I don't know how
that happened. It just means we're pretty

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scruffy. Really, we're very rough
around the edges in the mine's a Space

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Nuts shirt by the way. Yeah, I'm going to have to drag mine

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out because since we moved everything sort
of in different places and I haven't really

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gone looking for them. I know
they're probably not far away. I know

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they're not in that wardrobe behind me
that's just full of junk. Had to

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put it somewhere. Let's get stuck
into it because we've got a few questions

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to deal with and a bit of
homework to follow up. Our first question

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comes from a regular Duncans. Hello, s Duncan here from Wellmouth, Indorset.

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Just another quick question for you just
wondering with the Planet nine episode and

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so far we've not been able to
find it. Also with all the rogue

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planets that have been found recently,
is it possible that in the past a

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rogue planet would have come through our
Solar System, or at least near to

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it, and perturb the objects out
in the York Cloud and the Kuiper Belt

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so that they present this strange orbit
that they've got now, and that the

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road planet would have then gone on
its way back out of our Solar system,

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and therefore there is no planet knowing
to be found, but the objects

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still exhibit the strange orbit into which
they were perturbed. Just thinking, you

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know, is that a possibility?
So we're looking for something that might no

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longer be there. Okay, thank
you anyway, and thanks for the good

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work and keep it up and all
that. Thank you. Bye. All

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right, interesting idea. So possibly
a rogue planet or something else passing by

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that caused some interference that created the
anomalies that we now blame a planet on

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that may not be there. What
are your thoughts? Yes, so that's

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all possible, that's all possible.
Wow, But I think it's been basically

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eliminated by those people who are studying
the orbits of these distant transptune union objects.

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They're called extreme transceptuny on objects,
the ones whose orbits are aligned.

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So my feeling is that that,
if I remember rightly, so, there

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were papers published on this in twenty
sixteen and twenty seventeen. They were the

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kind of original proponent papers of the
idea that there has been that there is

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another planet in the Solar System,
co authored by Mike Brown, who's one

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of the main proponents of this.
Now I if I remember rightly, those

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he's looked at, you know exactly
these ideas that there have been more likely

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to be a passing star because the
Sun does wander near stars as it meanders

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around the galaxy, and those stars
do have a gravitational influence. We believe,

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for example that and this is not
a star, this is something even

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bigger, a giant molecular cloud.
But one of the theories that looked at

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the bombardment of the Earth by comets, done by colleague of mine in Edinburgh

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back in the day, they looked
at the idea that giant molecular clouds had

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influenced the Oort Cloud and basically dumped
comets into the inner Solar system, which

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meant that there were episodes of bombardment
on the Earth, which they found evidence

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for. So, you know,
it's an idea that is kind of well

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known in astronomy that the Sun is
fairly lonely at the moment. The nearest

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star is proxima centaury four point three
light years away, but they may well

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have been closer encounters throughout the history
of the Sun. And I'm pretty sure

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that this sort of thing was looked
at in those early papers. But if

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I may to segue to a new
paper that's come out, and this is

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featured actually by our good friends at
Universe Today, the Universe Today website.

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They I think have had a chat
with Mike Brown, who is actually the

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Richard and Barbara Rosenberg professor of astronomy
at Caltech, and he's certainly one of

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the main proponents of this. They've
done some new research and they've narrowed down

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the area in which we should be
looking, which you know, is really

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a step forward because the searches that
have been carried out so far have been

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over a very wide area. I
think they've narrowed it down. I can't

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remember to how many square degrees it
is, but it's narrowed down. And

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this is in advance of the via
SA Ruben telescope coming online, Andrew,

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which is going to be the world's
most effective survey telescopes, and eight point

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four meter telescope that will look at
the whole sky. Is it every three

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or four nights, the entire sky? Because it's a wide field telescope,

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and you know, the planet nine
will be high on the agenda of objects

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to be looking for by that telescope. A couple of quotes, if I

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may from from Mike Brown, planet
nine would be the fifth largest planet in

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the Solar System, and the only
one with a mass between the Earth and

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Uranus. Such planets are common around
other stars, and we would suddenly have

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a chance to study one in our
own mess would be your legs, like

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Jordie likes, I'm not going to
touch it, Andrew. Another another quote

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that I like, There are too
many signs. This is Mike Brown again,

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there are too many signs that planet
nine is there. The Solar System

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is very difficult to understand without planet
nine, and he goes on to say

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again talking to universe today, planet
nine explains many things about the orbits of

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objects in the outer Solar System that
we would be otherwise unexplainable and would each

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need some sort of separate explanation.
The cluster of the directions of the orbits

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is the best known, but there
is also a large perihelium distances of many

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objects, existence of highly inclined and
even retrograde objects. That's things that orbit

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the wrong way round clockwise are seen
from above the North Pole. It's the

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wrong way round. And the high
abundance of very eccentric orbits which cross inside

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the orbits of Neptune. None of
these should happen in the Solar System,

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but are all easily explainable as an
effect of planet nine. So Dr Brown

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is still very much the proponent of
planet nine. And well, does planet

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nine exist? And we will find
it in coming years and decades, as

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Universe today asks, only time will
tell, and that's why we do the

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science. Yes. Indeed, although
there was one theory that it may not

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be a planet but a cluster of
staff, that cluster of stuff has been

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one. Clusters of stuff are very
difficult to hold together, Andrew, and

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so it needs to be something solid. But a mini black hole has also

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been suggested, and that might be
something that's more difficult to eliminate. Right,

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wow, Okay, there you go, Duncan. Great question and very

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timely given there some new information,
So thanks for sending it in. And

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yeah, we continue our search for
planet Night, not me personally. I'm

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going to leave that up to other
people that you know occasionally take a peek

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us, Yeah, yeah, yeah, my three point five will find it.

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It's not three point five meters,
it's three point five inches. But

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it's actually Michael, I don't know. I can't remember what size it Isn't

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that terrible? Thank you Duncan.
Now we've got a follow up concept,

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let's call it from Rusty about his
soular pagola, which he told us about

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a few weeks ago. This was
aimed at reducing the Earth's exposure to the

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Sun by around two percent, and
he sent us an email about it and

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he said, I'm afraid I gave
you and Fred and Andrew the wrong idea.

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Although I briefly considered a megastructure at
L one, rather foolishly thought calling

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the sunscreen I have in mind the
solar pegola would garners in. It may

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have done that, but it also
gave people the wrong idea. What I

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do have in mind is a constellation
of starling proportions. Each satellite would throw

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a penumberal shadow on the Earth,
and the total two percent sunscreen would not

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be noticeable. I'm convinced that using
emerging technologies, we could have this done

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in ten years. What do you
think of that? Friend? It's good

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stuff. And Duncan is Rusty.
Sorry, Beggy, pardon Rusty, Sorry,

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Rusty, Sorry, I'm mixing up
my listeners. All of them are

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a big fun of by the way. So yeah, but there's a lot

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going on in the you know,
in the scientific world along similar lines.

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And in fact only was it a
fortnights ago, three weeks ago as we

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stand now, there was a big
article in the New York Times, and

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I think it was all have picked
up in the Cinney Morning Hral entitled could

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a giant parasol in outer space help
solve the climate crisis? Now, that's

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sort of a bit of a reference
to the megastructure idea that Duncan, Sorry,

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Rusty, let me just write down
Rusty was thinking about before. But

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that article was good because it pointed
back to a lot of the earlier research

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that's been done on this, and
indeed there's papers everywhere. One that I

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liked was goes back to scientists in
the University of Hawaii who wrote a paper

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back in July last year about the
idea of a sun umbrella. In other

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words, you know, a parasol
tethered to an asteroid in order to give

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it some sort of stability. So
once again it's a megastructure, but it's

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got an asteroid tethering it. But
this is probably disappointment to Rusty. The

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one that essentially is identical to what
Rusty is suggesting was written by somebody I

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know, actually a scientist called Roger
Angel, who is a professor I think

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he might be now retired at the
University of Arizona. He published a paper

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in the Proceedings of the National Academy
of Science back on November fourteenth, two

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thousand and six, which is feasibility
of cooling the Earth with a cloud of

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small spacecraft near the inner lagrange point
L one, which I think is exactly

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what Rusty's suggesting. And I'd actually
suggest to Rusti that you actually look at

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this paper. It's pretty easy to
find pnas Proceedings of the National Academy of

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Science feasibility of cooling the Earth with
a cloud of small spacecraft near the inner

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La Grande point, and he goes
through the mathematics the stability of spacecraft at

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the Grande point because it is actually
a gravitational sadde, which means they wander

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off if you don't if you don't
do something about them. Let me just

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read a few things from his abstract. If it were to become apparent that

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dangerous changes in global climate were inevitable
despite greenhouse gas controls, active methods to

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cool the Earth on an emergency basis
might be desirable. The concept considered here

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is to block one point eight percent
of the solar flux with a space sunshade

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orbited near the inner lagrange point L
one in line between the Earth and the

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Sun. Following the work of Ja
Early another Early if I mixed metaphors their

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worker on this back in nineteen eighty
nine, he says transparent material would be

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used to deflect the sunlight rather than
to absorb it to minimize the shifting balance

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out from L one caused by radiation
pressure. So there are some real subtleties

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here. Andrew three advances aimed at
practical implement presented. First is an optical

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design for a very thin refractive screen
with low reflectivity, leading to a total

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sunshade mass of in the region of
twenty million tons. Second is a concept

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aimed at reducing transportation costs to fifty
dollars per kilogram by using electromagnetic acceleration to

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escape the Earth's gravity, followed by
iron production propulsion. Some neat work there

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with basically with light sales, and
third is an implementation of the sunshade as

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a cloud of many spacecraft autonomously stabilized
by modulating solar radiation pressure. These met

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sized flyers will be assembled completely before
launch, avoiding any need for construction or

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unfolding in space. They would weigh
one gram each, be launched in stacks

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of eight hundred thousand, and remain
for a projected lifetime of fifty years within

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a one hundred thousand kilometer long cloud. The concept builds on existing technologies.

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It seems feasa that it could be
developed and deployed in a region in the

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region of twenty five years at the
cost of a few trillion dollars less than

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point five percent of the world gross
domestic product over that time. So Rusty's

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thinking is very much in line with
what Roger Angel was proposing, except Rustina

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thinks we could get it down to
ten years because of the new technologies that

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we have in space launch, and
that might be absolutely right. Yeah,

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Look, we've got to do something
because from what I've read about the progress

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we're making in dealing with the problem
of global warming and climate change on Earth,

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we can't possibly do enough to alleviate
the effect. And you know,

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not every country is conforming, so
there needs to be another way. And

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maybe this is it. Just maybe
I'm not a big fan of major geo

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engineering. But yeah, as you
say, we really have to stay up

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on it in regard to what individual
countries are doing. Plus increases our classification

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as a civilization and do it so
he does for anybody who helps to be

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watching. Yes, well it's important, it's very important. Thank you,

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Rusty. Yes, we've now given
you some homework, so have a look

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at that. Okay, well takes. Let's move on to our last question

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before we do our homework. This
one comes from David. Hey, your

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friend Andrew, This is David from
Singing Texas go one on favorite kinds of

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questions. What if if you could
step foot onto any planet outside of our

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Solar system, which planet would it
be? And why are you more interested

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in that planet than others? Thanks
for all shell back, all right,

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David. Well, aside from Planet
nine, which is, you know,

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we're not sure if it's part of
our Solar system, but it's got to

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be. It's just so far out. I'll go first because I haven't got

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much to say that. I did
a bit of homework on this, and

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I thought, loo, if we're
going to step onto another planet, we

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really want to find a planet that's
earth like. And that took me to

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the Kepler System, and the one
that they think is most earth like,

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even though it's sixty percent larger than
Earth, is Kepler four or five to

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two B, which I like the
idea of until I read that it's probably

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got a run away greenhouse effect and
it's developed more like Venus than Earth.

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But they reckon that is probably the
most earth like planet so far that they've

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found outside our Solar System. I
wouldn't mind having a look at that,

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setting foot on it might prove a
challenge, though, But I mean,

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there's there's so many planets that they've
discovered. Now most of them gas giants,

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so you know, you don't want
to step on any of those.

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But any any rocky planet in a
goldie Locks zone would probably be attractive to

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me. And Kepler four five two
B is in the Goldilock zone, Fred,

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so maybe so, maybe so,
But yeah, it is. It

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is a strange world compared to what
we know, and the drawn the comparison

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to Venus, but it's probably it's
in the Trappist One system, I think,

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discovered by the Kepler space telescope,
So that one sort of jumps out

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at me. But I did have
to do homework because I honestly I haven't

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really analyzed what we've learned about too
many exoplanets, but it would have to

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be earth like and it would have
to be in the Goldilocks zone. That's

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I'd want to have a look at
any one of those. Really. Yeah,

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that's exactly the way my thinking went
as well, Andrew. And I'm

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not sure the distance of the trappis
One system, but I went for it's

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forty light years away. Yeah,
Okay, so that's just too far for

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me. I'm getting old and I'm
not sure I could. Yeah, so

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I'd be going to the nearest star
Proxima Centauri four point three light years away,

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which has does have Proxima Centauri B, which I think is in Proxima

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Centauri's habitable zone. I don't think
it's an Earth like planet, but it

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is within the habitable zone. And
the problem with planets going around red dwarfs,

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which Proxima Centaury is, is that
they're irradiated by the flares that these

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red dwarfs tend to emit from time
to time. And so I'd have my

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radiation shield on full power, be
sitting there watching what the effect of a

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solar flare, giantgantic solar flare is
on this poor little planet around the nearest

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world. But what I'd have in
the back of my mind is it's not

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too far to get back to Earth
because it's only four point three light years.

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Yes, yes, you know,
when we get our light speed engines

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or sort of out. Yeah,
I'll do it. Yeah. It's still

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a long trip though, Isn't it
all right? David? You are your

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what if question answered somewhat and thanks
for sending it in Now to some homework.

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We were asked recently by Wane whether
or not a super and ova can

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cause a gravitational wave. And the
answer is it depends. Why did I

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know that? Yeah, so it
depends on how symmetrical the explosion is.

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In other words, if you know, if you've got a perfect explosion,

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everything goes outwards completely medially from the
center, then you won't get a gravitational

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wave because all the acceleration accelerating masses
are balanced, you know, it's balanced,

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the ones going away from us balanced
by the ones coming towards us,

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so you don't get one. But
if he had an asymmetric Supernover explosion,

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and I think most of them probably
are. I remember seeing some simulations years

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ago of the gas dynamics of the
Supernover explosion, and yeah, there's certainly

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looked as though there was a lot
going one way and not quite as much

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going the other way. So that
would give rise to a gravitational wave.

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Okay, there you go away.
Yes, sometimes it's the problem with the

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answer. And Lee asked us about
how insight on Mars was able to triangulate

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the impact point of meteorites and other
things hitting the surface. We had to

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follow that up. We did,
and I did that. I was going

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to, but you offered because I
thought it was an interesting one. I

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kind of wondered the same thing myself. And you might remember, Andrew that

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I did waffle about the fact that
seismic waves are not just you know,

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they're not just one uniform thing.
They've got different frequencies, they've got different

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polarizations. There are sheer waves and
what's the other pressure waves and sheer waves

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the two different sorts. So and
I think I think I might be sort

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of have been vaguely on the right
track. I'm going to read though,

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from someone's answer to the question this
is on the Stack Exchange website. Question

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was can we know where the mass
quakes come from? An insight? And

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actually the question not read it out
because it puts it exactly. When doing

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seismology on Earth, we use information
from multiple stations to determine where a signal

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is coming from using triangulation. On
Mars, we only have one seismomeitor insight.

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Is this enough to get a very
rough idea of where the mass quake

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occurred? If so, how is
it done? And the answer is from

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Okay, okay, it's from somebody
I actually know. I've had dinner with

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him, Tom Spilker, who's Linda
Spilker's other half, Tom is a space

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engineer and very good space scientist,
so I think we can we can take

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this with some gravitars. I hadn't
noticed that Tom was the author of this

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answer. So Tom's answer is according
to this paper by the Inside Seismometter team.

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And this paper has a link to
it so you can click on it.

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It's the SIS team with a list
of authors. As long as you

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are that sounds like tom techniques.
Combining data about the arrival times of various

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modes of seismic waves, the amplitude
or strength of the waves, and surface

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waves that travel around Mars's globe more
than once can determine the location of Mars

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quakes. My reading of the paper
this is Tom again, is that the

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process isn't a straightforward calculation, but
instead involves modeling of Mars's interior structure and

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wave propagation characteristics, adjusting the models
until the coherent solution is reached. That

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solution includes the depth and geographic position
of the quakes focus. So a great

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answer, by what a delight to
find who it's from, and that includes

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impacts because just anything that causes the
right kind of vibration or by modeling,

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you can work out where it's come
from. Fascinating. There you go,

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Lee, that's how it's done.
Now, don't forget. If you have

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00:25:48.240 --> 00:25:52.039
questions for us, please send them
in via our website. Just click on

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00:25:52.079 --> 00:25:56.160
the AMA tab where you can send
us a text question or an audio question.

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00:25:56.240 --> 00:26:00.599
We actually have very few audio questions
at the moment, so please get

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00:26:00.640 --> 00:26:03.680
them into us. You can also
click on the thing on the right hand

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00:26:03.720 --> 00:26:11.759
side, the greenish tearly sort of
spinmint colored button send us your question,

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00:26:11.039 --> 00:26:15.079
although when you hover on it at
tur it's purple. And just as long

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00:26:15.119 --> 00:26:21.319
as you've got a device with microphone, you can record your message. And

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don't forget to tell us who you
are and where you're from. And while

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you're on our website, have a
look around and see what you see.

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Fred, thanks so much. We'll
catch you on the next episode of Space

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Nuts very very soon. Sounds great, Andrew, take care and talk to

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okay, Professor Fred Watson, astronomer
at large and here in the studio.

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Who's got more editing to do than
a Disney cartoonist person who does Disney stuff.

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I don't know what they're called.
Animator all right, I'm out of

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here thanks to your company. Catch
you on the next episode of Space Nuts.

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Bye bye. You'll be listening to
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