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Retrograde Orbits & Cosmic Collaborations: Unraveling NASA's Boeing Deal and Backward Exoplanets · Space Nuts: Astronomy Insights & Cosmic Discoveries

0:00
Professor Fred Watson: Hi there.
0:00
Andrew Dunkley: Thanks for joining us. This is Space Nuts. My
0:03
name is Andrew Dunkley, your host. And thanks
0:05
for joining us today and every day you've
0:07
listened to us in the last decade or more.
0:10
It's fabulous. Uh, coming up, what are we
0:13
going to talk about? All right, uh, we're
0:14
going to talk about NASA and its association
0:16
with Boeing Starliner. There's news there.
0:19
We've also got a report of an exoplanet
0:22
that's orbiting its star, um, backwards.
0:25
Um, don't know why, and I don't think anyone
0:28
has figured it out yet. And the Square
0:30
Kilometre Array is in the news because it's
0:33
getting help from nature. Or maybe it's not.
0:36
We'll unravel that as well. That's all coming
0:38
up on this episode of space nuts.
0:41
Professor Fred Watson: 15 seconds. Guidance is internal.
0:44
10, 9. Ignition
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sequence start.
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Professor Fred Watson: Space nuts.
0:48
Professor Fred Watson: 5, 4, 3, 2. 1, 2, 3, 4,
0:51
5, 5, 4, 3, 2, 1.
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Andrew Dunkley: Space nuts.
0:55
Professor Fred Watson: Astronauts reported meals good.
0:57
Andrew Dunkley: Joining us, as always, is his good self,
0:59
Professor Fred Watson Watson, astronomer at
1:02
large. A very patient man you are,
1:03
Fred Watson. How many times did we try to get
1:05
this episode started?
1:07
Professor Fred Watson: Well, um, I can't, um,
1:10
say anything because I was late joining you
1:12
anyway, so it's been one of those days.
1:16
Andrew Dunkley: It has. Like everything went wrong.
1:19
Professor Fred Watson: Everything went wrong.
1:19
Andrew Dunkley: That's the way it goes sometimes. Um, um. And
1:22
that's the Internet, isn't it? But we used to
1:24
have these problems in radio as well. You'd
1:26
be just in the middle of doing something and
1:27
then there'd just be a blackout and all hella
1:30
break loose. That was never fun.
1:33
Uh, or you'd have a blackout. And when the
1:36
power came back, because it was later
1:39
in my career, because it was digital
1:40
technology, the microphone worked, but
1:43
nothing else. And you just
1:46
had to keep talking and talking and talking
1:48
until everything rebooted. Like
1:51
with analogue gear, it just turned back on
1:53
and you press play. But with digital
1:56
gear, no, it's not that simple. And that's
1:59
what we had today. I'm scared to touch my
2:02
panel because I'm worried that it might chuck
2:05
a wobbly at me. And, you know,
2:08
um, it has been known to do some
2:10
really weird things sometimes. Oh, see?
2:16
Very scary stuff.
2:17
Professor Fred Watson: Didn't know you were playing an LP there.
2:20
Andrew Dunkley: Yeah, I don't know what this button does.
2:23
Professor Fred Watson: Okay.
2:26
Andrew Dunkley: Uh, I don't know what else is on this.
2:29
Anyway, um. Oh, here's a famous one.
2:33
The nasatone. Yeah,
2:36
I've got that one on my system now. I've got
2:38
to find where I need to be so that we can
2:40
actually do this show.
2:43
And I think that's about it. All right,
2:45
Fred Watson, thanks for your patience. Um,
2:49
what are we talking about? Let's get started
2:50
with this NASA, uh, announcement that's, uh,
2:53
been came out recently.
2:55
Well, Monday our time, but by the time this
2:57
podcast's released, it'll be a few weeks
2:59
back. But, um, yeah, it's a really
3:02
interesting announcement because a lot of
3:04
people want to work with NASA and
3:07
I think this is a case of, um, had options
3:10
and they've decided they might stick with
3:13
Boeing in this regard.
3:16
You might want to fill in the blanks because
3:18
I might be crossing up stories here.
3:21
Professor Fred Watson: Uh, not at all. Uh, so
3:24
the current status, uh,
3:27
of affairs in terms of
3:29
getting astronauts up and down to the
3:31
International Space Station is that, uh,
3:34
SpaceX, with their Crew Dragon spacecraft and
3:37
their, uh, Falcon 9 launch vehicle have
3:40
been basically successfully flying
3:43
NASA astronauts up to the space station
3:46
and back for more than six years. It seems
3:48
like. It doesn't seem like that long, but
3:50
that's how long it is. And, but
3:53
right at the beginning of this process, um,
3:57
NASA also, as well as inviting
4:00
SpaceX, uh,
4:03
to bid for this job, this taxi job,
4:05
running astronauts up and down, Boeing
4:09
also were invited. And
4:11
their, uh, equivalent of the Crew Dragon is
4:14
the Starliner vehicle. Uh, but
4:16
it's had problems, um,
4:20
significant problems in 2019 and
4:22
2022, uh, and
4:25
then again in June 2024
4:28
when there were two astronauts on board
4:31
and there was this, uh, epic,
4:35
um, decision not to return those
4:38
astronauts in the Starliner
4:41
because there'd been thruster issues as it
4:43
docked with the International Space Station.
4:46
There was no appetite for taking the risk of
4:48
those cre. Uh, um,
4:51
uh, you know, returning in a, in a vehicle
4:54
that was unsafe. So the Starliner was.
4:56
Andrew Dunkley: There was a worry they wouldn't return at
4:58
all, if that's correct.
4:59
Professor Fred Watson: Yes, that's right. Yeah. Uh, and the
5:02
Starliner did actually, they sent it back on
5:04
its own and it did in the end make a perfect
5:07
landing. But that left those two crew members
5:11
stranded for how long? It was eight months
5:13
or something, wasn't it?
5:14
Andrew Dunkley: It was a long time. And part of the reason
5:17
was their spacesuits weren't compatible with,
5:20
um. Was it the crew Dragon?
5:22
Professor Fred Watson: That's right, that's correct.
5:26
Yeah.
5:26
Andrew Dunkley: It's crazy.
5:27
Professor Fred Watson: So, yeah, so, so Boeing has been
5:31
so picking up the pieces of that and um,
5:34
essentially modifying the design of
5:36
Starliner. And uh, there's
5:39
been sort of negotiations in terms of the
5:41
amount of money that's involved because of
5:43
course these are not cheap options.
5:46
Um, but uh, there is now,
5:50
um, a deal that uh,
5:53
is. It may have surprised
5:56
Boeing, probably not because they've got
5:58
their ears to the ground in terms of what
6:01
the deals are going to be. But NASA will
6:03
exercise its options
6:06
to order two additional crewed missions
6:09
in Starliner and that will bring the total
6:12
number of spaceflights that they've bought
6:15
on Starliner to six.
6:17
And I think probably, I don't know how many
6:20
of those have happened already because I
6:23
don't know whether the one that stranded
6:25
those astronauts counts among those. But
6:28
um, the thing that really interests me
6:31
in this article,
6:33
Andrew, is that there is
6:36
a comment from the
6:39
NASA administrator, the boss of NASA,
6:42
uh, Jared Isaacman, who said, I
6:45
do not think it's a secret that SpaceX
6:48
intends to sunset older platforms like
6:51
Falcon and Dragon as they concentrate on
6:53
their next generation capability, Starship.
6:57
Uh, and that tallies with things I was
6:59
hearing, uh, when I listened recently to
7:03
the launch of Starship Flight 14.
7:06
Some of the commentary was along the lines
7:08
that, um, SpaceX is
7:11
absolutely devoting its future launch
7:14
vehicle activities to Starship.
7:17
And it looks as though the Falcon, for
7:20
all it's been an absolutely historic and epic
7:23
and very reliable launch vehicle, um,
7:26
ever since they learned to land it back, uh,
7:28
on the ground to reuse it back in 2015.
7:32
It looks as though its time is numbered or
7:34
its days are numbered. Uh, and
7:37
that tallies with the almost
7:40
boundless enthusiasm that Elon Musk has
7:43
for getting Starship into a state where
7:46
he can launch. Wait for this, Andrew. A
7:49
thousand starships a year.
7:51
That's what he has in mind. What's that,
7:54
three a day? Yeah, endless.
7:58
Andrew Dunkley: And they'll be carrying who knows what a lot
8:00
of his stuff. Of course.
8:02
Professor Fred Watson: Yes, yeah, um, uh,
8:04
Starlink, uh, satellites will be part
8:07
and parcel of that. That test flight 14
8:09
recently, um, there were 26
8:13
of the version 3 Starlink satellites which
8:15
have a much greater capability in terms,
8:18
uh, um, the
8:20
telecommunications. It's a much bigger
8:22
bandwidth, uh, um,
8:27
um, that was a test. I think they can launch
8:29
up to 60 of those, uh, in
8:32
an empty, uh, Starship. 60
8:36
Starlink satellites and an empty Starship.
8:38
But of course, uh, the other aspect of this,
8:41
and this is where SpaceX really does have to
8:43
get its act together.
8:46
Starship is one of the two
8:49
crew landing vehicles that are selected
8:52
for testing in a competitive way for
8:55
The Artemis Project Artemis
8:58
3. The flight that will do that, uh,
9:01
is scheduled for early next
9:04
year. Um, I beg your pardon, late
9:07
next year. It's scheduled for late 2027,
9:10
uh, where both Blue Origin's blue moon
9:13
landing vehicle and SpaceX's
9:15
Starship landing vehicle will be tested, uh,
9:18
in orbit along with the Orion
9:21
capsule, which will carry the astronauts, uh,
9:24
to the moon, um, or to the vicinity of the
9:27
moon. One of these two landers will actually
9:30
be what puts them down on the surface and we
9:32
don't yet know which it'll be. Um,
9:35
I'm not a betting man, but uh, to
9:38
be honest, given the terrain that they're
9:40
going to try and land in, uh, near the moon's
9:42
south pole, I'm not sure that something long
9:44
and thin and 52 metres high actually cuts the
9:47
mustard given how many things have fallen
9:49
over on the moon's surface before.
9:52
Andrew Dunkley: Yeah, that does seem to be a factor. Uh,
9:54
and if he's steering his
9:57
attention into other things,
9:59
maybe that's going to come into play when
10:02
they make their decision. Um,
10:05
I'm intrigued by how competitive private
10:09
space ventures are becoming because you've
10:11
got Blue origin, you've got SpaceX, you've
10:14
got Boeing and you've also got
10:17
Airbus because they work very closely with
10:19
ESA and
10:22
you know, there are several other countries
10:24
that um, are running space programmes
10:26
these days and it's just getting more and
10:29
more competitive, but it's also advancing at
10:32
a rate of knots. We're seeing technology now
10:34
that's being developed so very quickly.
10:38
Professor Fred Watson: Exactly.
10:39
Andrew Dunkley: And I suppose if you look back to when it all
10:42
started, it was a slow burn, so to speak.
10:45
It was. Now it's accelerating
10:49
at an incredible rate.
10:51
Professor Fred Watson: Yeah, I mean, so
10:55
I guess what you've highlighted there is
10:58
uh, the fact that when it wasn't
11:01
competitive, when it was just NASA doing
11:02
things, uh, they really took
11:06
very small steps to advance things
11:09
in order to play safe. Uh, but when
11:12
you've got competition thrown in there, they
11:14
will take risks. And certainly Elon Musk has
11:17
taken risks in the past, although, um, he was
11:20
very risk averse with the starship, uh,
11:23
uh, Flight 14. Uh, and I think that was
11:26
one reason why they cut it short. It was uh,
11:28
cut short from six hours, I beg pardon, six
11:31
orbits down to, I think two. Uh, from um,
11:34
ten hours in space down to three. Uh,
11:37
so that's symptomatic of that slightly
11:40
more gung ho attitude. But nevertheless,
11:43
I think, um, the,
11:45
clearly the space industry, the commercial
11:48
ventures, take uh, the safety of their
11:51
crews extremely seriously. Uh, but
11:54
they can advance it um, much more quickly if
11:56
they've got financial backing behind them
11:59
that doesn't have to go through government
12:01
approval and things of that sort, which is
12:03
basically what's happening. Uh, in this
12:06
space. Um, just another snippet that
12:09
sort of plays into this, um, this
12:11
discussion Andrew, is that there
12:14
is consideration by NASA
12:17
in extending the lifetime of the
12:20
International space station to 2032.
12:22
They've been saying for ages that it will
12:24
come to an end by 2030, but it looks as
12:27
though it might be extended. And of course
12:29
that uh, actually uh,
12:32
highlights the need for Starliner because
12:35
it's likely that crew Dragon will
12:38
be retired before
12:40
2030. Uh, and so Starliner
12:43
will be the only U.S. vehicle that can access
12:45
the space station. The Soyuz flights will
12:47
still be going, I'm sure, but Starliner um,
12:50
will be the um, that'll be the
12:53
vehicle of choice to get people up and down.
12:56
Andrew Dunkley: So it makes sense that NASA has announced
12:59
those options to continue with them. So,
13:02
uh. Yeah, quite so.
13:05
Yeah. It's a good deal. And uh,
13:09
I think we're still only at the very early
13:11
stages of
13:14
Professor Fred Watson: private
13:14
Andrew Dunkley: um, operators in space. And
13:17
what's it going to be like in 50 or 100
13:19
years? It's just hard to imagine.
13:21
Professor Fred Watson: Absolutely. Well,
13:24
um, Elon wants us all on Mars by then.
13:27
Andrew Dunkley: Yes. I think in the meantime we'll probably
13:30
have a, um, a couple of hotels in space in
13:32
the next hundred years and you'll be able to
13:34
take a holiday up there if you want to.
13:36
Professor Fred Watson: Maybe so.
13:37
Andrew Dunkley: Yeah.
13:37
Professor Fred Watson: And if you're rich enough.
13:39
Andrew Dunkley: Yeah, well that'll be the thing, won't it?
13:41
Although I think once going into space
13:44
becomes more and more common,
13:47
the price will come down. But there
13:50
was a time where flying, flying was only for
13:53
the rich.
13:54
Professor Fred Watson: This is true. It is true.
13:57
But, um, let me just give you some figures.
13:59
Um, uh, this is a quote from an article
14:02
in uh, Ars Technica for the
14:05
Starliner 2 through Starliner 6
14:07
missions, NASA and Boeing have agreed to a
14:10
price point of approximately US$90 million
14:14
per seat. So yeah,
14:17
that's quite a fair, um,
14:20
Andrew Dunkley: that's getting up there.
14:21
I hope it's business class, but anyway,
14:24
Professor Fred Watson: I'm not sure that it is actually probably.
14:29
Andrew Dunkley: It's certainly a quicker flight than going
14:31
from Sydney to Istanbul, that's for sure.
14:34
Professor Fred Watson: Yeah, that's right. Um, and again that's one
14:36
of the um, uses that uh, Elon sees
14:40
in Starship. The fact that you can do
14:43
suborbital flights so that you could get to
14:46
Istanbul in 45 minutes
14:49
from here.
14:49
Andrew Dunkley: Yeah, I think that is where the future will
14:51
be.
14:52
Professor Fred Watson: Maybe so. Maybe so.
14:54
Andrew Dunkley: Won't be far down the track.
14:56
If you'd like to read all about that
14:58
particular deal with NASA and Boeing
15:00
Starliner you can do that. As Fred Watson
15:02
said@arstechnica. Uh.com. this
15:05
is Space Nuts with Andrew Dunkley and
15:07
Professor Fred Watson Watson.
15:13
Space Nuts. Okay Fred Watson, let's move on
15:16
to a weird planet. And when I
15:19
say a weird planet, there are many weird
15:21
planets that we have discovered. Exoplanets.
15:24
Uh, over five and a half thousand such
15:27
planets now have been catalogued and there
15:29
are many, many more waiting in line for their
15:32
name to be put in the little black book.
15:35
Um, but uh, this one uh, in
15:38
particular, uh, particular GJ,
15:41
uh 3090B
15:44
uh is um, doing some weird stuff
15:47
and they don't really know why. But if they
15:49
can figure out why, it might answer some
15:51
really interesting questions about planet
15:53
formation.
15:54
Professor Fred Watson: Indeed. That's exactly right. Um, so
15:57
this is research that's from Queen Mary
15:59
University in London. Uh and
16:02
it's uh, as you said, it's a star.
16:05
A planet by the way, um, a planet. I beg your
16:08
pardon.
16:10
GJ3090B. It's about
16:12
the size of Neptune. Uh, um,
16:15
I can't remember what its orbital
16:18
period is. I think it's quite short. These
16:20
things usually are. But it's going
16:23
backwards. It's going in the opposite
16:25
direction around the
16:28
star which is going to be called
16:30
GJ3090. Uh the parent
16:33
star. It's going in the opposite direction to
16:36
what that star rotates in. And
16:39
that's a big surprise because
16:42
uh, um, all our um,
16:45
models of planet formation they
16:48
start with uh, a cloud of gas and
16:51
dust which collapses under its own gravity.
16:53
And as it collapses, uh, that induces a
16:56
spin uh in a particular direction.
16:59
And out of that spinning blob of material
17:02
both the star and its planets form. And
17:05
that's why in our solar system certainly
17:08
the planets are all in a single plane. They
17:10
used to be in a disc, uh, um, call a
17:13
protoplanetary disc. But they're all going in
17:15
the same direction as the sun is rotating.
17:17
And that's the fossilised rotation. So
17:20
the suggestion is that this particular
17:24
planet uh is
17:26
going the wrong way because of
17:29
some interaction that has taken place
17:32
during its lifetime. Uh, it's
17:35
the first known planet around
17:39
um, an M dwarf to
17:41
follow, um, what we call a retrograde
17:44
orbit. A backward orbit. Retrograde. In the
17:47
case of the solar system, something going
17:49
retrograde would be going clockwise as seen
17:51
from above the North Pole. Um
17:54
so it's a ah, backward orbit. And in fact
17:56
it's not only backwards, it's slightly
17:59
inclined to the equator of
18:02
the parent star. Remember all the planets of
18:05
the solar system are in orbit In a plane
18:08
that's more or less coincident. It's not
18:10
quite, but more or less coincides with the
18:12
equatorial plane of the sun, its
18:15
equatorial plane of rotation. Uh, this one's
18:17
tilted at quite a significant angle to it,
18:20
if I remember rightly. I can't see the number
18:22
here, but I think It's. Was it 136
18:25
degrees, which is well over 90 degrees.
18:28
Um, that would make it
18:30
revolve over the star's poles.
18:33
Uh, but, um, this is going
18:36
further away than that. It's actually going
18:38
backwards. And I think, um, just to
18:41
basically tie up the loose end, I think this
18:43
comes from observations made with the
18:46
James Webb Space
18:49
Telescope. Uh, it's certainly an
18:52
instrument, uh, which is a near infrared
18:54
spectrometer. And I'm guessing
18:57
that's where it has been,
19:00
um, where that, um, instrument, uh, is
19:03
mounted.
19:04
Andrew Dunkley: It, um, does have an orbital
19:07
period of 2.85 to 2.9 Earth
19:10
days.
19:11
Professor Fred Watson: Yeah.
19:11
Professor Fred Watson: Quick.
19:12
Andrew Dunkley: Yeah. And, um, just in case
19:15
people are saying, well, how do you know it's
19:16
going backwards? Well, there's a GJ
19:19
3090C, which is going the other way.
19:23
Professor Fred Watson: Yeah, that's right.
19:26
So the question you've raised there, how do
19:28
you know it's going backwards? Is one
19:30
that depends on a phenomenon
19:33
whose name I can never remember. And it
19:35
really annoys me. I should look it up. You
19:38
might be able to look it up. It's. It's, uh,
19:40
the phenomenon that lets you
19:43
see the direction of rotation.
19:46
Sorry, the direction of revolution of a
19:48
planet around its star. You can measure
19:51
the star's revolution very easily by,
19:55
uh, its spectrum, the way its spectrum
19:57
behaves. Um, it's a bit less
19:59
easy with a planet, but you can do it with
20:02
the spectrum. But there is a phenomenon,
20:05
and I can never remember its name. But don't
20:07
worry about it because, um, I bet you can't
20:10
either.
20:11
Andrew Dunkley: No, I can't find it. Need more information?
20:15
Yeah, you would. Uh, so the bottom line
20:17
here is they don't think this has been caused
20:20
by some kind of collision event.
20:23
Um, they think it might be that this
20:26
star has ventured into, um,
20:29
some material that was a completely different
20:32
angle and may have
20:35
created a planet that was
20:38
in retrograde orbit.
20:40
Professor Fred Watson: Exactly. Yes. Um, there's a couple
20:43
of. I think, you know, I think you're right.
20:45
I think you're absolutely right. There's a
20:47
couple of comments. One comes from, uh,
20:49
Vincent Bourier of the University of
20:52
Geneva, uh, who says
20:54
the idea that a planetary system could be
20:57
rebuilt from a second
20:59
differently orientated disc is particularly
21:02
Exciting. It suggests that the environment
21:05
around a young star can play a much bigger
21:07
role in determining the architecture.
21:09
Architecture of its planets that we might
21:10
have expected. So what he's suggesting, um,
21:13
is that you've got not one, but
21:16
two protoplanetary discs,
21:19
uh, which are orientated differently.
21:22
And that is, uh, as he says, very
21:25
exciting. It's an extraordinary suggestion.
21:28
Uh, but there is another comment, uh, also
21:30
from, uh, somebody at the University of
21:33
Geneva. Um, we looked for the
21:35
kind of massive companion that could have
21:38
forced the planet into such an extreme orbit.
21:40
Orbit. But we don't find evidence for one.
21:43
That suggests we may need to think
21:44
differently about how this system acquired
21:46
its unusual architecture. Which is basically
21:49
going back to that comment that I just made.
21:52
So it's really um, uh, really a, uh,
21:55
very interesting issue.
21:56
And uh, I think this is quite a significant
21:58
story. Um, a surprise to find something
22:01
revolving backwards like that.
22:04
Andrew Dunkley: Yeah, I mean, we've got planets in our own
22:07
solar system that do weird stuff like,
22:09
um, they rotate backwards or they
22:12
rotate on sides. But we've put all that down
22:14
to probable early collisions in their
22:17
history. Being individuals. But
22:20
we don't have a planet that's actually going
22:22
the other way.
22:24
Professor Fred Watson: We do, however, have some satellites.
22:27
I think it's Neptune, uh,
22:30
maybe Uranus. But at least one of those two
22:32
ice giants has planets that go the wrong way
22:34
around. And that's suggesting that
22:37
it's something that's been captured. Probably
22:39
a trans neptunian object, One of these icy
22:42
asteroids deep in the solar system. That's
22:45
less likely, um,
22:49
in the wider interstellar space if you've got
22:52
a star. Unless it's been very
22:54
unlucky and there's been a rogue planet or an
22:56
orphan planet that's just wandered by and
22:58
been captured. But that would be, I think,
23:01
uh, um, an extremely rare event
23:03
if it could ever happen at all. Uh, so it's a
23:06
bit different from the situation in our solar
23:08
system where you've got candidate objects,
23:11
um, to be made into moons going the wrong way
23:14
around. You've got those sprinkled across the
23:16
outer solar system in the form of these trans
23:18
neptunian objects. So yeah, interesting
23:21
stuff. Uh, fascinating. There might be more
23:23
research on it, which I hope we will be able
23:25
to bring to our ah, listeners.
23:27
Andrew Dunkley: Yes, indeed.
23:28
Um, maybe there'll be something to learn from
23:30
this that will answer other questions. You
23:32
never know. It's the nature of astronomy,
23:35
isn't it? Okay, M.
23:38
If you'd like to read that story,
23:39
it's@scitechdaily.com or you can
23:42
read the whole paper, which has been
23:44
published in Astronomy and Astrophysics
23:47
Letters. You're listening to Space Nuts,
23:50
the podcast with Andrew Dunkley and Professor
23:53
Fred Watson Watson.
23:56
Professor Fred Watson: I'm going to step off the land now.
24:00
That's one small step for man,
24:06
one
24:08
Professor Fred Watson: Space Nuts.
24:11
Andrew Dunkley: And I want to send a shout out to Alan in
24:13
Melbourne who's listening, uh, live this
24:15
morning.
24:16
Professor Fred Watson: Fred Watson.
24:16
Andrew Dunkley: Um, you'll be amused to know that Alan is a
24:18
postman and he listens to us while he does
24:20
his deliveries. Uh, and he says keep up the
24:23
great work. Yeah, that's nice. See that's the
24:26
thing about these kinds of um, programmes.
24:28
You can listen to them anywhere, anytime. Uh,
24:31
indeed. Fantastic.
24:33
Uh, now our final story today takes
24:36
us to wa, Western Australia, uh,
24:39
and it is about the Square Kilometre
24:42
Array. And this story's a little bit
24:45
different in that they have um, now
24:48
they're still building the thing but uh, it's
24:50
got all those little Christmas tree antennas
24:53
uh, that they're spreading around. But uh,
24:54
it's the way they've spread them around that
24:57
is um, is detailed in this story.
25:00
But there might be an issue with it
25:04
I think.
25:05
Professor Fred Watson: That's correct. Uh, that's correct. Um, and
25:08
the reason I chose this story to cover today
25:11
Andrew, is that um, when I was astronomer at
25:13
large I was very close to the action in
25:16
the design and construction of the Square
25:19
Kilometre Array Low Ska Low as it's called.
25:22
This is the Low Frequency Arm, um, of the
25:25
uh, Square Kilometre Array Observatory. The
25:28
Mid Frequency Arm um of it is in
25:31
South Africa and the headquarters ah are in
25:34
the United Kingdom, in the north of England
25:36
at Jodrell bank and I think, I can't remember
25:39
how many um, uh, uh,
25:42
um, participating nations there are now in
25:44
Skao. It was seven when I was
25:47
involved. I think it's a bit more now. So,
25:50
um, the uh, Western Australian
25:53
site, it is at a place called
25:55
Inyarimana Ilgari Bundara, the
25:58
CSIRO Murchison Radio Astronomy Observatory.
26:01
That's a uh, Wodgery name meaning
26:03
sharing sky and stars. It's a lovely
26:06
um, first nations name for the observatory.
26:09
Andrew Dunkley: So 16 nations.
26:13
16.
26:14
Professor Fred Watson: Very good. That's good to know. Thank you.
26:16
Things have moved on since I was involved
26:19
quite a lot. Um, so uh,
26:21
the Squake and Metre Array Low is
26:24
not a radio telescope of the kind that
26:27
we're all used to thinking of, which is a big
26:30
dish on a mounting that'll let you point it
26:33
anywhere. And indeed um,
26:36
the Ska Mid, that's the mid
26:39
frequency arm, um, of this telescope in uh.
26:41
South Africa. It consists of I think it will
26:44
be 197uh, dishes which can
26:47
be steered around, which is what you need to
26:49
do at these mid frequencies. But at the low
26:51
frequency you can do something a bit more
26:53
clever. You can stick your antenna
26:56
vertically and it's just like
26:59
uh, one of these old fashioned TV antennas
27:02
that we used to see on everybody's rooftop.
27:03
Except instead of pointing horizontally it's
27:06
pointing vertically. And it's also uh,
27:08
got two uh, segments to it. So it actually
27:11
looks a lot like a Christmas tree, a metal
27:14
Christmas tree about two metres high. There
27:16
are going to be 131,000 of these,
27:19
uh, spread out in groups
27:22
of, I think it's 512,
27:25
um, might be 512 groups
27:28
that there. No, 512 stations. Each
27:31
of them has 256 of these
27:34
antennas. Um, and
27:37
the stations themselves are what lead to
27:40
this story. Because
27:44
the crucial uh, point about using
27:47
these vertically pointing arrays,
27:50
sorry, vertically pointing antennas
27:52
is that when you have enough of them
27:55
you've got what's called a phased array feed,
27:59
uh, which is a way of detecting
28:02
radio signals, uh, without actually
28:05
pointing the telescope in any given
28:07
direction. They're all sitting vertically
28:10
but they can basically each one of those
28:12
antennas can pick up signals effectively from
28:15
all over the sky. Not quite, but a lot of
28:18
the sky, uh, each single one.
28:21
So if you only had one of those you'd get
28:22
this total um, cacophony of
28:25
signals coming from different, you know,
28:28
different celestial objects all around the
28:30
sky. But when you've got
28:32
131,000 of them, you
28:35
basically can time the signals so that you're
28:38
effectively pointing the array electronically
28:40
in different directions. Um, but there's
28:43
a caveat to all this. It's the spacing
28:47
uh, of these antennas that is
28:50
crucial. If you just put them all in straight
28:52
lines you'd have peculiar
28:55
effects that come from the fact that
28:57
the signals have a particular wavelength.
29:00
And if they're all in straight lines it would
29:02
act like something we call a diffraction
29:04
grating. And you'd have null regions where
29:06
you couldn't see anything coming from the sky
29:08
because the waves would cancel out.
29:11
So the design has always been to
29:14
use a um, sort of
29:17
random, quasi random
29:20
layout, uh, that would um,
29:24
actually reflect uh, the
29:27
shape of what we call
29:30
sometimes called a Vogel spiral. Uh,
29:33
it's often called a Fibonacci
29:35
spiral. And um, I know that because
29:38
I'd recently been giving a talk on um,
29:41
mediaeval mathematics. Fibonacci,
29:44
uh, put his sequence together in A
29:46
publication? Not a publication, a manuscript
29:48
that he wrote in 1202. And it turns
29:51
out that you can derive from that Fibonacci
29:54
sequence, uh, where you just add
29:57
the previous two numbers together to get the
29:59
next one in the sequence. That's the recipe
30:01
for it. Um, you can plot that out in a
30:04
graphical way. And what you get is a spiral
30:07
shape. Um, and it turns out that that spiral
30:09
shape comes frequently in nature,
30:12
from seashells to galaxies to
30:15
sunflower seeds. Uh, and that is the
30:18
shape that was chosen to lay out these
30:21
antennas, um, with this kind of
30:24
spiral. Now,
30:27
um, they built a prototype, uh,
30:30
doing that. In fact, they've built more than
30:33
one. The second one was the Aperture Array
30:36
Verification System number two, AAVS
30:38
two. Uh, and that, um,
30:41
essentially mimicked this spiral.
30:44
But, uh, it turns
30:47
out that in the test that they did. I
30:50
beg your pardon. This is an AF
30:52
AAVS3. It's the third
30:55
prototype. I'm sorry. The second one was
30:58
random, simply random.
30:59
AAVS2 was a random distribution
31:02
of the 256 antennas in each of these
31:05
512 pads. Um,
31:07
AAVS3 is a Vogel
31:10
spiral or a Fibonacci spiral. Um,
31:13
but when they built the test
31:15
setup, uh, it turns out
31:18
that if you point the
31:21
telescope directly overhead, which
31:24
is where the Milky Way centre of the
31:26
Milky Way galaxy passes through,
31:29
um, then you have a problem
31:32
because there's a drop off in sensitivity,
31:35
uh, at one of the wavelengths. 125
31:37
MHz exactly. Caused by that
31:40
point, uh, um, that you've got
31:43
this null region, uh, directly overhead.
31:47
So what they're going to do is just
31:50
modify the, uh, the spiral a little
31:53
bit in order to check, uh, that
31:55
this will work. Uh, they call their
31:58
solution a perturbed Vogel pattern. Um,
32:01
they're not calling it a perturbed Fibonacci
32:04
pattern, but that will be the same thing. It
32:07
basically puts in a little sort of almost an
32:09
error, uh, into the position of each antenna.
32:12
And that means that you never get two that
32:15
are close enough together for their
32:17
wavelength sensitivity to cancel out, which
32:19
is what this is all about. Very technical,
32:21
but nevertheless showing how, uh, we take
32:24
lessons from nature, but sometimes we have to
32:26
modify them slightly.
32:28
Andrew Dunkley: That, uh, Vogel spiral pattern's beautiful,
32:31
isn't it?
32:32
Professor Fred Watson: Yeah, yeah.
32:34
Andrew Dunkley: It's worth looking it up online, uh, just,
32:36
uh, to have a look at it. But, uh, yeah,
32:38
quite amazing. I have to make a correction.
32:40
Sixteen countries in the SKA
32:43
project as a whole, but six on the SKA low.
32:48
Professor Fred Watson: Okay.
32:48
Andrew Dunkley: Including Australia, China, Italy, Malta, the
32:51
Netherlands and the United Kingdom.
32:53
Professor Fred Watson: Yeah, that Sounds right.
32:55
Andrew Dunkley: So, uh, every 16 involved in everything
32:58
but six on the low band
33:01
network, if you want to call it that.
33:03
Yeah. Uh, really good story,
33:06
which you can read about@universetoday uh,
33:10
dot com. I'm sure there's a paper somewhere
33:12
that's been published.
33:13
Professor Fred Watson: Um, yes, it's in these
33:17
journals of the, uh, sps, which is the
33:20
Society of
33:21
Photoelectronic
33:23
Instrumentation Engineers. I think that's
33:25
what it stands for. I used to be a member of
33:27
it, uh, when I was working on fibre optics
33:29
back in the day.
33:31
Andrew Dunkley: Indeed. Fantastic. Uh,
33:34
and that brings us to the end. Fred Watson,
33:35
thank you very much.
33:37
Professor Fred Watson: Oh, it's a pleasure, Andrew. I'm glad we
33:39
finally got there after all our, uh,
33:41
tribulations at the start. Good to talk to
33:44
you again as always.
33:45
Andrew Dunkley: And you. We will catch you very, very soon.
33:47
And in between episodes, don't forget to
33:49
visit us at our, ah,
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spacenutspodcast.com spacenuts IO.
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And don't forget to leave reviews wherever
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34:35
He'll be back sometime next week. And from
34:38
me, Andrew Dunkley, thanks for your company.
34:40
We'll see you on the next episode of Space
34:42
Nuts. Bye Bye. You've been
34:44
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