Latest / Space Nuts: Astronomy Insights & Cosmic Discoveries / Theia's True Origins, 40,000 Asteroids & Enceladus’ Organic Mystery

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Theia's True Origins, 40,000 Asteroids & Enceladus’ Organic Mystery · Space Nuts: Astronomy Insights & Cosmic Discoveries

0:00
Andrew Dunkley: Hi there. Thanks for joining us on Space
0:02
Nuts, where we talk astronomy and space
0:04
science. My name is Andrew Dunkley. Great to
0:06
have your company. Coming up on this episode,
0:09
uh, a new study from the Max Planck Institute
0:12
shedding some new light on the theia, uh,
0:14
Earth relationship, which might surprise you.
0:18
And just when you thought it was safe to go
0:19
back, uh, to sleep at night. 40,000
0:22
new near earth asteroids have been
0:25
discovered. Only 40,000? And they're all
0:28
coming our way. No, they're not. Uh, the
0:30
search for life just got another, um,
0:33
a bit closer. Thanks uh, to some Cassini
0:36
data. And 3i atlas still
0:38
making the news. We'll talk about all of that
0:41
on this episode of space nuts. 15
0:44
seconds.
0:44
Professor Fred Watson: Guidance is internal. 10, 9,
0:47
uh, ignition sequence start.
0:50
Space nuts.
0:51
5, 4, 3, 2, 1, 2, 3, 4,
0:54
5, 5, 4, 3, 2,.
0:56
Andrew Dunkley: Space nuts.
0:57
Professor Fred Watson: Astronauts report it feels.
1:00
Andrew Dunkley: And we rolled out the red carpet because.
1:01
He's back. It's Professor Fred Watson,
1:04
astronomer at large. Hello, Fred.
1:06
Professor Fred Watson: Hi, Andrew. I'm actually looking for the red
1:08
carpet.
1:09
Andrew Dunkley: Yeah, I rolled it back up again. It's had
1:12
a few moth holes in it.
1:14
Professor Fred Watson: Yeah, but, yeah, it's glad to hear it. Good.
1:17
And you too. And, um, well, we've missed you.
1:20
No, wait a minute. No, you've missed one or
1:22
the other.
1:23
Andrew Dunkley: Yes, we did have a few people starting to,
1:25
um. I found in radio, if you're away for
1:28
more than about three or four weeks, people
1:30
started ringing the station and emailing to
1:33
say, where's Joe Bloggs? Or where's. You
1:35
know, this started happening with you, Fred?
1:37
So.
1:38
Professor Fred Watson: Oh, seriously, where's Fred?
1:39
Andrew Dunkley: Where's Fred? What's going on with Fred? What
1:41
happened to Fred? Uh, and funnily enough,
1:44
I was able to say, yeah, I don't know.
1:48
Professor Fred Watson: We haven't seen him for weeks. He's just
1:51
disappeared.
1:51
Andrew Dunkley: But no, he's back. He's back.
1:54
So where did you go? What was the. Give us
1:56
the. Give us the precede version of your
1:59
seven weeks away.
2:01
Professor Fred Watson: Three weeks, um, leading one of Marnie's
2:04
tours, uh, which, uh, is the third
2:06
big one we've done this year, actually. Um,
2:09
after the Arctic in January and
2:11
February. And then it was, uh, Western
2:14
Australia in the middle of the year. And then
2:16
this time we went to Japan. Uh, so we had a
2:18
tour that took in interesting, uh, places
2:21
like Osaka and Kyoto and
2:23
Tokyo. And, um, Marnie and I actually made
2:26
a side trip down to Hiroshima, which is a
2:29
place I've always wanted to visit and I'm
2:31
very glad I did. Very sobering place to
2:34
be. Uh, But a welcoming city as well.
2:37
Um, it was a pleasure to be there. Uh, and
2:39
then, um, we wound up actually in Hokkaido,
2:42
right in the north of Japan, where it was
2:45
essentially coming onto winter. Uh, they get
2:47
lots and lots of snow up there. It's a lot
2:50
similar to, um, the Arctic, even though it's
2:52
at a much lower latitude. Um, yeah, that was
2:55
all fun. So we came back, we had four nights
2:57
in Sydney, at home in our own bed, do the
2:59
washing, and then off again to a conference.
3:01
Conference on dark skies in County Mayo in
3:03
Ireland. Uh, we were in Ireland for about a
3:06
week, a little bit more than a week. We did
3:08
some touring down in the South. We blew
3:10
a kiss to the Blarney Stone.
3:12
Andrew Dunkley: I did.
3:13
Professor Fred Watson: Uh. Yeah, I wasn't game to
3:16
kiss the Blarney Stone because you have to be
3:17
upside down.
3:18
Andrew Dunkley: Yeah.
3:19
Professor Fred Watson: Doesn't suit me at all.
3:20
Andrew Dunkley: We didn't do that either.
3:22
Professor Fred Watson: No. So we blew it a kiss, which is, uh,
3:24
enough, apparently, to get the gift of the
3:25
gab. And then, uh, in fact, Blarney was a
3:28
delightful place. It was the one sunny
3:29
afternoon we had in, um. And it was
3:32
lovely. Such an amazing castle. And the
3:34
grounds are picture perfect. Uh, then we went
3:37
over to Scotland, spent some time with my two
3:40
daughters, had a great time with them. Took a
3:42
weekend out. Uh, we all beetled off to St.
3:45
Andrews, where I was educated. A, uh, town
3:47
that's very close to my heart. We had a great
3:49
time there. Uh, didn't do any golf. I'm
3:51
sorry. But we did walk past the old course
3:53
and thought of you with your golf clubs and
3:56
that they don't float and things like that.
4:00
And then after that, we, um, took the
4:03
train down to Birmingham from Edinburgh, and
4:05
that was pleasant. And at Birmingham, we got
4:07
on a plane and went to Cyprus, uh, in the
4:09
eastern end of the Mediterranean. And we
4:11
actually had a holiday, six nights.
4:13
Andrew Dunkley: And you found an observatory, a brand new one
4:15
called Troodos.
4:16
Professor Fred Watson: Troodos Observatory. Yes, we did. Marnie had
4:19
checked it out, as she does with these
4:20
things. And so we made a pilgrimage up into
4:23
the hills. Not very far from the highest
4:25
point in the island, actually, Mount Olympus.
4:27
Uh, but, uh, it's got its own little
4:29
mountain, has, uh. Uh, the Troodos
4:32
Observatory. Uh, we went up there. We went
4:34
completely unannounced. They just had a tour
4:36
group through. So there were two coaches
4:38
which were just about to set off down this
4:41
road that was slightly narrower than a coach.
4:44
Ah, and an angle of 45 degrees. Uh, if
4:47
we'd been, um, you know, if we'd Been half an
4:49
hour later, we'd have probably not been able
4:51
to get there because these damn, um, coaches
4:53
going by. But when we arrived, um,
4:56
you know, they just got rid of all the coach
4:57
party, and we turned up and said, we're
4:59
astronomers. Can, uh, we have a look? And
5:01
they said, oh, no, no, you'll have to wait
5:03
till the next tour. Uh, but we managed to get
5:05
hold of the events manager who said, yeah,
5:07
come in, let's talk about what we do. And all
5:09
the rest of it. Had a great time. So that was
5:11
very, very nice. Uh, and if she's a Space
5:14
Nuts listener, um,
5:16
nice to have met you, I think it was. Irena
5:19
was her name. Greek version of that. And then
5:22
came home, uh, and we came home last week and
5:24
we're now jet lagged.
5:25
Andrew Dunkley: Yeah, it's hard to get over jet lag. I think
5:27
it's. It's an age thing, Fred. We take you.
5:30
Professor Fred Watson: Could be. Except, um, my other half is a lot
5:32
younger than I am and she's jet lagged too.
5:35
Andrew Dunkley: Just goes a bit territory. Yeah.
5:38
Well, I've got a golf story for you while
5:40
you're away. I won it. I won a championship.
5:42
Professor Fred Watson: You did? Yes. Well done. So it
5:45
was, um, 17 years between.
5:47
Andrew Dunkley: M. Ah, uh, well, no, I came, uh,
5:50
in the state championship, So I came third
5:53
on handicaps and top, uh,
5:56
10. I finished ninth, I think, in the state
5:59
championship. But then we had our own, um,
6:01
championship at Dubbo Golf Club the other
6:03
day, and I managed to win one of those. So,
6:05
uh, that's very good. And then today, just
6:07
before this, I played in the Pro Am because
6:10
we're hosting the New South Wales Women's
6:12
Open qualifying event. So. Played with
6:15
a young lass from Melbourne. Her name is
6:18
Piper. Um, Piper.
6:21
Oh, I've gone blank. Um,
6:24
anyway, come back to me, lovely, uh, young
6:27
lady hits a really mean ball and wishing
6:30
her well, hope she makes it to the New South
6:31
Wales Open. And, um, I'll be watching her
6:34
career closely, so. Very good.
6:37
Professor Fred Watson: She beat you.
6:38
Andrew Dunkley: Oh, uh, gosh, yes. Oh, uh, yes, well, it was
6:40
a teams event today, so we were technically
6:42
playing together, but she out drove Smoke
6:45
Miles. Yes, Chicken Head is interesting. It
6:47
is a long way, but, uh, just a pleasure. Just
6:50
a delight. We had a good day. We
6:53
should get down to it, Fred.
6:55
Professor Fred Watson: Yeah, we should. Yes. We're not here to talk
6:56
about golf, are we? Although, no, it doesn't
6:59
seem that way.
6:59
Andrew Dunkley: Not for a change.
7:01
Um, our first story takes us back four
7:04
and a half billion years when our neighboring
7:06
world, known as Thea, smashed into
7:09
Us and all hell broke loose, literally and
7:11
figuratively. But, uh, a new study has
7:14
just, uh, been released from the Max Planck
7:16
Institute Institute that's uh, shed a bit of
7:18
new light on the thea Earth relationship. Uh,
7:21
it doesn't sound like this was what
7:24
we originally thought. Just some m. Random
7:26
thing coming in and hitting us.
7:29
There's more to the story now.
7:32
Professor Fred Watson: There is, yes. Um, sorry Andrew, you broke up
7:34
there, but I think I know what you said. Uh,
7:37
um, the story of Theia, of course, this has
7:40
been the principal theory, uh, for the
7:43
origin of the Moon for at least the last 60
7:45
years. Uh, when the Apollo astronauts brought
7:47
back, what was it, 380 kg of lunar
7:50
rock and soil, which is still being analyzed.
7:53
Um, so, uh, Theia is the
7:56
hypothesized planet, uh,
7:59
perhaps protoplanet is a better word because
8:01
this was at a time when the solar system was
8:04
still in its infancy 4 1/2 billion years ago.
8:07
And this object, uh, basically clouted the
8:10
Earth. Uh, and uh, we think that what
8:13
happened in the aftermath of that collision
8:16
was a cloud of debris raised from the surface
8:19
of the Earth, went into orbit around the
8:21
Earth and eventually coalesced to form the
8:22
Moon. And so we've um,
8:25
had puzzles which you and I have spoken about
8:28
a number of times as to why it is.
8:32
Well, let me step back a bit. The first
8:34
theory was that because this is
8:37
a smaller object hitting a bigger object, so
8:40
theories thought to have been half the size
8:42
of the Earth to get the dynamics right, um,
8:45
the Earth's the bigger planet. Uh, what you
8:47
would expect is that the debris cloud
8:50
raised from the Earth when the collision
8:53
happened would be mostly made of Theia
8:55
material. Um, and
8:58
that's been a puzzle for a long time because
9:01
most of the lunar rocks and soil
9:04
have the same isotopic signature
9:07
which we've talked about before as well, the
9:09
same isotopic signature as the Earth. They're
9:12
identical, uh, to the Earth's rocks. And so
9:15
that was seen as a puzzle about probably five
9:17
years ago or so. We did cover it on space
9:19
notes. Some Japanese researchers, um,
9:22
figured out that if the Earth were still
9:24
effectively molten at that time, if it was
9:26
still a magma world when the collision
9:29
happened, then you'd get, um, a moon that
9:32
was formed largely of Earth
9:34
compounds. So, um, what has
9:37
now happened is that, um, a close
9:40
examination has been made and as you write
9:43
it, the Max Planck Institute for Solar System
9:45
Research, along with the University of
9:47
Chicago, um, they've really honed
9:50
in on um,
9:53
the exact, uh, details of
9:55
the isotopes in rocks from the, uh, Earth,
9:59
the Moon and meteorites, because they're part
10:01
of the story too. And it's not just
10:05
the sort of isotopes that have been looked at
10:07
before. These are, uh, iron, chromium,
10:09
molybdenum, molybdenum, ah,
10:11
zirconium, all these,
10:14
um, chemical elements. Their isotope
10:17
data have been analyzed to
10:20
look again at, uh, what we find, because,
10:23
yes, we still find that the Earth and the
10:26
Moon have very similar isotopic mixes.
10:29
Uh, but then you can identify
10:32
some slight differences that are
10:35
attributed to be isotopes that have come
10:38
from Theia itself. So they can tease out
10:41
what was Theia and what was Earth. And it
10:44
turns out that when you do that, you still
10:47
get a similar picture, that the
10:50
isotope ratios, uh, on
10:52
Theia were probably very similar to what
10:55
they are on Earth. Um, and
10:58
that is
11:01
symptomatic, if I can put it that way, of
11:04
the Earth and Theia being born
11:07
close together. And the reason why we think
11:10
that is that when you look at the solar
11:12
system, you find that these isotope ratios
11:15
change depending on how far out you are from
11:18
the Sun. So if you've got two planets
11:21
with very similar isotope ratios, then
11:24
what you can deduce from that is
11:27
that they were orbiting the sun close
11:29
together. And that makes complete sense
11:32
because eventually they run into one another.
11:34
Um, but what the outcome of this research
11:37
is is that, uh, Theia was not just
11:40
a random object that ran into the Earth in
11:42
the early solar system. It was actually, if
11:45
not a companion of Earth, but something in a
11:48
very similar orbit. So, you know, maybe we
11:50
had Mercury, Venus, Theia, uh, Earth, Mars as
11:53
the rocky planets. Um, although that order,
11:56
you know, I've made that up, but that's the
11:58
kind of thing it's bringing, bringing
12:00
Theia into the picture as something that
12:03
would have been maybe, had it not collided
12:05
with the Earth, it would have, uh, the ninth
12:08
planet, uh, in the inner part of the solar
12:10
system. So, uh, a very nice piece of work,
12:13
some very, very careful studies there that I
12:15
think has raised a lot of, um, interest in
12:17
the planetary, uh, science
12:20
community.
12:21
Andrew Dunkley: Yeah, I suppose that sort of, uh,
12:23
confirms that it was part of the solar system
12:26
and not just some random thing passing
12:28
through, knocking us over in the process.
12:31
Professor Fred Watson: That's right, yeah. And, um, I should just
12:34
explain how the Theia remnants have
12:36
been. The Theia isotopes have been
12:39
determined, and it's by looking at things
12:41
that we find in the crust of the, uh, Earth,
12:43
because we know that the heavy elements would
12:46
have already sunk to the. To the center of
12:48
the Earth when that collision happened. So
12:50
when we think fine things like these
12:52
molybdenum, iron, zirconium, things
12:55
of that sort, um, we can infer
12:58
that some of that actually came from Thee
13:00
itself. And that's how the similarity
13:03
has been deduced, along with looking at
13:06
meteorite samples too. So you're right. Um,
13:09
it is not something that's come from
13:12
another solar system like our current visitor
13:15
3i atlas. Uh, it's
13:17
definitely a homegrown planet that, uh, we
13:20
collided with.
13:21
Andrew Dunkley: Okay. And now it's sort of a. Well, it's not
13:23
a part of us. There's bits and pieces of it,
13:25
but most, um, of it, it's sort of vanquished
13:28
into the never never, didn't it?
13:30
Professor Fred Watson: Yeah, a lot of it would have done. But, um,
13:32
some of it's in the moon, some of it's on the
13:34
Earth as well.
13:35
Andrew Dunkley: Yeah.
13:35
Professor Fred Watson: All right.
13:36
Andrew Dunkley: So, yes, some new information from the
13:39
Max Planck Institute about, uh, theia
13:42
being a part of the inner solar system. If
13:44
you'd like to read about that, uh, there's a
13:46
really great
13:46
article@scienceblog.com
13:49
this is space Nuts with Andrew Dunkley and
13:51
Professor Fred.
13:56
Space Nuts.
13:58
Uh, now to some really good news, Fred.
14:00
40,000 near Earth asteroids have been
14:03
discovered. Is that all? Is that all I could
14:05
find?
14:07
Professor Fred Watson: Well, yeah, I mean, for a long time
14:10
we've known 39,999.
14:14
Um, maybe not for very long because we're
14:16
discovering asteroids at a very prolific rate
14:18
at the moment. And that comes about because
14:20
we've got such good technology discovering
14:22
them. Um, and so, yes, this is a
14:25
milestone that's been celebrated by esa, the
14:27
European Space Agency.
14:29
Andrew Dunkley: Uh.
14:31
Professor Fred Watson: So they've put out a press release saying
14:33
40,000 near Earth asteroids discovered. Uh,
14:36
what do we mean by a near Earth asteroid?
14:38
It's one that approaches within about
14:41
45 million kilometers of
14:44
the Earth. Uh, and that's nearly a third
14:47
of the distance to the sun. So when you
14:49
say near, it's a fairly
14:52
relative term. It's one, uh, with objects
14:55
that can get within that distance of Earth.
14:58
Then there's another subset of those, though,
15:00
that we tend to call PHAs,
15:02
potentially hazardous asteroids.
15:05
Uh, and, um, there are something like. I
15:08
think if I remember rightly, it's about two
15:09
and a half thousand of those. And they're the
15:12
ones whose orbits cross the orbit of the
15:14
Earth. Um, and so they are potentially
15:16
hazardous. And they're the ones that we keep
15:18
an eye on all the time, uh,
15:21
monitoring where they are, uh, and
15:24
checking forward, uh, in computers.
15:27
Once we know their orbits, checking forward
15:29
as to whether there's any likelihood of
15:31
collision. The good news is is that there's
15:33
not. Uh, over the next hundred years or so
15:35
we've got a fairly clean sweep of things.
15:38
At least things bigger than about 140
15:41
meters across and they can be very dangerous.
15:44
They could be city destroyers or even state
15:47
destroyers. So um, keeping an eye on
15:50
those is important. Uh, and I think the
15:52
reason why ESA has highlighted this is
15:55
because it does highlight the whole regime
15:58
of planetary defense. Uh, that's a very
16:01
active area in astronomy and um,
16:04
m actually almost civil defense as well. It's
16:06
not just astronomy that is concerned with
16:08
that. I think I probably mentioned before
16:11
when I was at the IAU a couple of years ago,
16:13
I actually got myself into a meeting uh,
16:16
which was the Planetary Defense Agency,
16:19
uh talking about uh, their next activities
16:22
which included uh, um,
16:25
a mock threatened uh, planetary asteroid
16:28
impact and how all the services would deal
16:30
with that. And from the astronomers
16:33
right to the, the people who get the fire
16:36
engines out to put out the fires and things
16:38
of that sort. It's a very interesting thing
16:40
to watch. So uh, what it did was
16:42
reassured me that we're in quite good hands.
16:45
Uh but yeah, the bottom line, 40 uh, thousand
16:48
near Earth asteroids known. Uh, the
16:51
good news is always that the big ones which
16:53
uh, are the most dangerous ones, they're the
16:55
easiest to find. And we think we know pretty
16:58
well all of the asteroids bigger
17:01
than a uh, kilometer which would be
17:03
um, dinosaur killers, they would wipe out,
17:06
you know, there'd be mass extinction objects.
17:09
Uh, we think one of those hits the earth
17:12
roughly every 200 million years. It's uh,
17:15
66 million years ago since the last one did,
17:18
which was, was the one that wiped out we, the
17:20
dinosaurs. Um, since then though we've
17:23
learned a lot about, not only about asteroids
17:25
but about how we might deflect uh an
17:28
asteroid if uh, if there was
17:31
one that could be shown to be on a collision
17:33
course with Earth. And you and I have talked
17:35
at length and with great enthusiasm about the
17:38
dart mission back in 2022 and the double
17:41
asteroid redirection test, a uh,
17:44
really well put together experiment by NASA
17:47
which succeeded uh, in changing the
17:50
orbit of a little world called Dimorphos.
17:53
Uh, and that's great news because we know
17:56
that it's now possible to do that. And just
17:58
as a postscript to this story, um, ESA
18:01
currently has a spacecraft called Hera H E R
18:04
A on um, its way to Dimorphos
18:07
to check out what the result of that impact
18:10
was. It's going to study that little world,
18:12
look at the debris that was raised by the
18:15
impact, get uh, a much better idea of whether
18:19
it really is just a rubble pile, which we
18:21
think it probably is, and just uh, learn more
18:24
about what an impact by uh,
18:27
a spacecraft does to an asteroid. Because
18:29
that's the key thing. If we're going to have
18:31
to save ourselves one day by, by doing this.
18:34
We want to know as much about it as possible.
18:36
And if I remember rightly, Hera will reach
18:39
Dimorphous. I think it's late next year. I
18:41
think it's towards the end of next year.
18:43
Andrew Dunkley: Very exciting. Yeah, nice to get a follow up
18:46
on that story too. Yeah. Um, and of course
18:49
this is not the end of finding these kinds of
18:51
things because, uh, the Vera C. Rubin
18:54
Observatory in Chile,
18:57
it's not its primary role, but it will be
19:00
looking for other, um, Near Earth
19:02
objects. And they expect it to find
19:05
tens of thousands of them.
19:06
Professor Fred Watson: Absolutely, that's right. By this time next
19:09
year we might be Talking about, uh, 80,000 or
19:11
100,000 near Earth asteroids
19:14
discovered. And of course again that's a good
19:16
news story because as soon as you discover
19:18
one of these things, first thing you do is
19:20
put its orbital elements into the computer
19:23
grind away, look at its trajectory in the
19:26
future. And that is all done automatically.
19:28
And if there is a need, uh, the system will
19:31
raise alerts that there could be a collision,
19:34
uh, in a certain window in the future. So
19:37
um, that whole process is really part of
19:39
planetary defense. It's what's safeguarding
19:41
us from the asteroid hazard.
19:43
Andrew Dunkley: Yeah, yeah. Um, I read a
19:46
story the other day, I think Vera C. Rubin,
19:48
um, had had it took its first
19:51
picture, first light. I think they refer to
19:53
it as in, was it June or July this year?
19:56
Professor Fred Watson: Yeah, I think it's about then.
19:57
Andrew Dunkley: Yeah, yeah. Uh, so we're almost at
20:00
the pointy end of that, um, observatory
20:02
kicking into action.
20:04
Professor Fred Watson: That's right. If I remember rightly, I might
20:06
have these figures slightly wrong, but it was
20:07
something like. Was it a 10 hour set of
20:10
observations they took and they discovered
20:11
more than a thousand asteroids in that
20:13
period. So imagine what it's going to be
20:16
like. This thing looks at the entire southern
20:18
sky every three nights. That's incredibly
20:21
remarkable. Yeah, it's quite, yeah.
20:23
Andrew Dunkley: Um, like we, we were so blessed to be able to
20:26
get so much information out of, um.
20:30
My brain's not working today. Um, the
20:33
other observatory, the one that's out on in
20:35
the L2.
20:37
Professor Fred Watson: Oh yeah, you mean the James Webb Telescope.
20:39
Andrew Dunkley: James Webb. Gosh, why Couldn't I think of
20:40
that? But, um, working side by
20:43
side with VC Rubin, this is just going to
20:45
open up a whole new.
20:47
Professor Fred Watson: Yep, that's right. At least a new registry of
20:50
new discoveries. Yeah, yeah. Very, very
20:52
exciting.
20:54
Andrew Dunkley: If you would like to read about those 40,000
20:56
Near Earth Objects, if you
20:59
really, you know, you can go to a horror
21:01
movie instead, probably much more fun. But,
21:03
um, 40,000 near earth objects, you can do
21:06
that through the European Space Agency
21:08
website.
21:11
Professor Fred Watson: Okay. We checked all four systems and being
21:13
with a girl space nats.
21:15
Andrew Dunkley: Now this, this is a story that really excites
21:17
me because, because, um, we've talked about
21:20
this so many times, but, um,
21:23
this story I saw pop up last weekend
21:26
and we have been talking so much
21:29
about the potential for life
21:31
elsewhere. Haven't found it yet, but the
21:34
signs are starting to build, particularly
21:37
within our own solar system. And
21:40
this particular story
21:42
is one again where we have taken a bit of
21:45
old data and reanalyzed it.
21:49
And this involves the Cassini
21:51
mission, uh, which has been taking
21:54
samples of the eruptions
21:57
from Enceladus. And what they've
22:00
discovered is very, very, uh,
22:02
exciting.
22:04
Professor Fred Watson: It is, uh, that's right. And uh, yes,
22:06
Cassini, you know, uh, was active, if I
22:09
remember rightly, between 2000
22:13
and I think. Was it 2004? Yes,
22:15
and 2017. So that was the period when
22:19
Cassini collecting its data. And as you've
22:22
just said, we're still learning things from
22:24
those data. Uh, and in particular
22:27
what has been identified is some
22:30
previously unknown organic
22:33
chemicals in the ice grains that
22:35
Cassini flew through, which are
22:38
erupting, as you said, from the ice
22:40
geysers near the southern, uh,
22:43
pole, the south pole of enceladus, that
22:46
little 500 kilometer diameter world which
22:49
is, uh, one of Saturn's moons with the
22:51
structure that we think is fairly common out
22:53
in that part of the solar system. Ah, a rocky
22:56
body overlaying with a liquid ocean
22:59
with ice on top of that. And the pressure of
23:01
the ice is what's keeping that ocean liquid,
23:03
along with the squeezing and squashing of the
23:06
rocky part of the body by the,
23:09
uh, tidal forces exerted by the giant planet
23:12
Saturn, uh, next door. And Saturn, by the
23:14
way, um, we've just gone through its ring
23:17
plane. So Saturn. If you looked at Saturn
23:19
through a telescope tonight or anytime within
23:21
the next couple of weeks, you won't see any
23:23
sign of the rings because we're the edge onto
23:25
us.
23:25
Andrew Dunkley: Oh, okay.
23:26
Professor Fred Watson: Yep. Just a little aside there. Um, so,
23:29
uh, what has happened is
23:32
that, uh, we've known about
23:35
these organic chemicals in
23:38
Ice grains, which we know come
23:41
from Enceladus because they actually
23:43
feed into the outer ring of Saturn,
23:46
something called the E ring, which is a very
23:48
diffuse ring. And we know that the
23:51
material in that ring, the ice crystals in
23:53
that E ring, actually come from the south
23:56
pole of Enceladus. And those
23:59
have been well analyzed, um, by Cassini
24:02
and also by other observations. And
24:05
so it was known that there were organics in
24:07
there. But the question was
24:10
these ice crystals may have been in
24:12
orbit, they may have been in space for
24:14
centuries. And so their
24:17
chemical structure might well have been
24:20
modified first of all by the sun's
24:23
ultraviolet radiation, which tends to change
24:25
chemistry. Uh, and the solar
24:28
wind, the wind of subatomic particles that
24:30
comes from the sun, that too can change the
24:33
chemistry of particles, uh,
24:36
grains of, um, ice
24:39
with their organics on them, the organic
24:42
chemicals, uh, it can, can change their
24:44
chemistry. And so there was always a question
24:47
whether these quite complex organic
24:50
chemicals that were identified, uh, in
24:52
the E ring, uh, whether they are
24:55
telling you that that's how the
24:58
ice crystals were when they came, when they
25:00
were spat out from M. Cassini's south
25:03
pole, um, it puts doubt on it.
25:06
And so what this new analysis
25:08
does is looks back to one of the
25:11
fly throughs of, uh, Cassini
25:14
through the ice plumes back in
25:16
2008. Uh, Cassini
25:19
flew through the plume at about, um, 18
25:21
kilometers per second at Ah, a height of
25:24
about 20 kilometers above the surface of
25:27
Cassini. And so the
25:30
ice crystals that it passed through,
25:33
um, only a few minutes earlier were actually
25:36
water in the ocean of
25:38
Enceladus. So these are fresh
25:41
crystals of ice straight from the ocean. In
25:44
other words, they're, you know, they're
25:45
effectively samples of the ocean water. And
25:48
what they've succeeded in showing, uh, what
25:50
the scientists who've done this succeeded in
25:52
showing is that the chemistry is still there.
25:55
The, the organic, the complex organics
25:58
are uh, there in this fresh
26:01
ocean spray, as they call it. I love that
26:03
idea. It's an ocean spray, uh, but it's ice
26:05
crystals and there's a whole, you
26:08
know, a whole list of um, things
26:11
like esters, aromatics, heteroatom
26:14
bearing organics. These are chemical terms
26:17
that, um, I'm not that familiar with
26:19
because chemistry was not my strong point.
26:22
Uh, but these chemicals are, ah, yes, they
26:25
are there in the ocean of Enceladus.
26:28
And what that has done is raised
26:31
again the possibility that living organisms
26:33
might exist in that ocean. Uh, and that
26:36
because these chemicals are, as we keep on
26:39
saying, the building blocks of life uh, so
26:42
just maybe there's something swimming around
26:44
in the ocean of Enceladus that we are yet to
26:46
discover.
26:47
Andrew Dunkley: Yes. And wouldn't it be exciting? And, uh,
26:49
hopefully in the not too distant future we'll
26:52
be able to confirm it. Um,
26:55
I think people are starting to get very
26:56
confident about the possibility, though.
26:59
Professor Fred Watson: Yep.
26:59
Andrew Dunkley: Yeah, that's right. Fingers crossed. But, uh,
27:02
yeah, the signs are starting to really build.
27:04
And even though it'll be
27:06
probably one of the most exciting things ever
27:09
discovered, should we succeed in finding
27:11
evidence of life elsewhere, we
27:14
also probably shouldn't be surprised because
27:17
water, we now know is prolific
27:20
throughout the universe. We know there are,
27:23
uh, probably exoplanets orbiting almost
27:26
every star in the universe. Stands to
27:29
reason that somewhere, somewhere out there,
27:32
there's. There's got to be some form of life,
27:34
even if it's only microbial, but.
27:38
Professor Fred Watson: Or krill. Krill would be
27:41
exciting. Green slime is what we're likely to
27:43
find. I think green slime. Green slime will
27:46
do. Green slime would do it. That's right. It
27:49
would indeed.
27:49
Andrew Dunkley: Indeed. If you'd like to read up on that
27:51
story about the latest from Enceladus,
27:55
you can find it in the journal Nature
27:57
Astronomy.
28:01
Space Butts.
28:02
One last story in this episode, Fred, and
28:05
it's a bit of an update on 3i Atlas the
28:07
XO comet that is currently,
28:11
um, doing its thing. It's doing whatever it
28:13
wants, really. Um, but, um,
28:16
it's, uh. It's. It's sort of reappeared. And
28:19
they're getting some great pictures of it,
28:21
not only from Earth, but from Mars. And,
28:24
um. Some of these photos are extraordinary.
28:28
Professor Fred Watson: Yes, they are. When you look at them, they're
28:30
a little bit underwhelming until you realize
28:32
that they've been taken by telescopes not on
28:35
Earth, but, um, in one case on the surface of
28:38
Mars. But, um. Uh, also, uh, from
28:41
Mars orbit. Uh, and there's a little bit of
28:44
a story to this because these images were
28:46
taken, um, when, um,
28:50
the interstellar comet 3I Atlas uh,
28:53
made its closest passage, uh,
28:56
closest flyby of Mars, basically, uh, 30
28:59
million kilometers of Mars. That's quite a
29:02
close approach compared with, um, the
29:04
distances that we are from it on
29:07
Earth. Uh, and that took place
29:10
actually nearly two months ago, uh, in early
29:12
October. Um, but what's held up the
29:15
release of the, uh, of the images, uh,
29:18
is the US Um government shutdown, which,
29:21
yeah, prevented these images being
29:24
situated.
29:25
Andrew Dunkley: He spoke about that at length. Oh, getting
29:27
back previous episode.
29:29
Professor Fred Watson: So, yeah, I think, yes, we're pretty.
29:31
Andrew Dunkley: Well squared away on the issue um, but he
29:34
had colleagues that was so badly affected by
29:36
that because, yes, the, um, you know, well,
29:39
basically no income for as long as the
29:42
shutdown existed.
29:43
Professor Fred Watson: It's very, very difficult situation.
29:44
Andrew Dunkley: But, yeah, so we, we know why
29:47
NASA couldn't do anything at the time.
29:50
Professor Fred Watson: Yeah, so that's right.
29:52
Um, but we now have these images revealed now
29:55
that things are up and running again. And
29:57
perhaps the best one has come
30:00
from the, um, HiRise
30:03
camera on board Mars Reconnaissance Orbiter.
30:06
And that's quite a detailed image of Comet
30:09
3I Atlas with its short
30:12
tail and its coma. That's the region around
30:15
the nucleus where, uh, material is outgassing
30:18
and, and um, shining because of, um,
30:21
excitation by the sun.
30:24
There's some interesting images from,
30:27
uh, the Maven, uh, spacecraft
30:30
as well, which, uh, has cameras on looking
30:33
in the ultraviolet. And in fact it's got a
30:35
spectrometer on that allows you to, uh, split
30:38
the light up into its component colors. Uh,
30:41
so we see the glow of hydrogen actually from,
30:44
uh, from 3i Atlas, uh, photographed by the
30:47
Maven spacecraft
30:50
cameras and the Mastcam camera, uh,
30:53
on the, uh, it's Mastcam
30:56
Z, it's called on Perseverance on the
30:59
surface of Mars, actually managed to capture
31:01
a very, very faint image, uh, of
31:04
uh, three Eye Atlas against a background of
31:07
stars. It's faint because that's. That
31:10
mastcam was never designed to do
31:13
astronomy. It's all designed to navigate on
31:15
the surface of Mars. But yet it's managed to
31:18
catch a picture, uh, by being pointed
31:20
upwards, obviously, uh, at this
31:23
celestial visitor. So the hope is that as
31:25
these images are analyzed, Andrew, we'll find
31:28
out more about 3i Atlas, maybe even to
31:31
get a good measurement of how big its nucleus
31:34
is, the icy component that gives rise to
31:37
all this luminosity. Um, the last
31:40
I heard was that the thinking was it was in
31:42
the region of 20 km across, which is large
31:45
for a comet nucleus. Uh, but I think the jury
31:47
is probably still out on that. Um, might find
31:50
more from these measurements.
31:52
Andrew Dunkley: So how much longer will 3i Atlas be
31:54
in our vicinity?
31:58
Professor Fred Watson: Quite a while. Uh, it's not. You know,
32:02
I, um, think it passes closest to Earth
32:05
this month, if I remember rightly. Um, and
32:07
then we'll be receding. Uh, it has passed
32:10
its closest to the sun, and so it certainly
32:12
brightened up when it did that, which is what
32:14
you expect as it leaves the
32:17
solar system. We'll continue to track it with
32:20
the world's big telescopes. Probably the
32:22
James Webb will have a few more looks at it.
32:24
Uh, and so, um, I Think we're going to
32:27
be observing it for several months yet.
32:29
Andrew Dunkley: Very good. All right. Keeps making the news.
32:31
And uh, I mean it's one of those
32:34
things like, like this is only one of a
32:37
handful of these things that we've
32:40
found, but it's starting to look like this is
32:42
not an uncommon thread.
32:44
Professor Fred Watson: That's right. And I think once again harking
32:47
back to the Vera C. Rubin telescope, we're
32:49
going to find more of these. Uh, when that
32:51
telescope comes online we're probably going
32:53
to have, you know, we've got three known
32:55
interstellar objects now. It'll probably be
32:57
20 by middle of next year. Who
33:00
knows, it'll be quite extraordinary indeed.
33:03
Andrew Dunkley: All right, uh, you can read more about the
33:05
uh, images that have been taken of 3i
33:08
Atlas and you can see them too at the
33:10
universetoday.com website.
33:14
Fred, that brings us to the end. Thank you so
33:17
much.
33:17
Professor Fred Watson: It's been a pleasure. Andrew. Um, uh, uh,
33:20
I've forgotten how much I miss uh, my
33:23
weekly dose of spacenauts. So it's good to be
33:25
talking again.
33:26
Andrew Dunkley: It's good to have you back. Um, thank you for
33:29
deciding to return
33:32
even without the red carpet. Oh and by the
33:34
way, that golfer uh, I played with today,
33:36
Piper Stubbs from Melbourne. Oh good, Stubbs.
33:39
Professor Fred Watson: Look up the name.
33:40
Andrew Dunkley: She uh, she studied um, at
33:43
college uh, in the United States and played
33:44
collegiate golf over there. Ah, she's
33:47
finished now and she qualified um, as a,
33:50
in political science. So.
33:52
Professor Fred Watson: Very good.
33:53
Andrew Dunkley: Yeah, uh, quite a bright young lady.
33:56
Uh, and um, thanks to Huw in the studio.
33:59
Although he couldn't be with us today because
34:00
he heard there were 40,000 near of asteroids
34:03
discovered. So he built himself a bunker.
34:05
He won't come out. And um,
34:09
and uh, by the way, if you would like to
34:11
become a patron, um, by all means, jump on
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35:00
And you can talk to each other about. About
35:02
anything you like to do with space and
35:04
astronomy. That's it for this episode.
35:07
Join us again soon when we do a Q A episode.
35:09
Um, and, and looking forward to having you
35:12
join us then from me, Andrew Dunkley. Until
35:15
next time.
35:16
Professor Fred Watson: Bye.
35:16
Andrew Dunkley: Bye. You'll be listening to the
35:19
Space Nuts podcast,
35:22
available at Apple Podcasts, Spotify,
35:25
iHeartRadio, or your favorite favorite
35:27
podcast player. You can also stream on
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demand@bytes.com. um, this has been another
35:32
quality podcast production from bytes.
35:35
Professor Fred Watson: Com. Um.