March 8, 2026

Martian Meteorites, Gas Giants & The Search for Alien Life | Q&A

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Show Notes
Transcript

Sponsor Links:
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Mars Meteor Showers, Gas Giants, and the Search for Alien Civilizations
In this engaging Q&A episode of Space Nuts, hosts Andrew Dunkley and Professor Fred Watson respond to intriguing questions from listeners about our universe. From the risks of meteor showers on Mars to the gravitational effects of Jupiter on its moons, this episode is filled with cosmic curiosities and insightful discussions.
Episode Highlights:
- Meteor Showers on Mars: David from the UK wonders about the potential hazards of meteor showers on Mars, given its thin atmosphere. Andrew and Fred discuss how the reduced atmospheric pressure could allow smaller meteorites to reach the Martian surface and the implications for future human habitation.
- Exploring Gas Giants: Penny asks whether there are plans to fly spacecraft through the atmospheres of Saturn and Jupiter. The hosts explain the challenges of such missions and highlight ongoing projects focused on the fascinating moons of these gas giants instead.
- The Gravitational Dance of Europa: Andy from London seeks clarity on how Jupiter's gravity affects its moon, Europa, without pulling it closer. Andrew and Fred elaborate on the tidal forces at play and how they create the intriguing geological activity observed on Europa.
- The Search for Alien Civilizations: Duncan raises the thought-provoking question of whether we are truly alone in the universe. The hosts discuss the vast distances involved in the Milky Way and the implications for potential communication with extraterrestrial life.

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Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.

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WEBVTT

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Hello again, thanks for joining us. This is a Q

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and A episode of Space Nuts where we answer astronomy

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and space science questions from our audience. Today. David wants

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to know about Mars meteor showers. Penny is asking about

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fly through emissions for Satin and Jupiter that could be messy.

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Andy is asking about the gravitational effect of Jupiter on

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its moons, particularly Europa. And Duncan wants to talk about

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alien civilizations. We will deal with all of that and

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more on this episode of Space Nuts fifteen in Channal

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ten nine Ignition sequence Space Nuts NY or three two

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Space Nuts. As Can I reported, Bill's good. This is

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Fred Watson's favorite segment. He's back again for more. Professor

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Fred Watson, Astronomer at Large, Hello, Hello Andrew, you I

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am quite well. It's been a long time, like an

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anatu or three minutes.

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I hope nobody's guests that we record these impairs. But

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never mind, never mind.

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If they haven't figured it out by now, they probably

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never will.

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That's right.

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I'm pretty sure most people know how it works. I mean,

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they just have to look at the shirts we're wearing

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every week. That's if they do it on the YouTube channel. Well,

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I don't know if I don't know if they put

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the video on anymore, because it could be could be

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a bit of a turn off. So I don't know. Anyway,

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all is well with you, I trust it is. Thank you. Yes,

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I I already knew the answer, but we have to

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ask because you know, this is just to be that light. Yes,

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that's exactly. Why don't we try and answer some questions? Oh?

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Or if you must, well you do it. I'm just

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going to push them in there. Let's go to our

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first question that comes from David.

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Kind of a Compson here otly Spring in the UK,

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Back to Mars. As a child of the fifties and sixties,

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reading the comics at the time, there was always a

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risk of meet your showers. I'm just wondering, given that

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Mars atmosphere is not as dense as the IRBs, what

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are smaller meteorites would be able to hit the surface

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of Mars and be a real hazard to anybody put

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in the house there. Find the podcast absolutely amazing. Everybody,

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have a great day. Bye.

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Thank you David, Thanks for those kind words. I'm glad

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you're enjoying the podcast. Sorry, way back to Mars I

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didn't push him there. I didn't. Everyone knows a lot

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of Mars, but yeah, your shows it makes up. It

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brings up an interesting point. It's got a much less

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significant atmosphere than Earth. So does that mean smaller things

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can get through?

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It does, Yeah, it does. David's absolutely right. I'm delighted

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we've got a listener in hot and this spring. I

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used to drive past there very very frequently. It's between

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Durham and Sunderland in the north of England, and I

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was a very very regular user of the A one

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m which goes us taught and the spring. And it's

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lovely to hear your voice, David, and hear that lovely

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North Durham accent there. The answer is yes, so because

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the atmosphere, you know, the atmospheric pressure on Mars is

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I think it's point six percent of our atmospheric pressure,

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which means that meteorites coming in are going to have

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a lot less resistance. We know of meteorites on Mars,

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many have been identified by both Curious City and Perseverance, usually.

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By there but by their color.

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But both those rovers were equipped with lasers appas that

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could give us an idea of the content and some

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of those meteorites have been found to be metallic. So

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meteorites on Mars are something that happens. And yes, there's

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probably a higher risk of damage from an incoming meteorite

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on Mars than on Earth because the likelihood is but

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their terminal velocity, the sort of final velocity after they've

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passed through the atmosphere, will be much higher than it

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will be on Earth just because of a lot lower pressure.

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And so yes, meteorite protection might turn out to be

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quite an important aspect of putting humans on Mars. We

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haven't had any reports of you know, there's how many

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rovers have been on Mars now, I can think of

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long two, three, four, five, six, at least six, probably

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more like seven or eight. They are Andrew is googling

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it as we speak.

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Yeah, six six rovers. Sojournal, Spirit, opportunity, curiosity, perseverance, and Jurong,

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the Chinese mission.

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The Chinese one. That's right, Yeah, so I did get

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the right answer.

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Six.

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Yeah, yeah, it's so none of those, as to the

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best of our knowledge, has suffered any kind of meteoritic impact.

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So at least, so far, so good in terms of

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our understanding of the meteorite hazard on Mars. But a

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good question to raise, David, and it's always always gives

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us a chance to talk about Mars.

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He did ask about the danger to housing on Mars.

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They probably won't build houses on Mars like they do

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on Earth. And because of the radiation issues, they're probably

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going to have to go underground, which would pretend get

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them from anything like that. But there will be surface

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something or other there one day, infrastructure. Yeah, perhaps domes

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that they could be susceptible. Maybe.

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Yeah, it looks like I mean what we imagine is

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something like White Cliffs in western New South Wales where

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people live underground. They do, and that's just to get

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out of the heat.

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So that's radiation.

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Yes, it is silver radiation, that's right.

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Yeah, indeed, yeah, sort of another question. Yeah, here it is.

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We are constantly monitoring for big objects that could be

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threatening to Earth, things that could destroy these cities or

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regions or god forbid, the planet itself as we know it.

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What about Mars? Do we keep an eye on anything

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that might hit that?

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So yes, to some extent. If you you know, if

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you can identify near Earth objects look at their orbits,

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you would certainly find out from the analysis very quickly

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if there was any risk of one of those hitting

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the planet Mars. But there's probably many small objects in

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the vicinity of Mars because it's closer to the asteroid

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belt than we are, which are undetectable from the distance

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of Earth. You know, objects that might even be as

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big as Phoebost, Mars's biggest moon. We would be able

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to detect that from Earth quite easily, but as we

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obviously can. It was discovered in the eighteen hundreds. But

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you know, if you had something that was only a

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few tensimeters across, which could pose a hazard to houses

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on Mars, that would be hard to detect from the

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distance of Earth unless it unless it was also a

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near Earth object, so it was coming close to closer

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to our telescopes.

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Yeah, there'd be nothing much we could do about a

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beefing hitting Mars anyways, there or they'd be good experiment

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if we want to test our capabilities.

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Well, that's right, if there was you know, the bigger

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ones are the ones that we know more about because

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they're easier to see. If something like that was looking

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as though it might collide with Mars, yes, it might

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be a good time to test out the theories that

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were put into place with the Dart mission a few

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years ago. Yes, see, whether it'll actually work on something

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a bit bigger.

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Than that, one can only wonder, And hopefully we don't

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ever have to put it to the test for ourselves.

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But you just never know. There's always something going on

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out there. There's so much stuff bumping into it. There's

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something else out there. It's only a matter of time

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before one of them kareems into our sector and becomes

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a potential threat. Although we seem to be finding them

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more and more now, don't we.

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Frere with And that's the good news parts of this story.

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Two good news sides of this story. One is that

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the big ones are the easiest to find, and the

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other is that we've been finding these things now for

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the last forty years and have a good idea of

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what this environment's like.

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Yep, great to hear from you, David. Great question and

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thanks for sending it in. Our next question comes from Penny.

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It's a short, quick one. I think I know where

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this one might go to in terms of an answer.

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As Satin and Jupiter are gas giants, are there any

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plans to fly a spacecraft through the Middle of one

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or both of them. Interesting question, Penny. I do recall,

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when you're talking about comet or asteroid impact, the impact

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with Jupiter many many years ago that we almost got

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footage of it was just quite not quite the right angle,

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but we did see the aftermath of it.

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That's Schumacher Levy.

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Yes.

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Second, the one Jupiter, Remember what year ninety four I

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think it might have been. So the issue is that

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the gas giant aspect of these planets is really just

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their outer envelope that's gassy, and we don't really know

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what's underneath that. The likelihood is there will be a

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solid core there. It may be rocky. Some have suggested

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that it will be made of metallic hydrogen, which is

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hydrogen in a very unusual form. So you've got a

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core of something called metallic hydrogen. So flying through is

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not anything that's planned because it will be impossible.

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But even if.

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These gas giants were sort of gaseous all the way through,

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it still would be a very hard thing to achieve

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because you're entering an atmosphere. You'd have to slow the

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rocket the spacecraft down enormously in order to prevent it

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from just melting by friction. With the atmosphere, which is

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what happened to Cassini. Cassini was plunged into Saturn's atmosphere

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at the end its mission in twenty seventeen. It didn't

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burn up because there's no oxygen in Saturn's atmosphere, but

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the friction made it melt. Basically, it just melted and

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felt pieces. In fact, NASA produced some real tear jerker

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footage of what that might have looked like, which we

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saw often at the end of the Cassini mission.

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You know, this thing which had.

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Performed valiantly for the previous thirteen years and done a

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marvelous job at revolutionizing our knowledge not just of Saturn

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and its rings and moons, but also the way planets

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form and things like that. This footage of Cassini hitting

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the top of Saturn's atmosphere and having its antennas ripped

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off and eventually just melting into becoming part of the

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atoms of the atmosphere of Saturn, and that is you know,

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any mission to try and penetrate down through the atmosphere

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would struggle because of the rapid increase in density, the

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fact that you've got to slow the spacecraft down in

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order to stop it just burning up my friction. I

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think one of the Jupiter missions, I can't remember which

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one might have been Galileo actually sensed as it hits

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Jupiter's atmosphere to burn up again or to melt. I

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think there were sensors on board that were giving us

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some readings of what the conditions were like.

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Yeah. I think the other big problem would be pressure,

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wouldn't it if you tried.

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To yeap, So the pressure just goes up, probably exponentially

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at some level.

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Yeah, and Penny might be interested to know that there

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are some missions slated for the near future, europea Clipper

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which will launch in it's already launched, I should recite

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it's quite yet twenty thirty. There's the Juice mission, which

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launched in twenty twenty three, which arrives in twenty thirty

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one and drag and fly with the helicopter off to Totem. Yeah,

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we'll launch in twenty twenty eight. So they're more interested

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in some of the moons around those gas giants. But yes,

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that they are fascinating, and of course we're most interested

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in Europa Clipper because we want enough anything's living in

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the ocean, and maybe there is, Maybe there isn't. Who knows,

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it could just be made of jelly. We don't really know,

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although the Juice mission is more likely to figure all

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that out. Boom boom, Thank you, Penny Lovely to hear

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from you. This is space Nuts Q and a edition

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with Andrew Dunkley and Professor Fred Watson. Let's take a

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space nuts. Okay, we take your space nuts. And speaking

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of Europa and Jupiter, we've got a question now from Andy.

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This is Andy the train driver from London.

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I just got a question about Europa.

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I know Europa erupts because it's being sort of squeezed

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by the gravity of Jupiter. But what I don't understand

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is if Europa is being affected by Jupiter's gravity, why

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is it not just being pulled closer to Jupiter. I

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thought gravity pulls things down, like when you throw a

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ball in air, gravity pulls it back down. I don't

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understand how Europa is being squeezed. That suggests to me

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that it's being affected by gravity from all directions. Squeeze

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it like you could squeeze the tennis ball. Maybe you

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can shed some light on this or tell me that

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I'm blocking up the wrong tree.

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Anyway.

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Thanks for the podcast, guys, really interesting and see you

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in the next one.

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It's Jordie's job to bark up the wrong tree.

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But nicely done, Andrew.

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Your point is well taken. Andy. It's not just Europer though.

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There are several moons orbiting the gas giants that do

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get that squeeze effect tightened. I think is one of them,

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and I look probably all of them to some degree.

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But Europe, yeah, it's it's it's in a difficult position.

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It's a good question though, why don't they just get

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sucked in? Doesn't? But we're not a gas giant.

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No, the same thing happens to our moon though, so

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it's actually probably I think the moon that and is

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thinking of his Eo, which is the innermost of the

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of the moons that the big moon, big four moons

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of Jupiter, and it is the one that gets the

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most squeezing and squashing because of its proximity to Jupiter.

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Europa probably also has the same phenomenon, and there may

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be eruptions of it on Europa that possibly a bit

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like Enceladus, where you've got stuff streaming out through the

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cracks in the in the ice. But the genuine volcanic eruptions,

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which they really are, it's hot lava, is what takes

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place on Eo, the innermost of those moons. So the

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way to understand this is to realize recognize that if

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you've got an object in a very strong gravitational field.

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First of all, let me just clarify the reason why

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objects in orbit around other objects don't just get pulled in.

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They are getting pulled in, but they've got a forward

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motion that compensates for the for the pull. So basically

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the motion of the object through space is what balances

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out the gravity of a giant like Jupiter. And so

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that you know, the greater the gravity of a of

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a planet, the faster its satellites have to orbit in

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order not to not to fall in. And so that's

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that's the mechanism that stops these things just immediately being

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sucked in to Jupiter. They're already moving. And that comes

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about why are they moving because they were formed that

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way with the way the you know, the planets and

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their satellites evolve the way they formed, they're basically swirling

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around right from the start and that swirling motion is

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what stops which is fossilized in the in the planets

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themselves and the moons of the planets, and stops them

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falling into their parent object. But the squeezing and squashing

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comes from what we call the tidal effect, and it

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is actually exactly the same thing that gives rise to

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tides on the Earth. But let's concentrate for a minute

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on EO. Here's this little world right next to gas

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giant Jupiter. One side of EO is feeling the gravitational

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pull of Jupiter. The other side is as well, but

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it's feeling slightly less because it's further away, because the

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gravitational pull falls off as the distant squared one of

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the distant squared, So further on the further side of

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EO from Jupiter, it's going to feel less force. And

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that is what contributes to this tension that there is

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and basically elongates the planets slightly in the direction of Jupiter.

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Now why we talk about squashing and squeezing is that

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throughout the orbit of EO, she's not a planet, it's

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a subtleite. But around the orbit of EO as it

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goes around is not circular. So sometimes that force is

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greater than others. That tension that's trying to pull it apart,

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it's greater than at other times. And basically it's that

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squashing stretching really is the best word for it. As

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it goes round, as it goes around Jupiter. That change

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in the stretch force that's being applied is what generates

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the heat that causes these eruptions to continually take place.

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And that's called the tidal effect. The fact that one

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side of a body feels a different gravitational force from

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the other. It's what makes us susceptible if we fall

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into a black hole to spaghettification. Spaghettification is just a

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nicer word than tidal effects.

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Yeah. So you've got a real combination of effected. Yeah,

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that's right. You've got the gravitational effect, You've got all

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little dynamics, yeah, or sort of coinciding to keep these

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things from falling into the planet that there's attack war

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going on. I saw a really good demonstration online or

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probably three or four weeks ago on how the tides

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work on Earth and of because most people, and I

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must confess guilt here, assume that the Moon causes the

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water to rise and then fall. But it's not. It's

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the fact that the Earth is rotating, the Moon is orbiting,

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and there's always a wave. It's just always there, and

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it's just that when it when the moon reaches your vicinity,

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that that lump of water comes up and goes down again.

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It's it's not the water so much rising, it's just

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it's always risen in proximity to the moon. Am I right?

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You are?

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You're partly right, because it's a bit more you I

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missed something.

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Yeah, that doesn't explain the bulge on the other side, because,

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as you will, you get a high tide every toye

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and that's because again it's the tidal effect. So the

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moon's pulling on the ocean on the near side, it's

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also pulling on the earth itself and that leaves behind

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the water on the other side, so you get a

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bulge on each side.

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That works. Fascinating. It's worth looking up that demo. I

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didn't really fine print obviously, but yeah, that makes sense.

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So the water's being poured earth sort of dragging with it,

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and then the water's been left behind on the other side.

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So you've got two bulges, two bulges exactly, so fascinating. So,

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and that's kind of ague. What's happening to all these

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these moons in various ways. If I have not water,

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something else has been.

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Well, that's right, it's the rock, does it as well?

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The same is true on Earth. The rock goes up

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and down as well. I've got a question for Andy though,

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if he's for getting back to us, I'd like to

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know what sort of trains he drives, because yeah, I'm

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a bit of a train myself. Of train drivers are

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my heroes.

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Yeah, I live next door to a retired train driver.

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So yeah. But when we flew into Dubbo the other day,

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I looked down at the rail maintenance facility. It's a

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brand new system facility that's just been built in Dubbo

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and they're fitting out all the new regional trains and

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you can see them all lined up, bright red, all

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getting ready to go. They're putting all the furniture in

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them and the Wi Fi systems, and yeah, they'll be

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rolled out pretty soon, not exactly sure when, but the

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plan is soon. That's the answer to the question.

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Officially, have you ridden on a new metro trains here

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in Sydney, Yes, I have, yes, so you'll know that

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they drive one hundred kilometers an hour. With new driver.

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You can stand at the front, look out the front

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window and pretend you're driving it.

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And I've done that in a taxi in San Francisco.

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Oh yes, yehs for rival as taxi. That's next level.

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That's just amazing. But yeah, yeah, pretty incredible stuff. Thanks. Andy,

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really enjoyed that question. And yeah, if you want to

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tell us what sort of train you drive, send us

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another message. We'd love to find out how their barlow.

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If I'm Provan.

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Spiece notutes. Our final question today, Fred comes from Duncan.

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He said, I've heard that a group of astrophysicists have

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