Viewing a single comment thread. View all comments

Sierra-117- t1_iu0yv16 wrote

Reply to comment by kozy138 in A recently released set of topography maps provides new evidence for an ancient northern ocean on Mars. The maps offer the strongest case yet that the planet once experienced sea-level rise consistent with an extended warm and wet climate, not the harsh, frozen landscape that exists today. by Wagamaga

No, because we aren’t sure if Mars ever had a hot core. Right now, it’s not hot enough to create geothermal activity. So if an ocean existed on mars today, life would not form via geothermal activity. But maybe in the far flung past, who knows?

Also, geothermal activity isn’t the only theory of abiogenesis. I’m quite fond of the clay hypothesis. Where molecules being wetted and dried continuously in the presence of silica crystals (like on the bank of a river) will form complex self assembling structures.

Edit: just to clear up some things. Yes, mars core is hot. But it’s much cooler relative to earth. But I’ve just learned that new research thinks mars may still be volcanically active! Just far more dormant than a planet with a very hot core and mantle like earth. Earth likely experienced a massive event (giant impact hypothesis) that gave it a lot of excess energy, which means a lot more active volcanoes. Perfect for life!

13

Darkelement t1_iu11o98 wrote

If Mars didn’t have a hot core, how could it have produced volcanoes? Or is that also something unknown?

11

Sierra-117- t1_iu1anpm wrote

Well you misunderstand what produces volcanos.

The core helps KEEP a planet warm, and keep lava flowing. But the lava itself is created and flows from the mantle, not the core. So some believe that Mars has a relatively cool core, but it’s mantle was still hot after formation.

Basically, a cool core with a short time of volcanic activity after formation due to heat trapped in the mantle.

Which is why we don’t see volcanic activity on mars today, but we see evidence of it in the past. The mantle is now cooled.

9

Darkelement t1_iu1bkfy wrote

I guess it could be a misunderstanding, but what heat the mantle up in the first place? Would those forces not also create a hot core? Does this imply the core was never warm?

6

Sierra-117- t1_iu1cvzm wrote

Well it takes a lot more energy to melt metals into liquid than rock.

Metal also has a higher rate of energy transfer. So the metal cools faster, and takes far more energy to stay hot.

The core is also more stable than the mantle, meaning is experiences less friction and therefore produces less excess heat.

The heat from the core will constantly radiate into the mantle, so the mantle is constantly gaining energy while the core cools. Because the core is HOT, just not hotter than we would expect under the given pressure.

Lots of factors, and there’s a lot more I could list! But basically it comes down to: the core has now cooled to a stable temperature, therefore the mantle has cooled to a stable temperature, therefore volcanic activity is likely to cease.

5

TheLastForestOnEarth t1_iu1vvbd wrote

In Earth's case I believe one hypothesis is that the impact of two planets created Earth and its moon. The incredible heat of our core may simply be left over from this collision.

2

goneinsane6 t1_iu26wio wrote

The primary contributors to heat in the core are the decay of radioactive elements, leftover heat from planetary formation, and heat released as the liquid outer core solidifies near its boundary with the inner core. This heat radiates/transfers to the mantle. Due to Mars' smaller size and the square-cube law, it has a higher surface area relative to its core and mantle (compared to a larger planet). This causes more heat to radiate out compared to the Earth and is the main reason why Mars' core is now mostly cooled. Mars simply cooled faster because it is smaller.

2

kozy138 t1_iu12mwq wrote

Without a core, how would Mars have been warm enough to contain liquid water? Extremely high salt concentrations that lower the melting temperatures?

3

Sierra-117- t1_iu19cto wrote

Very good question!

It was able to maintain liquid water through a thicker atmosphere than it currently has. Basically, a greenhouse effect. It would still be freezing at night though.

3

Sierra-117- t1_iu1dxy8 wrote

Also I realize my comment was confusing. I’m not saying it has a completely cool core, we’re a long way off from that. But it’s core is relatively cool, and therefore volcanic activity has pretty much ceased.

But the crust of a rocky planet gets most of its energy from the star it orbits

2

Dejan05 t1_iu19fo9 wrote

How would it not have a hot core? Under such pressure it sounds impossible for it to not be hot to some degree

2

Sierra-117- t1_iu1bhya wrote

Yes! It is still very hot, like the core of any planet. Gas giants have cores hotter than the surface of the sun.

But when you say “hot core” in planetary science, it means a REALLY hot core. As in, hotter than it should be given the pressures involved.

This excess heat usually comes from conditions experienced during formation. Earth’s core is a hot core, because we currently believe a small planet collided with the early Earth! (Though this is also still only theory).

But yes, the interior of mars is very hot. Just not hot enough to support continued volcanic activity in the mantle/crust.

4