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submitted 2 months ago by fossilesque@mander.xyz to c/science_memes@mander.xyz

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[-] cogitase@lemmy.dbzer0.com 8 points 2 months ago

I've been wondering what a hypothetical perfect habitable planet for spacefaring would look like. Could you have one where a plane line the SR-71 Blackbird or an even less capable aircraft could simply "fly" into orbit? Or what about something Earth-like but with a flat plateau at 15,000 m where you could launch rockets from?

[-] turdas@suppo.fi 15 points 2 months ago

I think Mars, assuming you terraform it, would be pretty close to that on both counts. Space planes might still be difficult, but the delta V is much lower and Olympus Mons would pretty much sit above the atmosphere.

[-] YellowParenti@lemmy.wtf 11 points 2 months ago

Holy shit, I hadn't considered that you could use Olympus Mons as a launch site cause it sticks so high up.

[-] turdas@suppo.fi 14 points 2 months ago

The best part about it is that it's an extremely gradual slope completely unlike the mountain ranges on Earth, so you could haul stuff up there on trucks or trains easily.

[-] CheeseNoodle@lemmy.world 14 points 2 months ago

The problem is you can't have mountains like that on tectonically active planets (a mountain that big on earth would sink into the mantle), which is kind of a prequisite for a long-term magnetosphere so its unfortunately not something a species could likely ever have except as a result of terraforming a world like mars and setting up some kind of artificial magnetosphere.

[-] cogitase@lemmy.dbzer0.com 5 points 2 months ago

Is there a lower density limit for having a magnetosphere though? A habitable planet with 1.5x earth radius and the same mass would be much easier to get off of.

[-] CheeseNoodle@lemmy.world 6 points 2 months ago

I guess that could work? Earth is actually the densest planet in the solar system so our baseline mass > size ratio might actually be a bit abnormal.

[-] MrFinnbean@lemmy.world 2 points 2 months ago

I was sure you were bullshitting, but no. Its true.

Iron and nickel core + enough mass for gravity to start compress the planed and we are just little more dense than Mercury.

[-] CheeseNoodle@lemmy.world 1 points 2 months ago

Our core is also just huge, the outer core is larger than the moon and mercury.

[-] Grail@multiverse.soulism.net 2 points 2 months ago

If that's true, how did Olympus mons get there in the first place? I thought it was a volcano.

[-] arrow74@lemmy.zip 5 points 2 months ago

Mars was geologically active but its core cooled.

[-] wonderingwanderer@sopuli.xyz 4 points 2 months ago* (last edited 2 months ago)

Classic planes require an atmosphere to generate lift. There's an outer limit where that would be a viable mechanism, and on Earth it's still far below LEO. Still too deep in the gravity well for ion thrusters to be viable. It requires chemical rocket fuels to bridge that gap.

Maybe someday fusion propulsion will break that limitations, but for now the best you can do is reduce the amount of fuel needed by flying to the upper atmosphere and reaching hypersonic speeds before kicking into rocket fuel propulsion.

Then after orbital injection, switching to ion thrusters to move around, and solar sails for exiting orbit into interplanetary/lunar routes.

[-] gandalf_der_12te@discuss.tchncs.de 1 points 2 months ago

Mars is better for launching rockets into deep space than Earth because it has a lower gravity field and also thinner atmosphere.

this post was submitted on 13 Apr 2026

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