Atmospheric Pressure of Mars

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Undocking Undocking's picture
Atmospheric Pressure of Mars

Does anyone know what the atmospheric pressure of Mars is in the contemporary EP setting?
As of 2013 it is about 6.4 kPa while Earth has 101 kPa. I want to have helicopters (probably with turbofans to create some thrust) on Mars without having the blades whipping around 40 times faster, or having 40 times larger blades. Though the gravity is lower than Earth's, it is the atmosphere that counts.
Helicopters on Venus, not a problem.

NewtonPulsifer NewtonPulsifer's picture
Probably .2 atmospheres if

Probably .2 atmospheres if the polar dry ice (solid carbon dioxide) has been melted.

http://eclipsephase.com/oxygen-content-ep-mars-atmosphere

The oxygen content is an unknown amount. Some nitrogen may have been introduced by various methods.

An 80% carbon dioxide atmosphere is going to feel like you're being constantly pepper sprayed! That would sting.

So you're at .2 atmospheres, but the gravity is only .38 gravities. That's about a .53 combined atmosphere/gravity lift factor compared to earth. Worse, but not insurmountable.

"I fear all we have done is to awaken a sleeping giant and fill him with a terrible resolve."- Isoroku Yamamoto

Kroeghe Kroeghe's picture
That's a good one - I can't

That's a good one - I can't find the exact value in any of the books, but it's explicitly stated (Sunward, pg. 99) that unaugmented humans can't survive on the surface.
I did some googling and it seams that so called "death zone" for us, flats, is 8000 metres - 35.6 kPa. The record altitude for a helicopter is 12192 metres - 18.7 kPa.

Take is as you want, but I think there's a good chance that, with their advanced materials, Martians are able to build helicopters that are functional at least at low altitudes. For higher altitudes they could switch to thrusters (they have "flying cars" after all...).

These are of course my speculations, based on a quick search and no actual knowledge about aviation. But I think you can have your choppers.

http://en.wikipedia.org/wiki/Death_zone#Death_zone
http://www.guardian.co.uk/notesandqueries/query/0,,-189928,00.html
http://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html

Undocking Undocking's picture
Kroeghe wrote:

Kroeghe wrote:

Take is as you want, but I think there's a good chance that, with their advanced materials, Martians are able to build helicopters that are functional at least at low altitudes. For higher altitudes they could switch to thrusters (they have "flying cars" after all...).

I think a tiltjet or a tiltrotor for VTOL flight would work better, considering Newton's calculation. Methane burning tiltjets would be pretty cool. I couldn't find it either, but I thought it was because I wasn't being careful enough. Having a helicopter would be a lot easier in EP than in the current reality, but eh.
NewtonPulsifer NewtonPulsifer's picture
There's more possibilities

There's more possibilities that EP tech could make feasible:

http://en.m.wikipedia.org/wiki/Pulse_detonation_engine

"I fear all we have done is to awaken a sleeping giant and fill him with a terrible resolve."- Isoroku Yamamoto

jackgraham jackgraham's picture
I imagine it as being

I imagine it as being comparable to the top of Mt. Everest, or, about 1/3 Earth surface pressure. Sorry for the miss. When we get around to a substantial revision of Sunward, I'll lobby for some planet stat blocks. (We talked about putting them in the first version, but Mars is the only one that's substantially different from the present day.)

I'd say there's some N, but not nearly the amount on earth. It'd come from splattering ammonia-rich iceteroids into the planet as part of the terraforming process. So you've got some buffer gas, but not a lot.

We left out helicopters, because they didn't seem super-feasible. But if you want one with giant rotor blades, hey, knock yourself out.

J A C K   G R A H A M :: Hooray for Earth!
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