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Momentum is building to explore Venus

nature.com

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Re: Momentum is building to explore Venus

#171

Post by bdamm »

stcredzero wrote: post #117
hathawsh wrote: post #90

Earlier quoted context omitted.

Most methods of flying things through Earth's lower atmosphere should apply well to Venus at 50 km: balloons, planes, helicopters, etc. To gather energy for rotors, maybe we could siphon heat from below to power a generator or other type of converter. Just playing with ideas. :-)

Send your mining robot below. It cools itself with phase change liquids, but also opens high pressure tanks to the 90 bar atmosphere. When you hoist it back, just plug those pressure tanks in to turbines connected to generators. That wouldn't be a huge amount of power, but maybe wildcat prospectors could operate like that in the early days.

Would it be enough energy to compensate for the work you'd need to do to lift the robot back up? Presumably there's some energy gained from sending it down but not enough to bring it back, especially since it is coming back heavier. I just don't know how to work the math on that.

Re: Momentum is building to explore Venus

#172

Post by bdamm »

ryacko wrote: post #145
hathawsh wrote: post #68

Earlier quoted context omitted.

We don't need to cool it down. We could float a platform about 49.5 km above the surface of Venus, where the temperature and pressure nearly match the earth at sea level. To launch a probe, we could simply drop it from the platform. This article about Venus is very enlightening: https://en.wikipedia.org/wiki/Atmosphere_of_Venus

Have you heard of Murphy's law? Floating above Venus provides the benefits of a gravity well, but there's the danger of sudden buoyancy loss.

Everything about exploring space and planets is a rebut to Murphy's law.

Re: Momentum is building to explore Venus

#173

Post by BurningFrog »

garmaine wrote: post #165
BurningFrog wrote: post #140

Earlier quoted context omitted.

Losing 0.00001% per year is not "very wasteful" to me. There are ideas for putting up a magnetic field based on putting a contraption in whichever L1/L2... point is between Mars and the Sun.

Convert that into tonnes, and then calculate how much biosphere could be supported with that volatile weight. And once it is gone, it is gone. It’s not a renewable resource. You’d be trading away billions of years of future Martian biosphere.

Oxygen and nitrogen are hardly rare substances in the solar system, and probably not even on Mars. There are near infinite number of "tonnes" on Mars.

Besides, if the alternative is to leave Mars dead forever, I'd rather let it live for a billion years.

But maybe I don't get what your alternative is, if any?

Re: Momentum is building to explore Venus

#174

Post by garmaine »

BurningFrog wrote: post #173
garmaine wrote: post #165

Earlier quoted context omitted.

Convert that into tonnes, and then calculate how much biosphere could be supported with that volatile weight. And once it is gone, it is gone. It’s not a renewable resource. You’d be trading away billions of years of future Martian biosphere.

Oxygen and nitrogen are hardly rare substances in the solar system, and probably not even on Mars. There are near infinite number of "tonnes" on Mars. Besides, if the alternative is to leave Mars dead forever, I'd rather let it live for a billion years. But maybe I don't get what your alternative is, if any?

Nitrogen and hydrogen are basically only really available via volatiles. They aren’t components of common minerals in the rocks.

The alternative is to spin up a magnetic field with superconducting magnets to protect that atmosphere from the solar wind.

Re: Momentum is building to explore Venus

#175

Post by killjoywashere »

contras1970 wrote: post #169
killjoywashere wrote: post #150

Earlier quoted context omitted.

Given a choice of death by fire and death by cold, death by cold is easier to mitigate against, and is the default problem in space. To survive Venus, you have to first survive the freezing trip to Venus. So you need heating and air conditioning. A lot. Of both. On Mars, you only need the heating systems that got you to Mars. Similar problem for radiation: going to Mars leads to less radiation. Going to Venus increas…

> death by cold is [...] the default problem in space well, actually... you need lower-energy atoms for higher-energy ones to rub against to carry away the excess. there's not many atoms in vacuum, so the default problem in space is overheating. see eg. https://en.wikipedia.org/wiki/External_Active_Thermal_Contro... or https://en.wikipedia.org/wiki/Liquid_cooling_and_ventilation... > you have to first survive the fre…

> you need lower-energy atoms for higher-energy ones to rub against to carry away the excess.

Wat? Conductive and convective heat loss are certainly things, but heat radiates away too, and that is exactly how the systems you describe perform. The fact that the hull doesn't radiate much heat away itself isn't suprising, but all things being equal, the system still dies cold. Put the other way: if heat was truly the problem, is there any outcome where ISS melts, short of re-entry?

Re: Momentum is building to explore Venus

#177

Post by turtlecloud »

hathawsh wrote: post #68
modzu wrote: post #63

Earlier quoted context omitted.

well you said it: we know exactly how to heat up mars (greenhouse gases) but its not so clear how to cool down venus. also mars has water.

We don't need to cool it down. We could float a platform about 49.5 km above the surface of Venus, where the temperature and pressure nearly match the earth at sea level. To launch a probe, we could simply drop it from the platform. This article about Venus is very enlightening: https://en.wikipedia.org/wiki/Atmosphere_of_Venus

What if your float thing pops? Everyone sinks and dies??

Re: Momentum is building to explore Venus

#178

Post by contras1970 »

killjoywashere wrote: post #175
contras1970 wrote: post #169

Earlier quoted context omitted.

> death by cold is [...] the default problem in space well, actually... you need lower-energy atoms for higher-energy ones to rub against to carry away the excess. there's not many atoms in vacuum, so the default problem in space is overheating. see eg. https://en.wikipedia.org/wiki/External_Active_Thermal_Contro... or https://en.wikipedia.org/wiki/Liquid_cooling_and_ventilation... > you have to first survive the fre…

> you need lower-energy atoms for higher-energy ones to rub against to carry away the excess. Wat? Conductive and convective heat loss are certainly things, but heat radiates away too, and that is exactly how the systems you describe perform. The fact that the hull doesn't radiate much heat away itself isn't suprising, but all things being equal, the system still dies cold. Put the other way: if heat was truly the pr…

> s there any outcome where ISS melts, short of re-entry?

i don't think so. should the cooling system fail, the sources of heat (mechanical work, biological processes) would cease way before that.

Re: Momentum is building to explore Venus

#179

Post by therein »

colordrops wrote: post #141
Baeocystin wrote: post #125

Earlier quoted context omitted.

Is Mars' gravity too low for long-term habitation? I know that we know that zero-G is a negative, but do we have any idea if it's a threshold that needs to be reached, a linear response to G-force that scales from untenable to fine, etc?

I would imagine that it's going to be a gradient. Just like any other form of exercise, the more effort you put in, the more positive effect. Humans would need to put in much less effort on Mars. Once we are spread across the solar system there will probably new exercise systems for 0 and .3 G environments.

I am also unsure about how it would affect the prenatal development as the way "layering" occurs is highly dependent on gravity.
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