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Comment by rwhitman | Hacker News Reader

Personally I think Venus is the more interesting planet to be exploring

I wonder if eating away at the current atmosphere of venus is more or less technically challenging then the task of creating an atmosphere from scratch on Mars. Since Venus also has way more mass, I'm guessing humans would feel more comfortable there then on Mars.

My thoughts exactly - Venus seems like a better place to start interplanetary exploration with - as I understand, if you could cool it down to an acceptable temperature, you could walk on the surface with just a breathing apparatus, right?

... and an umbrella which is resistant to sulfuric acid, given that a cooler temperature will no longer evaporate the acid before it reaches the ground.

It has 92 times Earth's atmospheric pressure at the surface. This would be a bad idea. It would be like being 900 meters deep in the ocean on Earth. 150 meters is about the limit for humans before High Pressure Nervous Syndrome stops the fun.

But around 50km above the surface of Venus, the temperatures are nice, and the pressure is 1 earth atmosphere. You just have to to stay up there.

Perfect. Given Venus's gravity is 0.904g, we could work something out in a few years.

  > around 50km above the surface of Venus, the temperatures
  > are nice, and the pressure is 1 earth atmosphere. You just
  > have to to stay up there.

Lando Calrissian just called. He wants his Cloud City back. :)

  > as I understand, if you could cool it down to an
  > acceptable temperature, you could walk on the surface
  > with just a breathing apparatus, right?

Sadly, probably not. Cooling it down is already a very tall order, and even then, you would need to find a way to remove most of the atmosphere in order to reduce the pressure (~90 atm at the surface).

Mars is a much better bet for human habitation in the short term. Chemically, it has all the ingredients we need to support human life. And it is much easier to build structures that can withstand the thin atmosphere (0.6 kPa) and relatively tame temperature range (-87 C to 63 C, all figures according to Wikipedia) than to build something that can survive the 9 MPa and 450 C on the surface on Venus.

Yeah, I remember Venus was sometimes called as the "other blue planet" but it was an actual Hell of a place to live in. Looking like Earth but nothing close to it that would make it inhabitable.

Although what about from a human health perspective? Can humans survive in a gravity that weak for a long time? What about animals?

What's long? a year? twenty?

And to answer that question and others is why we(humans) have bothered with Space Lab, Mir, IST. You can Google answer.

No, I mean if humans were to colonize Mars -- would gravity make that process difficult?

Definitely, with little gravity it could even be impossible for women to bear and give birth to a child

I'm unfamiliar with how gravity factors into pregnancy and birthing. Do you have any further details on that?

I found this: http://curious.astro.cornell.edu/question.php?number=702

I always kind of thought that Venus would be a neat place to preform "grey goo" experiments. Lots of matter and energy, and really the only thing you are going to do is make it a nicer place. Worse case is that it remains Venus.

> survive the 9 MPa and 450 C on the surface on Venus

not even mentioning the sulfur acid rains, lead sulfide snow and lack of magnetic field (cosmic rays penetrating atmosphere if it would be weakened)

Doesn't mars also lack a magnetic field?

  > Doesn't mars also lack a magnetic field?

Yes, that's correct. There is no global dipole magnetic field on Mars [1]. However there are weak fields "frozen" into some of the oldest rocks on Mars [2], which indicates that the planet did have a global magnetic field at some point in its early history. Scientists think that the lack of a global magnetic field was part of the reason that Mars lost its atmosphere. [3]

For humans to settle on Mars and stay for any length of time, we will need to find a way to shield ourselves from the ionizing radiation that reaches the surface. [4] On Earth, most of this radiation is either deflected by the global magnetic field, or absorbed by the atmosphere.

[1] http://www-ssc.igpp.ucla.edu/personnel/russell/papers/mars_m...

[2] http://cmex.ihmc.us/data/catalog/TectonismonMars/Paleomagnet...

[3] http://science.nasa.gov/science-news/science-at-nasa/2001/as...

[4] http://en.wikipedia.org/wiki/Colonization_of_Mars#Radiation

Building an atmosphere on Mars would surely be more of a challenge than on Venus, since Mars doesn't have a magnetosphere to keep solar winds from blowing the gases away.

Geoffrey Landis suggested that: Although the surface of Venus is an extremely hostile environment, at about 50 kilometers above the surface the atmosphere of Venus is the most earth like environment (other than Earth itself) in the solar system. It is proposed here that in the near term, human exploration of Venus could take place from aerostat vehicles in the atmosphere, and that in the long term, permanent settlements could be made in the form of cities designed to float at about fifty kilometer altitude in the atmosphere of Venus. Source: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2003002...

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