There's a lot of talk about sending humans to Mars.

But no one talks about Venus.

Why not?

And could Venus actually be the better option

for a human colony?

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Going to Mars has been a fixture in

our collective cultural consciousness

for a very long time.

It's inspired more sci-fi movies and stories than I can count,

a ride at Disney World, and a Twitter following for the Mars

Rover that's almost two million strong.

Meanwhile, Venus has inspired-- what?

Two Ray Bradbury stories, a plant

that eats flies, and a razor?

Basically, Venus has the worst public relations

team in the solar system.

And that hurts our sister planet,

not just in culture and media but in space policy.

Presidents Bush and Obama and the Chinese government

have all outlined goals for manned missions to Mars.

The Dutch nonprofit group Mars One

even held in international competition

to find volunteers for a one-way mission to the Martian surface.

But Venus?

No manned mission love-- at all.

Which is odd since in most respects,

Venus is actually an easier and less costly

colonization target than Mars is.

For starters, Venus is closer to Earth.

That's why we sent probes to Venus long before we sent them

to Mars and why we sent more of them.

Depending on the launch window, the round trip

can be 30% to 50% shorter, which is a major factor

for manned missions.

Shorter trips means less weightlessness and radiation,

less food and water to carry, and thus

less fuel and lower cost.

This would also be a huge advantage

in moving the people and equipment necessary to actually

colonize another world, because bear in mind,

there's no Craigslist in space.

If we ever start a colony, we'll need to bring along

almost everything.

And it's not just the shorter trip.

The planet itself has some significant advantages

over Mars.

It's closer to the sun, which means about four times

more available solar power then you have on Mars.

It also has a thick atmosphere, unlike that wispy layer

on Mars.

That means better protection from space radiation

and meteorites for our enterprising colonizers

and their future cities.

It also means more available carbon dioxide

from which, in principle, you might extract oxygen.

But the real kicker is gravity.

Venus has about 0.9 Earth g's-- pretty close--

while Mars has less than 0.4.

And one thing we do know is that prolonged low gravity

is bad for humans.

How bad?

In Earth orbit, astronauts lose bone mass

at about 10 times the rate of someone

with advanced osteoporosis.

Now no one knows exactly how bad Martian gravity

would be for humans, but it's definitely not

going to be good.

On Venus, that's far less of a concern.

And remember, we're talking about long-term colonization,

not just visits.

Even if we have the technological means

to add water to a planet's surface and oxygen to its air,

changing the planet's surface gravity

is currently not even within the realm of discussion.

So terraforming seems silly, and if people couldn't live there

more than a few months without their bones falling apart.

A theoretical Venutian colony thus

seems to have a lot going for it.

So why then this tunnel vision for Mars?

Surfacism.

OK, I just made that word up, but hear me out.

Ever since the days of seafaring exploration,

we've had an obsession with landing

on the surface of things.

If you don't plant a flag on something,

it's almost like having gotten there doesn't count.

So what's all this have to do with Venus, which

actually has a solid surface?

Well it does, but humans can't land on it.

See, there's a teensy problem with temperature.

There's so much CO2 on Venus that the greenhouse effect

makes the surface hotter than hell-- over 450 degrees

Celsius, well above the melting point of lead.

But the bigger problem is the barometric pressure

on the surface.

It's over 90 Earth's atmospheres.

That means that landing on the Venutian surface

would be like diving one kilometer underwater on Earth--

far beyond the crush depth of most military submarines.

In fact, most probes that NASA and the Soviets

sent to the surface of Venus imploded in midair.

We learned our lesson and a few reinforced probes

did manage to touch down and send images of the Venetian

surface.

But even those only lasted about two hours

before-- [SOUND OF AN IMPLOSION] --you know.

The point is-- I think surfacism is a real bias.

And the fact that we can't live on the Venutian surface

could help explain why Mars gets all the hype.

But maybe that's sensible.

I mean, if a surface will kill us,

there's no point in going there, right?

Not so fast.

See, around 50 kilometers or 30 miles

above the Venutian surface, some interesting things happen.

First, the temperature drops to only about 70 degrees Celsius.

That's still super hot, but firefighting equipment on Earth

can withstand proximity to forest fires with temperatures

that reach over 2,000 degrees Celsius.

The pressure at that altitude also

dropped to almost exactly one Earth atmosphere.

That means humans would need heat-resistant clothing

and oxygen masks, but not spacesuits to walk around

in that environment.

Granted, there's the minor nuisance

of sulfuric acid floating around in the Venutian air,

but that's potentially manageable.

And at that altitude, the atmosphere

is still dense enough for lots of stuff

to floae-- like balloons filled with helium

or maybe filled even with just regular Earth air.

Throw in the favorable gravity, and it

starts to look like the upper atmosphere of Venus

might be the closest thing in the solar system

to an Earth-like environment.

So it might make sense to colonize

Venus with cloud cities.

I am not making this up.

NASA Systems Analysis and Concepts Directorate

has unveiled a conceptual blueprint for this scheme.

They call it the High Altitude Venus Operational

Concept or HAVOC-- interesting branding choice,

but still super awesome.

We've linked the NASA videos in the description.

You should check them out.

Now for the record, this is all still conceptual.

We are very far from sending this guy

to lead our Venutian Cloud City.

But NASA is taking the idea seriously.

Right now, most of the chatter is still

about using Venus as practice for colonies

elsewhere-- like Mars.

So we haven't overcome surfacism just yet.

But this might change.

The gravity issue alone might make Venus the go-to option

for long-term human habitation.

Who know?

Centuries from now, if we learn how

to sequester enough carbon out of its atmosphere,

we might even be able to plant a flag or two.

So what do you guys think?

Is Venus a better colonization option than Mars?

Put your $0.02 in the comments-- or even better, tweet them,

#occupyvenus.

If we start a grassroots movement,

I'll let you know on the next episode of "Space Time".

Last week, we asked how you measure

the size of the universe?

Here are some of your questions.

awtizme asked, how can space be expanding faster

than light if the speed of light is the ultimate speed limit?

I'm going to answer you in two parts.

First, the speed of light speed limit

is for things moving through space, not about expansion

of space itself.

The second, you're right.

I shouldn't be talking about space

expanding at a given speed.

I should be talking about the size of the enlarge setting

on a photocopier button.

If I hit enlarge once every second,

then there will always be two points on the page

that-- if they're far enough apart to begin with--

will end up more than one extra light second apart after I

hit that photocopier button.

lingwingzing commented that this was a pretty intuitive way

to understand inflation.

Thanks for the compliment, but be careful.

We're talking about expansion of space in general.

Inflation refers to a very specific expansion

of space that occurred in just the first few instances

after The Big Bang.

The Mattman1313 says that the Hubble Bubble

is a possible alternative to the idea

that space is expanding at all.

That's not correct.

Space is expanding-- period.

What the Hubble Bubble offers is a potential alternative

to the currently observed, accelerated expansion of space.

Look it up.

And to Brandon Spears, sure, we could always

use help here at "Space Time".

Like the Hubble Space Telescope, we've

got schmutz on our lens too, so give it a wipe and help us out.

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