teeming with life thousands or perhaps millions of years ago?

And if so, could the planet be modified in such a way

that it could sustain human life?

It is NASA's stated goal to send astronauts

to Mars in the 2030s.

But while humanity's efforts to colonize space

are well underway, there is still a tremendous amount

of planning and scientific groundwork

to be done before we can truly begin to populate alien planets

with large numbers of humans.

Right now, we're basically just tourists in space.

We take everything we need with us.

And in order to make the next giant leap,

you're going to actually have to start using the materials

that you find in space to help you explore, OK?

As soon as you make that step to use the materials that

are available to you on the surface, now

you're truly a pioneer.

There's a number of resources that

are already available to us.

And then, of course, we're going to want

to start planting things.

We're going to have to grow food.

We're going to have to live off the land the best we can.

NARRATOR: Live off the land on Mars?

According to NASA, innovations in technology

will be able to make the Martian landscape

more hospitable to humans than was previously believed.

But could this same adjustment to a planet's environment

be similar to what extraterrestrials

could have accomplished here on Earth centuries ago?

Ancient-astronaut theorists say yes

and suggest that stories from nearly every ancient culture

prove this audacious notion to be true.

One of the strangest traditions in South America is

with the Kayapo people in Brazil,

and they have this legend of the Bep-Kororoti,

who came down from the sky in a lot of noise

and wind and landed his craft.

He then taught the people knowledge of civilization,

of herbs and medicine, of building

and agriculture and crops.

And today the Kayapo people celebrate him every year,

and a priest dresses up in this outlandish outfit

that looks like a space suit.

So you have to wonder, where are they getting these ideas

of people in space suits if not from some extraterrestrials who

landed there in the distant past?

Today, we are on the verge of going to other planets

and seeding them with life, and it makes complete sense

that something like that happened on our planet

in the very distant past.