Hi, I'm former NASA astronaut Scott Kelly,

and today I'm gonna answer some

of your questions on Twitter.

(upbeat music)

The first one is from Dirk.

So, what is the speed of he ISS?

Well, the ISS is in low-Earth orbit,

and things in low-Earth orbit are traveling,

generally, at a speed of around 17,500 miles per hour.

Which is 25 times the speed of sound,

so really, really fast.

Sent.

See, next question from CCTakato.

Would the people on the International Space Station

be able to see the effects of the eclipse?

While we were traveling in orbit around the Earth,

we orbit the Earth every 90 minutes,

so if you were in the right place at the right time,

you would see a big black spot over the Earth

which is the shadow from the moon.

On this last eclipse we had the astronauts

were able to get a picture of it

and it was really impressive.

Next question.

If I died in a space suit and was released

to drift through space would I decompose

or just be a floating corpse forever?

Asking for a friend.

Yes, you would decompose rather quickly.

It would, I think, quickly get kind of not too pleasant.

In microgravity, and I'm not exactly sure why,

but things seem to decompose much quicker.

But if you were in low-Earth orbit,

and you were doing a spacewalk from the space station

and drifted away,

eventually you would re-enter the Earth

you'd be, you know, a shooting star.

Hopefully, your friends would be able to see you.

I miss Scott Kelly's tweets from space.

Me too.

And is that flower still growing up there?

When I was onboard the space station,

we grew some stuff in space.

We grew some lettuce,

and after that, we grew something a little bit

more complex which was flowers, zinnias.

The idea is if we can grow a flower,

maybe we can grow a tomato, and eventually,

going to Mars we could use that as nutrition.

Unfortunately, I had to harvest those flowers

and send them back to Earth.

I actually have one at home pressed into a book.

But we've grown other stuff since then,

and our plan is to continue to try to grow

more complicated stuff.

Unfortunately, space flower is no long with us.

Let's see, next question.

How many times do you think someone on the bridge

of the space shuttle said, Punch it, Chewie

when the launch sequence started?

I would imagine for launch,

because it's so complicated, risky, incredible experience

that I would guess zero times.

Someone said, Punch it, Chewie.

But you never know.

If I was flying this...

Actually wouldn't say Punch it, Chewie

'cause it's not the Millennium Falcon.

Chewie wasn't in here.

I'd say, Punch it, R2D2.

He's right there.

Okay, from Jason Garcia.

Planned on sleeping tonight but now it's 5 a.m.

And Googling, quote,

How do astronauts make new oxygen

up in a space station for years?

I need answers.

Well, Jason I have answers.

On the space station we have few ways of making oxygen.

One, is we use a process called electrolysis.

So, we take water.

If this was a water molecule,

we would have one big hydrogen,

two smaller O2 modules.

I'm sorry, I messed that up.

This is the O,

and these are the Hs.

The two little ones are the Hs.

So, electrolysis will separate the two Hs from the O,

and with another O we can create O2.

Two oxygen molecules.

Like this.

Oxygen.

Which we didn't breathe, of course.

If you're in the International Space Station,

what time is it?

This isn't a riddle, I'm genuinely curious

how they keep time.

So, we're orbiting the Earth every 90 minutes,

so we have a sunrise and a sunset,

either or every 45 minutes, generally speaking.

And we have these control centers that are

all around the Earth,

we have in Houston,

and Huntsville, Alabama,

Cologne, Germany,

Moscow,

and in a place called Tsukuba, Japan.

You know, we need a standard of time, of course,

so we operate on Greenwich Time.

And the reason we chose Greenwich Time

was because the people that work

in the control center in Moscow,

most of them have to get to work on the Moscow subway

they don't really have an option to drive,

or walk, or ride a bike.

So, the time we use, Greenwich Time,

was very conducive to the folks in Moscow

using the metro which is not open 24 hours a day.

So, that's why we use Greenwich Time.

Because of the subway schedule in Russia.

Is suspended animation a viable option

for space travel, say to planets like Mars or further?

Well, I think when we go to Mars,

the way we're gonna get there it's gonna

probably only take around 200 days to get there.

You'll spend a year on the surface,

and it'll take around 200 days to get back.

Now, certainly if our technology improves

you could potentially get there faster.

So, I think for Mars it's not really

something that's necessary.

You know, if you were gonna go to Jupiter

or Saturn, the moons of Jupiter or Saturn,

or even further away,

and it's gonna take many, many years to get there,

and many, many years to get back,

if you could develop a technology like suspended animation

that would be really, really, good.

But I'm not sure anyone's actually working on that.

I think, at this point, that might be more science fiction

than science fact.

But you never know.

We'll see.

Any physical, mental residual effects

that are still with you after your year in space?

I don't think so.

At least, as far as I can tell.

Which I don't have any symptoms,

I don't have physical symptoms of being in space

for a long period of time.

Mental issues, I don't know,

I'd probably deny it if I did.

But then, there are the things that you can't see

like when I was on the space station,

I got of radiation, for instance.

Perhaps there are effects from that

that I don't even know about,

and hopefully, I'll never find out.

I don't think I will.

Just a simple question,

could astronauts hold their breath in space

instead of wearing the whole uniform?

Uh no, you couldn't do that.

Without any atmospheric pressure out in space,

all the gases that are in-solution in our blood,

they'd come out of solution and turn back into a gas.

Kind of like when you open a carbonated bottle of soda,

the pressure is decreased,

and that's why you see all the bubbles coming out.

Well, that's exactly what would happen

with our blood if we didn't have a space suit on.

Which would kill us within a few minutes.

Not to mention, without the pressure,

holding your breath would be really hard.

You ever wonder what happens to your organs in space?

Like other shit floats around...do your organs

float around your body or nah?

Everything floats, including your guts.

You can feel that.

I mean, you can feel your insides don't feel quite normal.

Certain processes that we have to deal with

every day, particularly, using the restroom takes time.

Because our body likes to have gravity

telling us which direction to push stuff.

So, when everything's floating,

including your organs and everything inside you,

it creates some challenges.

Also, the blood floats inside us,

and that's why you see at times,

astronauts in space have really big,

you know there heads are swollen, initially,

because all the fluid is redistributed throughout

our bodies and you get this big-headed astronaut.

Eventually, you get rid of some of that fluid

and you go back to maybe almost looking like normal.

Next question.

What was the most exciting, or fascinating,

science experiment you conducted in your year in space?

It's kind of hard to choose.

I would offer two experiments.

One, was we did some experiments with rodents

where we dissected 'em and we appreciated

them giving their lives to us for science.

And that science was involved in understanding the physical

effects that occur when we're in space,

like bone loss, the effects on our vision

which we have some negative effects we're trying to study.

Yeah, that was challenging.

I would say fascinating.

Sort of exciting, because it was very meticulous work

that takes a really long time.

And it's important to us on Earth.

Understanding processes that occur in space

at a very rapid rate.

Very similar to how we age on Earth,

we lose bone mass, muscle mass as we age,

but in space it happens much more rapidly.

The other experiment that I really liked

was the flowers that we grew.

I think it's very, very relatable to people on Earth,

and also has implications for exploration

as we go further out into space.

Having living things, I think, it'll also help

from a psychological aspect.

So, those two, growing plants

and working with the rodents were,

for me, the exciting or fascinating science experiment

that I did in my year in space.

Do you know how people get vacation blues?

How do astronauts cope with coming back to Earth

after seeing space?

It's not easy.

You know, when you get back from space,

after working there for a short or a long time

you generally miss it.

But I think you deal with it like people deal

with everything that is a challenge in your life.

You know, you appreciate the experience you had

and then you move on.

One of my former astronaut colleagues, Gennady Padalka,

he says,

When we are on Earth we miss space,

and when we're in space we miss Earth.

You definitely miss space when you're back on Earth.

Maybe someday I'll get to go again.

Maybe with you Lanny.

That was our last question.

And thank you for your attention.

And thank you for all the great questions.

Bye bye.