What time is it on Mars?

So many of you have probably seen
the movie "The Martian."

But for those of you who did not,
it's a movie about an astronaut

who is stranded on Mars
and his efforts to stay alive

until the Earth can send a rescue mission
to bring him back to Earth.

Gladly, they do re-establish communication
with the character, astronaut Watney,

at some point, so that he's not as alone
on Mars until he can be rescued.

So while you're watching the movie,
and even if you haven't,

when you think about Mars,
you're probably thinking about

how far away it is and how distant.

And, what might not
have occurred to you is,

what are the logistics really like
of working on another planet?

Of living on two planets when

there are people on the Earth and
there are rovers or people on Mars?

So think about when you have friends,
families and co-workers in California,

on the West Coast
or in other parts of the world.

When you're trying to communicate
with them, one of the things

you probably first think about is --

Wait, what time is it in California?

Will I wake them up? Is it okay to call?

So even if you're interacting
with colleagues who are in Europe,

you're immediately thinking about,

what does it take to coordinate
communication when people are far away?

So we don't have people on Mars right now,
but we do have rovers.

And actually right now, on Curiosity,
it is 6:10 in the morning on Mars.

We have four rovers on Mars.
The United States has put four rovers

on Mars since the mid-1990s,

and I have been privileged enough
to work on three of them.

So, I am a spacecraft engineer,
a spacecraft operations engineer,

at NASA's Jet Propulsion Laboratory
in Los Angeles, California.

And these rovers are robotic emissaries.

So, they are our eyes and our ears
and they see the planet for us

until we can send people.

So we learn how to operate
on other planets through these rovers.

So before we send people, we send robots.

So the reason there's a time difference
on Mars right now,

from the time that we're at

is because the Martian day
is longer than the Earth day.

Our Earth day is 24 hours because that's

how long it takes the Earth to rotate,
how long it takes to go around once.

So our day is 24 hours.

It takes Mars 24 hours and
approximately 40 minutes to rotate once.

So that means that the Martian day
is 40 minutes longer than the Earth day.

So teams of people who are operating
the rovers on Mars, like this one,

what we are doing is we are
living on Earth, but working on Mars.

So we have to think as if we are actually
on Mars with the Rover.

Our job, the job of this team, of which I'm a part of is to send commands to the rover to tell it what to do the next day. To tell it to drive or drill or tell her whatever she's supposed to do. So while she's sleeping -- and the rover does sleep at night because she needs to re-charge her battery and she needs to weather the cold Martian night.