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 batteries

and she needs to weather
the cold Martian night.

And so she sleeps.

So while she sleeps, we work
on her program for the next day.

So I work the Martian night shift.

So in order to come to work on the Earth
at the same time every day on Mars --

like, let's say I need to be
at work at 5:00 pm,

this team needs to be at work
at 5:00 pm Mars time every day,

then we have to come to work
on the Earth 40 minutes later every day,

in order to stay in sync with Mars.

That's like moving a time zone every day.

So one day you come in at 8:00,
the next day 40 minutes later at 8:40,

the next day 40 minutes later at 9:20,
the next day at 10:00,

so you keep moving 40 minutes every day,

until soon you're coming to work
in the middle of the night --

the middle of the Earth night.

Right? So you can imagine
how confusing that is.

Hence, the Mars watch.

This watch has been mechanically --

the weights have been mechanically
adjusted so that it runs more slowly.

When I got this watch in 2004

with Spirit and Opportunity,
the rovers back then,

we didn't start out thinking
that we were going to need Mars watches.

Right? We thought, okay,
we'll just have the time on our computers

and on the mission control screens
and that would be enough.

Yeah, not so much.

Because we weren't just
working on Mars time,

we were actually living on Mars time.

And we got just instantaneously confused
about what time it was.

So you really needed something
on your wrist to tell you, alright,

what time is it on the Earth,
what time is it on Mars.

And it wasn't just the time on Mars
that was confusing,

we also needed to be able
to talk to each other about it.

So a "sol" is a Martian day --
again, 24 hours and 40 minutes.

So when we're talking about something
that's happening on the earth,

we will say, today.

So, for Mars, we say, "tosol."

Yesterday became 'yestersol' for Mars.

Again, we didn't start out thinking,
"oh let's invent a language."

It was just very confusing.

I remember someone
walked up to me and said,

"I would like to do this activity
on the vehicle tomorrow, on the rover."

And I said, "tomorrow, tomorrow,
or Mars tomorrow?" Right?

We started this terminology because
we needed a way to talk to each other.

Tomorrow became "nextersol" or "solorrow"

because people had different preferences
for the words they use.

Some of you might say soda
and some of you might say pop.

So we have people who say
nextersol or solorrow.

And then something that I noticed after
a few years of working on these missions,

was that the people who work
on the rovers, we say "tosol."

The people who work on the
landing missions that don't rove around,

they say "tosol."
[Different vowel sound]

So I could actually tell what mission
you worked on from your Martian accent.

[Laughter]

So we have the watches and the language
and you're detecting a theme here, right?.

So that we don't get confused.

But even the Earth daylight
could confuse us.

If you think that right now,
you've come to work

and it's the middle of the Martian night
and there's light streaming in

from the windows,
that's confusing as well.

So you can see from
this image of the control room

that all of the blinds are down.

So that there's no light to distract us.

The blinds went down all over the building
about a week before landing

and they didn't go up
until we went off Mars time.

So this also works
for the house, for at home.

So I've been on Mars time three times,
and my husband is like, okay,

we're getting ready for Mars time.

And so he'll put foil all over the windows
and dark curtains and shades

because it also affects your families.

And so here I was living in kind of
his darkened environment but so was he,

and he'd gotten used to it,

but then I would get these plaintive
emails from him when he was at work.

Should I come home? Are you awake?
What time is it on Mars?

And I decided, okay,
so he needs a Mars watch.

[Laughter]

But of course, it's 2016,
so there's an app for that.

So now instead of the watches,
we can also use our phones.

But the impact on families
was just across the board,

it wasn't just those of us
who were working on the rovers

but our families as well.

This is David O,
one of our flight directors,

and he's at the beach in Los Angeles
with his family at 1:00 in the morning.

So because we landed in August

and his kids didn't have to
go back to school until September,

they actually went on to Mars time
with him for one month.

They got up 40 minutes later every day

and they were on dad's work schedule.

So they lived on Mars time for a month
and had these great adventures,

like going bowling
in the middle of the night

or going to the beach.

And one of the things
that we all discovered

is that you can get
anywhere in Los Angeles

at 3:00 in the morning
when there's no traffic.