COMMUNICATING WITH CURIOSITY
With cell phones and the
internet, we're used to
communicating with anyone,
anywhere, quickly and
easily. But how do scientists
communicate with things that
aren't on our planet—such as the
Curiosity rover on Mars? This
communication beyond Earth is
a bit more complicated.
We communicate with
spacecraft using radio signals.
Radio signals move at the speed
of light. However, they have a
long way to travel. Even when
it is closest to Earth, Mars is
still about 35 million miles away.
And sometimes it's much,
much farther! If you sent a text
message to Mars, it would take,
on average, about 14 minutes
for it to get there.
This long distance makes
talking with robots on other
planets difficult. Imagine driving
in a video game and waiting 28
minutes to see your car make
a turn! It would take forever to
drive the rover one turn at a
time. Instead, we send Curiosity
all the instructions for the day at
once. Most of the rover's daily
tasks—like taking photographs
and zapping rocks—are planned
out in advance.
Some days we can't directly
talk to the rovers. We use
antennas to send and receive
signals, but Mars and Earth are
both constantly spinning. On
Earth, the antennas are located
around the world so that at
least one is always facing Mars.
About half of the time, though,
Curiosity's location on Mars is
not facing toward Earth. During
these times, Curiosity can't send
signals directly to our antennas.
So how does the rover send its
messages to Earth? Through an
orbiter!
Orbiters are special
spacecraft that spend their time
continuously traveling around
an object, such as a moon or
a planet. There are several
orbiters traveling around Mars.
When Curiosity isn't facing
Earth, it can send a message
to one of these orbiters. Then,
once the orbiter reaches the
Earth-facing side of Mars, it
sends the signal.
Each day, Curiosity sends
information to at least one
Mars orbiter, and the orbiter
sends that information to Earth.
Hurray for teamwork!
In December 2012, Curiosity's
two-year mission was extended,
and on August 5, 2017, NASA
celebrated the fifth anniversary
of the Curiosity rover landing.
The rover is still operational,
and as of February 16, 2020,
Curiosity has been on Mars for
2676 sols (2749 total days) since
landing on August 6, 2012.
Elements of this image furnished by NASA.
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