NARRATOR: Way out into space,
the sun's energy-giving
rays grow weaker.
Solar panels would be
little use to Cassini
passing distant planets.
It needs a far longer
lasting source of power.
The radioactive power of
plutonium-238 In Idaho Falls,
behind high level
security, the United
States Department of Energy
harnesses this prized source.
The Cassini mission
required more nuclear power
than any other mission
in NASA's history.
NARRATOR: Three heavily shielded
thermo-electric generators
transformed the heat
of radioactive decay
into electrical power.
They hold
iridium-coated plutonium
pellets, lasting for decades,
but potentially deadly to life.
That energy source is
what keeps Cassini's
cameras taking pictures, and
powers its radio messages back
to Earth.
It runs all the devices
on the spacecraft,
plus the residual heat is
funneled into the spacecraft
and it keeps all the
instruments warm and in
their proper operating range.
NARRATOR: But how
do you stay warm
when outside temperatures are
dropping to minus 364 degrees
Fahrenheit?
You wrap up in a blanket.
In this room at NASA's
Jet Propulsion Lab,
there is over $1
million worth of them.
MARK DURAN: This
is the fabric we
use to shield Cassini
and protect it
against the environmental
fluxes of space.
NARRATOR: More than 20 layers
of specialized fabric protect
Cassini.
Not real gold, but colored,
aluminized materials.
$60,000 worth.
Cassini was one of the
most challenging spacecrafts
to even undertake.
It was menacing to think that
we had to develop shielding
for this entire spacecraft.
NARRATOR: It's taken decades
of dreaming, designing,
building, and testing.
Now, the mission is ready to go.
