VOYAGER MISSION CONTROL SITS a couple of
miles outside the JPL campus, in a cinder-block
building with no signs and high windows—a blink-
and-you-miss-it edifice plopped behind a wall of
foliage. There’s a McDonald’s next door. This is
where a team of 12 keeps the most distant objects
humans have ever made alive, steered, nursed,
and cajoled onward into the cosmos.
There, folks want to hear the signal, not the
noise. Spacecraft systems engineer Fernando Per-
alta cares deeply about the messages Voyagers I
and II send home—about the kids on Oudrhiri’s
proverbial bus. Anything that isn’t perfect, any fuzz,
troubles him. “When we get the signal, and I see it’s
wavy, I think, Why is it moving up and down? It might
be the general health of the spacecraft—or it’s just
the fact that you have a cloudy day, or a windy day.
But to us, too much noise is a catastrophe.”
A garbled ripple also risks losing views of a
soundscape only these craft can provide. Voyager I
has a digital eight-track on board to record plasma
waves, fluctuating ions and electrons that create a
sort of oceanic current beyond the bounds of the
solar system. The deck is still powered up (in part
because it gives off enough heat to keep the fuel
lines thawed) and captures 48 seconds of ambient
rumbles three times a week. When Voyager I dumps
the data, all the active antennas in either Califor-
nia or Spain spend at least four hours pulling down
the wavy, ethereal roar of blooping static from the
reaches of deep space.
Peralta walks through a huddle of cubicles.
Above him, a small sign suspended from the
ceiling reads MISSION CONTROL. Modern com-
puters flank a microfilm reader, where the team
consults old blueprints. He’s overseen, at this
point, the shutdown of many systems on both
Voyager probes. Each day that he’s able to come
in to find that the pair has called home again, it
feels like an extra day. “This is such a special lo-
cation in space, one we aren’t likely to return to
in my lifetime or, likely, any of our lifetimes,” he
says. “The data is very, very valuable. It’s precious
to us. It keeps us connected.”
Soon—a few months, a few years—that con-
nection will cease. The heat will diminish enough
on Voyager I or II that a fuel line will freeze, the
propellant will no longer be able to reach the
thruster, and the craft won’t be able to adjust
its flight path ever so slightly, steer its antennatoward Earth, and say hello. Its messages might
still cascade through space, but we won’t be able
to catch and decipher them. Project manager
Dodd is matter-of-fact when describing it: “You’d
lose the signal. And that will be that.”
Even before Voyager II runs out of gas, the
mission team is preparing for a period of discon-
nection. Because of the craft’s trajectory away
from Earth, which dips below the plane of the so-
lar system, only the dish Down Under can hear it.
That antenna won’t transmit for nearly a year as
NASA outfits it with test arrays of mirrors and op-
tical sensors for an upcoming push to supplement
radio-based communications with light. In let-
ting the probe float on its own for 10 months, the
agency is making a strategic sacrifice: stop sending
commands to Voyager II and its radio-only an-
tenna in order to allow a new generation of craft to
phone home long after the older probes go silent.
For decades, NASA has been experimenting
with augmenting its network this way—using
pulses of laser light, which can ferry exponen-
tially more data more quickly and to smaller sets
of ears. There are a couple of reasons for this.
First, space is getting crowded, and all those
signals are cluttering radio comms and making
scheduling on the Deep Space Network a com-
plex and time-consuming task. Second, as we
continue to prospect places like Mars, we will
need to dump far more video in far less time.
When it launches in 2022, NASA’s asteroid-
studying Psyche probe will be among the first to
get an optical-comms setup.
Light has its limits though. Clouds, for exam-
ple, can bend and block it, whereas radio waves
can wiggle right through most atmospheric
conditions. The systems are also quite cheap, rel-
atively speaking. “You always pay a heavy cost for
mass in space,” radio scientist Oudrhiri says. The
tech his work relies on rides on the backs of ex-
isting equipment, all of which have been around
since our earliest space explorations, from Echo
balloons to Apollo to today.
Deep-space communication via radio waves
will never go away because it’s straightforward and
flat-out works. “People often think of very com-
plex solutions to complex problems,” Oudrhiri says.
“But so often the solution can be found in the most
simplistic thing: Just look at all we’ve learned from
paying attention to how the signal varies.”
Quite a lot, it turns out: the density of the moon,
the age of Saturn’s rings, the bounds of the solar
system. The signal and its noise help us understand
our place in the universe—the roads and weather
around the lonely blue rock that is Earth.PG -- 71STATIC ON THE LINEAF
P (^) /
(^) G
ET
TY
(^) IM
AG
ES