voyager 2 launch august 20 1977 PIA01480
The Voyager 2 spacecraft
launched from NASA’s Kennedy Space Center at Cape Canaveral,
Florida, on August 20, 1977.


NASA/JPL


  • NASA’s twin Voyager space probes launched 40 years
    ago
  • The space agency recently fired Voyager 1’s thrusters,
    orienting the robot’s antenna toward Earth and helping extend
    its mission.
  • However, both of the Voyagers nearly failed during
    launch in 1977.
  • One probe refused to communicate with Earth while the
    other launched aboard a leaky rocket.

More than four decades after NASA launched the
Voyager probes
, the twin robots are still humming along in
deep space.

In fact, on November 29, the space agency fired up one of the
robot’s thrusters after 37 years of dormancy — and they worked
flawlessly.

The puffs of propellant rotated Voyager 1 into a position that
helps it communicate with Earth from 13 billion miles away, where
it’s traveling through the unexplored space between stars. The
maneuver will ultimately extend the
nuclear-powered
spacecraft’s lifespan by up to three more years, according to
NASA’s Jet Propulsion Laboratory.

The Voyager mission is easily most exalted in NASA’s history;
collectively, the probes explored Jupiter and Saturn more deeply
than ever before, surveyed Uranus and Neptune for the first time,
then left the solar system.

But, as detailed in a PBS documentary film called “The Farthest“, which premiered in
September and is now available to watch on Netflix, each probe almost didn’t survive
launch.

Voyager 2’s mutiny in space


voyager leaving solar system illustration nasa jpl
An
illustration of a Voyager probe leaving the solar
system.


NASA/ESA/G.
Bacon (STScI)



Voyager 2 launched first, on August 20, 1977. (The first probe
got a “2” label because Voyager 1 would travel faster through
space and overtake its twin.)

Lift-off was flawless, but “things went crazy” in the probe, John
Casani, the mission’s project manager, said in the film.

“Voyager was not in control of itself, it was just riding this
big rocket, and it was shaking it in such a way that it thought
it was failing,” Ed Stone, the mission’s chief scientist, said in
the film. “And so it started switching off various boxes,
changing to the backup this, to the backup that — trying to
figure out why all of this stuff was happening.”

These shutdowns made the probe essentially refuse to talk to
Earth, prompting one newspaper to title its story “Mutiny in
Space.”

“The Voyager spacecraft had decided it just didn’t want to follow
the instructions its human controllers were giving it, and it was
going to do what it wanted to do,” Dave Linick, a Voyager
engineer, said in the film.

The problem: Voyager 2’s computer wasn’t programmed to handle the
rocket’s twisting, shaking, and rattling on its way toward space
— so the system went on the fritz.

“For a couple of days, it was a real nail-biter. People were
asking us, ‘have you lost the spacecraft?’ and we would say, ‘we
don’t know for sure,’ because we didn’t,” Casani said.

Frank Locatell, the project engineer of Voyager’s mechanical
systems, added: “That was a cliffhanger. That was the end of the
mission — that could have been the end of the mission.”

Luckily, the person who coded Voyager 2 managed to reestablish
contact with the probe after several days, then patch its
software as well as Voyager 1’s before launch.

But Voyager 2 would have its own close call with failure weeks
later.

The leaky rocket that nearly sunk Voyager 1


voyager probe titan 3e centaur rocket launch vehicle diagram labeled nasa
A
labeled illustration of the Titan-Centaur rocket used to launch
NASA’s Voyager probes into space.


NASA
via Drew Ex Machina



The faster-moving Voyager 1 probe launched from Kennedy Space
Center on September 5, 1977, aboard a powerful Titan-Centaur
rocket.

This launch vehicle had several stages: two solid-fuel boosters
(stage 0), a liquid-fueled first- and second-stage motors (stages
1 and 2), and an upper stage, called a Centaur, that housed the
Voyager 2 probe.

Each stage fired after the prior one ran out of fuel and
separated, boosting the probe faster and faster toward Jupiter.

“We’re thinking everything’s ok, and then we begin to hear
something wasn’t right,” Charley Kohlhase, who was in charge of
Voyager’s navigation and mission design, said in the film.

Propellant appeared to be leaking from a fuel line that led to
the second stage, draining the tanks. “The second stage never got
to deliver its full thrust because it ran out of fuel,” Casani
said.

A computer in the upper-stage Centaur rocket knew it wasn’t
traveling fast enough to reach Jupiter, so it started burning
extra liquid hydrogen and oxygen fuel.

“The Centaur had used 1,200 pounds of extra propellant,” Kohlhase
said.” Now we’re all thinking, ‘is it gonna have enough left in
the tanks, or is it gonna run out of fuel?'”

Fortunately, he said, the Centaur had just enough — it cut off
its engines with enough fuel to power only 3.5 seconds’ worth of
thrusting.

“Three-and-a-half seconds,” he added. “Voyager 1 just barely made
it.”

Had the Centaur not saved the mission, it “would have gotten
almost to Jupiter, and then come back toward the sun, which would
not have been good,” Casani said.

Yet on
March 9, 1979
, Voyager 1 safely swung past Jupiter during its
closest approach and went on to Saturn.

Both probes sent back incredible images of the outer solar
system, including the first (and so far only) close-up photos of
Uranus, Neptune, and those planets’ moons and rings.

And 40 years later, they’re both still cruising while sending back
unprecedented details about the structure of our solar system and
interstellar space.

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