NASA's two
Voyager spacecraft are celebrating three decades of flight as they careen
toward interstellar space billions of miles from the solar system's edge.
Voyager 2
launched on Aug. 20, 1977, and Voyager 1 launched on Sept. 5, 1977. Both
spacecraft continue to return information from distances more than three times
farther away than Pluto, where the sun's outer heliosphere meets the boundary
of interstellar space.
"The
Voyager mission is a legend in the annals of space exploration. It opened our
eyes to the scientific richness of the outer solar system, and it has pioneered
the deepest exploration of the sun's domain ever conducted," said Alan
Stern, associate administrator for NASA's Science Mission Directorate,
Washington, D.C. "It's a testament to Voyager's designers, builders and
operators that both spacecraft continue to deliver important findings more than
25 years after their primary mission to Jupiter and Saturn concluded."
Voyager 1
currently is the farthest human-made object at a distance from the sun of about
9.7 billion miles (15.6 billion kilometers). Voyager 2 is about 7.8 billion
miles (12.6 billion kilometers).
Originally
designed as a four-year mission to Jupiter and Saturn, the Voyager tours were
extended because of their successful achievements and a rare planetary
alignment. The two-planet mission eventually became a four-planet grand tour.
After completing that extended mission, the two spacecraft began the task of
exploring the outer heliosphere.
During
their first dozen years of flight, the spacecraft explored Jupiter, Saturn,
Uranus, Neptune and their moons. These planets were previously unknown worlds.
The Voyagers returned never-before-seen images and scientific data and helped
make fundamental discoveries about the outer planets and their moons.
The
spacecraft revealed Jupiter's turbulent atmosphere, which includes dozens of
interacting hurricane-like storm systems, and erupting volcanoes on Jupiter's
moon Io. They also showed waves and fine structure in Saturn's icy rings from
the tugs of nearby moons.
"The
Voyager mission has opened up our
solar system in a way not possible before the Space Age," said Edward
Stone, Voyager project scientist at the California Institute of Technology,
Pasadena, Calif. "It revealed our neighbors in the outer solar system and
showed us how much there is to learn and how diverse the bodies are that share
the solar system with our own planet Earth."
In December
2004, Voyager 1 began crossing the solar system's final frontier. Called the
heliosheath, this turbulent area, approximately 8.7 billion miles from the sun,
is where the solar wind slows as it crashes into the thin gas that fills the
space between stars. Voyager 2 could reach this boundary later this year,
putting both Voyagers on their final leg toward
interstellar space.
Each
spacecraft carries five fully functioning science instruments that study the
solar wind, energetic particles, magnetic fields and radio waves as they cruise
through this unexplored region of deep space. The spacecraft are too far from
the sun to use solar power, and instead run on radioactive generators that
produce less than 300 watts of power, the amount of power needed to light up a
bright light bulb..
"The
continued operation of these spacecraft and the flow of data to the scientists
is a testament to the skills and dedication of the small operations team,"
said Ed Massey, Voyager project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
The
Voyagers call home via NASA's Deep Space Network, a system of antennas around
the world. The spacecraft are so distant that commands from Earth, traveling at
light speed, take 14 hours one-way to reach Voyager 1 and 12 hours to reach
Voyager 2. Each Voyager logs approximately 1 million miles per day.
Each of the
Voyagers carries a golden record that is a time capsule with greetings, images
and sounds from Earth. The records also have directions on how to find Earth if
the spacecraft is recovered by something or someone.
NASA's next
outer planet exploration mission is New Horizons, which is now well past
Jupiter and headed for a historic exploration of the Pluto system in July 2015.
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