Leaving the solar system, bound for interstellar space.
The starship Enterprise it's not. Voyager 1 is a spidery contraption with less computer memory than some calculators and barely enough power to light three 100-watt bulbs. Yet this 1970s-vintage space probe will soon become humanity's first envoy to the stars.
Now hurtling at nearly 40,000 miles an hour well past the orbit of Pluto, Voyager has traveled farther than any other spacecraft. In late 2004 it passed a space boundary called the termination shock, a milestone near the outer limits of the solar system where the thin wind of particles blasted from the sun begins to collide with winds from interstellar space. In another ten years Voyager will leave the last vestiges of the solar wind and venture into the space between the stars. "Interstellar space, for the first time!" exults Eric Christian, Voyager's NASA program scientist.
For as long as NASA funds it and its decades-old technology holds out, Voyager will continue its epic journey of exploration. Launched in 1977, Voyager 1 and its companion, Voyager 2, made a 12-year tour of the outer solar system, visiting planets and moons all the way out to Uranus and Neptune - places never reached before or since. Along the way it transformed our view of the solar system. "Voyager really was the transition from the basic nine planets to an incredibly mixed plethora of worlds," says Louis Friedman, executive director of the Planetary Society.
The probes have revealed that Jupiter has faint rings, that Saturn's rings - more intricate than anyone imagined - are peppered with moonlets, and that 900-mph winds churn Neptune's atmosphere. The moons of the outer planets had long been expected to be pitted and dead like our own, but Voyager found they were a study in diversity: seething with volcanic activity, swathed in hydrocarbon smog, crusted with ice floating atop what may be a hidden ocean. Says one scientist: "NASA in the 20th century is going to be remembered for two things: Apollo moon landings and Voyager."
Yet Voyager started out as a compromise. It was conceived in the early 1970s after NASA abandoned its plans to take advantage of a rare alignment of planets by sending a costly fleet of four spacecrafts on a "grand tour" from Jupiter out to Pluto. The two Voyagers were designed to go no farther than Saturn.
"Of course, we all had our hopes that the mission could go on," says Ed Stone, the Voyager chief scientist since 1972. He and his colleagues knew that if they sent a spacecraft careering past Saturn at just the right angle, Saturn's gravity would fling it straight toward Uranus and Neptune. After Voyager 1 explored Saturn and its moons, perhaps Voyager 2 could be vectored toward more distant planets.
Stone and his colleagues got their wish; in 1981 NASA extended the mission. In the following years Voyager 2 dazzled with close-ups of Uranus, Neptune, and their moons. Leaving Saturn, Voyager 1 climed out of the plane of the planets and headed directly toward interstellar space.
As the decades passed, both Voyagers stayed healthy in spite of brutal cold and a barrage of cosmic rays. The spacecraft had been built to survive intense radiation near Jupiter. "In a sense radiation is a very rapid aging effect," says Stone. After Jupiter, he notes, the additional aging over 28 years didn't make much of a difference.
As the planets dwindled behind it, Voyager 1 had a quiet journey until mid-2002, when it detected bursts of particles apparently sprayed from a nearby shock wave. On December 16, 2004, it reached the source. A sudden strengthening of the solar wind's magnetism indicated that the wind had slowed and piled up - just what was expected at the termination shock. Voyager 2, on a slower route out of the solar system, is expected to reach the shock in as little as two years.
In another decade Voyager 1 should finally cross the heliopause, the last gasp of the solar wind, then sail out among the stars. With some 15 years left in its plutonium power source, it may still be alert and talkative. If cash-strapped NASA can keep finding 4.5 million dollars a year - a bargain compared with other missions - Voyager will give scientists on-the-spot reports from interstellar space.
It will be 40,000 years before Voyager 1 drifts past a neighboring star. For any aliens they might meet, both Voyagers bear a gift: a disc storing images and sounds from Earth. This gold-plated copper record contains images and sounds such as:
- Scenes of Earth showing people, places, animals, technology.
- Sounds of Earth re-creating noises such as a rocket lift-off, surf, rain, and music - from Pygmy initiation-rite songs to Chuck Berry's rock-and-roll.
- Greetings in 55 languages.
The technology however, falls short of Star Trek standards. Each disc is designed to be played on a turntable, and a phonograph needle is thoughtfully included.
The starship Enterprise it's not. Voyager 1 is a spidery contraption with less computer memory than some calculators and barely enough power to light three 100-watt bulbs. Yet this 1970s-vintage space probe will soon become humanity's first envoy to the stars.
Now hurtling at nearly 40,000 miles an hour well past the orbit of Pluto, Voyager has traveled farther than any other spacecraft. In late 2004 it passed a space boundary called the termination shock, a milestone near the outer limits of the solar system where the thin wind of particles blasted from the sun begins to collide with winds from interstellar space. In another ten years Voyager will leave the last vestiges of the solar wind and venture into the space between the stars. "Interstellar space, for the first time!" exults Eric Christian, Voyager's NASA program scientist.
For as long as NASA funds it and its decades-old technology holds out, Voyager will continue its epic journey of exploration. Launched in 1977, Voyager 1 and its companion, Voyager 2, made a 12-year tour of the outer solar system, visiting planets and moons all the way out to Uranus and Neptune - places never reached before or since. Along the way it transformed our view of the solar system. "Voyager really was the transition from the basic nine planets to an incredibly mixed plethora of worlds," says Louis Friedman, executive director of the Planetary Society.
The probes have revealed that Jupiter has faint rings, that Saturn's rings - more intricate than anyone imagined - are peppered with moonlets, and that 900-mph winds churn Neptune's atmosphere. The moons of the outer planets had long been expected to be pitted and dead like our own, but Voyager found they were a study in diversity: seething with volcanic activity, swathed in hydrocarbon smog, crusted with ice floating atop what may be a hidden ocean. Says one scientist: "NASA in the 20th century is going to be remembered for two things: Apollo moon landings and Voyager."
Yet Voyager started out as a compromise. It was conceived in the early 1970s after NASA abandoned its plans to take advantage of a rare alignment of planets by sending a costly fleet of four spacecrafts on a "grand tour" from Jupiter out to Pluto. The two Voyagers were designed to go no farther than Saturn.
"Of course, we all had our hopes that the mission could go on," says Ed Stone, the Voyager chief scientist since 1972. He and his colleagues knew that if they sent a spacecraft careering past Saturn at just the right angle, Saturn's gravity would fling it straight toward Uranus and Neptune. After Voyager 1 explored Saturn and its moons, perhaps Voyager 2 could be vectored toward more distant planets.
Stone and his colleagues got their wish; in 1981 NASA extended the mission. In the following years Voyager 2 dazzled with close-ups of Uranus, Neptune, and their moons. Leaving Saturn, Voyager 1 climed out of the plane of the planets and headed directly toward interstellar space.
As the decades passed, both Voyagers stayed healthy in spite of brutal cold and a barrage of cosmic rays. The spacecraft had been built to survive intense radiation near Jupiter. "In a sense radiation is a very rapid aging effect," says Stone. After Jupiter, he notes, the additional aging over 28 years didn't make much of a difference.
As the planets dwindled behind it, Voyager 1 had a quiet journey until mid-2002, when it detected bursts of particles apparently sprayed from a nearby shock wave. On December 16, 2004, it reached the source. A sudden strengthening of the solar wind's magnetism indicated that the wind had slowed and piled up - just what was expected at the termination shock. Voyager 2, on a slower route out of the solar system, is expected to reach the shock in as little as two years.
In another decade Voyager 1 should finally cross the heliopause, the last gasp of the solar wind, then sail out among the stars. With some 15 years left in its plutonium power source, it may still be alert and talkative. If cash-strapped NASA can keep finding 4.5 million dollars a year - a bargain compared with other missions - Voyager will give scientists on-the-spot reports from interstellar space.
It will be 40,000 years before Voyager 1 drifts past a neighboring star. For any aliens they might meet, both Voyagers bear a gift: a disc storing images and sounds from Earth. This gold-plated copper record contains images and sounds such as:
- Scenes of Earth showing people, places, animals, technology.
- Sounds of Earth re-creating noises such as a rocket lift-off, surf, rain, and music - from Pygmy initiation-rite songs to Chuck Berry's rock-and-roll.
- Greetings in 55 languages.
The technology however, falls short of Star Trek standards. Each disc is designed to be played on a turntable, and a phonograph needle is thoughtfully included.
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