From: LARRY KLAES (firstname.lastname@example.org)
Date: Tue Aug 20 2002 - 06:46:03 PDT
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Headline: Voyagers pass 25-year mark, en route for interstellar space
Byline: Peter N. Spotts Staff writer of The Christian Science Monitor
For 25 years, a pair of sturdy robotic explorers have revolutionized
humanity's picture of our solar system.
Today, as Voyagers 1 and 2 hurtle toward the little-known boundary of
the solar system, they have come to symbolize mankind's deepening
understanding of Earth's place in the cosmos, and what some see as a
historic transition taking place in space exploration.
Even if they fall silent tomorrow, these craft, launched Aug. 20 and
Sept. 5, 1977, will have set the stage for an era of increasingly
specialized unmanned space missions.
The Voyagers revealed that active volcanoes exist beyond Earth, that
rings of dust are not limited to Saturn, and that auroras shimmer
around Jupiter's poles while lightning bolts lance through its clouds.
But perhaps the Voyagers' most fundamental legacy is perspective, says
Carolyn Porco, a planetary scientist who was deeply involved with the
In 1990, when Voyager 1 was 4 billion miles from the Sun, it turned its
cameras back for a "family portrait" of six of the nine planets. Earth
appeared as a single pixel, a white speck in the vast blackness of
"That to me spoke of evolution - that humankind had reached the point
where we could send a robotic explorer that far away to see ourselves,"
says Dr. Porco, who works at the Southwest Research Institute in
Boulder, Colo. "It's like our early ancestors finally stepping down
from the trees onto the savanna to take on a new life, and casting one
last look over their shoulders to see where they've come from."
New phase of discovery
Today, humanity's quest to extend that epic journey is shifting from
the age of reconnaissance, marked by flyby investigations, to the age
of understanding, typified by focused missions to specific planets,
moons, comets, and asteroids. "Twenty-five years ago, we were explorers
first putting our oars into the water," Porco says. "Now we are poised
at a threshold of understanding how our planet fits into the scheme of
things ... all with an eye toward learning why Earth became a
successful abode of life."
The shift began with the highly successful Galileo mission to Jupiter
and the current Cassini-Huygens mission to Saturn - both triggered by
questions that the Voyager flybys raised. And its momentum is growing.
For the coming decade, solar-system scientists in the United States
have given top priority to 11 new or existing projects - from a flyby
of Pluto to a trip back to Jupiter's moon Europa and missions that
would return samples from frigid comets and the furnace-like surface of
Venus. They detailed their choices and the rationale for them in a
report issued last month by the National Research Council in Washington.
The technological risks these missions face are mirrored in last week's
apparent breakup of the Contour spacecraft after a rocket motor ignited
to send the craft from Earth orbit toward a planned encounter with two
comets - Encke in 2003 and Schwassmann-Wachmann 3 in 2006. At press
time, mission controllers at the Johns Hopkins University's Applied
Physics Laboratory were trying to contact the craft, which fell silent
Coming projects, proposed in the July 11 report, focus on better
understanding the solar system's history, currently estimated at 5
billion years and counting. The scientists also hope to trace the
history of chemical compounds that were necessary for organic life to
emerge, the processes that led at least one planet to harbor life, and
the processes that shape planetary systems.
As they draw new plans, researchers are quick to acknowledge their debt
'Each ... flyby carried definite surprise'
"Much of the impetus for the exploration of the outer solar system has
come from the Voyager spacecraft," says Ellis Miner, science manager
for the Cassini mission at Cal Tech's Jet Propulsion Laboratory in
Pasadena, Calif., and former deputy project scientist for Voyager.
"Each Voyager flyby carried definite surprise. Our theories bore little
resemblance to what we actually saw."
For example, he says, many researchers expected the satellites of
planets such as Jupiter or Saturn to be rather inert objects, like
Earth's moon. Instead, they found a volcano erupting on Jupiter's moon
Io, the first object beyond Earth to display active vulcanism. Icy
Europa tantalized researchers with evidence of cracks on its surface
that hinted at an evolving surface.
Meanwhile, Voyager returned images from Jupiter of auroras, like those
around Earth's poles. And for the first time, researchers had a supply
of photos of Jupiter's Great Red Spot and other cloud features to begin
to piece together a detailed picture of the planet's circulation
Rings - the spectacular halos of dust and rock once thought to be the
province of Saturn - were found to be ubiquitous among the giant
planets, Dr. Ellis says.
If Voyager represented a scientific gold mine, it also represented a
technological tour de force, adds John Casani, who was Voyager's
project manager. Technologies developed for the mission - from small
plutonium-heated electrical generators to computer-aided systems
designed to run without human commands - have found their way onto a
growing number of craft.
Perhaps it's this theory-busting, precedent setting nature of Voyager
that sets it apart from its more focused descendants.
Veteran space-imaging scientist Porco says Voyager was unlike any
mission before or since. "It was far more romantic than anything we'll
ever do again. It was a mission of adventure as well as scientific
(c) Copyright 2002 The Christian Science Monitor. All rights reserved.
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