Wednesday, 6 August 2014

Looking Back at Our First Close-up of Saturn

Ray Bradbury at the 1980 Voyager Saturn Encounter at the Jet Propulsion Laboratory. Chris Gainor photo


This entry records my impressions from my visit in November 1980 to the Jet Propulsion Laboratory in Pasadena, California, for Voyager 1's encounter with Saturn. It is adapted from an article I wrote for Spaceflight magazine in August, 2004, on the occasion of the Cassini spacecraft's arrival in orbit around the ringed planet. In the ten years since, Cassini and the Huygens spacecraft it dispatched to the surface of Titan in 2005 have further revolutionized our views of the Saturnian system.


Cassini's arrival at Saturn marked the first visit by a spacecraft to the ringed planet in nearly 23 years. Only three spacecraft had gone there before, all of those visits taking place in a narrow two-year time span – Pioneer 11 on September 1, 1979, Voyager 1 on November 12, 1980, and Voyager 2 on August 26, 1981.

Pioneer 11’s mission was mainly as a pathfinder, proving that spacecraft could survive the rigors of passages through the asteroid belt, the Jovian and Saturnian magnetic fields, and Saturn’s ring plane. Its primitive imager gave scientists and the public only a taste of the views Jupiter and Saturn offered.

Both Voyagers had passed by Jupiter in 1979, providing stunning views of the planet and its moons, most memorably the active volcanoes on Io. As Voyager 1 approached Saturn in the fall of 1980, more than the usual amount of anticipation was in the air at the Jet Propulsion Laboratory in Pasadena, California.


Much of the future of planetary exploration hinged on the success of this encounter, because Voyager 1 had the dual mission of passing close to both Saturn and its moon Titan, the only moon in the solar system known in 1980 to have an atmosphere.


Titan's importance was shown by the fact that Voyager 1's path by Titan would direct it away from the orbital plane of the other planets. Only if Voyager 1 succeeded in getting data from Titan on its way in toward Saturn would Voyager 2 be freed to take a path by Saturn that would direct it to Uranus and hopefully Neptune. A failure of Voyager 1’s Titan encounter would mean that Voyager 2 would be directed to pass close to Titan, and that path would exclude further Voyager planetary encounters.

We know today that both Voyagers succeeded – Voyager 1 obtained its crucial data from Titan and Voyager 2 visited in its turn Saturn, Uranus and Neptune. Voyager 1’s encounter with Titan wound up raising more questions than it answered, and those questions inspired the European Space Agency to send the Huygens probe to Titan's surface in 2005 after riding aboard  Cassini to the Saturnian system.

I was privileged to be one of the journalists at JPL covering Voyager 1’s dramatic encounter with Saturn and Titan, and my memories of that event provide an interesting backdrop to the discoveries that Cassini and Huygens have been making. In a dispatch to my newspaper, I described the findings of those few days in November 1980 as a “knowledge explosion.”

When it came to coining superlatives to describe the encounter, I had plenty of competition.  In addition to the scientists and engineers at JPL, there was a crowd of nearly 1,100 reporters and science fiction fans, including a number of celebrities, whose activities were chronicled by a reporter from People magazine.

Science fiction great Ray Bradbury came to JPL and declared: “This is another of those days that will be remembered a billion years from now. We are privileged to be here and be a part of it.”

Carl Sagan, then at the height of his fame as the star of television's Cosmos, rubbed shoulders with the media horde to shoot segments for a news programme on an American TV network. Many past leaders of the space program, including former JPL director William Pickering, joined the crowd. A large British media delegation was headed by Patrick Moore.
California Governor Jerry Brown spent several hours at JPL on encounter day, accompanied by his science advisor, former Apollo astronaut Rusty Schweickart.

Brown repeated his contention, which even then sounded tired, that "resource efficiency and technological innovation are the keys to the future."

One of the biggest celebrities was a short, stooped man with a shock of white hair,
Clyde Tombaugh, who 50 years earlier had discovered Pluto. He autographed copies of his new book on a recent spate of discoveries about the planet he had discovered as a young man.

Most of the information was given out in daily morning press briefings, which drew standing room only crowds to JPL's von Kármán Auditorium. After scientists presented the latest photos and other data, journalists vied with one another for the first and best questions.
A large model of Voyager dominated one wall of the auditorium, and formed the backdrop for television news reporters and interviews. The crowds grew and contracted in direct relation to the proximity of the Nov. 12 encounter.

There was activity in the press area almost around the clock that week as Voyager 1 sent home a seemingly ceaseless stream of photographs that flashed in their raw forms onto television screens at the Voyager control centre at JPL.

Following the daily press briefings, reporters lined up to pick up their own copies of the best images. The photo office just outside the auditorium was adorned with a cartoon showing a hand clutching a photo of Saturn sticking out of an ocean surface, circled by shark fins. Most reporters still used typewriters and telephones to file their stories, since the internet, word processors, portable computers and even fax machines were still in the future.

Even before most reporters arrived for the encounter, Voyager 1 had sent back dramatic photos showing the structure of Saturn’s rings, including ringlets and hundreds of divisions that showed the rings to be similar to a phonograph record. Late in encounter week, scientists had found between 800 and 1,000 ringlets circling Saturn within the six major ring systems extending 480.000 kilometres from Saturn.

As Voyager flew by, the rings had more stunning surprises. The Cassini Division and the Encke Division were found not to be gaps in the rings at all, but ring systems that do not reflect as much light as brighter rings.

Intertwined "braids" and “knots” in the outermost ring appeared to defy the laws of orbital dynamics. “Spokes" were found in Saturn's major ring, apparently caused by interaction between the rings and Saturn's magnetic fields. Talk of shepherd moons filled the air at JPL.
“In this strange world of Saturn’s rings, the bizarre becomes commonplace,” said Dr. Bradford Smith, the head of Voyager’s imaging team.

Saturn's atmosphere defied predictions that it would be topped by haze, and instead revealed Jupiter-like bands, storms and spots.

Saturnian moons Mimas, Enceladus, Tethys. Dione. Rhea, Hyperion and Iapetus, were found to be made up mainly of ice, and all with the exception of Enceladus, which was not well placed for Voyager 1’s cameras, were seen to be peppered with craters.

Mimas, the closest large moon to Saturn, was photographed with a crater 130 km across, one quarter the diameter of Mimas. A photo of the crater and its central peak drew gasps at a press conference and a comment from Dr. Smith: “This is not an optical illusion.” Soon photocopies of the Mimas photo, complete with additional lines to make the moon look like a dead ringer for the Death Star from Star Wars, circulated around JPL and elsewhere.

The photos of Titan, on the other hand, were a disappointment. Titan's orangeish atmosphere obscured the surface. But Voyager’s instruments found Titan’s atmosphere to be deeper and denser than expected. Expectations of a methane atmosphere were dashed when Voyager’s instruments showed that Titan's atmosphere is made up mainly of nitrogen, the element that makes up 78 per cent of Earth's atmosphere. Methane makes up a few percent of Titan's atmosphere and dominates the haze atop Titan's clouds.

Titan, which long had been thought to be the largest moon in the Solar System, lost its title due to Voyager’s measurements to the Jovian moon Ganymede, although the matter remained in some question pending information on Neptune’s moon Triton.

As Voyager 1 moved away from Saturn, Dr. Smith proclaimed himself “stunned” by the images. “I cannot recall being in such a state of euphoria over any previous planetary encounter. We have learned more about the Saturnian system in the last week than we had in all previous recorded history.”

The amazing photos and data from Saturn and Titan opened the door for Voyager 2 to fly on to Uranus and Neptune. And the following August when Voyager 2 arrived at Saturn, the crowds of press and celebrities at JPL were even larger than for Voyager 1.

But despite Voyager’s success, apprehension hung over JPL the week Voyager 1 went by Saturn. Everyone knew that Voyager 2’s Saturn encounter would be the last planetary encounter by a U.S. spacecraft for at least five years. It was already being labelled by some pessimists as "the last picture show.”

The U.S. space program was ending a decade that began with the heights of Apollo on the Moon and Mariner at Mars, followed by years of cuts that grounded both NASA’s human and planetary programs.

President Jimmy Carter had shown little interest in space exploration during his term of office. And eight days before Voyager 1’s arrival at Saturn, Carter had been defeated in the 1980 presidential election by Ronald Reagan, who ran on a platform of major reductions to government spending.

 As a result, concerned NASA officials were present in force in the von Kármán Auditorium to court reporters in hopes of tapping public support.

 Angelo Guastaferro, NASA's director of planetary programs, surprised many reporters when he asked them for suggestions on how NASA could improve its image and get support for more missions to the planets.

And a press conference marking the culmination of the Voyager program became a discussion of the causes of the looming hiatus in planetary exploration.

Bruce Murray, then the director of JPL, said Voyager showed the potential of what America can do, but explained the hiatus this way: “As a people, we broke our concentration.”
Andrew Stofan, another NASA official, blamed over-optimism in the development of the space shuttle, which was then still five months away from its first flight. While the vast amounts of money needed to develop the shuttle in the 1970s starved other programs, Stofan added that NASA had ordered only enough large launch vehicles to support programs until the shuttle was due to begin flying in 1979.

Guastaferro said one casualty of the Shuttle delays was the Galileo spacecraft, which had been scheduled for a shuttle launch in 1982 toward a mission in orbit around Jupiter.
The NASA officials also discussed how shuttle problems were delaying the Solar Polar mission, a two-spacecraft international effort, and how political problems were besetting the Venus Orbiting Imaging Radar (VOIR) spacecraft.

"What scientists want to do in the later part of this century will be more difficult to describe and defend" than the Voyager missions or the 1976 Viking landings on Mars, said NASA’s John Naugle. Those future missions included a Saturn orbiter, a Titan orbiting imaging flight, and encounters with comets. NASA was talking with European nations about sending a mission to Halley's comet in anticipation of its close approach to the Sun and Earth in 1986.


As we know now, NASA’s planetary exploration program was put on the back burner for most of the 1980s, with the exception of Voyager 2, which encountered Uranus in 1986 and flew by Neptune and its moon Triton in 1989. Voyager 2 found Triton to be smaller than Jupiter’s four large moons and Titan, although Triton was found to possess a thin atmosphere.

NASA did not launch any new planetary missions until 1989, when the shuttle returned to service following the Challenger disaster in 1986.

Galileo was launched that year and it didn’t begin its mission at Jupiter until 1995. The Solar Polar Mission was reduced to the European Ulysses spacecraft, which was launched from the shuttle in 1990. VOIR was replaced by the less ambitious but very successful Magellan spacecraft, launched by the shuttle in 1989. A European spacecraft is exploring Venus from orbit today, and an American spacecraft is orbiting Mercury.

NASA never did launch a craft to Halley’s comet, but European, Soviet and Japanese spacecraft probed the comet, followed by NASA spacecraft that have since visited other comets. This week the European Rosetta spacecraft went into orbit around a comet.


After a two-decade hiatus interrupted only by the failed Mars Observer spacecraft, NASA returned to Mars in 1997. Among the many spacecraft that have gone to Mars since then, two rovers are today roaming the surface of the red planet.

And now Cassini is entering its second decade of exploring the Saturnian system. Together with Huygens, Cassini picked up on the exploration of Titan where Voyager 1 left off in 1980. I
n less than a year, the New Horizons spacecraft will give humanity its first close-up view of Pluto. 


Voyager 1 image of Tethys, Dione, and Saturn, November 3, 1980. NASA photo

2 comments:

  1. Most excellent recollections Chris.

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  2. I remember the astounding photos from the Voyagers, they were front page news on the Vancouver Sun the day after the flyby. I didn't learn until later that it was the JPL amateur radio group that had sent them out via slow scan TV.

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