The Interstellar Age (6 page)

Gary was also a fan of rocketry and of the history of the
academic field known as celestial mechanics—the calculation and prediction of the orbits of planets, moons, asteroids, comets, and eventually spacecraft. In an interview published by
Voyager
mission chronicler and University of Hawaii sociologist David Swift, he pointed out that “
the basic ideas behind gravity assist were known as far back as the 1800s.” These ideas were partially based on analysis by early celestial-mechanics pioneers, such as Urbain Le Verrier from France, of deviations of the orbits of comets passing by Jupiter. Le Verrier would later go on to use the same calculations to deduce in the 1820s that the planet Uranus had performed a distant gravity-assist flyby of a massive but as-yet-unseen object, which altered its orbit slightly. With Le Verrier’s help, that massive mystery object was eventually revealed to be the planet Neptune. It was on the shoulders of such giants that Gary Flandro began to search for similar ways to use gravity boosts to speed up the decades-long interplanetary travel times that would be required for direct-from-Earth outer solar system robotic missions.

One of Gary’s goals was to find out if gravity assists could be used to get to Saturn, Uranus, Neptune, and/or Pluto
quicker
than direct trajectories (essentially by using a close flyby of Jupiter as a slingshot), while still allowing a spacecraft to carry a significant amount of mass for propellant, power/communications/thermal systems, and science instruments. His flash of insight, in the spring of 1965, appears to have been to check if the alignments of the outer planets in the near future could, perhaps, allow not just one slingshot, but multiple slingshots that might permit a spacecraft to be fast-tracked to more than one outer planet after swinging by Jupiter. His investigation quickly showed that there would be a rare alignment of all four giant planets, plus Pluto, on the same side of the
solar system in the 1980s. “So, why not look for a
single trajectory
that would
pass each planet with the shortest possible trip time between?” he thought. Indeed, his calculations showed that it would
be possible for a single spacecraft to visit Jupiter, Saturn, Uranus, and Neptune, or just Jupiter, Saturn, and Pluto, if it were launched about a decade hence, in the mid-1970s.

The Uranus Flyby of Neptune in 1821.
Schematic diagram of the positions of Uranus and Neptune between 1810 and 1830, showing how Uranus made a distant flyby of the then unknown Neptune in 1821. The resulting tweak of the orbit of Uranus allowed mathematicians to predict the existence of Neptune, and then for Johann Galle to discover Neptune in 1846.
(Jim Bell; SkyGazer 4 [Carina Software])

The potential efficiency of the gravity-assist process, which had been worked out in detail by others at JPL and elsewhere well before Gary Flandro began his work on the problem, nonetheless appeared in full bloom in his calculations:
nearly twenty years
could be shaved off direct-flight times to Neptune or Pluto by using well-timed gravity assists. Gary could “distinctly remember the feeling of awe as it first dawned on me that this mission was available at just the right time, leaving about ten years to market the mission concept and to design and build a spacecraft. Yes! Here is the way to do it!
The next opportunity would not appear until about 175 years later!”

He is still excited about that profound Eureka moment from fifty years ago when he first imagined what JPL’s chief scientist at the time, Homer Joe Stewart, would dub “The Grand Tour.” “Wow—bang! There it was, right there! This is wonderful!” He describes the feeling of “flying this whole thing in my mind,” imagining, for example, a spacecraft traveling between Saturn and its innermost ring in order to get the maximum possible gravity assist. “When it actually happened later, it felt like, ‘I’ve already been there!’” Back in the summer of 1965, Gary excitedly described his results to his boss, who encouraged a more detailed study of the opportunity.

It was a spectacular cosmic coincidence that the technology needed in order to perform such a Grand Tour mission happened to have developed to a sufficient degree on the small planet from which the mission would be launched at precisely the time when the planets would line up just right to make it possible. Through the halls of JPL, Gary’s trajectory for a Jupiter, Saturn, Uranus, and Neptune
flyby, augmented and enhanced by the work of others, became the “Grand Tour” trajectory. By July of 1965, while JPL’s
Mariner 4
probe was making the first robotic flyby of Mars (and while I was busy being born), Flandro had worked out the details of the Grand Tour, including the best times to launch the spacecraft from Earth (the fall of 1977 or 1978).

Even though his multiplanet trajectory calculation work at JPL was far earlier than his PhD dissertation work at Caltech, he still had the good sense to write up his findings and get them published in an academic journal called
Acta Astronautica
in 1966. However, the response to Gary’s work was rather negative. “
Many openly scoffed at the idea,” he said. At the time, JPL was being pushed to the limits to successfully operate missions to the moon and nearby planets that would last a mere several days to several years. The Grand Tour would call for a spacecraft that could operate for maybe a decade or more. Such longevity was unheard-of at the time and difficult for many to imagine. But Gary was now on a quest.

When I was a student at Caltech, one of my friends was a fellow student named Katie Swift, who was also studying astronomy and planetary science. We kept in touch after graduation, partly because she went back to her home state of Hawaii, where I went to graduate school. I got to know her father, David Swift, whose book about the many members of the
Voyager
team included a profile of Gary Flandro.

Despite the fact that the actual trajectories of the
Voyagers’
Grand Tour were selected based partly on Gary’s 1965 research, he received little credit for his role at the time. He was still a graduate student, without any real authority or power. His contribution might have gone nowhere—certainly not into interstellar space—and even if it had, his role could well have been completely
forgotten. Nevertheless, Gary is pragmatic about the part that he played in making the
Voyagers
happen and, still, rightfully, considers himself a part of the mission. “
Many myths have arisen about the origins of the
Voyager
mission,” he told David Swift in his interview. “Since I was pretty low on the totem pole . . . no one felt much need to mention my connection with the discovery of the mission. I accepted those misconceptions, but it was sometimes difficult. As a rather naïve young fellow, I could not conceive of the possibility that I would not in time be acknowledged in some fashion for the work I had done. I thought this would happen automatically, since I had properly documented my work and presented it to many people both at the Caltech campus, at JPL, and in various technical meetings.” Despite what would be justifiable sour grapes over his lack of recognition, Gary was still gracious about the project overall: “
Those at JPL who brought everything together certainly deserve major credit for the magnificent job that they did.” It wasn’t until 1998 that NASA finally did recognize his contributions, awarding him their Exceptional Achievement Medal. When I first heard this story as a graduate student myself, one line of Gary’s jumped out at me: “You have to learn not to be discouraged by experts.”

When it came to trying to actually get the Grand Tour mission off the ground, there would be plenty of discouragement to go around. In 1969 and 1970, JPL proposed an aggressive series of missions that would accomplish the Grand Tour. Four spacecraft would be launched: two in 1977 to fly by Jupiter, Saturn, and Pluto;
then two in 1979 to fly by Jupiter, Uranus, and Neptune. The spacecraft would be based on JPL’s successful
Mariner
series (which by 1969 had successfully flown by Venus and Mars, and which would soon fly by Mercury). It would include probes launched into the atmospheres
of the giant planets, and multiple launches per opportunity would help reduce one of the engineers’ biggest concerns and risks: keeping the spacecraft alive and functioning for more than a decade. This set of Grand Tour missions was not only ambitious, it was also expensive, with an estimated cost in 1970 of more than $900 million, equivalent to almost $5.5
billion
today.

Despite the compelling proposal to conduct an exciting and historic mission that would take advantage of the unique Grand Tour opportunity, both NASA and the administration of President Richard Nixon balked at the steep price tag and did not approve the concept. Part of the reason was due to overall NASA budget cuts and belt-tightening as the
Apollo
moon program was winding down (Nixon canceled the planned
Apollo 18
,
19
, and
20
missions in 1970), and part of the reason was that NASA was being directed to start ramping up more of their shrinking funding for a new human exploration vehicle called the Space Shuttle.

However, as JPL Grand Tour mission manager Harris “Bud” Schurmeier had recalled in a recent interview on the topic, the door was left a little open. “
They told us, ‘If you guys can come up with something less grandiose, we’ll consider it.’ So we went home and quickly put together what we called
Mariner Jupiter Saturn ’77
(MJS-77).” Bud and his colleagues at JPL scrapped two spacecraft, designed the remaining two so they would primarily use technology already developed for the
Mariner
series, took off the atmospheric entry probes, and scaled the mission back to just flybys of Jupiter and Saturn. The price tag dropped to about $250 million (about $1.5 billion today), and in 1972 the scaled-back proposal was accepted by NASA and the Nixon administration.

As crazy as it seems in hindsight, NASA managers officially
passed up on the Grand Tour opportunity as Gary Flandro and others had originally conceived it
.
The
Voyagers
were missions to Jupiter and Saturn, and scientists and mission managers could only hope that at least one of them could continue on to Uranus and maybe Neptune. Ed Stone recalls that “the idea of getting to Uranus and Neptune was being pursued, but quietly, partly because nobody wanted the mission to be considered a failure if we didn’t survive past Saturn!” If the Grand Tour was to be resurrected, it would have to be put together in pieces added later—after success at Jupiter, Saturn, and Titan was in hand. Building spacecraft that could fly farther and last longer than any ever had was now the challenge.

CONSTRUCTING THE CRAFT

Once funding for
MJS-77
was approved by Congress and the upper administration of NASA, they handed the job of actually making it happen to the engineers, scientists, and mission managers at JPL. Outwardly, JPL has the look and feel of a college campus, a mishmash of buildings from high-rises to trailers nestled into the (sometimes smoggy) foothills of the San Gabriel Mountains in the small city of La Cañada Flintridge. Tame wild deer roam around under the pine trees and walkways, and the sound of horses and riding instructors can often be heard from the riding stables nearby. JPL began as a US Army–funded rocketry lab on the Caltech campus in the 1930s; as the tests and launches got more ambitious, the facility was eventually transferred to an off-campus location near a more spacious arroyo about seven miles away in what was then northern Pasadena. In the late 1950s, JPL became affiliated with a new federal
agency called NASA. Not officially one of the ten “Centers” run by NASA across the country, JPL is instead one of a few hybrid university-government entities called a Federally Funded Research and Development Center, administered by Caltech. JPL employees are actually Caltech employees, not government civil servants, though they all have NASA badges and work with many of the same privileges and restrictions of those on the civil servant pay scale. It is a strange twist of federal bureaucracy that can sometimes create awkward situations, such as when the government closes down over budget disputes in Congress. Some JPLers are sent home; others are deemed “essential employees” who need to stay on the job to protect the taxpayers’ investments and keep government spacecraft or facilities running.

JPL has been the epicenter of the American robotic space program since its beginning. Early successes included the
Ranger
and
Surveyor
missions to the moon, the
Mariner 2
flyby of Venus in 1962 (the first spacecraft flyby of another planet), the
Mariner 4
flyby of Mars in 1965, the
Mariner 5
flyby of Venus in 1967, the
Mariner 6
and
Mariner 7
flybys of Mars in 1969, the
Mariner 9
Mars orbiter in 1971 (the first spacecraft to orbit Mars), and the
Mariner 10
flybys of Venus and Mercury in 1974–1975. While JPL had proven itself more than capable in conducting these previous missions,
MJS-77
would be the most complex and advanced planetary mission that the lab had ever attempted.