Just how did we get there? and space; like Tarzan swinging from technology, and human expertise As the outer planets plod through vine to vine through the jungle, missing to catch up. the frozen void, once every 175 years a transition by even the smallest of JPL formally proposed the Grand they line up in such a way that Jupiter’s margins would spell disaster. A few Tour in 1970, with Harris M. “Bud” gravity can be used to fing a properly months and several reams of graph Schurmeier (BS ’45, MS ’48, ENG aimed spacecraft on toward Saturn, paper later, Flandro had worked out ’49) as the project manager. This was and thence to Uranus and Neptune. In hundreds of itineraries—some reaching an A-team effort: Schurmeier had just THE the spring of 1965, Caltech aeronautics all the way to then-planet Pluto—for presided over the Mariner 6 and 7 grad student Gary Flandro (MS ’60, the upcoming launch window. His fybys of Mars, and his collaborators PhD ’67) was working part-time up boss, Elliott “Joe” Cutting, booked included JPL’s planetary program at JPL analyzing so-called gravity- him a meeting with the chief of JPL’s director, Robert Parks (BS ’44), and its assist trajectories when he realized that advanced technical studies offce, spacecraft systems manager, Raymond OTHER such a four-for-one alignment would aeronautics professor Homer Stewart Heacock (BS ’52, MS ’53). It was also occur between 1976 and 1979; (PhD ’40). Stewart embraced the idea, a gold-plated Cadillac of a mission—a intrigued by the possibilities, he set christening it the Grand Tour. fotilla of four mother ships carrying about matching possible paths of But despite Stewart’s passionate probes on parachutes to be dropped departure from one planet to lines promotion and some glossy off at the various planets en route. of approach to the next one. publications, the Grand Tour failed The billion-dollar price tag (much of SIDE All the path segments to get off the ground. In 1965, simply it for technology development) proved by Douglas Smith had to align hitting the broad side of the moon was too much, and the Tour was axed in perfectly in hard enough, and getting Mariner 4 December 1971; the following month time close enough to Mars to take a handful President Nixon signed a NASA budget of decent pictures had pushed JPL to authorizing $5.5 billion to be spent the limit. Still, the notion lingered developing a space shuttle instead. out on the fringes—much like But all was not lost. “They told n a press conference on September launch on September 5, 1977. It’s now 40 years ago, that this would happen. Uranus and Neptune us, ‘If you guys can come up with 12, NASA announced that Voyager more than 11 billion miles from home But none of us knew how big this themselves— something less grandiose, we’ll consider I1 is now offcially cruising among and still going strong. bubble was, and none of us knew any waiting for it,’” Schurmeier recalls. “So we went the stars. This resilient robot, built “We got there!” exulted Ed Stone, spacecraft could last as long. Setting time, home and quickly put together what we by NASA’s Jet Propulsion Laboratory the Voyager mission’s project scientist, sail on the cosmic seas between the called Mariner Jupiter Saturn [MJS] (JPL), had burst through the sun’s principal investigator for the Voyager stars, Voyager has joined other historic ’77.” Saturn was a mere three-year magnetic “bubble” and crossed into Cosmic Ray Experiment, and Caltech’s journeys of exploration such as the frst journey instead of 10; instead of interstellar space on August 25, 2012— David Morrisroe Professor of Physics. circumnavigation of the earth, and the four spacecraft, only two almost 35 years to the day after its “We all hoped, when we started on this frst footprint on the moon.” would be built, largely 10 ENGINEERING & SCIENCE WINTER 2013 WINTER 2013 E NGI N EER I NG & SCI E NCE 11 YOU ARE HERE with existing technology; and the engineering-based approach when 1973 and encountered intense radiation. craft up and out of the plane of the the solar wind like a tsunami crosses the probes were deep-sixed. The scaled- it became part of NASA in 1958—if Although the Grand Tour proposal had solar system. ocean,” says Stone. “Although the solar back proposal was worked up within something doesn’t work, tweak it and called for “hardened” spacecraft to be On Valentine’s Day, 1990, Voyager wind ions don’t travel out to Voyager, weeks, and MJS was offcially approved try again. JPL’s frst steps into space built with armored shielding around 1 took one last look over its shoulder, the wave energy does, and our antennas in May 1972 by NASA administrator had had a 50 percent success rate, delicate instruments and military-grade snapping a family portrait of the solar pick up the plasma oscillations caused James Fletcher (PhD ’48). perfectly reasonable for the times. But electronics designed to withstand system from about 32 degrees above— by the arriving wave. The frequency of JPL had promised Saturn, but still after going one-for-eight in the early nuclear war, this fendishly expensive and 4 billion miles away from—it. The the oscillation tells us the density of the intended to deliver the full Tour. “One 1960s, director William Pickering (BS option had been discarded in favor of cameras were then turned off for good. plasma Voyager is traveling through.” of the Grand Tour’s key objectives had ’32, MS ’33, PhD ’36) had assigned simply keeping a safe distance. After all, The ship is now fying blind, but The plasma team members at the been to measure cosmic rays that were Schurmeier and Jack James, who no one had known how strong Jupiter’s it’s not deaf. On August 25, 2012, the University of Iowa realized that they unmodifed by the sun,” Schurmeier had overseen the Lab’s only recent radiation belts actually were. Now they cosmic-ray data changed dramatically were hearing the reverberations of the says. “Of course, the scientists then success—Mariner 2’s 1962 fyby of Of course, components that work did. “If we few far enough away to and Voyager’s magnetic-feld readings cold, dense interstellar medium from didn’t really think the heliopause was Venus—to write an operations manual fawlessly on the ground can still get need no radiation-hardened parts, we jumped by 60 percent—both signs that within. They went back through their so far away. So we thought, OK, if we that might have been subtitled How to fried in deep space, so each Voyager wouldn’t have a mission,” Schurmeier the spacecraft might have reached the data, and found a fainter signal with the can make it to Saturn, maybe we can Build a Spacecraft Without Embarrassing carries A and B copies of every critical says. “That forced a very large change heliopause. However, the key data— same rising pitch that had been recorded last long enough to get out there.” Yourself. Says Schurmeier, “In the early system. “For the Grand Tour, we’d very late in the process, but we got the plasma measurements proving from October 23 through November 27, The heliopause is the theoretical days, people would say, ‘Oh, gee—I designed a triply-redundant computer enough hardening so we could fy close that Voyager had left the hot, diffuse 2012. The pitches fell on a line pointing boundary where the sun’s outward had a glitch, but it’s gone now, so forget that would control everything,” enough for a decent mission.” “solar wind” behind and entered the straight back to August 25 as the date fow of charged particles meets a it.’ We said, ‘Any glitch—any time Schurmeier says. “With Voyager, we Mariner Jupiter Saturn was cold, dense interstellar medium—was of entry to be stamped on Voyager’s counterfow from the Great Beyond— the electronics don’t do what they’re couldn’t afford to do that, but we did offcially renamed Voyager in March unobtainable because Voyager’s plasma interstellar passport. “Voyager is now the unmodifed cosmic rays that supposed to—we fnd the reason and fx make dual radios, dual computers, 1977; Voyager 1 was launched that science experiment had died just after on a 10-year journey through the space Voyager 1 is now sampling. “The it. And if we can’t fnd it, we’ve got to and a lot of other dual equipment.” September and few by Jupiter in 1979. the Saturn encounter 20 years earlier. between the stars,” says Stone. “We Cosmic Ray Experiment was proposed create work-arounds for all of the pos- The Voyagers’ computers were In November 1980, it dove around and Fortunately, on April 9, 2013, Voyager’s should have enough power to keep all by [Caltech physics professor Rochus] sible failures that could have caused it.’ designed to be reprogrammable to an behind Saturn’s Mercury-sized moon, plasma-wave antennas began picking of the instruments running for another ‘Robbie’ Vogt,” says Stone, who And that had to be done before launch.” unprecedented degree—and over un- Titan, in order to study its atmosphere up oscillations of the plasma that had six years, and we’ll turn the last one off inherited the instrument when Vogt Schurmeier practiced what he precedented distances. Space is a harsh before skimming past Saturn’s rings on a steadily increasing pitch.