A NASA mis­sion to Jupiter probes Earth’s ori­gins


Smithsonian Magazine - - Features - by Robert Irion

JUPITER GUARDS SE­CRETS about the early so­lar sys­tem,” says Scott Bolton, stand­ing in the cav­ernous and dimly lit mis­sion con­trol room at NASA’s Jet Propul­sion Lab­o­ra­tory in Pasadena, Cal­i­for­nia. “It grabbed most of the left­overs af­ter the Sun formed. When we want to go back and try to un­der­stand how the plan­ets were made—where the stuff that made us came from—Jupiter rep­re­sents that first step.”

Bolton is the lead de­signer and prin­ci­pal in­ves­ti­ga­tor for NASA’s Juno space­craft, cur­rently loop­ing around Jupiter af­ter trav­el­ing nearly two bil­lion miles. The mis­sion’s goal is to un­der­stand the planet’s struc­ture and the amount of wa­ter it con­tains. The re­sults could yield rich new in­sights into how plan­ets are born and how wa­ter ap­peared on Earth.

Bolton’s un­ortho­dox pro­posal got crit­i­cal feed­back at first. Ear­lier mis­sions to the outer so­lar sys­tem were nu­clear-pow­ered, but Bolton’s team de­signed Juno to run on so­lar en­ergy. To pro­tect the space­craft from Jupiter’s ra­di­a­tion—“the throat of hell in our so­lar sys­tem,” in Bolton’s words—they cre­ated an ar­mored vault with more than 400 pounds of ti­ta­nium and crammed in the del­i­cate cir­cuitry Bolton calls Juno’s “cen­tral brain.” To limit the most in­tense ex­po­sure at the equa­tor, Bolton’s team de­signed an el­lip­ti­cal or­bit that races from the north pole to the south pole in just two hours and then ducks below the high-ra­di­a­tion belt. At its clos­est ap­proach, Juno is a mere 3,000 miles above the planet’s cloud tops. For the rest of its 53-day loop, the space­craft cruises mil­lions of miles away from the planet.

Most rad­i­cally, Bolton came up with a new way to solve the ma­jor puz­zle left by the Galileo probe. That ear­lier mis­sion to Jupiter had dropped a lo­cal­ized probe—which meant it may have sam­pled a par­tic­u­larly dry spot and missed more abun­dant wa­ter else­where. This time, in­stead of just mea­sur­ing spe­cific lo­ca­tions, Bolton thought of us­ing mi­crowave ra­diome­ters to es­ti­mate the wa­ter ev­ery­where on Jupiter. The idea was so novel that Bolton’s team had to de­sign a new in­stru­ment and plan a very dif­fer­ent type of mis­sion around this new kind of mea­sure­ment. “I have al­ways had a lit­tle el­e­ment of me that was a rebel,” Bolton says wryly. “I rarely did some­thing be­cause peo­ple said it was the way we al­ways did it.”

Bolton’s fas­ci­na­tion with space emerged in the Apollo era. He was born in 1958, the same year as NASA. He and his pals in the Detroit sub­urbs watched “Star Trek” (“I wanted to be on the En­ter­prise,” he says), and he joined a club where he re­ceived new sci­ence-fic­tion books each month. In the late 1970s, when he was study­ing aero­space en­gi­neer­ing at the Univer­sity of Michi­gan, a speaker from JPL showed the class glo­ri­ous im­ages of Jupiter from the re­cently launched Voy­ager mis­sion. “I was to­tally amazed,” re­calls Bolton. Dur­ing his se­nior year, he was hired by JPL, where he would work on the Galileo mis­sion be­fore com­plet­ing a PhD in as­tro­physics at the Univer­sity of Cal­i­for­nia, Berke­ley.

Juno is only half­way through its planned life­time (it’s sched­uled to dive into the planet in 2021), but it has al­ready up­ended much of the ac­cepted wis­dom. “I’m in to­tal won­der that we could have been so wrong,” Bolton says. Sci­en­tists ex­pected the planet’s fast ro­ta­tion and whirling winds to mix all its gases into a uni­form blend. In­stead, they found that its col­ored bands and long-last­ing storms, such as the Great Red Spot, have

Scott Bolton says he first dreamed of trav­el­ing through the galaxy when he was a boy camp­ing out un­der the stars.

PHYS­I­CALSCIENCESScott BoltonJuno Mis­sion

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