Long perched on the icy edge, Pluto to have its day in the sun

The Washington Post Sunday - - FRONT PAGE - BY JOEL ACHEN­BACH

Pluto is so far away (3 bil­lion miles) and so small (about two-thirds the size of our moon) that we’ve never had a good look at it, not even with the Hub­ble Space Te­le­scope. In Hub­ble im­ages, Pluto has al­ways been a tiny, pix­e­lated blob. Un­til now. A NASA space­ship, New Hori­zons, is bear­ing down on the dwarf planet at 32,000 miles per hour. The ro­botic probe, which weighs half a ton and is shaped like a vac­uum cleaner at­tach­ment, will fly past Pluto, cam­eras and in­stru­ments ravenously gob­bling data, at 7:49 a.m. Eastern time on July 14.

That, at least, is what we can ex­pect to hap­pen given the cur­rent tra­jec­tory of New Hori­zons and the laws of physics. But this is not a mis­sion free of haz­ard. A space­ship trav­el­ing so fast— New

Hori­zons is the fastest space­ship ever launched from Earth — can be dis­abled by a col­li­sion with some­thing as small as a grain of rice.

Pluto had been left out in the cold for decades as NASA probes ex­plored larger and flashier plan­ets. Re­cently, it en­dured a down­grade among astronomers who de­clared that it wasn’t a full-blown planet at all. But it’s def­i­nitely some­thing in­trigu­ing — easily the most fa­mous of the small, icy worlds that in­habit the ex­urbs of the so­lar sys­tem.

“We are run­ning the an­chor leg in a 50-year ex­plo­ration of the plan­ets,” says Alan Stern, the prin­ci­pal in­ves­ti­ga­tor — the leader — of the New Hori­zons mis­sion. “I tell peo­ple, this is it, it’s the last pic­ture show, it’s the last train to Clarksville. Bet­ter watch!”

That’s vintage Alan Stern: He is a tire­less pro­moter of New Hori­zons. You could call Stern “mer­cu­rial” if that weren’t in­ap­pro­pri­ate for a plan­e­tary sci­en­tist fo­cused on Pluto.

In a world in which sci­en­tists tend to speak in jar­gon, and where pro­ject man­agers de­fault to bureaucratese, Stern, 57, a for­mer NASA as­so­ciate ad­min­is­tra­tor who is now at the non­profit South­west Re­search In­sti­tute in Boul­der, Colo., speaks in tweets, news alerts, sound bites, head­lines and pull-quotes.

“This” — he pauses dra­mat­i­cally — “is a mo­ment. Peo­ple should watch it. They should sit their freakin’ kids down and say, think about this tech­nol­ogy. Think about peo­ple who worked on this for 25 years to bring this knowl­edge. . . . It’s a long way to go to the outer edge, the very edge of the so­lar sys­tem.”

32,000 mph How fast the New Hori­zons space­craft is fly­ing.

The head­quar­ters of the New Hori­zons mis­sion is the Johns Hop­kins Univer­sity Ap­plied Physics Lab­o­ra­tory, in Lau­rel, Md. A mu­ral out­side the New Hori­zons mis­sion con­trol room reads “The Year of Pluto.”

Even at the speed of light (186,000 miles per sec­ond), a one-way mes­sage to or from New Hori­zons re­quires a 4.5hour trip. When send­ing a mes­sage, APL tech­ni­cians have to aim where the space­craft will be 4.5 hours in the fu­ture, the way a skeet shooter aims in front of the clay tar­get.

Many peo­ple at APL have been with New Hori­zons since the launch in 2006.

“We know this space­craft very well. It’s our baby,” said Alice Bow­man, the mis­sion oper­a­tions man­ager. “It went through its tod­dler stage where it was a lit­tle ornery.”

The space­craft’s main com­puter re­booted it­self oc­ca­sion­ally. Her team has had to upload cor­rec­tive soft­ware. Even with ad­vanced tech­nol­ogy, she said, “There’s al­ways risks in­volved when you’re send­ing 1’s and 0’s across bil­lions of miles of space.”

Stern keeps on dis­play in his of­fice the Au­gust 1970 is­sue of Na­tional Ge­o­graphic de­scrib­ing a fu­ture “grand tour” of the plan­ets by ro­botic space­craft. An ar­ti­cle fore­told a visit to Pluto in 1986. NASA’s two Voy­ager space­craft car­ried out the grand tour, fly­ing by Jupiter and Saturn, with Voy­ager 2 go­ing all the way to Uranus and Nep­tune, but the best route for study­ing Saturn and its huge moon Ti­tan didn’t per­mit Voy­ager 2 to visit Pluto, Stern said.

More­over, NASA didn’t re­al­ize, when it put to­gether the Voy­ager pro­gram, that there are thou­sands of icy ob­jects be­yond the or­bit of Nep­tune — a re­gion dubbed the Kuiper Belt. The two Voy­ager space­craft turned off their cam­eras once they reached that re­gion of sup­pos­edly empty space, said NASA di­rec­tor of plan­e­tary science Jim Green.

“We be­lieve there are tens of thou­sands of Kuiper Belt Ob­jects,” Green said.

The sci­en­tists be­hind New Hori­zons say the mis­sion will help us un­der­stand the ori­gin and evo­lu­tion of the so­lar sys­tem. Al­ready, the lit­tle space­ship’s long-range cam­era has de­tected in­trigu­ing pat­terns on the sur­face of Pluto that sci­en­tists can­not easily ex­plain.

The tiny world may have moun­tains and val­leys, pos­si­bly frozen meth­ane lakes or even a liq­uid wa­ter ocean far be­neath the frozen sur­face. Or maybe Pluto has no to­pog­ra­phy at all and is just a smooth ball cov­ered in a deep layer of ni­tro­gen slush.

Stern said he be­gan push­ing for a Pluto mis­sion in 1988. NASA con­sid­ered nu­mer­ous pro­pos­als be­fore de­cid­ing in 2001 to go with the New Hori­zons mis­sion, which called for a rel­a­tively in­ex­pen­sive, no-frills space­craft us­ing off-the-shelf tech­nol­ogy.

The probe rode into space one af­ter­noon in 2006 atop an At­las V rocket, reach­ing record­break­ing ve­loc­ity. Be­fore the day was out, it had al­ready flown past the or­bit of the moon.

A grav­ity boost from Jupiter short­ened the trip to Pluto by three years. “You had to hit a lit­tle key­hole in space near Jupiter,” said pro­ject sci­en­tist Hal Weaver.

New-Hori­zons will come within 7,800 miles of Pluto’s sur­face at its clos­est ap­proach. Be­cause of the way the in­stru­ments and the an­ten­nae are con­fig­ured, New Hori­zons can­not ob­serve Pluto and si­mul­ta­ne­ously trans­mit data to Earth. Nor­mally, it does one or the other. But the flyby is so fast, and such a pre­cious op­por­tu­nity, that the space­craft will fo­cus en­tirely on Pluto dur­ing the July 14 en­counter, at the cost of leav­ing the sci­en­tists and engi­neers back home in sus­pense.

Sci­en­tists and prom­i­nent of­fi­cials will have a count­down to the flyby, and they will celebrate at 7:49 a.m. that day, but they won’t know un­til late that evening whether the space­craft sur­vived the en­counter. They’ll get a sim­ple batch of data, ba­si­cally a health re­port, about 9 p.m.

A very bad sce­nario would in­volve red alarms go­ing off.

“The worst case is we don’t hear at all,” Stern said.

His team came up with 249 “con­tin­gen­cies,” or prob­lems, rang­ing from power brownouts on the space­craft to a cat­a­strophic fire at mis­sion con­trol. The big­gest con­cern has been de­bris around Pluto.

Pluto has five moons, the largest of which, Charon, is half Pluto’s size. The four smaller moons of Pluto don’t have much of a grav­i­ta­tional field. When a rock from space strikes one of these moons, de­bris hur­tles into space and goes into or­bit around Pluto and Charon.

“There could be boul­der-sized par­ti­cles strewn all over the place,” Green said.

The sci­en­tists think New Hori­zons will prob­a­bly sail through the Pluto sys­tem with­out any nasty col­li­sions. Prob­a­bly.

“My big­gest worry is some­thing we haven’t thought of,” Stern said.

9 years How long it has taken the space­craft to reach Pluto.

In the early 20th cen­tury, there were only eight known plan­ets, but as­tronomer Per­ci­val Low­ell be­lieved there must be a ninth, “Planet X,” which had per­turbed the or­bit of Nep­tune. Low­ell died be­fore he could find it, and astronomers to­day ques­tion his cal­cu­la­tions.

In 1930, a young as­tronomer named Clyde Tom­baugh, work­ing at the Low­ell Ob­ser­va­tory in Flagstaff, Ariz., stum­bled upon an ob­ject be­yond the or­bit of Nep­tune that was clearly mov­ing with re­spect to the back­ground stars. Tom­baugh’s ob­ject be­came known as Pluto, for the Ro­man god of the un­der­world, with a nod, in the first two letters, to Per­ci­val Low­ell.

Its sta­tus as a planet be­came con­tro­ver­sial a decade ago af­ter astronomers dis­cov­ered that the outer re­gions of the so­lar sys­tem are crowded with icy worlds. Amid a rag­ing de­bate, the In­ter­na­tional As­tro­nom­i­cal Union re­clas­si­fied Pluto as a “dwarf planet.”

NASA’s Jim Green is dis­mis­sive of the con­tro­versy: “That’s nomen­cla­ture. To me, that’s unim­por­tant. What’s im­por­tant is that this is a body well worth go­ing to. It rep­re­sents a brand new fron­tier.”

Does Alan Stern think Pluto is still a le­git­i­mate, no-qual­i­fiers “planet”?

“Of course I do!” Stern said. “It has all the at­tributes of a planet. Screw the astronomers! Would you go to a po­di­a­trist for brain surgery? They don’t know what they’re talk­ing about!”


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