Tele­scope on jour­ney be­fore mis­sion

NASA’s long-de­layed deep-space diver Webb is clos­ing in on launch

The Washington Post Sunday - - POL­I­TICS & THE NA­TION - BY JOEL ACHEN­BACH joel.achen­bach@wash­post.com

The world’s most ex­pen­sive tele­scope is parked for the mo­ment in Green­belt, Md., shrouded in a pro­tec­tive tent at the NASA God­dard Space Flight Cen­ter. In just two years, this longde­layed, $8 bil­lion, cos­mos-pen­e­trat­ing in­stru­ment is sup­posed to be nearly a mil­lion miles from Earth.

If it works, the James Webb Space Tele­scope will col­lect the old­est light in the uni­verse, emit­ted soon after the big bang, when the first stars lit up and the first gal­ax­ies be­gan to form. It will study black holes lurk­ing at the cen­ter of gal­ax­ies. It will scru­ti­nize the light from plan­ets around dis­tant stars and look for at­mos­pheres you would ex­pect to see on worlds ri­ot­ing with life.

But that’s only after an epic jour­ney. It’s not a straight shot from the Wash­ing­ton sub­urbs to space.

The tele­scope first must be sealed in a cli­mate-con­trolled con­tainer. Then, in late March or early April, a truck will haul it slowly and gen­tly in the dead of night along a par­tially closed Cap­i­tal Belt­way. A lead car will watch for road ob­sta­cles and pot­holes.

Ar­riv­ing at Joint Base An­drews, the Webb should slide, barely, into the cargo hold of a C-5C mil­i­tary trans­port plane.

Then comes a flight to Hous­ton, to the NASA John­son Space Cen­ter, where it will be tested in a vac­uum cham­ber that will sim­u­late the en­vi­ron­ment of deep space. From Hous­ton it will be flown to Los An­ge­les, to a fa­cil­ity run by the project’s pri­mary con­trac­tor, Northrop Grum­man, where it will be mated with its sun shield and nav­i­ga­tional hard­ware.

Then comes a boat ride, one that will carry the tele­scope down the south­west­ern coast of North Amer­ica and through the Panama Canal to French Guiana. That’s where, in Oc­to­ber 2018, it will be blasted into space atop a Euro­pean Ari­ane rocket — a quar­ter-cen­tury after the Webb was con­ceived. What could go wrong? “It’s won­der­ful and ter­ri­fy­ing,” says as­tronomer Heidi Ham­mel of the As­so­ci­a­tion of Uni­ver­si­ties for Re­search in As­tron­omy, one of six sci­en­tists guar­an­teed ob­serv­ing time with the in­stru­ment. “The ter­ri­fy­ing part comes be­cause we know that this is rocket sci­ence for real, we are tak­ing our fab­u­lous tele­scope — it’s a beau­ti­ful ma­chine — and we’re go­ing to put it on a rocket ship and light the fuse.”

As­tronomers have a com­pli­cated and an­guished re­la­tion­ship with the Webb. It’s amaz­ing. It’s also wildly ex­pen­sive. And it was sup­posed to be in space years ago.

John Mather, a No­bel lau­re­ate who is the se­nior project sci­en­tist, be­gan work­ing on it in 1995. He and his team had to achieve a long list of in­no­va­tions to get the Webb built — things such as the gold-cov­ered mir­rors, the sun shield and the means of keep­ing ev­ery­thing very cold.

“This job was just so hard, and when you’re at the be­gin­ning you don’t have the imag­i­na­tion to see how hard it is. No one had ap­pre­ci­ated the dif­fi­culty of the test pro­gram,” he said this week.

Cost over­runs led to bud­get re­views, bat­tles in Congress, near-death ex­pe­ri­ences, re­crim­i­na­tion and, fi­nally, to a re­con­fig­ured bud­get and timetable that law­mak­ers ap­proved. The project de­voured NASA money that might have gone to other sci­ence en­deav­ors. It be­came known as the tele­scope that ate as­tron­omy.

The Webb, which in­cludes ma­jor con­tri­bu­tions from the Cana­dian and Euro­pean space agen­cies, has long been seen as the suc­ces­sor to the Hub­ble Space Tele­scope. The lat­ter is still work­ing fab­u­lously but get­ting long in the tooth.

There have been ru­mors that the Trump ad­min­is­tra­tion could some­how gin up a Hub­ble re­pair mis­sion with as­tro­nauts on a new shut­tle-like space­craft, but of­fi­cials at NASA God­dard say they haven’t been asked to plan for any­thing like that.

The Webb is quite dif­fer­ent from the Hub­ble, start­ing with the fact that it’s much big­ger. The Hub­ble has a 2.4-me­ter mir­ror, but the Webb has 18 hexag­o­nal mir­rors that col­lec­tively are 6.5 me­ters — more than 21 feet — in di­am­e­ter. It can col­lect seven times as much starlight.

The new tele­scope can ob­serve the uni­verse in in­frared wave­lengths of light that are in­ac­ces­si­ble to the Hub­ble. In deep space, shaded from the sun, the Webb is de­signed to op­er­ate un­der ex­tremely cold con­di­tions. That’s nec­es­sary for in­frared as­tron­omy, be­cause oth­er­wise the heat from its in­stru­ments would block out the faint light from dis­tant ob­jects.

As things turned out, the Webb’s prob­lems with sched­ule may have been for­tu­itous.

The orig­i­nal goal was to look at very faint ob­jects in deep­est space — the first stars and gal­ax­ies, so far away that their light, emit­ted about 13.7 bil­lion years ago, is only now reach­ing our so­lar sys­tem. But the Webb may play a key role in the search for hab­it­able worlds that are rel­a­tively nearby, or­bit­ing stars in our own ga­lac­tic neigh­bor­hood.

The first “ex­o­planet” — a planet or­bit­ing an­other star — was dis­cov­ered 22 years ago, right about the time Mather be­gan work­ing on the Webb. Thou­sands of ex­o­plan­ets have been found since.

Ear­lier this week, as­tronomers an­nounced the re­mark­able dis­cov­ery of a sys­tem with seven Earth-size plan­ets around a star named TRAP­PIST 1, about 39 light-years away. Sev­eral have or­bits that might al­low wa­ter, if present, to be liq­uid at the sur­face.

There’s no way for the Webb or any other cur­rent tele­scope to see th­ese plan­ets di­rectly, be­cause they’re too close to the par­ent star. But as they tran­sit the star — pass­ing across the face of the star as seen from the tele­scope — the starlight will dim slightly. That’s how they were dis­cov­ered.

An at­mos­phere around a planet will skew the wave­lengths of the starlight. As­tronomers can then use spec­troscopy to dis­cern which kinds of mol­e­cules make up the ex­o­planet at­mos­phere.

The Hub­ble has looked at the TRAP­PIST sys­tem and al­ready de­ter­mined that the plan­ets are prob­a­bly rocky rather than gaseous like Jupiter or Saturn. But the Webb has so­phis­ti­ca­tion the Hub­ble lacks. The Webb can de­tect the clear sig­na­tures of at­mos­pheres con­tain­ing wa­ter, ozone, oxy­gen, meth­ane and other mol­e­cules. That could pro­vide com­pelling ev­i­dence of a hab­it­able planet.

As as­tro­physi­cist Michelle Thaller of NASA points out, while it wouldn’t be the same thing as di­rect de­tec­tion of life, it would be a ma­jor achieve­ment for the still-young sci­en­tific field known as as­tro­bi­ol­ogy.

Closer to home, the Webb’s prime view­ing tar­gets in­clude the Great Red Spot of Jupiter, Saturn’s in­trigu­ing moon Ti­tan, the dwarf planet Pluto and its moon Charon, plus the gag­gle of “tran­sNep­tu­nian ob­jects” way out in the ex­urbs of the so­lar sys­tem — lit­tle-known worlds such as Sedna, Quaoar and Make­make.

But first the tele­scope, which is sup­posed to be­gin ob­serv­ing in April 2019, has to func­tion as planned. It would be hard to re­pair some­thing parked at L2, the Webb’s des­ti­na­tion point in space, which is 930,000 miles from Earth on the op­po­site side of our planet from the sun.

“I can tell you that we’re do­ing what we need to do to make sure that it’ll work,” Mather said. “You test. And test and test.”

And look for pot­holes along the way — lit­er­ally.

NASA

The James Webb Space Tele­scope is sched­uled to blast into space in 2018, a quar­ter-cen­tury after the $8 bil­lion in­stru­ment was con­ceived.

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