NASA’s New Climate Satellite Hopes to Save Lives — and Maybe the Planet

NASA wants to measure every raindrop and snowflake on Earth. Here’s why that matters.

National Journal
Alex Brown and Reena Flores
Feb. 27, 2014, 5:40 a.m.

The mis­sion for NASA’s shi­ni­est new toy doesn’t sound all that com­pel­ling. The Glob­al Pre­cip­it­a­tion Meas­ure­ment satel­lite “will be used to uni­fy pre­cip­it­a­tion meas­ure­ments made by an in­ter­na­tion­al net­work of part­ner satel­lites,” the space agency says on its web­site. But don’t be fooled by the sci­ence jar­gon; GPM’s mis­sion is su­per­cool — and su­per-im­port­ant.

The satel­lite, a product of NASA’s God­dard Space Flight Cen­ter and the Ja­pan Aerospace Ex­plor­a­tion Agency, will blast off from Tane­g­ashi­ma, Ja­pan, on Thursday af­ter­noon. It’s the corner­stone of a mis­sion to track all pre­cip­it­a­tion on Earth, with real-time meas­ure­ments every three hours. Why that’s mean­ing­ful prob­ably es­capes most of us who haven’t stud­ied the wa­ter cycle since ele­ment­ary school. We’ll let the sci­ent­ists ex­plain.

“Know­ing where, when, and how much it’s snow­ing and rain­ing around the world is ex­tremely im­port­ant for un­der­stand­ing ex­treme events like bliz­zards, or drought in Cali­for­nia, mon­soon rains in Asia,” said Dalia Kirschbaum, GPM’s mis­sion ap­plic­a­tions sci­ent­ist. “So by hav­ing the glob­al pic­ture, all the way from what’s hap­pen­ing in our at­mo­sphere around the plan­et down to what’s hap­pen­ing in my back­yard — it gives us really power­ful in­form­a­tion to tell us about weath­er, about how our cli­mate is chan­ging and how we can im­prove our un­der­stand­ing and mit­ig­a­tion of nat­ur­al haz­ards.”

For ex­ample, NASA satel­lites tracked Hur­ricane Sandy’s makeup in 2012 — un­til it passed Flor­ida and headed north. That’s where it left the range of the Trop­ic­al Rain­fall Meas­ur­ing Mis­sion. That mis­sion is the pre­curs­or to GPM, and gave NASA its first chance to “look three-di­men­sion­ally through storms and look at the ac­tu­al in­tern­al dy­nam­ics and in­tens­ity of a hur­ricane, for ex­ample,” Kirschbaum said. “It gives you a lot of in­form­a­tion about how it might be in­tensi­fy­ing and where it’s go­ing.”

With GPM and its part­ner satel­lites in the sky, that in­form­a­tion will soon be avail­able at every point on the globe. If it works as ex­pec­ted, it will provide more ac­cur­ate mon­it­or­ing of cata­stroph­ic weath­er and bet­ter fore­cast­ing of fu­ture events.

(Cour­tesy of NASA)

“By be­ing able to see ex­actly what’s go­ing on today, that’s how we im­prove our mod­els to fore­cast what will hap­pen to­mor­row,” said Can­dace Carl­isle, the mis­sion’s deputy pro­ject man­ager. “GPM and our part­ner­ship with all of the data from the vari­ous space­craft will in fact help save lives.”

In the long-term, that in­form­a­tion will also help track how cli­mate change is af­fect­ing Earth’s most pre­cious re­source. “[GPM] is crit­ic­al for long-term — what are we look­ing at over time, over dec­ades, how is pre­cip­it­a­tion chan­ging?” Kirschbaum said. “GPM provides that im­port­ant data, that long-term re­cord … to give us that pic­ture, to put data in­to mod­els or com­puter pro­grams that can es­tim­ate where areas might be get­ting wet­ter, where they might be get­ting drier. There’s still a lot of un­knowns about what’s go­ing to hap­pen to our cli­mate sys­tem in a chan­ging cli­mate.”

How im­port­ant is it to know where our wa­ter is go­ing? Its ne­ces­sity for sur­viv­al is ob­vi­ous, but wa­ter’s im­port­ance be­comes mag­ni­fied when you real­ize its com­par­at­ive scarcity. Less than 1 per­cent of the wa­ter on Earth is ac­cess­ible fresh­wa­ter.

For farm­ers in de­vel­op­ing coun­tries or res­id­ents in land­slide- or mon­soon-prone re­gions, un­der­stand­ing its cycle — and how that might change along with the cli­mate — is es­sen­tial for life.

So how does NASA col­lect all this data? GPM uses a pair of in­stru­ments to gath­er both wide-ran­ging and su­per-pre­cise in­form­a­tion. Its mi­crowave im­ager gives sci­ent­ists a two-di­men­sion­al look at a 562-mile swath of Earth. Mean­while, dual-fre­quency pre­cip­it­a­tion radar provides three-di­men­sion­al mod­el­ing; one radar band will cov­er a 152-mile swath, the oth­er will see a nar­row­er 75 miles with­in that. GPM will or­bit 250 miles above Earth.

In ad­di­tion to ex­tend­ing the range from the TRMM mis­sion, GPM will be able to bet­ter de­tect light rain and fall­ing snow. With that pre­ci­sion in­form­a­tion, NASA will be able to make bet­ter use of the oth­er satel­lites in its fleet. When they cross the same weath­er pat­terns, sci­ent­ists can com­pare data — and use it to re­cal­ib­rate the meas­ure­ments it’s get­ting from oth­er satel­lites. “[GPM] crosses over the or­bits of all of the oth­er space­craft,” Carl­isle said. “We’ll have a cal­ib­ra­tion stand­ard for all of the oth­er space­craft in the con­stel­la­tion.”

But be­fore GPM can start send­ing back hy­per-pre­cise data, it will first have to get off the ground. After it leaves the launch­pad and sep­ar­ates from its Ja­pan­ese rock­et, the sci­ent­ists at God­dard will take over. They’re pre­par­ing for a tense couple weeks of put­ting it through its paces, test­ing its in­stru­ments and nav­ig­a­tion.

Thursday’s launch will be the cul­min­a­tion of years of plan­ning, build­ing, and test­ing for NASA’s GPM crew. It’s the largest satel­lite built and as­sembled at the God­dard fa­cil­ity. But sci­ent­ists didn’t take it easy on their biggest toy as they pre­pared it for launch.

First, they put it in a va­cu­um-sealed con­tain­er and heated it to 212 de­grees Fahren­heit. Then they turned the ther­mo­stat down to -320. After that, the sci­ent­ists poun­ded it with elec­tro­mag­net­ic in­ter­fer­ence to make sure its in­stru­ments would still func­tion. A vi­bra­tion test con­firmed its read­i­ness for the shakes of launch. Fi­nally, a ginorm­ous speak­er with a gap­ing mouth the size of a sub­way tun­nel blas­ted it with ex­tremely loud sound.

Only after it passed all those tests was GPM ready to ship to Ja­pan.

In a few days, GPM will start send­ing back its one-of-a-kind data, and the team at God­dard can’t wait — even if they put it in terms that would only ex­cite a NASA sci­ent­ist. “This isn’t just an­oth­er weath­er satel­lite,” Kirschbaum said. “It’s a phys­ics ob­ser­vat­ory in space.”