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NASA is taking a closer look at the weather. Late this summer, the space agency plans to launch two unusual weather satellites. They won't track tropical storms or cold fronts. They'll be studying weather in space, as NPR's Jon Hamilton reports.

JON HAMIILTON, BYLINE: You may have heard about solar storms because there is weather in space. But it doesn't get much attention until it makes trouble here on Earth. The trouble starts when the sun ejects a massive cloud of particles and energy that heads toward our planet. When the cloud gets close enough, it begins to interact with the Earth's magnetic field. The result can be radiation so intense it threatens anything in orbit.

BARRY MAUK: We have communication satellites. We have navigation satellites in space. Those assets are strongly affected by radiation.

HAMIILTON: That's Barry Mauk from the Applied Physics Laboratory at Johns Hopkins University. Mauk says satellites are especially vulnerable to highly energized electrons and protons.

MAUK: These electrons and protons penetrate the boxes that comprise these spacecraft. They can damage the circuitry. We have had failed spacecraft because of this space weather.

HAMIILTON: It can also cause problems on the ground. Radio signals don't get through. GPS systems fail. Power grids go down. And unfortunately, scientists aren't very good at predicting the impact of space weather. Mauk says one reason is a poor understanding of how solar storms affect the Earth's radiation belts; high-energy particles held in place by the Earth's magnetic field.

MAUK: We do not understand the dynamics of the radiation belts. Sometimes storms cause increases in radiation belts. Sometimes they cause decreases in radiation belts. Sometimes they have no effect at all.

HAMIILTON: Mauk says if scientists can solve this mystery, predicting the impact of space weather could be more like predicting a hurricane's landfall. But to study the problem, scientists need to see what's happening inside the radiation belts as a solar storm arrives. And that's where the new satellites come in.

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HAMIILTON: Jim Stratton is an engineer on the mission. He says the idea is to put the twin spacecraft in an orbit that takes them through the radiation belts, then wait for a solar storm.

JIM STRATTON: When one of these big storms comes in, it can actually change and flex the magnetic field around the Earth. And so, we'll measure that and then we'll see how all of that energy that's coming out of the sun deposits into the Earth's magnetic field, into the radiation belts. And then watch how it changes over time.

HAMIILTON: Ordinary satellites wouldn't survive. So a team at the Applied Physics Lab has spent years designing and building two very tough spacecraft called the Radiation Belts Storm Probes. Stratton has brought be to a place where we can see one of the probes.

STRATTON: It's an octagon, essentially kind of looks a big stop sign. It's about four feet tall. And this is each one of the spacecrafts and they're both the same size.

HAMIILTON: The probe is behind glass in a clean room where technicians are making last minute checks. Stratton says the room protects the satellites' delicate instruments from dust.

STRATTON: You can see everybody is wearing their white lab coats and their hair covers and clean booties and everything.

HAMIILTON: In space, though, the problem won't be dust. It will be high doses of radiation. So the probes were built with heavy shielding to protect electronic components. And they're designed to preserve data gathered by on-board instruments, even if radiation temporarily knocks out the computers.

STRATTON: Most spacecraft try to avoid flying through the radiation belts because radiation is harmful. We're going right into the middle of the environment.

HAMIILTON: Researchers say the mission should improve their understanding of space weather and could help explain the origin of mysterious radiation bursts in distant galaxies.

But all of this depends on getting the probes into orbit and then coaxing them into precisely the right position, one following the other at a specified distance. That's the responsibility of scientists in the Applied Physics Lab's mission control center. Julia Andersen, of the Mission Operations Team, says fine-tuning an orbit is especially tricky when two satellites are involved.

JULIE ANDERSEN: Having two at the same time means you have to have two of everything. In here we've got two separate pits that are set up - one for A, one for B.

HAMIILTON: Andersen says on launch day, those pits will be teeming with scientists and technicians who will take charge of the satellites once they leave the atmosphere.

ANDERSEN: It's always fun knowing that you are in control of a spacecraft.

HAMIILTON: Or in this case, two spacecraft. The probes are scheduled to launch from Kennedy Space Center on August 23rd.

Jon Hamilton, NPR News.

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