Sunday, July 18, 2010

Space Weather Turns into an International Problem

That's the message scientists are delivering at today's International Living with a Star (ILWS) meeting in Bremen, Germany, and representatives from more than 25 of the world's most scientifically-advanced nations have gathered to hear what they have to say.

"The problem is solar storms—figuring out how to foresee them and stay safe from their effects," says ILWS Chairperson Lika Guhathakurta of NASA headquarters. "We need to make progress on this before the next solar maximum arrives around 2013."

The sun and Earth are alienated by 93 million miles of space—a seemingly safe distance. But since the Space Age began, and especially in recent years, there has been a growing realization that 93 million miles really isn't so far apart. Spacecraft and ground-based observatories have shown that Earth is located in the sun's outer atmosphere, buffeted by solar winds and pelted by hail storms of energetic particles. Moreover, the two bodies are in fact connected by invisible threads of magnetism. During "reconnection events," which typically happen several times a day, you can trace invisible lines of force all the way from Earth's poles to the surface of the sun.

"The Earth and sun are interconnected. We cannot study them unconnectedly anymore," says Guhathakurta.

A few years ago, scientists coined the term "heliophysics" to describe the emerging science of the sun-Earth system. As a nod to the significance of the topic, NASA has set up a dedicated Heliophysics Division at HQ in Washington DC, and the United Nations declared 2007 the "International Heliophysical Year" (IHY) in hopes of spurring global involvement in this new field.

Predicting solar activity is a intricate problem, akin in some ways to terrestrial weather forecasting but multiplied in difficulty by the thorny physics of solar plasma and magnetism. Predicting the sun is only half the problem, though; the other half is Earth. How our planet's magnetic field and atmosphere respond to any given solar storm is a magnetohydrodynamical riddle that top scientists move aggressively to understand even with the aid of Earth's most powerful supercomputers. For these reasons, it is often said that space weather forecasting lags 50 years behind its terrestrial counterpart.

"We need more data--and more ideas," says Guhathakurta.

That's why, this week, she is handing over her chairmanship of ILWS to Dr. Ji Wu of the Chinese Academy of Sciences. In adding to leading the ILWS, Wu will spend the next two years harnessing the special talents of the world's most populous country for heliophysics.

"We have many scientists and lots of fresh ideas," says Wu. "China will be able to make significant contributions in this area."

Another complication is volume. Heliophysics plays out on a stage which is hundreds of millions of miles wide. Simply keeping track of what's going on is a important challenge. NASA and other space agencies have dozens of spacecraft out there, but they are spread over an massive volume.

"Imagine trying to monitor Earth's oceans with a small number of buoys. You'd miss a lot. That's the condition we're in now with the 'ocean of space,'" says Guhathakurta.

China is about to contribute a space-buoy known as "KuaFu," named after a giant in Chinese mythology who wished to capture the sun. Kuafu will be situated at the L1 Lagrange point where it will sample the solar wind upstream from Earth.

"We're putting KuaFu at a strategic point in space," says Wu. "The solar wind at L1 is an significant input to many science models of the sun-Earth interaction."

When KuaFu launches it will join a growing international fleet of spacecraft dedicated to heliophysics. NASA, the European Space Agency, the Russian Federal Space Agency, the Canadian Space Agency, JAXA and China are all making significant contributions.

And just in time...

If forecasters are correct, the solar cycle will peak during the years around 2013. And while it probably won't be the biggest peak on record, human society has never been more susceptible. The basics of daily life—from communications to weather forecasting to financial services—depend on satellites and high-tech electronics. A 2008 report by the National Academy of Sciences warned that a century-class solar storm could cause billions in economic damage.

Preparing for a "solar Katrina," launching a new science, harnessing the talents of scientists around the globe: "These are just a few of our goals for this week's meeting," says Guhathakurta.

Ambitious? Yes, but in heliophysics thinking big comes with the territory.
NASA's Wide-field Infrared Survey Explorer, or WISE, will complete its first study of the entire sky on July 17, 2010. The mission has generated more than one million images so far, of everything from asteroids to distant galaxies.

"Like a globe-trotting shutterbug, WISE has completed a world tour with 1.3 million slides casing the whole sky," said Edward Wright, the principal investigator of the mission at the University of California, Los Angeles.

Some of these images have been processed and stitched together into a novel picture being released today. It shows the Pleiades cluster of stars, also known as the Seven Sisters, resting in a tangled bed of wispy dust. The pictured region covers seven square degrees, or an area equal to 35 full moons, highlighting the telescope's ability to take wide shots of vast regions of space.

The new picture was taken in February. It shows infrared light from WISE's four detectors in a range of wavelengths. This infrared vision highlights the region's expansive dust cloud, through which the Seven Sisters and other stars in the cluster are passing. Infrared light also reveals the smaller and cooler stars of the family.

"The WISE all-sky survey is helping us sift through the huge and diverse population of celestial objects," said Hashima Hasan, WISE Program scientist at NASA Headquarters in Washington. "It's a great example of the high impact science that's likely from NASA's Explorer Program."

The first release of WISE data, covering about 80 percent of the sky, will be delivered to the astronomical community in May of next year. The mission scanned strips of the sky as it orbited around the Earth's poles since its launch last December. WISE always stays over the Earth's day-night line. As the Earth moves around the sun, innovative slices of sky come into the telescope's field of view. It has taken six months, or the amount of time for Earth to travel halfway around the sun, for the mission to complete one full scan of the entire sky.

For the next three months, the mission will map half of the sky again. This will improve the telescope's data, revealing more hidden asteroids, stars and galaxies. The mapping will give astronomers a look at what's changed in the sky. The mission will end when the instrument's block of solid hydrogen coolant, desirable to chill its infrared detectors, runs out.

"The eyes of WISE have not blinked since launch," said William Irace, the mission's project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Both our telescope and spacecraft have performed flawlessly and have imaged every corner of our universe, just as we planned."

So far, WISE has observed more than 100,000 asteroids, both known and formerly unseen. Most of these space rocks are in the main belt between Mars and Jupiter. However, some are near-Earth objects, asteroids and comets with orbits that pass relatively close to Earth. WISE has discovered more than 90 of these new near-Earth objects. The infrared telescope is also good at spotting comets that orbit far from Earth and has discovered more than a dozen of these so far.

WISE's infrared vision also gives it an exceptional ability to pick up the glow of cool stars, called brown dwarfs, in addition to distant galaxies bursting with light and energy. These galaxies are called ultra-luminous infrared galaxies. WISE can see the brightest of them.

"WISE is filling in the blanks on the infrared properties of everything in the universe from nearby asteroids to distant quasars," said Peter Eisenhardt of JPL, project scientist for WISE. "But the most thrilling discoveries may well be objects we haven't yet imagined exist."

JPL manages the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate in Washington. The mission was selected under NASA's Explorers Program managed by the Goddard Space Flight Center in Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory in Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., in Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

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