NASA to launch Sun-studying satellite

With its Solar Dynamics Observatory (SDO), NASA will probe the Sun in greater detail than ever before and, with luck, begin to answer some of its biggest mysteries.
by: Bill Andrews, Assistant Editor
February 2, 2010

Despite being our planet's nearest star, the Sun can still perplex scientists, who don't understand much of its behavior and its effects on our weather system. NASA plans to launch a satellite February 9 that will gather more data than ever before about the Sun and — scientists hope — begin to provide answers.

Taking off on an Atlas V rocket, the Solar Dynamics Observatory (SDO) will observe the Sun's atmosphere and inner workings with more precision than ever before, including collecting 60 images a minute with 10 times the resolution of high-definition television. It will be the first mission of NASA's Living With a Star Program.

"SDO will take full-disk, high-definition images of the Sun all of the time," says project manager Liz Citrin at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "These advances will provide the data to better understand how the Sun works and will allow us to develop the tools to predict its behavior."

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New Space Telescope to Target Sun Storms

While astronomers gaze at stars farther and farther out in the heavens, some scientists want to take a closer look at the star closest to us: the sun.

NASA plans to launch a new spacecraft, the Solar Dynamics Observatory (SDO), to take the most detailed observations ever of the sun to understand its complex weather and storms.

"The sun changes every time we look at it, [it] is never the same," said Dean Pesnell, SDO project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md., in a Thursday briefing.

Scientists hope data from the new probe will help them understand changes in the sun's magnetic field, which gets more and less active on an 11-year cycle, sending out periodic flares of charged particles that can disrupt technology on Earth.

The $808 million spacecraft is slated to launch Feb. 9 at 10:36 a.m. EST (1536 GMT) atop an Atlas V rocket from Cape Canaveral, Fla.

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Published By SPACE.com
Article By Clara Moskowitz
SPACE.com Staff Writer
posted: 21 January 2010
05:19 pm ET

Register for the NASA SDO Goddard Tweetup

SDO is GO for Launch! Come to Goddard Space Flight Center in Greenbelt, Md., to watch the Solar Dynamics Observatory launch into space. Meet scientists and engineers, tour the cleanroom where SDO was built, and connect with common minds. Fifteen lucky Tweeps will be selected to join SDO scientists, engineers and invited guests at NASA's Kennedy Space Center in Florida to watch SDO ride a rocket into orbit and begin a new era in Heliophysics, the study of our sun and its effects on Earth and the solar system.

Can't make it? Launch your own tweetup. Take over your classroom, local library or your neighbor's house to celebrate this event.

Click here to learn more.

Can a lull in solar activity head off climate change?

It might help but don't expect it to last, scientists say - the sun isn't the real issue



CAMBRIDGE - Old Sol these days is showing a strikingly bland face, one nearly unmarred by the usual wild magnetic storms, whipsawing coronal loops, and fiery plasma ejections

"The sun is in the pits of the deepest solar minimum in almost 100 years," said Madhulika Guhathakurta, lead program scientist for NASA's Living With A Star program, whose focus is solar variability and its effects on the earth.

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New Space Telescope to Watch the Sun

A new solar telescope, scheduled to launch this winter, will probe the sun's atmosphere and inner workings, helping scientists better understand how solar storms.

During its five-year mission, the Earth-orbiting Solar Dynamics Observatory (SDO) will seek to reveal how the sun's magnetic field works, what governs the ups and downs of the solar cycle and how solar activity affects Earth.

"The sun is a magnetic variable star that fluctuates on times scales ranging from a fraction of a second to billions of years," said Madhulika Guhathakurta, lead program scientist for the Living With a Star program (of which SDO is a part) at NASA Headquarters in Washington, D.C. "SDO will show us how variable the sun really is and reveal the underlying physics of solar variability."

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Solar Dynamics Observatory investigates the Sun's cycle of highs and lows

This is the first mission of NASA's Living With a Star program, which seeks to reveal how solar activity is generated and to understand the causes of solar variability and its impact on Earth.



How intense will the next solar cycle be? Can we predict when a violent solar storm will blast Earth with energetic particles? Could a prolonged period of inactivity on the Sun plunge Earth into a prolonged winter? These are a few of the questions that scientists anticipate the new Solar Dynamics Observatory (SDO) will help to answer.

Scheduled to launch this winter on an Atlas V rocket, SDO will peer into the Sun's atmosphere and probe the Sun's inner workings. SDO is the first mission of NASA's Living With a Star program, which seeks to reveal how solar activity is generated and to understand the causes of solar variability and its impact on Earth.

"Contrary to popular belief, the Sun is a magnetic variable star," Says Madhulika Guhathakurta, lead program scientist for Living With a Star at NASA Headquarters, Washington. "SDO will show us just how variable the Sun really is and will reveal the underlying physics of solar variability."

To accomplish the ambitious goals of the science team, "SDO will take full-disk, high-definition images of the Sun all of the time," says project manager Liz Citrin at NASA's Goddard Space Flight Center, Greenbelt, Maryland. Previous missions could not capture images at as rapid a cadence as SDO will, nor did they have the bandwidth to transmit all of the data back to Earth for processing. "These advances will provide the data to better understand how the Sun works and will allow us to develop the tools to predict its behavior."

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EVE: Measuring the Sun's Hidden Variability

Every 11 years, the sun undergoes a furious upheaval. Dark sunspots burst forth from beneath the sun's surface. Explosions as powerful as a billion atomic bombs spark intense flares of high-energy radiation. Clouds of gas big enough to swallow planets break away and billow into space. It's a flamboyant display of stellar power.

So why can't we see any of it?

Almost none of the drama of Solar Maximum is visible to the human eye. Look at the sun in the noontime sky and—ho-hum—it's the same old bland ball of light.

"The problem is, human eyes are tuned to the wrong wavelength," explains Tom Woods, a solar physicist at the University of Colorado in Boulder. "If you want to get a good look at solar activity, you need to look in the EUV."

EUV is short for "extreme ultraviolet," a high-energy form of ultraviolet radiation with wavelengths between 1 and 120 nanometers. EUV photons are much more energetic and dangerous than the ordinary UV rays that cause sunburns. Fortunately for humans, Earth's atmosphere blocks solar EUV; otherwise a day at the beach could be fatal.

When the sun is active, solar EUV emissions can rise and fall by factors of hundreds to thousands in just a matter of minutes. These surges heat Earth's upper atmosphere, puffing it up and increasing the air friction, or "drag," on satellites. EUV photons also break apart atoms and molecules, creating a layer of ions in the upper atmosphere that can severely disturb radio signals.

To monitor these energetic photons, NASA is going to launch a sensor named "EVE," short for EUV Variability Experiment, onboard the Solar Dynamics Observatory this winter.

"EVE gives us the highest time resolution and the highest spectral resolution that we've ever had for measuring the sun, and we'll have it 24/7," says Woods, the lead scientist for EVE. "This is a huge improvement over past missions."

Although EVE is designed to study solar activity, its first order of business is to study solar inactivity. SDO is going to launch during the deepest solar minimum in almost 100 years. Sunspots, flares and CMEs are at a low ebb. That's okay with Woods. He considers solar minimum just as interesting as solar maximum.

"Solar minimum is a quiet time when we can establish a baseline for evaluating long-term trends," he explains. "All stars are variable at some level, and the sun is no exception. We want to compare the sun's brightness now to its brightness during previous minima and ask: is the sun getting brighter or dimmer?"

The answer seems to be dimmer. Measurements by a variety of spacecraft indicate a 12-year lessening of the sun's "irradiance" by about 0.02% at visible wavelengths and 6% at EUV wavelengths. These results, which compare the solar minimum of 2008-09 to the previous minimum of 1996, are still very preliminary. EVE will improve confidence in the trend by pinning down the EUV spectrum with unprecedented accuracy.

The sun's variability and its potential for future changes are not fully understood—hence the need for EVE. "The EUV portion of the sun's spectrum is what changes most during a solar cycle," says Woods, "and that is the part of the spectrum we will be observing."

Woods gazes out his office window at the Colorado sun. It looks the same as usual. EVE, he knows, will have a different story to tell.