NASA spacecraft will aim straight for sun

Chicago Tribune

In a space exploration mission 60 years in the making, NASA announced Wednesday that it will send a spacecraft to touch the sun. The mission will bring the craft seven times closer to the sun than any other has come.

Speaking at the University of Chicago, mission project scientist Nicola Fox said the Parker Solar Probe will swoop through the corona — the sun's atmosphere — where temperatures can be up to 3 million degrees Fahrenheit.

Data the probe collects could help researchers find answers to what they say are seemingly simple questions, such as why the corona is hotter than the surface of the sun (a phenomenon that defies the laws of physics) and how solar winds form.

"I think we've really come as far as we can with looking at things," Fox said. "It's now time to go up and pay it a visit."

The Parker Solar Probe is named for Eugene N. Parker, a renowned University of Chicago physicist who wrote a seminal 1958 paper about the sun's corona and coined the term "solar wind."

Wednesday, the 89-year-old Parker was awarded NASA's distinguished public service medal, the highest form of recognition the agency awards to nonemployees, for his lifetime of scientific achievement.

The Parker probe is scheduled to launch July 31, 2018, at NASA's Kennedy Space Center in Cape Canaveral, Fla.

It looks like a short flashlight with an upside-down lampshade where the lightbulb should be. Four long antennas, which emanate from the front of the probe like the spokes of a wheel, will collect data.

Eight weeks after launch, the probe will reach Venus. Often, a spacecraft will use the gravity of another planet to pick up speed and slingshot itself toward its destination. Instead, the probe will use Venus' gravity to slow down and move on a precise path to enter the sun's orbit.

In another eight weeks, the probe will surf around the sun at blistering speeds — about 430,000 mph, or 118 miles a second. A plane moving that fast could travel from New York to Tokyo in less than a minute, according to NASA.

Over the next seven years, the probe will fly past Venus six more times, shaving off speed and tightening its orbit around the sun.

At its closest point, the probe will fly 3.9 million miles from the surface of the sun, in the outermost part of the corona, where the temperature is 2,500 degrees Fahrenheit. That may not sound very close, but if the Earth and the sun were separated by 1 meter, the probe would be 4 centimeters from the sun, Fox said.

In 1976, the Helios 2 spacecraft came within 27 million miles of the sun's surface.

Parker's conception of a solar wind was controversial when his article was published in 1958, but it is now widely understood that the bursts of electrically charged particles are responsible for Earth's dazzling northern lights.

He proposed that "nanoflares," small solar flares all over the sun, with enough abundance, could heat the corona to millions of degrees — up to 450 times hotter than the surface of the sun. Critics argued that his calculations were so simple they could not possibly be correct.

Almost 60 years later, researchers hope the NASA probe will help explain why Parker was right.

"One should proceed with caution, but not with your heels dug in," Parker told the crowd at U. of C. "I am greatly honored to be associated with this heroic scientific mission."

jsteinbauer@chicagotribune.com

Twitter @JamesSteinbauer

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