So how do you send a spacecraft to the sun without broiling it to a cinder?
"We go at night," said Andrew A. Dantzler, project manager for Solar Probe, a new space science mission announced yesterday by the Johns Hopkins University's Applied Physics Lab near Laurel.
That has been the running joke around the lab, Dantzler said. But APL scientists and engineers are perfectly serious about the $750 million NASA-funded mission - the first ever to fly scientific instruments through the sun's million-degree corona and to within 4.1 million miles of its roiling surface.
Launch is planned for 2015, with the craft's first solar flyby just three months later - thanks to a boost from the sun's gravity.
If it succeeds, Solar Probe will fulfill a dream that solar scientists have struggled with for half a century. It could solve critical mysteries about how the sun works and how that affects Earth and everything on it.
"Fifty years ago it was brought up as one of the most important things you could do in heliophysics," Dantzler said. Understanding how the sun affects Earth without understanding the sun's corona is like trying to predict hurricanes without factoring in the ocean. "A hurricane model without the ocean is almost useless," he said.
Solar physicists want this mission to help them answer two of their most vexing questions:
How temperatures in the corona - the sun's outermost atmosphere - can reach more than a million degrees centigrade, while those down on the surface are only around 6,000 degrees.
How the solar wind, which is not very strong near the sun's surface, is accelerated to several million miles per hour as it moves out of the corona and across the solar system.
"The only way we can try to answer this is ... to send a spacecraft into the environment which will actually measure those particles and nail it," said Madhulika Guhathakurta, a scientist in NASA's Living with a Star program.
We need to know, she said, "because we live in the outer atmosphere of the sun, and this environment couples with the Earth's magnetosphere and ionosphere to create space weather, and that is becoming very important."
Solar storms unleash radiation, electrical and magnetic energy on and around Earth that can knock out satellites, threaten humans in space or flying polar air routes, and affect utility grids on the ground.
