Monday, June 16, 2008

Solar probe: into the sun for science

NASA has announced plans to send a spacecraft on repeated forays into the sun.

How are they going to keep it from burning up?

They're going at night.

(Image: false color photo of the sun from the Extreme ultraviolet Imaging Telescope, NASA Goddard Space Flight Center.)

Nah. Couldn't resist, but on the exceedingly slim chance anyone bit, that's a joke.

In fact, the seven-year Solar Probe Plus mission, set to launch in 2015, will use a heavily insulated spacecraft full of instrumentation. It will make repeated passes through the Sun's corona, followed by swings around Venus to gain some gravitational slingshot oomph.

The Johns Hopkins' Applied Physics Lab will design and build the spacecraft. Appropriately, it will use solar panels for its energy, but they'll be liquid cooled, and will retract when it gets too intense out there. The probe will be designed with a carbon composite shield to handle up to 1400 degrees Centigrade. That's significantly hotter than your standard pizza oven, and also hotter than most electronics are made to handle.

At its closest, the probe should be nine times the radius of the sun from the surface—a little more than 4 million miles.

Two key questions about the sun need to be answered, NASA says.

One is why does the temperature rise when you move away from the sun. Another: Where is the start of the solar wind, which sends charged particles blasting through the solar system. It doesn't seem to be actively blowing coherently when you get near the sun.

University of Hawai'i solar astronomer Shadia Habbal, who works at the university's Institute for Astronomy, has been involved in the planning for the mission. Her particular interest, she said, is the source of the solar wind—how it goes from apparently being disorganized near the sun to flowing in a much more organized fashion as it moves out among the planets.

According to NASA's Solar Probe Science and Technology Definition Team Report:

“Solar Probe will be the first spacecraft to venture into the unexplored inner reaches of the heliosphere where the solar wind is born. Through high-cadence in-situ measurements of the solar wind plasma, energetic particles, and fields... supplemented by coronal and photospheric imaging, Solar Probe will provide the data needed to solve, finally, the twin mysteries of coronal heating and solar wind acceleration.”

To learn more about the solar probe, see

© 2008 Jan W. TenBruggencate