Mission to the sun

An ambitious project to cruise through the sun's high-temperature corona has taken a significant step forward. The National Aeronautics and Space Administration has given the green light to develop the $750 million mission that would launch an unmanned spacecraft by 2015. Its goal is to gather up-close data that will help scientists figure out the structure and motions of the sun's magnetic fields, the source and behavior of the energy that heats particles in the corona to between 1 million and 2 million degrees F., and how the charged particles that make up the solar wind are generated and hurtled into space.

The project is one of several US and European missions over the next decade or so to help scientists understand the sun's activity and turn that knowledge into better space-weather forecasts. It also represents an enormous technological challenge. The spacecraft must be engineered to withstand temperatures reaching 2,700 degrees F. and it must survive an environment where it will face intense radiation and high-energy dust particles. NASA has selected the Applied Physics Laboratory at the Johns Hopkins University to design and build the craft.