NASA’s mission to the sun
Having successfully sent spacecraft to the moon, Mars, and the distant dwarf planet of Pluto, NASA is now focusing on an even more challenging destination: the sun. Next year, the space agency is planning to send an unmanned probe to within 4_million miles of the star at the center of our solar system—23_mi llion miles closer than any spacecraft has reached before. The probe, Solar Probe Plus, will have a 4.5-inch-thick carboncomposite shield to enable it to withstand solar radiation and temperatures of nearly 2,500 degrees Fahrenheit. The primary goal of the mission is to learn more about the corona, the outermost layer of the solar atmosphere. While the sun’s surface burns at 10,000_degrees, the corona reaches 3.5_million degrees—an enigma that has confounded scientists. “You’d think the farther away you get from a heat source, you’d get colder,” NASA’s Eric Christian tells LiveScience.com. Solar Probe Plus is also expected to shed light on the origins of solar wind—charged particles that flow out of the sun in all directions at a million miles an hour—and why the sun occasionally emits storms of high-energy particles that can endanger astronauts and spacecraft. A separate solar mission, a joint venture between NASA and the European Space Agency, is also scheduled for launch next year.