For one NASA mission, flying too close to the sun isn’t a concern. It’s the whole point.
On Wednesday, the space agency announced some details about its planned mission to send a robotic spacecraft into the sun’s upper atmosphere, a first for humanity. NASA said it would rename the Solar Probe Plus mission after Eugene Parker, an American astrophysicist who first wrote about the dynamics of solar wind in the 1950s. The Parker Probe Plus is scheduled to launch in summer 2018 to study the sun’s scorching corona, which is hotter than the core itself.
NASA has taken some poetic license by describing it as a mission to “touch the sun,” but it’s certainly close enough. At its closest approach, the spacecraft will fly within 3.9 million miles of the sun’s surface, coasting at about 450,000 miles per hour as it circles the star’s atmosphere.
“The sun doesn’t have a sharp edge, but we’ll be getting into a part of the sun where ‘real action’ takes place,” said Jeff Kuhn, an astronomer at the University of Hawaii who has worked on NASA’s solar observatories for almost 20 years.
The instruments on Parker Probe Plus will investigate the sun’s corona, its outer layer of hot plasma that produces streams of charged particles known as the solar wind. The corona, a white-hot halo around the star, can be imaged by sun-tracking satellites or seen by the naked eye during total eclipses. Temperatures in the corona can exceed 1.8 million degrees Fahrenheit (1 million degrees Celsius), while the photosphere—the visible surface of the sun we can see from Earth—stays comparatively cooler, at 10,000 degrees Fahrenheit (6,000 degrees Celsius). Scientists don’t know why the corona is so hot or how it can eject solar wind at supersonic speed, and they’re hoping Parker Probe Plus will provide some answers.