United Launch Services of Centennial, Colo., has been selected by NASA to launch the Solar Probe Plus (SPP) mission after winning a $389.1 million contract, according to a press release from NASA. The spacecraft will launch aboard a Delta IV Heavy rocket in July 2018 at the start of a 20-day launch period.

SPP will be the first spacecraft to fly through the sun's outer atmosphere and will strive to answer two questions that have been a top goal for more than 50 years:

1.   Why is the corona so much hotter than the sun's surface?

2.   What accelerates the solar wind that affects Earth and our solar system?

SPP will orbit the sun 24 times, getting as close as 3.9 million miles of the sun's surface with the aid of seven Venus flybys, according to the press release.

The Launch Services Program at NASA's Kennedy Space Center in Florida is responsible for management of the Delta IV Heavy launch services for SPP. The Johns Hopkins University Applied Physics Laboratory, managed by NASA's Goddard Space Flight Center in Greenbelt, Md., is designing and building the spacecraft for NASA's Living with a Star Program.