Plans to send a probe into the Sun’s corona date back to 1958 and the very start of NASA. At the space agency’s inception, a special committee listed 14 different missions that NASA should pursue, including visiting all the planets of the Solar System. All 14 missions have been accomplished in some form apart from one: a probe to visit near the Sun.

Source: NASA’s newest spacecraft will fly through the Sun’s scorching hot atmosphere – The Verge