After the Parker Solar Probe blasts off from Cape Canaveral, Florida on August 11, it will become the first spacecraft ever to fly through the sun's scorching atmosphere, known as the corona.
Understanding how the corona works will help scientists anticipate dangerous space weather storms, which can disrupt the power grid on Earth.
"It's of fundamental importance for us to be able to predict space weather much the way we predict weather on Earth," explained Alex Young, a solar scientist at NASA.
The corona is a "very strange, unfamiliar environment for us."
The unmanned probe is named after Eugene Parker, the 91-year-old pioneering solar astrophysicist, and the US space agency has coined it as the first mission to "touch the sun."
It will actually skim by at a distance of 6.16 million kilometers above the sun's surface.
Mission managers say that may sound like a lot but is really quite a close shave, given the sweltering conditions out there.
The sun-facing side of the probe will endure temperatures of about 1,370 C.
The spacecraft is protected by a heat shield that will keep it closer to room temperature, about 29.4 C.
Speeding by at a pace of 430,000 miles per hour will make it "the fastest human-made object," said project scientist Nicky Fox of the Johns Hopkins University Applied Physics Lab.
Over the course of its seven-year mission, the spacecraft aims to pass through the corona 24 times, which Fox said makes for an "incredibly daring journey."
The heat from the sun gets more intense further away from its surface.