A NASA spacecraft aims to fly closer to the sun than any object sent before. The Parker Solar Probe was launched in 2018 to get a close-up look at the sun. Since then, it has flown straight through the sun’s corona: the outer atmosphere visible during a total solar eclipse. The next milestone: closest approach to the sun. Plans call for Parker on Tuesday to hurtle through the sizzling solar atmosphere and pass within a record-breaking 3.8 million miles (6 million kilometers) of the sun’s surface. At that moment, if the sun and Earth were at opposite ends of a football field, Parker “would be on the 4-yard line,” said NASA’s Joe Westlake. Mission managers won’t know how Parker fared until days after the flyby since the spacecraft will be out of communication range. Parker planned to get more than seven times closer to the sun than previous spacecraft, hitting 430,000 mph (690,000 kph) at closest approach. It’s the fastest spacecraft ever built and is outfitted with a heat shield that can withstand scorching temperatures up to 2,500 degrees Fahrenheit (1,371 degrees Celsius).