Flying in an autonomous mode out of contact with ground controllers, the solar probe was on a trajectory that reached its closest point to the sun at 10:28 p.m. EST Monday (0328 GMT Tuesday), according to NASA.

Parker Solar Probe is circling the sun in an elliptical loop that takes the spacecraft from perihelion — the closest point to the sun which it passed Monday — to a distant point between the orbits of Venus and Earth. The spacecraft's perihelion Monday reached a position less than half the distance from the sun as Mercury.

"You're going into an environment that's completely unforgiving," said Andy Driesman, Parker Solar Probe's project manager at the Johns Hopkins University Applied Physics Laboratory, which built and operates the spacecraft. "The temperatures that we are seeing on the spacecraft have not been seen by any other spacecraft ever before. The first perihelion we're going into, we have very minimal contact. All we can get is a tone."