NASA's Parker Solar Probe to pass Venus on record-breaking approach to the sun

NASA is gearing up for its Parker Solar Probe to do a final flyby of Venus on Wednesday on its way to making history as the closest any human-made object has ever been to the sun.

Parker will use the planet's gravity to alter its speed and direction so that it can enter its final orbit around the sun and break its own record, set just over a year ago.

The probe is expected to pass within an "unprecedented" 3.86 million miles of the solar surface on Dec. 24, according to NASA. At that close distance, "Parker will cut through plumes of plasma still connected to the Sun," NASA says, adding that the probe will be "close enough to pass inside a solar eruption, like a surfer diving under a crashing ocean wave."

"This is a major engineering accomplishment," Adam Szabo, project scientist for Parker Solar Probe at NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in a statement.

The Parker Solar Probe launched Aug. 12, 2018, with the goal of studying the outermost layer of the sun's atmosphere, also known as the outer corona.

During the probe's Dec. 24 close approach, known as perihelion, NASA mission control will be unable to contact Parker for some three days. If successful, the probe will send a beacon tone to the team on Dec. 27, which will also confirm that the probe is functioning properly.

"Parker will remain in this orbit for the remainder of its mission, completing two more perihelia at the same distance," according to NASA.

Throughout its mission, Parker has moved closer to the sun. In October 2018, it broke the record of being the closet human-made object to the sun at 26.55 million miles, a record that was originally set by the Helios 2 spacecraft in 1976. In September 2023, Parker broke its own record when it approached within 4.51 million miles of the sun. The December close approach will be its third record-breaking achievement.

The Venus flyby, which will be Parker's seventh and final flyby of the planet, will also allow NASA scientists to study it even more closely. During the probe's third Venus flyby in July 2020, its camera – the Wide-Field Imager for Parker Solar Probe, or WISPR – captured images of Venus' scorching-hot surface through the thick cloud cover.

"The WISPR cameras can see through the clouds to the surface of Venus, which glows in the near-infrared because it's so hot," Noam Izenberg, a space scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, said in statement.

The team is hoping the Wednesday flyby will provide data that can help distinguish physical or chemical properties of Venus' surface.