Nasa scientists and fellow space watchers face a tantalising wait over the Christmas period while the Parker probe continues its unprecedented circuit around the outer rim of the sun.
The craft, which blasted off from Cape Canaveral in Florida on 12 August 2018, sent out a beacon on 22 December to say it was en route to its date with destiny some 6.2 million kilometres from the surface of the sun.
Parker has swept past the star on 21 occasions, edging nearer to pave the way for the closest approach – known as perihelion.
Mission teams on Earth, who have been out of contact with the probe for the past three days, must wait for another beacon on Friday to confirm whether the spacecraft has successfully completed its moment in the sun.
“This is one example of Nasa’s bold missions, doing something that no one else has ever done before, to answer longstanding questions about our universe,” said Arik Posner, the Parker solar probe programme scientist.
“We can’t wait to receive that first status update from the spacecraft and start receiving the science data in the coming weeks.”
Heat
Although the heat shield on the probe will endure temperatures of about 870 to 930 degrees Celsius, its internal instruments will remain near room temperature – 29 degrees C – as it explores the sun's outer atmosphere, called the corona.
Not only will the temperatures be extreme, but Parker will also be moving at around 690,000 kilometres per hour – the fastest any craft has travelled.
"No human-made object has ever passed this close to a star, so Parker will truly be returning data from uncharted territory," said Nick Pinkine, Parker Solar Probe mission operations manager at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland.
"We're excited to hear back from the spacecraft when it swings back around the sun."
By venturing into these extreme conditions during its seven-year mission, Parker will help scientists tackle some of the sun's biggest mysteries: how the solar wind originates, why the corona is hotter than the surface below, and how the corona throws out massive clouds of plasma that hurl through space.
Thierry Dudok de Wit, a professor of space science at the University of Orleans in western France, which developed one of instruments aboard the probe, told RFI: “It’s a general question that not only addresses the sun but also other stars.
"Whenever you venture into such unknown territories, you are likely to make major discoveries. And for that reason, this probe has a major potential as a revolutionary mission."
