The Parker Solar Probe is making history as it plunges into the Sun’s outer atmosphere, enduring extreme temperatures and intense radiation. During this daring fly-by, the spacecraft will be out of communication for several days, with scientists awaiting a crucial signal on 28 December at 05:00 GMT to determine if it has survived.

The mission aims to unlock new insights into how the Sun functions. Dr Nicola Fox, head of science at NASA, explained to BBC News: “For centuries, people have studied the Sun, but you don’t truly understand the atmosphere of a place until you visit it. We can’t experience the atmosphere of our star unless we fly through it.”

Launched in 2018, the Parker Solar Probe is journeying toward the heart of our solar system. It has already completed 21 orbits of the Sun, steadily getting closer, but the Christmas Eve fly-by marks a new milestone. At its closest approach, the probe will be just 3.8 million miles (6.2 million km) from the Sun’s surface.

Although this distance may seem vast, Dr Fox put it into perspective: “We are 93 million miles away from the Sun, so if the Sun and Earth were one metre apart, the Parker Solar Probe would be just four centimetres away – that’s incredibly close.”

The spacecraft will face temperatures of 1,400°C and radiation intense enough to potentially damage its onboard electronics. However, it is shielded by a 11.5cm (4.5 inches) thick carbon-composite shield, and the spacecraft’s strategy is to pass through quickly. Moving at a staggering speed of 430,000 mph – the equivalent of flying from London to New York in less than 30 seconds – Parker Solar Probe takes advantage of the immense gravitational pull as it falls towards the Sun.

The mission’s purpose is to uncover the mysteries of the Sun’s outer atmosphere, or corona. Dr Jenifer Millard, an astronomer at Fifth Star Labs in Wales, explained: “The corona is extremely hot, but we have no idea why. The surface of the Sun is around 6,000°C, yet the corona reaches millions of degrees – and that’s further away from the Sun. So how is its outer atmosphere heating up?”

The spacecraft’s journey will also help scientists better understand the solar wind – the constant stream of charged particles bursting from the corona. These particles create stunning auroras when they interact with Earth’s magnetic field, but they can also disrupt power grids, electronics, and communication systems, making the study of space weather vital.

“Understanding the Sun, its activity, space weather, and the solar wind is crucial to our everyday lives on Earth,” Dr Millard added.

With the spacecraft out of contact over Christmas, NASA scientists are nervously awaiting news of its survival. Dr Fox revealed that as soon as a signal is received, the team will send her a green heart emoji to confirm the probe’s safety. While acknowledging the anxiety of the moment, she expressed confidence in the spacecraft’s resilience: “I will worry about the spacecraft, but we’ve really designed it to withstand these brutal conditions. It’s a tough, tough little spacecraft.”

If the Parker Solar Probe survives this unprecedented challenge, it will continue its mission to explore the Sun’s mysteries, pushing the boundaries of scientific knowledge.