At the beginning of Christmas in 2024, NASA’s spacecraft flew at high speed through the solar system.
The Parker Solar Probe, equipped with a thermal shield, made the closest approach to our variable star, coming within about 3.8 million miles (6.1 million kilometers) of the star’s surface. That’s seven times closer than any other investigation. The mission is designed to fly into the solar system, or outer space, which generates powerful solar storms and weather that affect Earth.
To understand the behavior of our star, the craft had to go where it had never gone before.
“It’s really exciting,” Nour Raouafi, an astrophysicist at the Johns Hopkins Applied Physics Laboratory and project scientist on the mission, told Mashable. “The sun is like a laboratory for us.”
Although NASA announced the craft made a historic flight on Christmas Eve, the probe will be in a position to send a beacon to Earth on December 27, which will ensure its safety.
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To make this record-breaking pass, the nearly 10-foot-tall probe made 22 orbits around the sun, allowing it to penetrate deeper into the corona. And while we were doing that, the spaceship was picking up speed. When you repeatedly orbit an object so large and powerful – the sun is a sphere of hot gas 333,000 times as hot as our planet – you accumulate a lot of speed. Outside of space, nothing will stop this movement.
On this close flyby, the probe reached about 430,000 kilometers per hour (692,000 kilometers per hour).
“It’s the fastest human-made thing.”
“That’s like going from Philadelphia to Washington, DC in one second,” marveled Raouafi. “It’s interesting. It’s the fastest thing ever.”
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The spacecraft can survive extreme immersion in the corona because it is equipped with a strong heat shield designed to withstand the intense solar radiation. The shield itself, which is 2.4 meters wide and 4.5 inches (about 12 centimeters) thick, heats up to 2,500 degrees Fahrenheit, but just a few meters behind the shield, the surroundings are surprisingly pleasant. The instruments operate below room temperature.
Why did the Parker Solar Probe go into the sun?
In 2022, the probe flew into “one of the most powerful coronal mass ejections (CMEs) ever recorded,” NASA explained. A CME is an explosion of a mass of hot gas (plasma) in the atmosphere.
Raouafi hopes it will happen again. (The sun is at its highest, called solar maximum, so the odds are as good as it gets.)
When the sun emits bursts of energy and particles, the corona accelerates these particles. Such solar storms have major impacts on our power grids and communication systems on Earth, as well as on astronauts in space – especially as NASA prepares to return astronauts to the moon, and eventually, beyond.
“That’s why we want to fly in places where these particles are accelerating,” said Raouafi. “We want to understand how acceleration is done.”
Parker Solar Probe instruments.
Credit: Johns Hopkins APL / NASA
The green lines show the Parker Solar Probe’s path around the sun as of 2018. The green dot shows its position as of Dec. 23, 2024.
Credit: Johns Hopkins APL
Parker solar probe researchers expect that the spacecraft, equipped with instruments to measure and image the solar wind (the continuous stream of charged particles from the corona), will enable us to better predict when and where a powerful CME or solar flare might strike.
For example, if a CME explodes on the surface of the sun, it has to travel more than 92 million miles to reach Earth. Along the way, this hot gas will “stack” the solar wind ahead of it.
“That will affect the time of its arrival on Earth,” explained Raouafi. Information about these atmospheric changes is important: A good atmospheric weather forecast can allow electric utilities to temporarily shut off power to avoid conducting surges from CMEs, potentially knocking out power to millions.
Tragically, in 1989, a powerful CME associated with a solar flare knocked out power to millions in Quebec, Canada. The CME struck the Earth’s magnetic field on March 12 of that year, and NASA astronomer Sten Odenwald wrote, “Just after 2:44 a.m. on March 13, currents detected a weakness in the Quebec power grid. In less than two minutes, all of Quebec’s electricity went out. During the 12-hour blackout that followed, millions of people found themselves in darkened buildings and underground pedestrian tunnels. the elevators stopped.” The same toasted sun event a $10 million transformer at the Salem Nuclear Power Plant in New Jersey.
“We hope to see something that surprises us.”
Following this Christmas Eve visit to the corona, the probe has two passes planned in March and June 2025 that will bring it the same distance to the sun. This is a true experiment in an uncharted territory, a place where scientists are looking for the unexpected.
“I hope we will see something that will surprise us,” said Raouafi.
