NASA’s Parker Solar Probe, falling into the inner solar system on its way to repeated close flybys of the Sun, is now closer to Earth’s star than any spacecraft ever built. On 29 October, Parker passed within 42.7 million kilometres (26.55 million miles) of the Sun, beating the previous record set by the Helios 2 spacecraft in 1976.
Parker also eclipsed the Helios 2 speed record of 246,980 kilometres per hour (153,454 miles per hour). If all goes well, the spacecraft will pass within 6.4 million kilometres (4 million miles) of the Sun during its final close approach in 2024.
“It’s been just 78 days since Parker Solar Probe launched, and we’ve now come closer to our star than any other spacecraft in history,” said Project Manager Andy Driesman of the Johns Hopkins Applied Physics Laboratory. “It’s a proud moment for the team, though we remain focused on our first solar encounter, which begins on Oct. 31.”
Launched 12 August from the Cape Canaveral Air Force Station, the Parker Solar Probe flew past Venus six weeks after takeoff, using the planet’s gravity to help slow down and fine-tune the trajectory, setting up the first of seven close-in aim points, a pass within about 24 million kilometres (15 million miles) from the Sun on 31 October.
During each close approach, Parker will fly through the outer regions of the Sun’s outer atmosphere, or corona, enduring heat shield temperatures of up to 1,370 degrees Celsius (2,500 degree Fahrenheit) while whipping past the star at nearly 700,000 kilometres per hour (430,000 mph).
The goal is to study the corona in unprecedented detail to answer a fundamental question about the Sun’s behaviour: what heats the corona to several million degrees hotter than the sun’s visible surface and what accelerates electrically charged particles in the solar wind to enormous velocities.