NASA spacecraft set for second close encounter with the sun—what it hopes to learn

LOS ANGELES - NASA’s Parker Solar Probe is set to make another daring plunge through the sun’s outer atmosphere, continuing its mission to unlock the secrets of our star. This will be the probe’s second of three planned passes through the solar corona, the superheated outer layer of the sun that remains one of astronomy’s biggest mysteries.

The spacecraft, launched in 2018, is expected to reach record speeds of 430,000 mph (690,000 kph) during its closest approach, making it the fastest human-made object ever built. Since the flyby occurs in an area where real-time communication is impossible, NASA won’t receive data from Parker until Tuesday afternoon.

Why is NASA sending a spacecraft so close to the sun?

The backstory:

The Parker Solar Probe was designed to get closer to the sun than any spacecraft in history. Its mission is to study the solar wind, the continuous stream of charged particles that flows from the sun and affects space weather throughout the solar system.

One of the biggest puzzles Parker hopes to solve is why the sun’s corona is hundreds of times hotter than its surface—a phenomenon that defies conventional physics. By flying directly through this intense region, Parker is gathering data that could help scientists better predict solar storms, which can impact satellites, communication networks, and power grids on Earth.

How close will Parker get to the sun?

By the numbers:

To withstand this extreme environment, Parker is equipped with a 4.5-inch-thick (11.4 cm) carbon-composite heat shield, which keeps its instruments at a safe operating temperature despite the intense heat outside.

• The spacecraft will fly within 3.8 million miles (6 million kilometers) of the sun, much closer than any previous mission.
• It will reach speeds of 430,000 mph (690,000 kph), fast enough to travel from Los Angeles to New York in about 20 seconds.
• The sun’s corona, where Parker is flying, can reach temperatures of several million degrees Fahrenheit.

What scientists hope to learn

What we know:

Previous flybys have already provided unprecedented insights into how solar wind is generated and how the sun’s magnetic field behaves. The latest close encounter will build on that data, potentially offering new clues about:

• Why the corona is so much hotter than the sun’s surface.
• How solar wind is accelerated to supersonic speeds.
• What triggers powerful solar storms that can impact Earth.

What we don't know:

Despite decades of research, scientists still don’t fully understand the mechanisms behind these phenomena. The more Parker Solar Probe can observe, the better researchers can predict and mitigate space weather effects on Earth.

What’s next for the Parker Solar Probe?

What's next:

After this flyby, Parker will make one more close pass through the corona in the coming months before continuing its long-term mission. NASA plans to gradually bring the probe even closer to the sun over time, eventually reaching within 3.83 million miles (6.16 million kilometers) by 2025.

With each encounter, Parker is expected to deliver even more groundbreaking data, helping scientists unravel the mysteries of the sun and improve our ability to predict space weather events.