NASA’s Parker Solar Probe has done something no spacecraft had managed before: fly directly into the outer atmosphere of a star and survive the trip. On its closest orbits, the probe swoops within a few million miles of the sun’s visible surface at speeds no human-made object has ever reached, gathering direct measurements of the solar wind and corona that ground-based telescopes and even other spacecraft farther away simply cannot capture.
A Seven-Year Plan to Get Close to a Star
Parker Solar Probe launched on August 12, 2018, aboard a Delta IV Heavy rocket, one of the most powerful launch vehicles ever flown, because reaching a tight solar orbit takes roughly 55 times more energy than reaching Mars. Any spacecraft leaving Earth starts out moving sideways at about 67,000 miles per hour along with the planet, and shedding that sideways speed is what actually lets a probe fall closer to the sun.
Rather than shedding all of that speed at launch, engineers built the mission around seven separate flybys of Venus, using each pass’s gravity to bend and shrink the probe’s orbit a little further. The first of those flybys came on October 3, 2018, and each subsequent one dragged the spacecraft’s closest approach to the sun down to a fraction of its starting distance, letting Parker reach its final, tightest orbit using only the fuel it carried at launch.
Setting the Record for Closest Approach to the Sun
Parker Solar Probe broke its first distance record on October 29, 2018, passing closer to the sun than Germany and the United States’ Helios 2 spacecraft had in 1976, and it kept breaking its own record on nearly every orbit since. By its 17th close approach, in September 2023, the probe had closed to about 4.51 million miles from the solar surface; on its final planned approach, reached on December 24, 2024, it came within roughly 3.8 million miles, the closest any human-made object has ever traveled to a star.
According to NASA’s own mission overview, the spacecraft has continued repeating that same record-setting distance on subsequent orbits, treating what was once a single historic milestone as its new routine closest approach. Mission updates describe the probe confirming its own safe passage through a brief radio beacon after each encounter, since the pass itself makes real-time communication with Earth impossible.
Moving Faster Than Anything Else Humans Have Built
Closing in on the sun also means falling under the pull of its enormous gravity, and Parker Solar Probe’s speed during its closest passes reflects that: up to 430,000 miles per hour, fast enough to travel from New York to Tokyo in under a minute. That speed makes it the fastest human-made object ever recorded, well ahead of any previous spacecraft, including missions that covered far greater total distances but never accelerated to comparable velocities.
The spacecraft’s builders at the Johns Hopkins Applied Physics Laboratory, which designed and operates the mission for NASA, described the achievement as a genuine engineering milestone in its own right, separate from the scientific data the close pass produced. A mission update from the laboratory noted that both the distance and speed records were set on the same encounter, underscoring how tightly linked the two figures are for any object orbiting this close to a star.
Surviving Heat That Would Destroy Most Spacecraft
Flying this close to the sun exposes the probe’s sun-facing heat shield to temperatures reaching roughly 2,500 degrees Fahrenheit, hot enough to melt most conventional spacecraft materials outright. Engineers addressed the problem with a custom carbon-composite shield made of foam sandwiched between two carbon plates, positioned to cast a protective shadow over the instruments and electronics mounted behind it.
That design keeps the spacecraft’s sensitive components at a comparatively mild 85 degrees Fahrenheit even while the shield itself absorbs the brunt of the sun’s heat, a combination that lets Parker Solar Probe operate its scientific instruments normally during the very passes that subject it to the harshest conditions any NASA spacecraft has ever been built to survive. A water-based cooling loop protects its retractable solar panels the same way, circulating a single gallon of water to draw heat away from the arrays before it radiates back into space.
Why Getting This Close to the Sun Matters
The mission is named for Eugene Parker, the physicist who first predicted the existence of the solar wind, the constant stream of charged particles flowing outward from the sun, in 1958, decades before any spacecraft could confirm it directly. Parker’s namesake mission, described on its project page, was the first NASA spacecraft named for a living scientist; Parker himself watched the 2018 launch in person and died in 2022 at age 94.
Measuring the solar wind and the sun’s corona directly, rather than from a distance, helps researchers understand the processes that drive space weather, the flares and eruptions capable of disrupting satellites, radio communications, and power grids on Earth. Data gathered on these closest approaches is expected to keep improving forecasts of that space weather for years after the mission’s primary observing campaign wraps up.
This article was produced with the assistance of AI and reviewed by Morning Overview editors.
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