On Christmas Eve, NASA’s Parker Solar Probe will approach closer than it ever has to “touching the sun,” getting more than eight times nearer than Mercury does to our central star. Additionally, it will break its own speed record, becoming the fastest human-created object as it swiftly passes our home star.
While the probe will execute a few more final flybys in the next 12 months, it seems improbable that it will get substantially closer than it will on Tuesday.
Parker was launched in 2018 with the intention of gaining a deeper understanding of the sun’s atmosphere, or corona, by navigating through it, a feat the probe successfully accomplished for the first time in 2021. To achieve this, the spacecraft has repeatedly utilized slingshots around our home star, as well as occasionally around Venus, to gain sufficient speed and momentum for progressively closer approaches with each pass. So far, it has successfully completed 21 solar slingshots.
The probe has already reached a proximity to the sun that any other spacecraft in history hasn’t achieved, coming as near as approximately 4.5 million miles (7.2 million kilometers) from our home star during its close encounters in October 2023 and in March this year. Furthermore, it has previously set the record for the fastest human-made object, reaching speeds of about 395,000 mph (635,000 km/h) — roughly 150 times faster than a bullet from a rifle.
However, at 6:53 a.m. EST on Dec. 24, the probe will approach within 3.8 million miles (6.1 million km) of the sun and achieve a maximum speed of roughly 435,000 mph (700,000 km/h), according to NASA. To do so, the craft must withstand temperatures exceeding 2,550 degrees Fahrenheit (1,400 degrees Celsius), a challenge it is expected to meet due to the virtually indestructible heat shield designed to protect the sun-facing side of the probe.
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“This will be an extraordinary accomplishment for all of mankind,” Nour Raouafi, an astrophysicist at the Johns Hopkins University Applied Physics Laboratory and project scientist for the Parker Solar Probe mission, previously stated regarding the impending flyby. “This is akin to the moon landing in 1969.”
Closer than ever
Parker initiated its current trajectory in early November when the probe successfully completed its seventh and final planned slingshot around Venus, as reported by Live Science’s sister site Space.com. This “gravity assist” provided the spacecraft with the final boost it required to eventually surpass its own speed record.
The forthcoming flyby caps off an eventful year for the probe, which has also traversed through a coronal mass ejection (CME) for the first time and contributed to illuminating a long-standing enigma related to how the corona heats itself.
This close approach coincides with the dramatic peak of the sun’s approximately 11-year activity cycle known as solar maximum, which has been ongoing for the majority of this year and is likely to persist well into 2025. Consequently, this close encounter could also allow us to gain further insights into the sun’s magnetic field behavior as it shifts, ultimately enhancing scientists’ capabilities to better forecast space weather that affects Earth.
The Parker Solar Probe is anticipated to execute up to four additional close flybys of the sun in 2025. It may draw slightly nearer to the sun than it does now, but not by a significant amount.
After that, the probe’s thrusters will deplete their fuel, and the majority of the inactive spacecraft will eventually be disintegrated by the sun. Nonetheless, the heat shield might remain in orbit around our home star for thousands of years, Space.com has previously reported.