On Christmas Eve (Dec. 24), a NASA spacecraft accomplished a milestone by approaching the sun closer than any other spacecraft to date.
This record-setting achievement was performed by the Parker Solar Probe, which flew within 3.8 million miles (6.1 million kilometers) of the sun, enduring the searing temperatures of the star’s outer atmosphere, known as the corona.
The flyby was intended to take place at 6:53 a.m. EST (1153 GMT) and marked the 22nd occasion that Parker had made a close approach to the sun. Although the NASA craft is projected to execute at least two additional flybys of the sun, this is the nearest it has ever and will ever be to the star. Furthermore, we use “intended to” because NASA lost contact with the spacecraft during this flyby; the first confirmation that Parker survived is expected to arrive on Dec. 27, according to the agency.
Parker is accustomed to setting records. On Sept. 21, 2023, Parker reached a velocity of 394,736 miles per hour (635,266 kilometers per hour), solidifying its reputation as the fastest object ever created by humanity.
During its Christmas Eve encounter, researchers believe the sun-sampling spacecraft would have been traveling at 430,000 mph (692,000 kph), once again surpassing its own speed record. For context, that is approximately 300 times swifter than the highest speed of a Lockheed Martin fighter jet on Earth.
This astonishing pace was achievable thanks to the assistance of seven gravitational “boosts” from Venus flybys, with the last one taking place in November 2024.
The Parker Solar Probe pursues its primary mission
However, setting records is merely a secondary outcome of Parker’s primary objective: to gain deeper insights into the sun. Specifically, the spacecraft needed to withstand the sintering heat of 1,800 degrees Fahrenheit (980 degrees Celsius) to gather information regarding the solar corona.
Experts are optimistic that this information can help unravel a long-standing enigma regarding the sun’s outer atmosphere, which has puzzled them for many years. The so-called “coronal heating problem” pertains to the phenomenon where, despite being farther from the sun’s primary energy source (its core), the corona is significantly hotter than the sun’s surface, known as the photosphere.
The prevailing model of stars suggests that the closer one approaches the stellar core, the hotter it becomes, as main sequence stars like the sun perform nuclear fusion to convert hydrogen into helium and release energy.
All layers of the sun seem to stringently adhere to this principle — except the corona, which can soar to temperatures exceeding 2 million degrees Fahrenheit (1.1 million degrees Celsius). Merely 1,000 miles nearer to the heat’s origin, the photosphere manages a relatively mild 7,400 degrees Fahrenheit (4,100 degrees Celsius). That’s akin to discovering this Christmas that your chestnuts only roast when you transport them a mile away from an open flame!
Thus, there must be an additional mechanism heating the solar corona, and researchers are understandably eager to discover what that may be.
Parker will persist in its mission, performing flybys of the sun on March 22, 2025, with its final scheduled flyby occurring on June 19, 2025.
During both of these encounters, the spacecraft will approach the sun almost as closely as it did on Christmas Eve while traveling at a comparable velocity.