NASA's Parker Solar Probe, one of the most daring spacecraft in history, reached a major milestone in December 2024. After a flyby just 6.1 million kilometers from the surface of the Sun, a record historic, the probe transmitted its first updates, confirming its proper functioning and the collection of new scientific data.
A record for proximity and speed
On December 26, the Parker probe made a close flyby of the Sun, reaching an unprecedented speed of 690,000 km/h. This impressive record corresponds to traveling from Tokyo to Washington in just one minute. She also broke her own proximity record by coming as close as 6.1 million kilometers of the solar surface, a feat made possible thanks to its innovative design.
To survive these extreme conditions, the probe is equipped with a revolutionary heat shield 4.5 inches thick, capable of withstanding temperatures up to 982°C. Despite the intense heat of the solar corona, Parker managed to transmit a signal confirming its proper functioning shortly after midnight on December 26, relieving and delighting the ground crews.
On January 1, 2025, scientists at the Johns Hopkins University Applied Physics Laboratory then received telemetry data confirming that the probe and its instruments were still in perfect condition. Specifically, the data showed that Parker executed commands that had been programmed into his flight computers before the flyby, and that his scientific instruments were operational during the flyby itself. Confirmation of these updates reassured the ground team and renewed enthusiasm for the discoveries to come.
A look at the mystery of the solar corona
Note that science data transmission will begin later this month, when the spacecraft and its antenna are better aligned with Earth to transmit at higher rates.
This data could help answer more questions. One of the most intriguing phenomena of the Sun is the paradox of the temperature of its crown. Contrary to what one might intuitively think, the visible surface of the Sun, called the photosphere, reaches temperatures of around 5,500°C. However, the Sun's outer atmosphere, or corona, happily exceeds 1 to 2 million degrees Celsius, despite its apparent distance from the main heat source.
This paradox, known as the “corona problem,” has challenged classical models of heat transfer for decades. Scientists suspect that this extreme heat could be linked to specific phenomena such as Alfvén waves, magnetic oscillations that move along the Sun's magnetic field lines, or to rapid magnetic reconnections that release enormous quantities of energy.
-The Parker probe, thanks to its sensitive instruments, is best equipped to directly explore this crucial region of the Sun. By approaching closer than any other spacecraft, it can observe these energetic interactions directly and measure magnetic fields, charged particles and plasma waves in the corona. The data collected could finally make it possible to understand how this energy is transferred and dissipated in the solar atmosphere.
Solar winds: another scientific challenge
Besides the crown, Parker is also looking to clarify how solar winds workthese continuous streams of charged particles ejected by the Sun. These winds, consisting mainly of electrons and protons, travel at speeds of up to 800 km/s, carrying with them an interplanetary magnetic field.
On Earth, solar winds are responsible for spectacular natural phenomena such as the Northern and Southern Lights. However, they can also disrupt satellites, communications networks, and even ground-based power grids. During massive solar flares, intense bursts of these particles can cause geomagnetic storms, putting modern technological infrastructure at risk.
One of Parker's major goals is to study the origins of these solar winds and understand how they accelerate so quickly after leaving the Sun's surface. Researchers also want to determine why some winds are so turbulent, while others maintain a relatively stable structure.
Parker's onboard instruments measure variations in the speed, density and chemical composition of solar winds, providing unparalleled insight into the processes behind these energy flows. The observations will help develop more accurate models to predict solar activity and minimize its potential impacts on human technologies.
Finally, note that Parker's mission is far from over. Two other close flybys are planned for 2025, in March and June. Each close pass promises to enrich our understanding of the Sun and its processes.
