On Christmas Eve, a spacecraft will approach the Sun like never before, captivating the imaginations of Earth’s inhabitants. On December 24, the Parker solar probe of the NASA passed 3.8 million kilometers from the Sun. This daring maneuver allowed the probe to approach our star seven times closer than all previous missions. While passing through the Sun’s outer atmosphere, known as the corona, Parker reached an unprecedented speed of 430,000 miles per hour, breaking his own record for the fastest speed ever achieved by an object made by the Sun. man.
« It’s a journey of discovery said Nicky Fox, associate administrator of NASA’s Science Mission Directorate. “ We are truly venturing into the unknown. Nothing has flown in a star’s atmosphere, and no other mission will for a long time. »
Since its launch in 2018, the Parker Solar Probe has regularly approached the sun through a series of 21 solar flybys, called perihelions. This mission, a collaboration between NASA and the Johns Hopkins Applied Physics Laboratory, revolutionized our understanding of the Sun, revealing new knowledge about solar winds, magnetic fields and the corona. Along the way, it also provided stunning images, discovered comets and delivered valuable data about Venus.
The technical challenges posed by a flight so close to the Sun are immense. The probe’s heat shield must withstand temperatures of nearly 2,000 degrees Fahrenheit. “ We are convinced that the mission is going very well, and even much better than expected “, declared Nour Raouafi, scientific manager of the project at the applied physics laboratory. “ But this remains a very high-risk mission. Anything can happen at any time. »
During previous journeys, the probe passed through a region called the Alfvén surface, where the solar wind — a stream of charged particles emitted by the Sun — escapes into space. During his 22nd encounter, Parker will dive hundreds of thousands of kilometers deep into a never-before-explored region of the Sun’s atmosphere. This close approach could provide unprecedented insights into the mechanisms that accelerate the solar wind and heat the corona.
« We barely passed this Alfvén point during our previous meetings said Adam Szabo, mission scientist at NASA’s Goddard Space Flight Center. Further exploration could provide valuable data on interacting waves that may help accelerate the solar wind in the solar system.
With the Sun currently in its most active phase, known as solar maximum, the probe could observe spectacular solar events up close. It has already encountered coronal mass ejections (CMEs), massive explosions of plasma and magnetic fields that can have a significant impact on space weather. The mission team hopes that encounters with such phenomena will provide a better understanding of the processes that heat the corona and power the solar wind.
« If the Sun gives us one of those huge explosions, like a coronal mass ejection, when Parker is very close to the Sun, that would be fantastic “, said Dr Raouafi.
The probe will be unreachable until December 27, when it should send a message to Earth to confirm its status. If all goes well, the probe will return observations of this unprecedented close-up in the coming months. Two more perihelions are planned for 2025, and Parker has enough fuel for several more years, although he won’t venture any closer to the Sun.
The mission’s approach to the Sun is the culmination of a vision that dates back to the dawn of the space age. Progress, however, has been delayed for decades due to immense technical challenges, particularly the energy needed to propel a spacecraft so close to our star. Traditional gravity assist maneuvers were insufficient to meet the unique requirements of this mission.
In 2007, Yanping Guo, responsible for mission design and navigation at the Applied Physics Laboratory, imagined a solution: a trajectory comprising seven gravity assist maneuvers from Venus. This innovative approach allowed the probe to gradually change its orbit, getting closer to the Sun with each pass. The mission was eventually named after Eugene Parker, the physicist who first predicted the existence of the solar wind in the 1950s. Parker lived until the launch of his namesake spacecraft, before passing away in 2022 at the age of 94.
Since its launch, the Parker solar probe has made numerous advances. It confirmed the existence of magnetic “switchbacks” — zigzag structures in the solar wind that help propel these charged particles outward. The probe also observed a dust-free zone near the Sun, as predicted by astronomer Henry Norris Russell in 1929.
« By flying so close to the Sun, Parker is now detecting conditions in the magnetism-dominated layer of the Sun’s atmosphere, the corona, that we have never been able to observe before “, said Dr Raouafi. “ We see evidence of our presence in the corona in magnetic field data, solar wind and visually in images ».
In April 2021, during its eighth flyby, the probe crossed the corona for the first time, directly sampling particles and magnetic fields. This milestone marked a major breakthrough for solar science. “ Parker “touching the Sun” is a monumental moment for solar science and a truly remarkable feat said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters. “ Everything we learn about our own star also allows us to learn more about stars in the rest of the universe. »
As it continues its journey, the probe promises to reveal other secrets about the Sun’s atmosphere and its influence on the solar system. Understanding the mechanisms behind solar winds and coronal heating has implications not only for protecting our technology-dependent civilization from space weather phenomena, but also for expanding our knowledge of stellar physics.
« I can’t wait to see what Parker discovers during his repeated stints in the crown in the years to come said Nicola Fox, head of the Heliophysics Division at NASA Headquarters. The potential for new discoveries is enormous, and each pass brings the probe closer to phenomena that were once beyond our reach.
The mission has already provided valuable information on the formation of needles in the solar wind. In recent encounters, the Parker Solar Probe collected data showing that these zigzag magnetic structures originate near the Sun’s surface, in regions called ” magnetic funnels “. This discovery helps scientists understand how the solar wind is heated and accelerated, a mystery that has intrigued researchers for decades.
As Parker gets closer to the Sun on its next flybys, it will have more opportunities to pass through the corona. The size of the corona expands and contracts depending on the solar cycle, and during periods of increased solar activity, the outer edge of the corona extends further into space. The probe therefore has a better chance of staying longer inside the crown and collecting more data.
« This is a very important region to explore, because we believe all kinds of physical phenomena can occur there said Justin Kasper, lead author of a paper on this step published in Physical Review Letters. Exploring this region could provide new insights into how the Sun’s magnetic fields affect the solar wind and contribute to coronal heating.
Parker’s mission has practical implications for life on Earth. By understanding solar phenomena such as coronal mass ejections and solar winds, scientists can better predict space weather phenomena that can disrupt communications, satellite operations, and even power grids.
Although the mission has already yielded significant results, the potential for future discoveries remains high. The probe is equipped to study the Sun’s environment like never before. Each pass brings new data, challenges existing theories and offers the opportunity to closely observe rare solar phenomena.
Dr Raouafi expressed his enthusiasm at the idea of participating in such an innovative mission. “ I wish I could go back, be a kid and start all over again he said, thinking about the future of solar exploration and the advances that await the next generation of scientists.
Barring anything unforeseen, the Parker Solar Probe will continue to advance our understanding of the Sun. His journey represents not only a milestone in human history, but also a beacon for future exploration. This mission testifies to human curiosity and our incessant quest for knowledge about the universe in which we live.
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