The Parker Solar Space Probe set out in 2018 to discover one of the last unexplored places in the Solar System: its star. After a year of observations, it revealed, very close to the Sun, an extremely dynamic environment constantly disrupted by material ejections of all sizes. The first results of the mission are the subject of four articles published in the journal Nature on 4 December 2019.
Why is the Sun’s atmosphere two hundred times warmer than its surface? It is one of the greatest mysteries that literally surrounds the Sun. To answer this question, NASA launched the Parker Solar Probe in August 2018 for the closest exploration mission to the Sun ever conducted. Like an interplanetary colon, the probe is currently defying the furnace of the solar corona to conquer new data on the properties of the solar wind, the ionized gas that transports part of the Sun’s magnetic field. When gusts of this wind reach the Earth, they cause aurora borealis, sometimes even power outages or disruptions to GPS systems, upon which autonomous cars and other automated systems will depend in the future. These phenomena are part of space weather like atmospheric weather phenomena. A better understanding of this wind is therefore fundamental to our knowledge of the Sun and to the development of our technologies.
One year after its launch, the mission offers surprising initial results. In particular, the researchers discovered that the solar wind is strongly disrupted by small supersonic plasma jets. These could impact the mechanism of solar wind formation and crown heating.
These early observations also suggest that the dust cloud in orbit around the Sun gradually disappears as it approaches its surface: a result that would confirm a long-standing proposed theory. The discovery of energetic particles emitted and accelerated permanently by small solar storms is also a real surprise: it suggests the existence of a pool of energetic particles around the Sun that could be essential to the formation of very high energy particles that threaten the proper functioning of our satellites and human flights to the Moon or Mars. Finally, these discoveries, although made only on the Sun, are also relevant to better understand other categories of stars. For example, researchers observed a higher than expected rotational speed of the corona around the Sun, which could have an impact on our broader understanding of star rotation.
Thus, the probe already offers several puzzle pieces that will meet the objective of its mission. The twenty-two other passages closer and closer to the star planned for 2025 promise great discoveries.
The five French laboratories involved in the Parker Solar Probe mission are the Institut de recherche en astrophysique et planétologie (CNRS/Université Paul Sabatier Toulouse III/CNES), the Laboratoire d’études spatiales et d’instrumentation en astrophysique (CNRS/Observatoire de Paris/Sorbonne Université/Université de Paris), the Laboratory of Environmental and Space Physics and Chemistry (CNRS/CNES/Université d’Orléans), the Laboratory of Plasma Physics (CNRS/École Polytechnique/Observatoire de Paris/Université Paris-Sud/Sorbonne Université) and the Processes, Materials and Solar Energy Laboratory of the CNRS.
- Alfvénic velocity spikes and rotational flows in the near-Sun solar wind. J. C. Kasper et al., Nature, 4 décembre 2019, Doi: 10.1038/s41586-019-1813-z
- Highly structured slow solar wind emerging from an equatorial coronal hole. S. D. Bale et al., Nature, 4 décembre 2019, Doi: 10.1038/s41586-019-1818-7
- Near-Sun Observations of an F-corona Decrease 1 and K-Corona Fine Structures. R. A. Howard et al., Nature, 4 décembre 2019, DOI 10.1038/s41586-019-1807-x
- Energetic Particle Environment near the Sun from Parker Solar Probe. D.J. McComas et al., Nature, 4 décembre 2019, McComas et al., https://doi.org/10.1038/s41586-019-1811-1
- Alexis Rouillard, firstname.lastname@example.org