Science and Technology Daily News (Reporter Jie Manbin) On August 7, the reporter learned from the Institute of Modern Physics, Chinese Academy of Sciences that recently, by the Macau University of Science and Technology, China University of Geosciences (Beijing), the Institute of Modern Physics of the Chinese Academy of Sciences, Lanzhou Institute of Space Technology Physics, A research team composed of the University of Science and Technology of China, the University of Alabama at Huntsville, and the National Space Science Center of the Chinese Academy of Sciences obtained the first scientific results using the Tianwen-1 Mars Energy Particle Analyzer. A solar energetic particle event observed in a fire transfer orbit.
The results were recently published in The Astrophysical Journal Letters, and were selected by the American Astronomical Society (AAS) as a highlight work and featured in a special report.
The Mars Energy Particle Analyzer is the first payload in my country to study the interplanetary and near-Mars space radiation environment. It was jointly developed by the Institute of Modern Physics of the Chinese Academy of Sciences and the Lanzhou Institute of Space Technology Physics. It will be mounted on the Tianwen-1 Mars in July 2020. The probe was launched into the sky, officially starting the detection mission.
On November 29, 2020, the Mars Energy Particle Analyzer observed the first large-scale solar energetic particle event of the 25th solar cycle at a ground fire transfer orbit of 1.39 astronomical units (au) from the sun.
At the time of the event, Tianwen-1 and the Earth were approximately on the same magnetic field line, which enabled Tianwen-1 and spacecraft near the Earth to observe solar energetic particles from the same source region at a distance of tens of millions of kilometers. The propagation of energetic particles in interplanetary space along magnetic field lines provides a valuable opportunity.
Understanding the acceleration and propagation mechanism of solar energetic particles has always been one of the important topics in space physics and space weather research.
Once they leave the near-Earth environment and enter space and lose the protection of the Earth's magnetic field, astronauts and spacecraft are bound to be exposed to intense high-energy particle radiation.
Unlike galactic cosmic rays whose fluxes are long-term stable, solar energetic particle events occur sporadically and unpredictably.
The energy particles generated in the eruption of such events usually originate from the shock acceleration process driven by solar flares and coronal mass ejections, and their flux can be several orders of magnitude higher than the background cosmic rays. The environment has a huge impact, and it also poses a huge threat to space missions such as manned spaceflight and deep space exploration.
By comparing and analyzing the proton flux observation data of the Mars Energy Particle Analyzer and the spacecraft near the earth during the event of November 29, 2020, the research team found that the magnetic field lines associated with Tianwen-1 and the spacecraft near the earth were not connected to the surface of the sun The explosion source region and interplanetary shock wave, which means that high-energy particles must cross the magnetic field lines to reach Tianwen-1 and spacecraft near the earth.
In addition, the research team also found that the shapes of the proton energy spectra observed at the two locations are very similar, both showing a double power law spectrum, and their proton intensity time curves also have a similar evolution trend during the decay stage of the solar energetic particle event, showing A typical cistern phenomenon.
The research team believes that the double power-law energy spectrum is likely to be generated in the source region of the shock acceleration, and the vertical diffusion effect during the propagation process is the key factor to explain the reservoir phenomenon in this event.
In addition, the research team also discussed the radial dependence of the peak intensity of solar energetic particle events and the length dependence of magnetic field lines.
In this solar high-energy particle event, the observation data of the Mars Energy Particle Analyzer and the near-Earth spacecraft are very consistent, which shows that the function and performance of the Mars Energy Particle Analyzer are in line with the design expectations, and the data measured by the instrument The quality is reliable, which has laid a good foundation for the follow-up research on Mars circumnavigation data, and is expected to help better understand the Martian radiation environment and plan deep space exploration missions.