Development of High-energy Particle Detectors for Space Exploration

Space environment exploration is a hot topic globally.The scope of space exploration ranges from near-Earth space to the moon,other planets in the solar system,and even the heliosphere and interplanetary space.It is used for various crucial applications,including aerospace technology development,space weather research,understanding the origin and evolution of the universe,searching for extraterrestrial life,and finding human livable places.Although China’s space environment exploration started late,its progress has been rapid.China is gradually narrowing the gap with advanced countries and may eventually lead the world in space research.This article briefly reviews the development history of China’s space environmental detectors.

Proton pitch angle distributions in the Martian induced magnetosphere: A survey of Tianwen-1 Mars Ion and Neutral Particle Analyzer observations

The pitch angle distributions of ions and electrons can be affected by various processes;thus,they can serve as an important indicator of the physical mechanisms driving the dynamics of space plasmas.From observations from the Mars Ion and Neutral Particle Analyzer onboard the Tianwen-1 orbiter,we calculated the pitch angle distributions of protons in the Martian induced magnetosphere by using information from the magnetohydrodynamically simulated magnetic field,and we statistically analyzed the spatial occurrence pattern of different types of pitch angle distributions.Even though no symmetrical features were seen in the dataset,we found the dominance of the field-aligned distribution type over the energy range from 188 to 6232 eV.Maps of the occurrence rate showed the preferential presence of a trapped-like distribution at the lower altitudes of the surveyed nightside region.Although our results are more or less restricted by the adopted magnetic field,they indicate the complexity of the near-Mars proton pitch angle distributions and infer the possibility of wave–particle interactions in the Martian induced magnetosphere.

Thermosphere joint observations by TM-1 constellations and Swarm-B during the April 2023 geomagnetic storm

The response of thermosphere density to geomagnetic storms is a complicated physical process.Multi-satellite joint observations at the same altitude but different local times(LTs)are important for understanding this process;however,until now such studies have hardly been done.In this report,we analyze in detail the thermosphere mass density response at 510 km during the April 23−24,2023 geomagnetic storm using data derived from the TM-1(TianMu-1)satellite constellation and Swarm-B satellites.The observations show that there were significant LT differences in the hemispheric asymmetry of the thermosphere mass density during the geomagnetic storm.Densities observed by satellite TM02 at nearly 11.3 and 23.3 LTs were larger in the northern hemisphere than in the southern.The TM04 dayside density observations appear to be almost symmetrical with respect to the equator,though southern hemisphere densities on the nightside were higher.Swarm-B data exhibit near-symmetry between the hemispheres.In addition,the mass density ratio results show that TM04 nightside observations,TM02 data,and Swarm-B data all clearly show stronger effects in the southern hemisphere,except for TM04 on the dayside,which suggest hemispheric near-symmetry.The South-North density enhancement differences in TM02 and TM04 on dayside can reach 130%,and Swarm-B data even achieve 180%difference.From the observations of all three satellites,large-scale traveling atmospheric disturbances(TADs)first appear at high latitudes and propagate to low latitudes,thereby disturbing the atmosphere above the equator and even into the opposite hemisphere.NRLMSISE00 model simulations were also performed on this geomagnetic storm.TADs are absent in the NRLMSISE00 simulations.The satellite data suggest that NRLMSISE00 significantly underestimates the magnitude of the density response of the thermosphere during geomagnetic storms,especially at high latitudes in both hemispheres.Therefore,use of the density simulation of NRLMSISE00 may lead to large errors in satellite drag calculations and orbit predictions.We suggest that the high temporal and spatial resolution of direct density observations by the TM-1 constellation satellites can provide an autonomous and reliable basis for correction and improvement of atmospheric models.

Mars Ion and Neutral Particle Analyzer (MINPA) for Chinese Mars Exploration Mission (Tianwen-1): Design and ground calibration

The main objective of the Mars Ion and Neutral Particle Analyzer(MINPA)aboard the Chinese Mars Exploration Mission(Tianwen-1)is to study the solar wind-Mars interaction by measuring the ions and energetic neutral atoms(ENAs)near Mars.The MINPA integrates ion and ENA measurements into one sensor head,sharing the same electronics box.The MINPA utilizes a standard toroidal top-hat electrostatic analyzer(ESA)followed by a time of flight(TOF)unit to provide measurement of ions with energies from 2.8 eV to 25.9 keV and ENAs from 50 eV to 3 keV with a base time resolution of 4 seconds.Highly polished silicon single crystal substrates with an Al2O3 film coating are used to ionize the ENAs into positive ions.These ions can then be analyzed by the ESA and TOF,to determine the energy and masses of the ENAs.The MINPA provides a 360°×90°field of view(FOV)with 22.5°×5.4°angular resolution for ion measurement,and a 360°×9.7°FOV with 22.5°×9.7°angular resolution for ENA measurement.The TOF unit combines a-15 kV acceleration high voltage with ultra-thin carbon foils to resolve H+,He2+,He+,O+,O2+and CO2+for ion measurement and to resolve H and O(≥16 amu group)for ENA measurement.Here we present the design principle and describe our ground calibration of the MINPA.

Simulation of ENA Imaging Measurements on a Geosynchronous Orbit

Geosynchronous orbit is located in the ring current region,where the energetic particle emission environment challenges the ion deflection design limit of the Energetic Neutral Atom(ENA)imager.Therefore,there is no measurement record of ENA imaging in this area before.On the basis of possessing the patent of high-energy ion deflection technology,ENA imaging under different Kp index in geosynchronous orbit is simulated.The simulation images show the characteristics of low-altitude ENA emission source and the rough sketch of magnetosphere.Due to the north-south conjugation observation of geosynchronous orbit,the simulated ENA images at different positions all have north-south symmetry.Aiming at the unsolved problems,such as the input source of ring current energetic ions during geomagnetic activities and its evolution process,we analyzed the possible results of ENA imaging combined with in-situ particle measurements in the same satellite,as well as the subversion effect of any north-south asymmetry of ENA map on the inversion model.

Influence of low-energy supersymmetric vector-like quirk particles on W mass increment and muon g–2 anomaly

In the low energy realization of the quirk assisted Standard Model,the couplings between the exotic particles"quirks"and gauge bosons may contribute to the W mass and muon g−2 anomaly reported by FermiLab.We calculate the contributions from supersymmetric quirk particles as an example.By imposing the theoretical constraints,we determined that the CDF II W-boson mass increment strictly constrains the mixing and coupling parameters and the quirk mass mF,while the muon g−2 anomaly cannot be solely attributed to the involvement of exotic particles,considering their significantly large masses.

The technology of space plasma in-situ measurement on the China Seismo-Electromagnetic Satellite

The China Seismo-Electromagnetic satellite(CSES) was designed to study the ionospheric disturbances associated with earthquakes. Satellite payload includes nine instruments. Among them, we recall instruments for plasma analysis, electric,magnetic fields and high energy particle detectors. Langmuir probe(LP) and plasma analyzer package(PAP) are the in-situ payloads to measure space plasma. Its scientific objective is to research space plasma physics phenomena and the ionosphere changes caused by seismic. It is the first application of in-situ measurement technology in the field of space exploration in China.The Langmuir probe and Plasma Analyzer Package have been tested and calibrated to verify the performance in INAF-IAPS.Currently, on-orbit testing is being performed with satellites.

Precise Orbit Determination for the FY-3C Satellite Using Onboard BDS and GPS Observations from 2013, 2015, and 2017

Using the FengYun-3C(FY-3C)onboard BeiDou Navigation Satellite System(BDS)and Global Positioning System(GPS)data from 2013 to 2017,this study investigates the performance and contribution of BDS to precise orbit determination(POD)for a low-Earth orbit(LEO).The overlap comparison result indicates that code bias correction of BDS can improve the POD accuracy by 12.4%.The multi-year averaged one-dimensional(1D)root mean square(RMS)of the overlapping orbit differences(OODs)for the GPS-only solution is 2.0,1.7,and 1.5 cm,respectively,during the 2013,2015,and 2017 periods.The 1D RMS for the BDS-only solution is 150.9,115.0,and 47.4 cm,respectively,during the 2013,2015,and 2017 periods,which is much worse than the GPS-only solution due to the regional system of BDS and the few BDS channels of the FY-3C receiver.For the BDS and GPS combined solution(also known as the GC combined solution),the averaged 1D RMS is 2.5,2.3,and 1.6 cm,respectively,in 2013,2015,and 2017,while the GC combined POD presents a significant accuracy improvement after the exclusion of geostationary Earth orbit(GEO)satellites.The main reason for the improvement seen after this exclusion is the unfavorable satellite tracking geometry and poor orbit accuracy of GEO satellites.The accuracy of BDS-only and GC combined solutions have gradually improved from 2013 to 2017,thanks to improvements in the accuracy of International GNSS Service(IGS)orbit and clock products in recent years,especially the availability of a high-frequency satellite clock product(30 s sampling interval)since 2015.Moreover,the GC POD(without GEO)was able to achieve slightly better accuracy than the GPS-only POD in 2017,indicating that the fusion of BDS and GPS observations can improve the accuracy of LEO POD.GC combined POD can significantly improve the reliability of LEO POD,simply due to system redundancy.An increased contribution of BDS to LEO POD can be expected with the launch of more BDS satellites and with further improvements in the accuracy of BDS satellite products in the near future.

Tianwen-1 MINPA observations in the solar wind

The Mars Ion and Neutral Particle Analyzer(MINPA)is one of the three scientific instruments onboard the Tianwen-1 orbiter to investigate the Martian space environment.During Tianwen-1’s transfer orbit to Mars,the MINPA was switched on to measure the solar wind ions.Here,we present the first results of the MINPA observations in the solar wind.During cruise,nearly half of the MINPA ion field-of-view(FOV)was blocked by the lander capsule;thus only the solar-wind ions with azimuthal speeds pointing towards the unblocked FOV sectors could be detected.We perform a detailed comparison of the MINPA’s solar wind observations with data from Earth-based missions when MINPA reached its count-rate peak,finding a general consistency of the ion moments between them.The blocking effect due to the lander is evaluated quantitatively under varying solar-wind velocity conditions.Despite the blocking effect,the MINPA’s solar wind measurements during the transfer orbit suggest a good performance.

Exploring Greenhouse Gases Water and Climate Changes:Scientific Opportunities for the Climate and Atmospheric Composition Exploring Satellites Mission

The Essential Climate Variables(ECVs),such as the atmospheric thermodynamic state variables and greenhouse gases,play an important role in the atmosphere physical processes and global climate change.Given the need of improvements in existing ground-based and satellite observations to successfully deliver atmosphere and climate benchmark data and reduce data ambiguity,the Climate and Atmospheric Composition Exploring Satellites mission(CACES)was proposed and selected as a candidate mission of the Strategic Priority Research Program of Chinese Academy Science(SPRPCAS).This paper presents an overview of the key scientific questions and responses of EC Vs in relation to global change;the principles,algorithms,and payloads of microwave occultation using centimeter and millimeter wave signals between low Earth orbit satellites(LEO-LEO microwave occultation,LMO)as well as of the LEO-LEO infrared-laser occultation(LIO);the CACES mission with its scientific objectives,mission concept,spacecraft and instrumentation.

Proton belt variations traced back to Fengyun-1C satellite observations

We used historical data to trace trapped protons observed by the Fengyun-1C(FY-1C)satellite at low Earth orbits(~800 km)and chose data at 5–10 MeV,10–40 MeV,40–100 MeV,and^100–300 MeV from 25 March to 18 April 2000 to analyze the proton variations.Only one isolated strong storm was associated with a solar proton event during this period,and there was no influence from previous proton variations.Complex dynamic phenomena of proton trapping and loss were affected by this disturbance differently depending on the energy and L location.The flux of 5–10 MeV protons increased and created new trapping with a maximum at L^2.0,and the peak flux was significantly higher than that at the center of the South Atlantic Anomaly.However,at higher L,the flux showed obvious loss,with retreat of the outer boundary from L^2.7 to L^2.5.The increase in the 10–40 MeV proton flux was similar to that of the 5–10 MeV flux;however,the peak flux intensity was lower than that at the center of the South Atlantic Anomaly.The loss of the 10–40 MeV proton flux was closer to the Earth side,and the outer boundary was reduced from L^2.3 to L^2.25.For the higher energy protons of 40–100 MeV and 100–300 MeV,no new trapping was found.Loss of the 40–100 MeV protons was observed,and the outer boundary shifted from L^2.0 to L^1.9.Loss was not obvious for the 100–400 MeV protons,which were distributed within L<1.8.New proton trapping was more likely to be created at lower energy in the region of solar proton injection by the strong magnetic storm,whereas loss occurred in a wide energy range and reduced the outer boundary on the Earth side.Similar dynamic changes were observed by the NOAA-15 satellite in the same period,but the FY-1C satellite observed more complex changes in lower energy protons.These results revealed that the dynamic behavior of protons with different L-shells was due to differences in the pitch angle.Possible mechanisms related to new trapping and loss are also discussed.These mechanisms are very important for understanding the behavior of the proton belt in the coming solar cycle.

An Introduction to Magnetosphere-Ionosphere-Thermosphere Coupling Small Satellite Constellation

A future Chinese mission is introduced to study the coupling between magnetosphere,ionosphere and thermosphere,i.e.the Magnetosphere-Ionosphere-Thermosphere Coupling Small Satellite Constellation(MIT).The scientific objective of the mission is to focus on the outflow ions from the ionosphere to the magnetosphere.The constellation is planning to be composed of four small satellites;each small satellite has its own orbit and crosses the polar region at nearly the same time but at different altitude.The payloads onboard include particle detectors,electromagnetic payloads,auroral imagers and neutral atom imagers.With these payloads,the mission will be able to investigate acceleration mechanism of the upflow ions at different altitudes.Currently the orbits have been determined and prototypes of some have also been completed.Competition for next phase selection is scheduled in late 2015.

Key Questions of Solar Wind-Moon Interaction

Key questions on solar wind-Moon interaction are reviewed.As the nearest celestial body to Earth,Moon’s space environment is distinctive to Earth’s mainly because of lack of a significant atmosphere/ionosphere and a global magnetic field.From a global respective,solar wind can bombard its surface,and the solar wind materials cumulated in the soil record the evolution of the Solar System.Many small-scale remanent magnetic fields are scattered over the lunar surface and,just as planetary magnetic fields protect planets,they are believed to divert the incident solar wind and shield the local lunar surface beneath,thus producing unique local surface environment that is critical to activities of human beings/facilities,thus providing unique landing sites to explore the origins of lunar swirls and remanent magnetic fields.Evidences have hinted that this local interaction,however,may be also distinct with the interacting scenario on planets,and the specific process has not been revealed because of lack of in situ observations in the near-Moon space or on the ground.The global and local solar wind interactions of the Moon represent 2 types of characteristic interaction of celestial bodies with stellar wind in deep space,i.e.,the interactions of nonmagnetized bodies and of small-scale magnetized bodies,both of which may occur on asteroids and Mars.The deep-space celestial bodies,either difficult or impossible to reach for human beings or artificial satellites,are hard to measure,and the exploration of the Moon can reveal the mystery of stellar wind interaction on these bodies.

The solar wind plasma upstream of Mars observed by Tianwen-1:Comparison with Mars Express and MAVEN

On the great journey to Mars,China’s first planetary exploration mission,the Tianwen-1 came within 26 million kilometers of Mars from 31 October 2020 to 25 January 2021 and was getting closer to its destination,the red planet,in search of answers to the cataclysmic climate change that occurred in Martian history.Both the escape of the Martian atmosphere and the loss of surface water were firmly influenced by solar activities.Tianwen-1 provided a unique chance to depict the solar wind streams between Earth and Mars during the minimum of Solar Cycle 25.During the three-month cruise phase of Tianwen-1,the solar wind flows were successively observed at Earth,Tianwen-1,and Mars.After the field of view correction and noise reduction,the solar wind velocity and density measured by Tianwen-1 show good agreement with those at Earth and Mars.The results indicate that the performance of the ion analyzer onboard the Tianwen-1 orbiter is reliable and stable.It is worth looking forward to the joint observations of ion escape with other Mars probes in the following Martian years.