Progress of the Quantum Experiment Science Satellite(QUESS)Micius Project

The Micius satellite was successfully launched on 16 August 2016,from Jiuquan,China,orbiting at an altitude of about 500 km.The main scientific goals,including satellite-to-ground quantum key distribution,satellite-based quantum entanglement distribution,ground-to-satellite quantum teleportation,and satellite relayed intercontinental quantum network,were achieved in 2017.As a starting point,the Micius satellite has become a platform for quantum science experiments at the space scale.Here,we introduce the latest experimental achievements(in 2018–2020)based on the Micius satellite.

Evolution of electron“zebra stripes”in the South Atlantic Anomaly:Initial observations from Macao Science Satellite-1

“Zebra stripes”denote banded structures characterized by periodic peaks and valleys in the spectrograms of energetic electrons in the Earth's inner radiation belt and slot region.In contrast to previous investigations primarily grounded in equatorial observations,this study presents two events exhibiting the evolution of electron zebra stripes within the South Atlantic Anomaly,as observed from the Macao Scientific Satellite-1 in low Earth orbit.Our findings affirm that the structural and evolutionary features of zebra stripes in both events accord with the drift echo hypothesis.The start time extrapolated from the electron spectrograms correlates with substorm onsets,consistent with prior conclusions.Notably,the duration of zebra stripe evolution during the event of June 5–6,2023,reaches an impressive 34.7 h,a markedly longer interval than findings from the Van Allen Probes.This discrepancy suggests that the observed lifetime of electron zebra stripes may not inherently reflect natural limitations but could be constrained by instrumental capabilities.The results implicate that high-energy-resolution detectors have the potential to significantly enhance our capacity to scrutinize the dynamics of the radiation belt.

High-precision modeling of tide-induced 3-D magnetic field and analysis of geomagnetic satellite orbit requirements

Ground-based magnetic observatories and geomagnetic satellites can observe the induced magnetic field generated by the motion of seawater containing sodium and chlorine ions.Calculating the three-dimensional(3-D)spatial distribution of tide-induced magnetic fields(TIMF)is crucial for inverting the electrical conductivity structure of the oceanic lithosphere.It also serves as an essential basis for designing optimal geomagnetic observatories and satellite orbits.However,existing methods for simulating TIMF suffer from limitations in inaccurately modeling realistic coastlines,heterogeneous land and sea surface properties,and complex deep Earth structures,thereby the interpretational level of TIMF data is reduced.To overcome this issue,we developed a tetrahedral-based finite element method for simulating TIMF,which can efficiently approximate realistic coastlines,heterogeneous land and sea surface properties,and complex deep Earth structures.Firstly,we derived the boundary value problem for the seawater motion-induced electromagnetic field,which was solved using the vector finite element method based on tetrahedral elements.Secondly,using the latest ocean depth and seafloor sediment layer models,we constructed a 3-D conductivity model of the Earth,which includes realistic coastlines,heterogeneous land and sea conductivity distributions.We then computed the TIMF using the M_(2)tidal source as an example and validated our method by comparing it with results obtained from spherical harmonic finite element and integral equation methods.Finally,utilizing the computed high-precision M_(2),N_(2),and O1 TIMF signals,we marked global observatories capable of observing strong M_(2),N_(2),and O1 TIMF signals and predicted alternative stations suitable for tide signal observations.Additionally,we calculated TIMF at heights of 450 and 200 km for the Macao Science Satellite 1 and its subsequent satellites.The results indicate that the amplitude of the tidal-induced magnetic field at 200 km is approximately twice that at 450 km.The maximum amplitudes of M_(2),N_(2),and O1 TIMF at 200 km are eight,two,and three times the measurement accuracy of the magnetic sensing payload(0.5 nT),respectively.The 200 km orbit has great potential for detecting high-resolution electrical structures of the seafloor lithosphere and asthenosphere in regions such as New Zealand,southern Iceland,the southern Indian Ocean,the Ross Sea region of Antarctica,and the Sea of Okhotsk.It also holds the potential for studying large-scale oceanic dynamic processes and properties.