The Mars orbiter magnetometer of Tianwen-1:in-flight performance and first science results

The Mars Orbiter MAGnetometer(MOMAG)is a scientific instrument onboard the orbiter of China’s first mission for Mars—Tianwen-1.Since November 13,2021,it has been recording magnetic field data from the solar wind to the magnetic pile-up region surrounding Mars.Here we present its in-flight performance and first science results,based on its first one and one-half months’data.Comparing these early MOMAG observations to the magnetic field data in the solar wind from NASA’s Mars Atmosphere and Volatile EvolutioN(MAVEN)mission,we report that the MOMAG magnetic field data are at the same level in magnitude,and describe the same magnetic structures with similar variations in three components.We recognize 158 clear bow shock(BS)crossings in these MOMAG data;their locations match well statistically with the modeled average BS.We also identify and compare five pairs of datasets collected when Tianwen-1’s orbiter and the MAVEN probe made simultaneous BS crossings.These BS crossings confirm the global shape of modeled BS,as well as the south-north asymmetry of the Martian BS.Two cases presented in this paper suggest that the BS is probably more dynamic at flank than near the nose.So far,MOMAG performs well,and provides accurate magnetic field vectors.MOMAG is continuously scanning the magnetic field surrounding Mars.Data from MOMAG’s measurements complement data from MAVEN and will undoubt edly advance our understanding of the plasma environment of Mars.

Shadow–highlight feature matching automatic small crater recognition using high-resolution digital orthophoto map from Chang’E Missions

This paper introduces a new method of small lunar craters’ automatic identification, using digital orthophoto map(DOM) data. The core of the approach is the fact that the lunar exploration DOM data reveal contrasting highlight and shadow characteristics of small craters under sunlight irradiation. This research effort combines image processing and mathematical modeling. Overall it proposes a new planetary data processing approach, to segment and extract the highlight and shadow regions of small craters,using the image gray frequency(IGF) statistical method.IGF can also be applied to identify the coupling relationships between small craters’ shape and their relative features. This paper presents the highlight and shadow pair matching(HSPM) model which manages to perform highprecision automatic recognition of small lunar craters.Testing was performed using the DOM data of Chang’E-2(CE-2). The results have shown that the proposed method has a high level of successful detection rate. The proposed methodology that uses DOM data can complement the drawbacks of the digital elevation model(DEM) that has a relatively high false detection rate. A hybrid fusion model(FUM) that combines both DOM and DEM data, was carried out to simultaneously identify small, medium, and large-sized craters. It has been proven that the FUM generally shows stronger recognition ability compared to previous approaches and it can be adapted for high precision identification of craters on the whole lunar surface.The results meet the requirements for a reliable and accurate exploration of the Moon and the planets.

Nomenclature for lunar features at the Chang＇e-3 landing site

Nomenclatures for lunar features always accompany the progresses of human lunar exploration,which has an important dual meaning in culture and science. The naming of lunar features not only can commemorate the outstanding contributions of academics,masters in various fields, and popularize the traditional cultures of ethnic groups all over the world, but also have a critical function of providing accurate indicative information on features with special morphology, origin, nature and scientific value. However, nomenclature for features at the Chang'e-3 landing site, which has a more arbitrary form without many constrains posed by a uniformed system, is unlike the features for other morphological units.This paper originated from the actual needs for the description of scientific exploration activities, interpretation of scientific research and dissemination of scientific results. Some prominent morphological units with great scientific importance and identification purpose were chosen from the images taken by the terrain camera, panorama cameras and landing camera onboard the Chang'e lander and Yutu rover. A nomenclature system was established under the three enclosures, four quadrants and twenty-eight lunar lodges' system of the Chinese ancient sky division method. Finally, a standard feature names set waspublished after some necessary approval procedures by the International Astronomical Union.

An Imported Case and an Infected Close Contact of the Omicron Variant of SARS-CoV-2—Guangdong Province,China,December 13,2021

On November 27,2021,a 67-year-old male returning from Canada via airplane was transferred to the central isolation hotel in Shanghai.During the quarantine,his 1st,4th,7th,and 14th days of specimens returned negative for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),which causes coronavirus disease 2019(COVID-19).On December 11,he completed 14 days of centralized isolation and returned to Guangzhou from Shanghai via airplane,then he was closed-loop transferred to Yuexiu District for a 7-day home isolation.On December 12,the local Community Health Service Center routinely collected his throat swab and the result returned to COVID-19 positive on December 13,2021.He was transported to the Guangzhou Eighth People’s Hospital for isolated treatment by negative pressure ambulance on the same day.The patient had two inflamed lungs according to the chest computed tomography(CT)examination,but his most recently updated condition was stable.An estimated 600 close contacts were identified and were placed in centralized isolation.On December 16,one of the close contacts,a 70-year-old female also tested positive for COVID-19.She lived on the lower floor of the same type of apartment as the imported case and spent 19 hours in the same building.