Wei Zuo

Data processing for the Active Particle-induced X-ray Spectrometer and initial scientific results from Chang'e-3 mission

The Active Particle-induced X-ray Spectrometer (APXS) is an important payload mounted on the Yutu rover, which is part of the Chang’e-3 mission. The scientific objective of APXS is to perform in-situ analysis of the chemical composition of lunar soil and rock samples. The radioactive sources, 55 Fe and 109 Cd, decay and produce α-particles and X-rays. When X-rays and α-particles interact with atoms in the surface material, they knock electrons out of their orbits, which release energy by emitting X-rays that can be measured by a silicon drift detector (SDD). The elements and their concentrations can be determined by analyzing their peak energies and intensities. APXS has analyzed both the calibration target and lunar soil once during the first lunar day and again during the second lunar day. The total detection time lasted about 266 min and more than 2000 frames of data records have been acquired. APXS has three operating modes: calibration mode, distance sensing mode and detection mode. In detection mode, work distance can be calculated from the X-ray counting rate collected by SDD. Correction for the effect of temperature has been performed to convert the channel number for each spectrum to X-ray energy. Dead time correction is used to eliminate the systematic error in quantifying the activity of an X-ray pulse in a sample and derive the real count rate. We report APXS data and initial results during the first and second lunar days for the Yutu rover. In this study, we analyze the data from the calibration target and lunar soil on the first lunar day. Seven major elements, including Mg, Al, Si, K, Ca, Ti and Fe, have been identified. Comparing the peak areas and ratios of calibration basalt and lunar soil the landing site was found to be depleted in K, and have lower Mg and Al but higher Ca, Ti, and Fe. In the future, we will obtain the elemental concentrations of lunar soil at the Chang’e-3 landing site using APXS data.

Data preprocessing and preliminary results of the Moon-based Ultraviolet Telescope on the CE-3 Lander

The Moon-based Ultraviolet Telescope (MUVT) is one of the payloads on the Chang’e-3 (CE-3) lunar lander. Because of the advantages of having no atmospheric disturbances and the slow rotation of the Moon, we can make long-term continuous observations of a series of important celestial objects in the near ultraviolet band (245~340 nm), and perform a sky survey of selected areas, which cannot be completed on Earth. We can find characteristic changes in celestial brightness with time by analyzing image data from the MUVT, and deduce the radiation mechanism and physical properties of these celestial objects after comparing with a physical model. In order to explain the scientific purposes of MUVT, this article analyzes the preprocessing of MUVT image data and makes a preliminary evaluation of data quality. The results demonstrate that the methods used for data collection and preprocessing are effective, and the Level 2A and 2B image data satisfy the requirements of follow-up scientific researches.

Scientific data and their release of Chang’E-1 and Chang’E-2

The Chang’E-1 and Chang’E-2 missions have successfully obtained a huge amount of lunar scientific data, through the seven onboard instruments including a CCD stereo camera, a laser altimeter, an interference imaging spectrometer, an X-ray spectrometer, a microwave radiometer, a high-energy particle detector and a solar-wind ion detector. Most of the Chang’E data are now publicly available to the science community, and this article serves as an official guide on how these data are classified and organized, and how they can be retrieved from http://159.226.88.59:7779/CE1OutENGWeb/. This article also presents the detailed specifications of various instruments and gives examples of research progress made based on these instruments.

Chinese and Russian Language Equivalents of the IAU Gazetteer of Planetary Nomenclature: an Overview of Planetary Toponym Localization Methods

ABSTRACT The Gazetteer of Planetary Nomenclature (GPN) is maintained by the International Astronomical Union Working Group for Planetary System Nomenclature. It contains the internationally approved forms of place names of planetary and lunar surface features. In the last decades, spacefaring and other nations have started to develop local standardized equivalents of the GPN. This initiated the development of transformation methods and created a need for auxiliary information on the names in the GPN that is not available from the database of the GPN. The creation of ‘localized’ (local language) variants of the GPN in non-Roman scripts is an unavoidable necessity, but is also a cultural need. This paper investigates the localization methods into Chinese and Russian; two nations with different scripts, and two that are spacefaring ones. The need for the creation of a localized GPN is related to the local importance of scientific papers published in the local language and the existence of locally developed and operated scientific planetary spacecraft, but exceptions exist.

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 was published after some necessary approval procedures by the International Astronomical Union.