W.G. Wang

A new lunar absolute control point： established by images from the landing camera on Chang＇e-3

The establishment of a lunar control network is one of the core tasks in selenodesy, in which defining an absolute control point on the Moon is the most important step. However, up to now, the number of absolute control points has been very sparse. These absolute control points have mainly been lunar laser ranging retroreflectors, whose geographical location can be observed by observations on Earth and also identified in high resolution lunar satellite images. The Chang’e-3 (CE-3) probe successfully landed on the Moon, and its geographical location has been monitored by an observing station on Earth. Since its positional accuracy is expected to reach the meter level, the CE-3 landing site can become a new high precision absolute control point. We use a sequence of images taken from the landing camera, as well as satellite images taken by CE-1 and CE-2, to identify the location of the CE-3 lander. With its geographical location known, the CE-3 landing site can be established as a new absolute control point, which will effectively expand the current area of the lunar absolute control network by 22%, and can greatly facilitate future research in the field of lunar surveying and mapping, as well as selenodesy.

Positioning of the CE-1's impact site based on CCD image data photographed during the controlled impact on the Moon

Up to now, many lunar explorations concluded their scientific mission through the impact on the lunar surface. The prediction and positioning of impact sites are based on the extrapolated orbiting data together with the real time orbiting data and observations from ground based telescope provided by TT & C System. As most lunar missions carried cameras onboard, a new method of positioning of CE-1 impact site is put forward. It is based on the CCD image data photographed during the controlled impact and the existing lunar terrain data. Test results from this new method also validate the published impact site position.

Terrain reconstruction from Chang＇e-3 PCAM images

The existing terrain models that describe the local lunar surface have limited resolution and accuracy, which can hardly meet the needs of rover navigation, positioning and geological analysis. China launched the lunar probe Chang’e-3 in December, 2013. Chang’e-3 encompassed a lander and a lunar rover called “Yutu” (Jade Rabbit). A set of panoramic cameras were installed on the rover mast. After acquiring panoramic images of four sites that were explored, the terrain models of the local lunar surface with resolution of 0.02 m were reconstructed. Compared with other data sources, the models derived from Chang’e-3 data were clear and accurate enough that they could be used to plan the route of Yutu.

Fabrication of Carbon Nanotube Reinforced Aluminum Matrix Composites via Friction Stir Processing

In this study, CNTs reinforced pure Al, 6061Al and 2009Al composites with uniformly dispersed CNTs were successfully fabricated by a combination of powder metallurgy and subsequent multi-pass friction stir processing (FSP). As the FSP pass increased, the CNT clusters were broken down due to the shear flow of the Al matrix during FSP, however, the CNTs were cut short. After 4-pass FSP, the CNTs were individually dispersed in the aluminum matrix along grain boundaries resulting in a much finer grain size. Although the CNTs were shortened and some Al4C3 formed in the matrix, the layer structures of the CNTs were well retained and the CNT-Al interface was good bonded. Compared to the Al matrix, the strength, especially the yield strength of the composites increased significantly.

Effects of the orientation of microgravity on the concentration distribution in crystallization from solution

A quasi-steady state growth and dissolution in a 2-D rectangular enclosure is numerically investigated. This paper is an extension to indicate the effects of the orientation of gravity on the concentration field in crystallization from solution under microgravity, especially on the lateral non-uniformity of concentration distribution at the growth surface. The thermal and solute convection are included in this model.