Yang Fumin

Current status and future plans for the Chinese Satellite Laser Ranging Network

The Chinese SLR Network consists of 5 fixedstations located in Shanghai, Changchun, Beijing, Wuhan and Kunming respectively and 2 mobilesystems. The single shot precision for Lageos for these stations is in therange of 12–30 mm. Improvements of system performance for all stations are under way.The Chinese SLR Network participates in the national project “CrustalMovement Observation Network of China”, and is actively supporting the global and regionalprojects, such as ILRS, IERS, WPLTN (Western Pacific Laser Tracking Network) andAPSG (Asia-Pacific Space Geodynamics). The operation center and the datacenter for the Chinese SLR Network is located at Shanghai Observatory. The Lageos dataanalysis report for the global stations has been published every two weeks at the web siteof Shanghai Observatory since September 1999.

Review on Time Transfer by Laser Pulses

The paper reviews the experiments and plans of the time transfer by laser pulses. The time transfer experiments and results between ground-ground, ground-aircraft and ground-satellite (LASSO project) with laser pulses are summarized. The status of the proposed plans, such as T2L2, LTT projects, is also presented.

Laser altimeter for planetary exploration technology demonstrator: the timing system

The European Space Agency has nominated the laser altimeter as one of the principal devices for planetary research for the next decade. The first mission in view is Mercury with scheduled launch in 2010. The device should be capable to range over the distances 400 to 1000 km and to acquire the information about the probe altitude above the planet surface and about the surface terrain profile with the precision of the order of one meter. The requirements on the device are rather strict: total mass below 5 kilograms, power consumption below 10 Watts. Recently, the Technology Demonstrator of the altimeter is under development at German Air and Space Agency, Institute of Planetary Research, Germany. The altimeter Technology Demonstrator is based on the diode pumped frequency doubled Nd:YAG laser delivering 50 mJ at 532 nm in 3 nanosecond long pulses with the repetition rate of 20 kHz. The solid state echo signal detector in photon counting mode will be used. The optical part of the altimeter is scaled down to simulate the real background count rate scenario and to reduce the energy budget link by a factor of 104 at the same time. The demonstrator should be capable to range objects at distances 0 - 5 kilometers in both night and day time. We are presenting the concept, design and construction of the timing system part of the laser altimeter technology demonstrator, which has been developed at the Czech Technical University in Prague optimized for photon counting altimeter concept. The timing system has interval resolution 0.25 ns, stability and linearity ~0.1 ns, epoch resolution 100 ns and accuracy 1 μs, and programmable range gate.