ABSTRACT
This paper presents the principal considerations when designing DC-DC converters for space instruments, in particular for the power converter module as part of the first European space laser altimeter: "BepiColombo Laser Altimeter" on board the European Space Agency-Japan Aerospace Exploration Agency (JAXA) mission BepiColombo. The main factors which determine the design of the DC-DC modules in space applications are printed circuit board occupation, mass, DC-DC converter efficiency, and environmental-survivability constraints. Topics included in the appropriated DC-DC converter design flow are hereby described. The topology and technology for the primary and secondary stages, input filters, transformer design, and peripheral components are discussed. Component selection and design trade-offs are described. Grounding, load and line regulation, and secondary protection circuitry (under-voltage, over-voltage, and over-current) are then introduced. Lastly, test results and characterization of the final flight design are also presented. Testing of the inrush current, the regulated output start-up, and the switching function of the power supply indicate that these performances are fully compliant with the requirements.
ABSTRACT
The European Space Agency's Rosetta mission encountered the main-belt asteroid (2867) Steins while on its way to rendezvous with comet 67P/Churyumov-Gerasimenko. Images taken with the OSIRIS (optical, spectroscopic, and infrared remote( )imaging system) cameras on board Rosetta show that Steins is an oblate body with an effective spherical diameter of 5.3 kilometers. Its surface does not show color variations. The morphology of Steins is dominated by linear faults and a large 2.1-kilometer-diameter crater near its south pole. Crater counts reveal a distinct lack of small craters. Steins is not solid rock but a rubble pile and has a conical appearance that is probably the result of reshaping due to Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) spin-up. The OSIRIS images constitute direct evidence for the YORP effect on a main-belt asteroid.
