The TUBSAT-1 Attitude Control and Stabilization System

TUBSAT-1 (Technical University Berlin Satellite) is an experimental low-cost satellite being financed by the German BMFT. The dimensions and weight are determined by the NASA Gas-Program and it will be ejected from the Space Shuttle within the German spacelab mission D2 by December 19, 1991, into a 298 km circular orbit and at a 28.5° inclination. To enable a large variety of useful experiments to fly with TUSSAT, it was necessary to develop a rather precise attitude control and stabilization (ACS) system. The ACS should be low cost, flexible (in view of changing ACS modes and parameters during the mission time), minimum component number and a low power consumption. A sun/star orientation with an additional spin mode was chosen and developed. The system is based on a microcomputer, fixed momentum wheel (FMW), one magnetic torquer, one sun and two star sensors. The closed loop pitch control consists of FMW, sun and star (for the eclipse phase) sensors, achieving a pitch pointing accuracy of 0.26° for any slew maneuver by using momentum transfer from the wheel to the satellite. Control of the wheel momentum (desaturation) without affecting the pitch axis orientation can be accomplished by executing a pitch slew maneuver. Positioning the magnetic torquer (which is mounted perpendicular to the pitch axis) to interact with the geomagnetic field vector. The pitch axis reorientation maneuver due to interaction between the magnetic torquer and the magnetic field vector component can be controlled by the one axis star sensor (roll/yaw rotation). A further pitch slew maneuver of 90° is necessary for positioning the sensor (roll = yaw)

Panel Discussion

Panelists will be challenged to offer and defend their opinions on the efficacy of adopting standards at all levels within the design of small satellite systems—payload interfaces, bus subsystems and at the board-level within subsystems. Panelists will also be asked to comment on the concept of modular satellites that employ plug and play adaptability as a technique to enable lower cost and more rapidly fielded missions. Conference attendees are encouraged to submit topical questions which will be used to form panel questions

Commercial Earth Observation with Small Satellites at OHB-System

OHB-System, located in Bremen, Germany, is a mid-sized company mainly active in the fields of space, wireless communication and environmental technology. This paper covers the OHB activities in the field of Earth observation with small satellites. It describes the advanced technology approaches of the company in the low-cost and user dedicated design and development of small satellites for earth science derived commercial oriented Earth observation approaches. The paper gives an overview on the activities and long term strategy of OHBSystem concerning the development of Earth observation capabilities in Germany

A Spaceborne Wind Sounder Lidar (SBL)

This paper presents a commercial oriented SpaceBorne wind sounder LIDAR (SBL) system, which is designed for advanced remote sensing purposes. The main objectives of SBL are the measurement of wind velocities, by measuring its Doppler shifted reflection from the various atmospheric layers. This represents a unique way to map the three dimensional wind field around the globe

Panel Discussion

Panelists will be challenged to provide candid views on current small satellite market trends including factors that which indi­cate real growth in the market, impediments to market expansion, where small satellites fit in the global space market, and the key drivers and indicators to of the future business health of the small satellite industry. The panel will explore these issues from all mar­ket sectors—missions, satellites, launchers, and customers.This year’s panel will be interactive, with real-time audience participation

DAVID: A Multi Spectral High-Resolution Small Satellite

DAVID is a small satellite for advanced remote sensing purposes - designed to meet the specific requirements of today\u27s and tomorrow\u27s Earth observation users in the fields of environmental monitoring, hazard warning and damage assessment. The development is a joint German-Israeli co-operative project. The satellite is designed to provide earth images with high spatial and spectral resolution and good radiometric sensitivity, despite its small size and low cost. It will have more spectral bands in the VIS/NIR range than sensors on most existing or planned multi-spectral high-resolution satellites and higher ground resolution than planned hyperspectral space sensors like LEWIS or MODIS. DAVID will be able to meet the actual tendencies in Earth observation by delivering 12 narrow bands with a spatial resolution of about 5 m. By its slewing capability DAVID will get the important performance gain of short data delivery times due to short target revisit cycles of 3 days can be established. This is particularly important for the monitoring of dynamic processes. Existing space-rated sub-systems will be used or adapted for this system, combined with new satellite and detector technologies, to achieve the low cost and high performance goals. The two principal companies involved, OHB System in Germany and El-Op in Israel are both experienced in the design and construction of space systems, some of which have already been successfully launched. In addition, another German company, GAF, is actively involved in the parameter defamation and image product distribution aspects of the system. A feasibility study has been completed. This paper will describe the updated system concept