Coldgas Propulsion System for Student Satellite
- Paper number
IAC-05-C4.P.16
- Author
Mr. Sascha Tietz, University of Stuttgart, Germany
- Year
2005
- Abstract
In 2000, the Student Space Exploration and Technology Initiative (SSETI) supported by the Education Office of the European Space Agency started to create a network of european students to build the micro-satellite ESEO (European Student Earth Orbiter). The german team at the University Stuttgart has the responsibility for the Propulsion System Design. To pre-qualify important hardware pieces the "low cost, quick launch" mission EXPRESS was created in January 2004, equiped only with an Attitude Control System (ACS) - classified as payload - of the german students. According to major design drivers in this case, the students decided to implement a coldgas propulsion system based on nitrogen as propellant. The propellant is stored at 300bar in a 6l full-composite tank. A propellant management system (PMS) regulates the pressure in two stages down to 2,7bar for 4 ACS thrusters. To reduce the required funding, only safety critical parts are space-qualified, while the other parts are purchased as COTS equipment. The assembly of all subsystems was done in parallel to the verification tests. Problems like a complicated electron beam welding of the armed pyro valve and the difficult tube bending had to be solved. To perfom the required pressurised vibration test, the propulsion system had to be integrated into the primary structure of the spacecraft. This was done in a selfmade cleantent. After the test, spacecraft and propulsion system were delivered to ESTEC for further integration and launch preparation. Following that, a lot of documentation and management work could be finished. It is very difficult to estimate the performance of the ACS in operation, because not every test could be made with the usual setup and accuracy. In case of a failure in the propulsion payload, the primary Attitude Control and Determination System which consists of with magnetometers and magnettorquers is able to bring the satellite back into the nominal attitude. After the launch, the propulsion system with the swiss ICU Box will be operated via the mission control computer and a secure web-interface. All the lessons learned with EXPRESS will help the team to finish the design of a propulsion system for ESEO with a complicated Orbit Control System, a distributed PMS and a Thrust Vector Control. Many technical details will be improved and a lot of tests and scheduling will be necessary to provide more reliable system. The experience in working in space project is a unique opportunity for all students involved in this project.
- Abstract document