Young Engineers' Satellite 2 - The YES2 Project

The YES2 Project

Most of the work done in this ambitious project (like design, manufacturing and integration) was done by students and young engineers. In total some 450 students participated.

Soon after the beginning of the project 4 so called "Centres of Expertise" were created. These were universities which were responsible for parts of the satellite or subsystems. The centres were: Samara State Aerospace University, Russia (mission analysis, GPS); University of Modena and Reggio Emilia, Italy (re-entry capsule); Hochschule Niederrhein in Krefeld, Germany (tether); University of Patras, Greece (mechanical and thermal). Coordination and system engineering was carried out by prime contractor Delta-Utec SRC from the Netherlands.

Towards the end of the project, in the manufacturing and integration phase, the work concentrated on the Delta-Utec office in Leiden and ESA's ESTEC in Noordwijk, where the satellite was built and tested.

The test program included:

• electromagnetic compatibility testing in the "Maxwell" EMC test chamber
• simulation of space environment in a thermal vacuum chamber
• vibration testing on a shake table
• functional tests of all components and sub-systems

The satellite was handed over to ESA at the beginning of May 2007 and was shipped to Samara (Russia) soon after, where YES2 was mated to Foton-M3 for the first time for test purposes. Afterwards YES2 and Foton were separated again and brought to Baikonur (Kazakhstan) by train where the whole satellite was completely integrated and mated with the launcher, a Soyuz-U rocket. Foton-M3 and YES2 finally launched on 14 September 2007 at 13:00 (CEST) from the Gagarin launch pad at Baikonur Cosmodrome.

The main contribution of the project has been the demonstration of a complex controlled deployment in two stages. Post-flight, several independent sources of deployment data were collected, including deployment length and rate measurements from YES2 itself as well as highly precise triaxial accelerometer data from a separate experiment on the Foton carrier spacecraft. These data confirmed that the deployment did progress mostly successfully, in particular the critical first stage and stage transition and the tether deployer performed nominally. The data that has been recovered has helped to understand the deployer performance and tether dynamics in yet unseen detail, including explicit signatures of sound waves, transverse waves and spring-mass motion. The small reentry capsule Fotino, intended to demonstrate the SpaceMail concept, was not successfully recovered. Calculations based on YES2 sensor data indicate that the landing site should be in or near the Aral Sea. Alternatively, the capsule, experimental in itself, may have burnt up or crashlanded.