Thermal modelling of E.S.A second young engineers satellite

Second Young Engineer Satellite (YES2) is a demonstration satellite which will fly attached to the Russian scientific Foton-M3. YES2 aims at demonstrating the tethered Space Mail technology, i.e. delivery of a small payload from Low Earth Orbit (LEO) using a tethered re-entry capsule. The entire current YES2 system consists of 3 major components: a) FLOYD: Foton LOcated YES2 Deployer, including tether, tether spool, friction tether brake mechanism and ejection system, on FOTON batterypack as well as control, data and power system inside the FOTON capsule (20 kg); b) FOTINO; Reentry capsule (5 kg); c) MASS: Mechanical and data Acquisition Support System (7 kg). A 30 km, 6 kg tether is deployed from a passive spool into a swinging configuration within some hours time. MASS and Fotino, which are ejected with a spring ejection system, are attached by a tether to FLOYD/Foton. When the tether swings back to the vertical in the opposite of the flight direction, Fotino will be released from MASS at a fixed time after ejection from FLOYD/Foton, to lower, through the momentum-transfer effect, the capsule's perigee by 13 times the tether length, sufficient to induce a re-entry. This can be done with considerable accuracy and with simple low-cost hardware. The final application of the tether technology is foreseen to support the research done on the International Space Station or other stations build in the future to deliver samples from space. The purpose of the thermal analysis of YES2 is to verify that the thermal design of the satellite is suitable for the mission and meets the interface requirements imposed by the Foton-M3 carrier. The satellite must also be suitably designed to control the heat paths and the high heat dissipations throughout its mission. In the work presented in this paper, a lumped parameter thermal network model of 166 nodes was created in order to model YES2. The software used was ALSTOM's ThermXL. The worst case scenarios and corresponding steady state cases, the applied thermal loads, the thermal budget and the temperatures are presented and discussed. The transient results of YES2's 11 day mission are also presented.