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QB50 is a mission establishing an international network of 50 nano-satellites for multi-point, in-situ measurements in the lower thermosphere and re-entry research. As part of the QB50 mission, the Delft University of Technology intends to contribute two nano-satellites both being equipped with a highly miniaturized propulsion system in addition to the science payload. This allows to demonstrate formation flying between these two nano-satellites which will enhance the mission both with respect to technology demonstration and science return. The opportunities and challenges of formation flying by a subset of satellites within a constellation of freely floating spacecraft are systematically identified and analyzed.

This paper provides results and conclusions on a survey on the implementation and reliability aspects of CubeSat bus interfaces, with an emphasis on the data bus and power distribution. It provides recommendations for a future CubeSat bus standard. The survey is based on a literature study and a questionnaire representing 60 launched CubeSats and 44 to be launched CubeSats. It is found that the bus interfaces are not the main driver for mission failures. However, it is concluded that the Inter Integrated Circuit (I 2 C) data bus, as implemented in a great majority of the CubeSats, caused some catastrophic satellite failures and a vast amount of bus lockups. The power distribution may lead to catastrophic failures if the power lines are not protected against overcurrent. A connector and wiring standard widely implemented in CubeSats is based on the PC/104 standard. Most participants find the 104 pin connector of this standard too large. For a future CubeSat bus interface standard, it is recommended to implement a reliable data bus, a power distribution with overcurrent protection and a wiring harness with smaller connectors compared with PC/104.

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In this paper we analyze and explain the performance of CIGS on Ti cells which have been mounted in the Dutch Delfi-C 3 nanosatellite that was launched in April 2008. The CIGS experiment includes several novel technologies for thin film solar cells in space. A new interconnect method based on pressure contacts between the cells was developed to minimize stresses between the electrical contacts. A thin protective coating was developed especially for a high emissivity. An electrical model is presented to predict the electrical characteristics. The thermal properties of the cells have been modeled and simulated. Effective cell temperatures in space were in between -100 ºC and 82 ºC. The following measurements were taken: IV-curves, indirect cell temperatures and irradiance in the array plane. The monitoring fraction was 1.4 %. The efficiency at 25 ºC was 10.3 % at 700 W/m² irradiance. The performance in space has been compared to solar simulator measurements in the laboratory. The performance after three months in space is equal to laboratory measurements for all four solar arrays. There has been no indication of degradation during the first three months.