Page 26 - 2019 Mil/Aero eBook
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off-the-shelf (COTS), COTS-Plus, and mil-spec components can offer ideal solutions for nanosatellite applications while helping to keep costs low, as true space-grade are very expensive.
Recent studies undertaken at the Grenoble University Space Center (CSUG) show that many CubeSat failures are due to bad connections. In fact, in a January 2019 meeting with the Nicomatic design team, Mathieu Barthelemy, an astrophysicist at the Grenoble Institute of Planetary and Astrophysics (IPAG-OSUG) and the director of the CSUG said, “The current-carrying capacity of connectors used in nanosatellites and CubeSats is very important and can endanger the entire mission. In these projects, components are often taken off-the-shelf and are therefore more likely to be more sensitive to current variations.”
 The U.S. Army’s Space and Missile Defense Command an d Army Forces Strategic Command (USASMDC/ARSTRAT) developed the electro-optical Kestrel Eye nanosatellite to improve mission command for combat teams on the move. The CubeSat allows tactical leaders to better synchronize action, seize initiative, and maintain near-real-time situational awareness.
For this reason, the current-carrying capacity of a connector’s signal or power pins is one of the most important specifications to consider. This figure defines how much current can be safely passed through the connector contacts but must be considered in association with any derating curves that will reduce the amount of current due to environmental and test factors.
Current-Carrying Capacity and Derating Curves
The current-carrying capacity of a connector is determined by the thermal properties of the contact, terminal, and insulator materials and is dependent upon the self-generated heat and the ambient temperature at which the connector operates. IEC standard IEC 60512 describes how current-carrying curves are determined under given conditions. The highest temperature (tb) of a point on a connector and its immediate environmental temperature (tu) are measured at various currents and ambient temperature levels, and the difference between the two temperatures is the self-heating generated in the connector by the applied current. This is expressed as tb – tu = Δt (C°) and can be illustrated as a basic current-carrying curve graph.
A graphical representation of the basic current-carrying curve.

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