A third‐generation small spectroscopy experiment for hard transient events

We describe an experiment for monitoring high‐energy transient events (X‐ray and γ‐ray bursts from both solar and stellar sources) as proposed for the OPEN (Origin of Plasmas in the Earth’s Magnetosphere) mission. This experiment contains Si(Li) detectors, a high‐purity germanium detector, and a bismuth germanate scintillation counter for high‐energy response. Cooling for the solid‐state detectors is provided by a passive radiator. The instrument gives broad spectral response with high energy resolution; its mass of 15 kg and telemetry requirement of 200 bps impose only modest demands upon spacecraft resources. The use of a passive cooler does also place a constraint upon the orbit of the satellite; deep space would be the preferred location but other orbits may also be suitable. The ideas embodied in the design may be of interest in the design of other spectroscopy measurements from deep space, as for example for participants in a future triangulation nework for transient events.