Space sails are a continuum of lightweight, thin, large-area, deployable technologies which are pushing forward new frontiers in space mobility and exploration. They encompass solar sails, laser-driven sails, drag sails, magnetic sails, electric sails, deployable membrane reflectors, deployable membrane antennas, and solar power sails. Some have been flight tested with operational heritage, while some are concepts planned to reach maturity in the coming decades. The number of flown and planned missions has increased rapidly in the past fifteen years. In this context, it is time to recognise the advantages of space sails for supporting the achievement of a wide range of major space exploration goals. This paper evaluates, for the first time, synergies between the broad spectrum of space sail technologies, and major space exploration ambitions around the world. The study begins by looking to the past, performing a global, historical review of space sails and related enabling technologies. The current state of the art is mapped against this technological heritage. Looking to the future, a review of major space exploration goals in the next decades is conducted, highlighting domains where space sails may offer transformational opportunities. It is hoped that this paper will further the ongoing transition of space sails from a promising flight-proven technology into a go-to component of space mission programme planning.

The next generation of far infrared space observatories will require extremely sensitive detectors that can be realized only by combining extremely low intrinsic noise with high optical efficiency. We have measured the broad-band optical response of ultra-sensitive transtion edge sensor (TES) bolometers (NEP ≈ 2 aW / Hz) in the 30-60-μm band where radiation is coupled to the detectors with a few-moded conical feedhorn and a hemispherical backshort. We show that these detectors have an optical efficiency of 60% (the ratio of the power detected by the TES bolometer to the total power propagating through the feedhorn). We find that the measured optical efficiency can be understood in terms of the modes propagating through the feedhorn with the aid of a spatial mode-filtering technique.