LATT – Large Aperture Telescope Technology

High sensitivity space based observations (either for Earth observation or astronomical purposes) require the use of large sized apertures (mirrors) in order to collect as many photons as possible.  Given the limitation in terms of mass and launcher sizes the necessity turns to lightweight mirror structures that can be stowed into a suitable launcher vehicle and deployed in orbit.

I have been a member of a UK-based consortium investigating LATT as part of a European Space Agency (ESA) funded design study.  The member institutions in this consortium (led by the Rutherford Appleton Laboratory) are as follows: Rutherford Appleton Laboratory, UK Astronomy Technology Centre, ABSL Space Products and University College London.  The design study is for a differential lidar (DIAL) system, monitoring water vapour in the Earth's atmosphere, but the technology is also applicable to other telescope systems requiring a large aperture of similar specifications.  The primary mirror when deployed is 4m in diameter, but is folded to fit into a 2.1 m diameter rocket faring.  The central observation wavelength for this application is 935 nm and the RMS corrected wavefront error on the primary mirror must be λ/6 or better, a surface micro-roughness of < 5 nm and an areal density of < 16 kg/m² (which includes support structures).

I presented a summary of this work at the International Conference on Space Optics in Rhodes (October 2010); the accompaning paper can be downloaded from the ICSO website.