Systems Engineering has been used throughout the development of the Visible and Infrared Survey Telescope for Astronomy (VISTA). VISTA was originally conceived as being a classic 4m telescope with wide-field imaging capability. The UK Astronomy Technology Centre (UK ATC) radically changed this thinking by treating the whole design as one system, integrating the camera optics into the telescope design.
To maximise the performance, an f/1 primary mirror was adopted resulting in a very compact telescope and enclosure. Amongst other benefits, this reduced the overall mass of the telescope from 250 to 90 tonnes. During this optimisation process, the concept of a direct imaging K-short camera was developed. This development, in conjunction with an increase in IR field of view, produced a system with uniform image quality and throughput across a 350 mm diameter focal plane, 1.65 degree field.
While this has presented some major engineering challenges, the approach has produced a system which is both scientifically rewarding and achievable. The optimisation, design trade-offs and Technical Specification developed in the conceptual design phase were achieved through a systems analysis approach.
This paper describes some of the key systems engineering decisions and the tools employed to achieve them. Current systems engineering activities are described and future plans outlined.