The deployable telescope: A cutting-edge solution for high spatial and temporal resolved Earth observation

The increase of spatial and temporal resolution for Earth observation (EO) is the ultimate driver for science and societal applications. However, the state-of-the-art EO missions like DigitalGlobe's Worldview-3, are very costly. Moreover, this system has a high mass of 2800 kg and limited swath width of about 15 km which limits the temporal resolution. In this article, we present the status of the deployable space telescope (DST) project, which has been running for 6 years now at the Delft University of Technology, as a cutting-edge solution to solve this issue. Deployable optics have the potential of revolutionising the field of high resolution EO. By splitting up the primary mirror (M1) of a telescope into deployable segments and placing the secondary mirror (M2) on a deployable boom, the launch volume of a telescope can be reduced by a factor of 4 or more, allowing for much lower launch costs. This allows for larger EO constellations, providing image data with a much better revisit time than existing solutions. The DST specification baseline, based on Wordview-3, aims to provide images with a ground resolution of 25 cm (panchromatic 450-650 nm) from an orbital altitude of 500 km. In this paper, the current status of the optical, thermo-mechanical, and active optics systems design are described. The concurrent design approach combined with a strict bottom-up and top-down compliant systems engineering approach show that the DST is a healthy system concept.