2018.B.3.5. CubeSat Camera: A Low Cost Imaging System for CubeSat Platforms

Author(s)

William Brzozowski (1)
William Easdown (2)
Steve Greenland (1)
Stephen Todd (1)
Steve Payne (2)
Maria Milanova (1)
David Pearson (1)
Max Hodgkins (2)
Dylan Feore (2)
Elise Allthorpe-Mullis (2)
William Grainger (2)

UK Astronomy Technology Centre, United Kingdom
RAL Space, United Kingdom

Session

B.3

Keywords

Imaging system; camera; cubesat; RAL Space; UK ATC; earth observation; planetary observation

Abstract

RAL Space and UK Astronomy Technology Centre have a wealth of knowledge in developing bespoke imaging systems for various applications, from astronomy to earth observation. Interest in the capabilities of small satellites led to the CubeSat Camera (CCAM); a proof of concept design for a modular, low cost imaging system, compatible with a CubeSat platform
CCAM’s imaging system consists of a Cassegrain-style telescope with a field correcting lens and CMOS detector, all within a 1.5U volume. CCAM’s telescope and detector are two separate modules, which allows each to be tested and used separately. By having the imaging system consist of modular components, CCAM can be modified according to specific missions. For example, imaging in the near-infrared by removing the NIR blocking filter and changing the detector module to a monochrome detector.

CCAM is designed to be diffraction limited – or near diffraction limited – across visible and near-infrared wavebands and continues this performance across a 400km-700km orbital height range. Radiation hardening for Low Earth Orbit allows for a 1-2yr lifetime. Many opto-mechanical design points are considered to reliably achieve high image performance in such a small volume. For example, the design of light baffles to eliminate stray light and the optical mounting mechanisms to maintain tight tolerances whilst not vignetting science light. The CCAM system is designed to be optically aligned within its 1.5U, and therefore independent of the rest of the CubeSat platform.

The electronics will be laid out on a double-sided PCB. A custom mount will attach the PCB to the camera. The CMOS sensor takes ~500µs exposures that can be stitched into a swath (at the ground station). Data are fed to the customer’s On-Board Computer via 16 pairs of LVDS lines at 28Mbps. The electronics require a 3.3V, 3A power supply. The supply is subdivided into 5 voltage rails (1.5V, 2.1V, 2.5V, 3V, 3.3V) where no one rail will exceed 2A.

CCAM aims to achieve 5m ground sampling distance across the visible wavebands at a 400km orbit. This is a high resolution for a small satellite, and enables CCAM to be utilised in a broad range of Earth Observation applications. However, the applications are not limited to EO. This technology could be used to observe other solar system bodies. For example, the geological activity of Europa, the meteoroid environment of the Moon, or the weather systems and landscapes of Mars.