South African private-sector space company SCS Space is looking forward to establishing the spaceworthiness credentials of its Gecko imager, which is mounted on South Africa’s nSight-1 nanosatellite and which was scheduled to have been launched from the International Space Station on May 23. nSight-1 is part of the global QB50 programme to place 36 nanosatellites in orbit (the original plan was 50), coordinated by Belgium’s Von Karman Institute on behalf of the European Union. The primary aim is research into the region of the atmosphere known as the lower thermosphere. (As such, nSight-1’s main payload is the Flux-Phi Probe Experiment from the Technical University of Dresden.) nSight-1 has a mass of 2.5 kg and has dimensions of 20 cm × 10 cm × 10 cm.

“The Gecko is important for us because we are developing several new imagers using the same core technology that we developed for Gecko,” explains SCS Space Imaging Systems product manager Dr François Malan. “This mission will give us important space heritage on this intellectual property (IP). In the space industry, no one is confident that a technology works until it has been flown, and proven reliable, in space. Gecko has been subjected to all the required testing, but nothing can substitute for an actual space flight.”

There is also significant commercial potential for the Gecko in its own right as a modular nanosatellite imager payload. It is currently available for sale on the CubeSat Shop, an online store managed by the Netherlands-based Innovative Solutions in Space BV. CubeSats come in standard sizes of 1U, 2U, 3U and larger – the ‘U’ refers to a standard size unit of 10 cm × 10 cm× 10 cm. The very first CubeSats were indeed cubes, being 1U nanosatellites, but nSight-1 is a 2U nanosatellite.

“The Gecko imager is quite innovative,” he reports. “Our imager is of modular design and construction.” It is composed of four main elements. These are a separate sensor unit, a control unit, the optics or lens and the frame on to which the other elements are mounted.

The sensor unit can support a number of different sensor types, and more can be added without having to change the rest of the camera. The different sensors cover different spectral bands and can have different pixel sizes. The sensor unit plugs into the control unit.

“The control unit is really the heart of the camera and contains much of the IP that is required to make space imagers,” he highlights. “It has a large amount of high speed memory (scalable to 512 gigabytes). The control unit can capture data at nearly six gigabits per second, allowing it to function as a high-performance interface device. The control board also hosts a fast field-programmable gate array, or FPGA, processor that allows for real-time image processing. On nSight-1, the camera also implements a low-resolution thumbnail mode that allows several thumbnails to be downloaded during a single overpass. This feature allows the operator to select and download only full-resolution images that are of interest – for example, avoiding images of areas occluded by clouds. This is especially useful because all downloads from the tiny nSight-1 have to take place over the limited speed downlink. An S-band transmitter would have ameliorated this downlink bottleneck, but nSight-1’s size placed restrictions on what we could fit into its frame. A larger form factor, such as 3U, would in future missions be able to contain such equipment while also carrying the desired scientific payloads.”

The choice of optics was optimised for the 30 m ground resolution desired for this specific mission. SCS Space will keep in contact with the nanosatelllite by means of its ground station at its rented facility at Houwteq, near Grabouw, in the Western Cape.

“Gecko is our smallest imager, weighing 0.5 kg; our largest is Basilisk, at 125 kg,” reports Malan. “We are currently constructing an example of the Tegu earth observation, which can support 11 spectral bands. We’re also finding a lot of market interest in the gecko. With each new product evolution, we provide our spacefaring customers with products of increasing capability.”

Tegu and Gecko share a lot of core technology, especially in the control unit. We’re also finding a lot of market interest in the components we use in the Gecko, especially the sensor unit (which can be adapted to take totally different sensor instruments) and the control unit. We constantly upgrade our components to provide customers with ever better specifications.”