The European Space Agency (ESA) is set to launch a pair of new CubeSats, GomX-4B and GomX-4A, from China early next year.

The near-identical satellites will be launched as secondary payloads with China’s CSES-1 seismo-electromagnetic satellite and deployed to test intersatellite communication links and propulsion.

They will maintain their links via flat, patch antennas and software-controlled radios at a maximum distance of 4,500km.

Similar to the size of a cereal box, GomX-4B has already been cleared for launch along with its twin from Danish manufacturer GomSpace in early December.

“GomX-4B is the first CubeSat to fly our new HyperScouthyperspectral imager.”

The satellite is a ‘six-unit’ nanosatellite and double the size of its predecessor GomX-3, which was launched from the International Space Station in 2015.

The GomX-4B and GomX-4A satellites passed the majority of its tests at GomSpace and other facilities in Denmark, while ESA’s technical centre in the Netherlands carried out the satellite’s thermal–vacuum testing, which ensured the probes’ capacity to withstand the extreme hard vacuum and temperature of low-orbit atmosphere.

ESA Technology CubeSat head Roger Walker said: “GomX-4B is scheduled to be launched on a Chinese Long March rocket on 1 February, along with GomX-4A, owned by the Danish Ministry of Defence.”

Following their launch, both CubeSats will orient themselves to align their antennas and then GomX-4B will gradually fly away from GomX-4A, pausing at 100km intervals to see how well their intersatellite links work.

The separation will be controlled by new cold-gas propulsion on GomX-4B provided by Sweden’s NanoSpace, using highly miniaturised thrusters.

Walker added: “As well as operating together, the two also have separate payloads.

“GomX-4B is the first CubeSat to fly our new HyperScouthyperspectral imager, developed by cosine Research in the Netherlands through ESA’s General Support Technology Programme.”

GomX-4B will also be equipped with a new small startracker for precise attitude determination developed by Innovative Solutions in Space in the Netherlands.