Optical satellite communication: The next generation communication instruments for space science and exploration

Creating the opportunity

Technological advances allow for more sophisticated instrumentation, which in turn helps us learn more about the universe by gathering more data. But these increasing amounts of data will require a system with high data rate uplink and downlink to transfer the data between the source and Earth. For example, on the International Space Station (ISS), astronauts have uplink speeds of up to 25 Mbps, and downlink speeds of 300 Mbps. These speeds drastically decrease over great distances.

For deep-space exploration, including a Lunar Gateway, Space Weather Missions or an orbiter around Mars, a faster, more stable type of communication is needed. TNO and the European Space Agency (ESA) signed a two-year contract to investigate the use of optical communication technology to enable swift and efficient optical communication for deep-space missions. A first goal in this deep-space optical communication development is to provide a 300 Mbps downlink when transmitting from the Moon, which is a thousand times farther away than the one on ISS.

Increasing exponentially

Optical communication technology will enable very high data rate links to the Moon, Mars – and perhaps beyond. It may also be able to provide aggregate communication lines from relays down to planetary surfaces.

‘Optical communication in deep space shows great potential,’ explains Martijn Dresscher, System Engineer and Lead Scientist of the Deep-Space Optical Communication programme at TNO. ‘We estimate that we can increase data rates by roughly a factor of 20, using a 22-centimetre diameter optical telescope with a 4-Watt laser. This instead of a 35-Watt, 3-metre diameter radio antenna.’

Partnering for progress

To explore the possibilities, the ESA needed project partners that shared its vision. TNO is contributing its more than seven years of experience in optical satellite communications, and is utilising the expertise of two subcontractors. Namely, Gooch & Housego’s laser source expertise and Teledyne e2V’s detector innovations. Together, the team will develop and test key technologies for communication in space. In particular, the space terminal laser source, modem and detector systems.

The first step is to demonstrate the feasibility of an end-to-end optical solution at breadboard level. If successful, the team hopes to further develop the technology together. “The partnership with TNO for the development of optical telecommunication systems will enable to bring to practical reality some of the most challenging scenarios for high speed links. It demonstrates once again why the European Industry is the world leader in optical telecommunications.” says Jorge Piris, Technical Officer of the European Space Agency.

TNO Space wants to stimulate economic growth in the Netherlands and Europe by enabling companies to realise new products, generate new business and improve their competitive position. The development of technologies under this activity is one example of these goals in practice.

Utilising Europe’s leading position

Europe leads the world in the development of inter-satellite and space-to-ground optical communication terminals (OCTs) from Low Earth Orbit (LEO) and Geostationary Orbit (GEO). When adapted for the long range deep-space environment, those same terminals are suitable for lunar and deep space exploration.

‘This project builds on TNO’s extensive knowledge and history of developing critical components for optical satellite communication, and on the expertise of our two subcontractors,’ says Oana van der Togt, Senior Business Developer Space and Scientific Instrumentation at TNO. ‘The successful adaptation of an existing LEO OCT to the needs of deep-space exploration missions will ensure the next technological step forward, and will result in providing a full European solution for lunar and deep-space explorations. For TNO, this activity enhances our optical satellite communication portfolio with an application area beyond our planet Earth.’