March 1, 2024

Laser connection of the ESA container to space

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02/08/2024
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ESA’s latest laboratory extension is portable by nature: housed in a standard shipping container, this ESA Transportable Optical Ground Station, ETOGS, can be transported across Europe as needed to perform laser-based optical communications with satellites – including NASA’s Psyche mission, millions of miles away in space.

Deployable telescope inside shipping container

Formally part of the Agency’s Optics and Optoelectronics Laboratory, the station will serve as a flexible testbed for optical telecommunications hardware and systems. ETOGS can also support other activities that require looking at the sky with a telescope or pointing at the sky with a laser, such as monitoring space debris or determining orbit through laser measurement.

The ETOGS consists of a standard 6 m (20 ft) long container, customized to accommodate an 80 cm diameter telescope on a lift platform and a climate-controlled operator area. Laser transmitters, receivers and other necessary equipment can be attached to this flexible structure to suit each specific campaign. Transported by truck, the station can be deployed wherever needed and powered via mains electricity, diesel generator or solar-powered battery pack.

Telescope elevated to the roof of ETOGS

Responding to optical communications priorities

ESA optoelectronics engineer Jorge Piris explains: “This station was really created in response to the needs of the rapidly developing optical communications community for a flexible testbed that can be deployed in a representative terrestrial environment. One of the most relevant questions in optical communications is the extent to which the surrounding environment can affect the quality of the connection – such as backlighting in urban areas or atmospheric turbulence due to weather.

“This is key when it comes to receiving signals from quantum communication systems, as the amount of light involved is extremely low, with information transmitted via individual photons. With this station we can really start to answer these questions by operating from several different locations. By providing our partners with a ready-made test platform like this, we support hardware validation and iteration without the high development costs of a dedicated ground station.”

Space Quantum Key Distribution

Light-based messaging enables a quantum leap in security

Optical and quantum technologies promise to revolutionize connectivity on a global scale. By using pulses of light with a much higher frequency than radio waves, optical communication allows the transfer of more data at a given time. Optical communications through fiber optic cables underpin the modern terrestrial Internet infrastructure, but satellite links continue to be largely dependent on low-frequency, lower-bandwidth radio waves.

And by exploiting the quantum properties of light, systems like “quantum key distribution” will help safeguard data to a previously inconceivable degree; The security of the exchange of cryptographic keys is safeguarded by the physical properties of light particles, making messages resistant to eavesdropping by criminals.

NASA Psyche Mission

Jorge adds: “The station’s 80cm telescope is the anticipated base size for commercial-scale quantum key distribution, so we envision the station being used for the demonstration and validation of satellite-based quantum communications.”

Shining a light in deep space

The first operational mission of this new ESA capability will be to support the demonstration of optical communication in deep space with NASA’s Psyche mission scheduled for 2025.

Kryoneri Observatory, Greece.

ESA is collaborating with a European consortium and the Athens National Observatory to develop and deploy ETOGS at the Kryoneri Observatory in Greece to host a multi-beam Terrestrial Laser Transmitter.

The goal is to connect a powerful infrared laser signal of up to 7kW, allowing the laser terminal aboard NASA’s Psyche spacecraft to point back toward Earth. This link will cover unprecedented distances of up to 2.7 astronomical units – around 403 million km – to mark a new era for optical communications in deep space.

Observing from the roof of ETOGS

The ETOG container was built by WtW in Germany, with its telescope coming from Astrosysteme Austria. The remaining elements to complete an operational system will largely come from the results of the project and activity. Jorge notes, “One of the interesting parts of this project is bringing together the various results from different projects into a single configuration and then demonstrating their synergy to function as a system.”

For now, ETOGS is being equipped at ESA’s ESTEC technical center in the Netherlands. The OOEL Laboratory team will use its telescope to acquire images of the International Space Station and other satellites to validate that the station has the necessary stability and tracking capabilities.

ETOGS looking at the sky

Later this year, ETOGS, with the deep space laser transmitter mounted on it, will be tested in Kryoneri, Greece, using ESA’s Alphasat satellite in geostationary orbit at 36,000 km altitude, which is equipped with a communications system optics.

Once operational, the station will function as part of the OOEL Laboratory, meaning it will be available to ESA projects, as well as companies and research institutions in the Agency’s Member States.

The station was developed and is being managed by ESA’s Opto-Electronics section, which is dedicated to systems that use or control light. This section is part of the Agency’s Technology, Engineering and Quality Directorate, with the mission of preparing advanced technologies and providing engineering support to enable future missions and projects.

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