Wireless laser communication systems developer Astrolight successfully performed a satellite-to-ground laser communication test using a portable OGS-1 optical ground station.

Astrolight, working with the European Space Agency (ESA), established the laser communication
link using the OGS-1 optical ground station, located near ESA’s Izaña-1 (IZN-1) ground station,
located at Teide Observatory in Tenerife, Spain, and an experimental laser transmitter system Osiris
onboard the ‘Flying Laptop’ satellite, flying in low Earth orbit at around 600 km altitude.

The final objective of this test campaign is to demonstrate a reliable, high-bit-rate ad-hoc low-Earth
orbit (LEO)-to-ground laser communication capability between a representative satellite and
Astrolight’s OGS-1 portable optical ground station.

The experiment highlighted the unique portability and ease-of-use of Astrolight's solution. The
complete system, including the telescope, receive optical head, tracking computer, detector and
modem, was disassembled at Astrolight’s facility in Vilnius, Lithuania, and placed into four pieces
of luggage each under 32 kg, which were then transported 480 km by a compact SUV, placed on a
plane via regular check-in desk, flown to Tenerife and then transported up the mountain by car.
Astrolight’s OGS-1 was then reassembled and ready for operation in two hours, which is also the
time it took to prepare the ground station for the trip.

With OGS-1 operating from a car battery, a light signal transmitted from the Flying Laptop satellite,
equipped with the OSIRIS optical communication terminal, was successfully coupled into the
detector despite the uncharacteristically strong wind conditions at Teide Observatory at the time.
Besides LEO-to-ground downlink experiments, special calibration procedures for satellite tracking
with the portable mount were tested and various large pieces of space debris and satellites were
tracked.

The repeated tracking experiments showcased the OGS-1 tracking software’s ability to compensate
for imperfect mounting and actuation of the telescope using commercial-off-the-shelf (COTS)
equipment. The week-long test campaign concluded with successful disassembly of the ground
station and a journey back to Vilnius, where OGS-1 was also operational immediately after the trip.

“We were able to couple the signal from the satellite laser transmitter into a 105 μm fibre while the
satellite was travelling at 7.8 km/s, about 2000 km away from us at 5 degrees of elevation above the
horizon,” says Laurynas Mačiulis, Astrolight co-founder and CEO.

ESA is presently upgrading the Agency’s optical ground station at Tenerife, which until now could
only be used for laser ranging, with an optical communication package.

“For this optical communication test, we are tracking and receiving a laser light signal from LEO at
ESA’s IZN-1 station using the portable ground station from Astrolight as well as with our existing
laser terminal,” says Clemens Heese, Head of the Optical Technologies Section at the European
Space Agency

“By performing this test with two terminals simultaneously, we can see and study differences in the
links, which is very useful for joint assessment and for optimising the respective systems – there
was a lot of engineering discussion which was very fruitful for both ESA and Astrolight.

“This test was important because a portable optical ground station that you can pack in a suitcase
and move to a place where you need to send or receive data offers a lot of possibilities for
connecting remote locations – like disaster areas – that don’t have data communications.”

The test aimed to verify the portability and ruggedness of Astrolight’s portable optical ground
station design. The terminal provided excellent performance despite being subject to rough handling
and mechanical stress during the trip to Teide Observatory and being operation in very windy
conditions.

“Our next milestone is to develop and install a larger optical ground station permanently situated in
southern Europe. It will re-use design elements from our portable system but with a larger telescope
and will be capable of achieving 10 Gbps downlink speeds from LEO satellites. We plan to install
the ground station by Q1 of next year,” says Laurynas Mačiulis.

Strong need for satellite laser communication

The volume of data that needs to be transmitted from Earth to space and vice versa is growing
tremendously. The needed data throughput will only increase with the expansion of spaceflight
activities in all domains, including weather forecasting, broadcast, data relay, scientific and climate
data gathering and navigation services, as well as human missions.

The revolution that fibre internet has brought to terrestrial internet data capabilities is comparable to
what laser communication can bring to the ‘space internet’. Laser communication is by its nature
much more secure, has a much narrower beam width and is more difficult to intercept or jam. Laser
communication will enable next-gen security and the implementation of protocols working with
quantum principles, such as quantum key distribution for a secure key exchange.

“We are at the technology development stage where the support of ESA and its infrastructure is
crucial, and we are extremely satisfied with our cooperation,” says Laurynas Mačiulis.

This test is the first cooperation in the field of free space optical communications between the
European Space Agency and the Lithuanian-based company Astrolight.