Private internet satellite company joins China’s hypersonic race
- Researchers test feasibility of providing stable broadband connection to drones and aircraft travelling faster than sound
- Six GalaxySpace satellites remained in continuous communication with each other and a fast-moving terminal during early test, they said
Some space experts said it is “somewhat unusual” for a private business to take part in China’s hypersonic programme, more typically associated with military applications. Others described the move as an important step forward, highlighting the potential for private sector innovation to advance the country’s space capabilities.
Details of an early experiment in low earth orbit (LOE) to test the technology’s feasibility were published last month by the Chinese peer-reviewed journal Space-Integrated-Ground Information Networks.
The researchers, led by the company’s chief scientist Zhang Shijie, said they achieved continuous communication between six GalaxySpace satellites and a fast-moving terminal for about 25 minutes with no interruption in bidirectional data transmission.
The results suggest the technology has the potential “to provide reliable communication services for high mobility aerospace craft in long-range and high dynamic environments, including hypersonic drones or spacecraft travelling at high speeds”.
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Zhang and his colleagues said the new technology was designed to address the challenges of maintaining stable connections with highly mobile, fast-moving spacecraft.
Traditional satellite communication systems may struggle to maintain stable connections under these conditions, but the GalaxySpace innovation appears capable of maintaining a stable connection, even during satellite switching, they said.
The results suggest the technology could potentially be used to provide broadband internet service to hypersonic drones or aircraft travelling at up to Mach 25, although further testing and development will be needed to confirm this, the researchers said.
China’s hypersonic flight programme aims to develop advanced hypersonic drones or aircraft capable of travel speeds up to Mach 5 or higher. Reliable communication services are essential, to safely control and operate these high-speed craft.
Hypersonic constellation
The GalaxySpace system is based on a low earth orbit broadband satellite internet architecture, similar to SpaceX’s Starlink, which uses a constellation of satellites to provide continuous coverage and support high-speed data transmission.
According to the researchers, the GalaxySpace satellites can emit and receive radio beams in a form that can adapt dynamically to changes in the position and speed of the craft.
A high dynamic access process enable the satellites to quickly establish and maintain connections with moving targets.
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The system also includes a terminal architecture optimised for use on hypersonic drones or aircraft, with its low power consumption and compact size.
New kid in town
GalaxySpace – formally titled YinheHangtian (Beijing) Telecommunication Technology C. Ltd – was founded in 2016, making it a relative newcomer among the private sector operators helping China to compete with US rivals such as SpaceX.
Other companies developing innovative technologies and offering launch services at competitive pricing include iSpace, Galactic Energy and Landspace. All are benefiting from strong government support, including research and development funding.
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China’s encouragement of private sector involvement in its aerospace programmes is part of a broader effort to promote innovation and economic growth, but the GalaxySpace research is an unusual step forward.
This is because China’s hypersonic programme is largely a military affair, with applications ranging from reconnaissance and surveillance to strike missions.
“It is possible that the company’s expertise in satellite communication technologies could be useful for supporting hypersonic flight operations or other related activities,” said a Beijing-based researcher who asked not to be named because of the issue’s sensitivity.
The company did not respond to a request for comment.
High-speed challenges
Zhang and his team said the main challenge to establishing and maintaining an internet connection with a hypersonic craft is the combination of its speed and course, which can be unpredictable.
The researchers had to consider the Doppler effect – the phenomenon that makes the frequency of the transmitted signal appear to the receiver to shift, because of the relative motion between it and the transmitter.
The effect can cause problems for communication systems because of its potential impact on timing and synchronisation between transmitter and receiver.
Another important factor in providing communication services to a fast-moving object is the frequency change rate, or how quickly a signal’s frequency changes over time – a particularly challenging calculation at hypersonic speeds.
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The frequency of signals will also be highly volatile when transmitted from an aircraft that is rapidly changing its position and velocity, making it difficult to maintain a stable connection, the researchers said.
Both of these factors can introduce errors into the transmission process which, if left uncorrected, could lead to data loss or corruption and affect both speed and quality of service, they said.
The team said specialised communication technologies may be required, designed to compensate for these twin challenges in real time, including advanced modulation schemes, error correction codes, and adaptive filtering algorithms specifically designed for high-speed environments.
The researchers also need to overcome the heat, vibration and electromagnetic interference that can jam communications during hypersonic flight.
Early days
The GalaxySpace test established communication between six of its internet satellites and an unnamed satellite simulating the flight of a hypersonic drone, the researchers said.
While the results do not directly prove the feasibility of providing broadband internet service to hypersonic drones or aircraft, they do show the underlying technology is capable of achieving high-speed, stable connections between LOE satellites and other communication systems, they said.
Additional testing and development will be needed to confirm whether similar connections could be established with hypersonic vehicles in flight, according to the study.
The researchers said they are developing communication terminals to attach directly to hypersonic drones and plan more test flights to further verify the technology.
