Low earth orbit (LEO) satellites hit the news when Elon Musk offered them to Ukraine to allow residents to keep communicating with the outside world when existing telecommunications networks were knocked out. But that’s only a small illustration of what LEO satellites can do for humanity if a Korean-led research team has its way, reports Sarah Morris.
You may have never heard of low earth orbit (LEO) satellites but you’ve probably seen broadcasts of Ukraine thanks to them. Ukraine's existing telecommunications and internet infrastructure has been badly damaged, so Elon Musk and his SpaceX Starlink satellites stepped in, using LEO to beam high-speed internet to some 20,000 portable terminals in Ukraine.
To date, this is the most high-profile illustration of the role LEO technology can play in reaching places where cable infrastructure is destroyed or hard to roll out, but it’s just one example of the role the satellites will increasingly play in the future, say experts.
“One day soon, every household will be operating two or three robots, doing the cleaning and the cooking and so on, thanks to this technology,” predicts Mike Kim (Haesoo), vice president of satellite modem manufacturer ASAT in Korea. He headed up a research team, working with Korea’s Electronics and Telecommunications Research Institute, and the Spanish technology and engineering company Inster, which has successfully developed and tested a prototype modem to make LEO more efficient, thereby fully tapping into its potential. If such a modem reaches the market, LEO satellites could revolutionise telecommunications, he says.
Kim isn’t surprised to see the billionaire Musk testing and developing LEO satellites: much of the success of his most ambitious projects will depend on them, he believes. “In the future, without LEO satellites, even the autonomous car industry, for instance, won’t be able to operate, nor will the Tesla robot that Musk is developing”, he says.
Current autonomous cars operate using sensors, but car companies are working towards a car that will be fully autonomous. These will be Level 5 autonomous cars and require a seamless internet connection that Kim believes could only be supported by LEO satellites. “The data collected via sensors for those cars would have to be interfaced with the Cloud for machine learning to decide how and where to drive,” he explains.
Self-driving cars won’t be able to be without satellite and seamless communications, he says. “An autonomous car could have an enormous crash the moment it passes a zone outside terrestrial coverage, but that won’t happen if the connectivity is supported by LEO satellite constellation.”
LEO is not only suitable for connecting remote areas. It is also faster for urban telecommunications between continents, says Kim. Satellite communication works through electromagnetic radiation (EM radiation), which travels in waves at the speed of light. For short distances, since the waves have to travel back and forth to the satellite, fibre optics are fastest.
However, since light travels faster in space than it does through a fiber optic cable, once a fiber optic cable reaches a certain length, LEO services can start making up the extra distance it has to travel back and forth to the satellite. At this point, LEO satellites can outperform fiber, where speed and efficiency is subject to the type and age of cable, the amount of switching panels on the route, the latitude of the start and endpoints of the connection and other variables.
“If you are communicating between Madrid to Seoul, LEO is 1.5 times faster than over fiber optics. From London to Sydney, LEO will be 2.4 times faster,” says Kim.
Kim has believed in a satellite revolution for 28 years ever since a friend, and the ex-CEO of the precursor to ASAT, persuaded him to abandon a secure job as a civil servant to join the then startup SatCom. “Working in bureaucracy was not suitable for a young guy like me,” recalls 62-year-old Kim (in a video call between Seoul and Madrid).
The early years of satellite modem development weren’t easy, though. Kim had a degree in business administration rather than engineering. “I thought as a commercial man I wouldn’t be able to survive,” he remembers. Kim educated himself in engineering and electronics, studying round-the-clock. “Now everyone in this sector knows me,” he notes with satisfaction.
Kim’s commercial outlook has helped him steer ASAT’s research and development towards a technology called “beam hopping”, which he believes will make LEO satellites highly profitable. Beam hopping allows the allocation of more bandwidth to areas of the ground requiring more data and less to those where people are sleeping or idle. It achieves this in real time on demand. Kim outlined the benefits of beam hopping to the International Symposium on Satellite Communication Systems and Services (SCSS) earlier this year.
His team has also researched using beam hopping for GEO satellites, which are generally positioned 36,000 km above the earth. The team concluded the technique would be most effective on LEO satellites where most resources are wasted and so commercial applications would be more in demand.
The modem developed in two international R&D projects ensures that, unlike current satellite technology where the satellite beam illuminates all ground terminals continuously without discriminating based on demand, when a ground terminal requests information (for example, during a Google search), the satellite beam contains a scheduler that transmits the beam only to the zone in the time domain that has requested it, “bouncing” over non-requesting ground terminals. “The beam will be like a sniper, it won’t waste any bullets,” says Kim.
This level of precision will make the satellite more effective with less latency or delay to the transfer of data. Since LEO satellites are closer to the earth, they require more power to stay in orbit and generally last five or six years compared to the 15 or so for higher altitude GEO satellites. However, the coverage provided by the LEO satellite will also be greater. On-demand illumination through beam hopping will make the market for LEO satellites “explosive”, predicts Kim.
The potential of LEO satellites is not just attracting companies like Musk’s StarLink, which plans to deploy 42,000, but also the likes of Amazon whose subsidiary, Kuiper, plans to launch more than 3,000 and Boeing, targeting a similar number. The British company OneWeb is also increasing its planned launches and China’s GaoWang and Huawei are each talking about thousands.
All these companies are potential clients for Kim’s LEO modem, as is the finance sector. Since light travels faster in a vacuum, a round trip via satellite between, say New York and London, can deliver stock-exchange data with less delay than over fiber optic cable. “That’s worth billions for delay-sensitive sectors,” he says.
Seeing the potential, the Korean Ministry of Trade, Industry and Energy and the Korea Institute for the Advancement of Technology are helping fund the research and development.
Ultimately, Kim believes LEO satellites will help meet the challenge of connecting the world’s population to the internet and ensuring seamless coverage for the fast-evolving internet of things world. Internet providers can share satellites, whereas cable is rolled out individually through buildings and ground infrastructure: “With the sort of investment spent on fiber optics for a small region, in the future, we’ll be able to cover the whole globe with LEO.”
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