On June 15 of this year, the Internet in Vietnam slowed to a crawl, and some International Websites were inaccessible. The cause? Damaged subsea cables. According to Vietnam’s state media organization, VNA, this incident “significantly affected Vietnam’s internet connection with the world…”

That’s only the latest such incident. CNN reported that in February of this year, “Cables belonging to four major telecoms networks,” were damaged, “causing significant disruption to communications networks in the Middle East…and forcing providers to reroute as much as a quarter of traffic between Asia, Europe and the Middle East...”

Approximately one month after the Red Sea cables were disabled, in March 2024, four subsea cables servicing Western Africa were damaged in a suspected undersea landslide. Later, in May 2024, a cut subsea cable impacted Internet connectivity for countries in Eastern Africa, including Kenya.

Four incidents in approximately four months may seem surprisingly frequent, but it probably shouldn’t be considering the number and variety of threats facing subsea cables.

“There are multiple different threats to subsea cables. The first one that comes to mind is natural disasters. Earthquakes, tsunamis, and other events that can shake up the ground under the cables at the bottom of the sea can cause damage and outages,” said Ali Younis, VP of Commercial Sales at Mynaric. “But what we’ve also seen – especially over the past two years – is increased attacks against subsea cables. There is also a cyber threat, where the hardware and network infrastructure on either side of the cable can be compromised.”

Should these cables be damaged or destroyed, the impact on a region’s Internet access and connection to the outside world could be severely impacted.

“…if you’re a banking institution that relies on a very short, low-latency subsea connection from London to New York, and that cable gets cut, you may lose your competitive advantage,” said Ashesh Mishra, the Head of Client Solutions at Aalyria. “If you are on an island, let’s take Papua New Guinea as an example. There is one cable that comes into the country. If that gets cut, you’re left with whatever alternate means of communication you have.”

Backing up subsea cables from space

It’s clear that connectivity must be restored quickly if a subsea cable is damaged or severed. However, repairing these cables can take months, making effective backups for subsea cables essential.

This has led many within the industry to look for new, potentially more resilient ways to back up subsea cables, with satellites the primary method being explored.

“[Satellite] is going to be more robust from an infrastructure perspective because it’s more challenging to inadvertently damage. A big storm is not going to take it out. Fishing vessels are not going to have an impact on it,” said Mishra. “While we’ve seen state actors be perfectly capable of disrupting satellites…it is still more challenging to create that impact in space than on the ground - especially if you don’t want to be detected.”

While satellites might be more resilient than subsea cables, one significant challenge keeps them from being a complete and viable backup: capacity.

Subsea cables are used for a reason—they can transmit terabytes per second (Tbps), something that even the most advanced modern satellites cannot do.

“The primary challenge that you have with backing up any part of subsea cable traffic over satellite is the fact that satellites are still limited to a few Gigabytes per second (Gbps) worth of traffic,” explained Mishra. “There is no commercial satellite service out there that can claim to deliver more than five to ten Gbps to a location,”

The amount of data that would need to be transmitted should subsea cables be damaged will only increase as the demand for digital services increases – making this a problem that will only worsen over time. “…global internet consumption and data demand grows by 30 percent year over year,” said Younis. “That 30 percent, alone, is worth an entire satellite constellation.”

Despite these constraints, there have been instances where impacted parties have used satellites to restore the connectivity lost when a subsea cable was damaged. During the incident in the Red Sea, Rhys Morgan of Intelsat told Space News that the satellite operator, “…[was] providing backup connectivity for a couple of customers that were sending data via subsea cable before the Red Sea incident.

Satellite’s potential to back up subsea cables is drawing increased attention from global governments and militaries, which have long viewed the vulnerability of subsea cables as a threat to their national interests and national security. The desire to seamlessly transition subsea cable data over satellites has led NATO to introduce Project HEIST (Hybrid Space and Submarine Architecture to Ensure Information Security of Telecommunications), intended to detect subsea cable disturbances and automatically reroute data via satellite.

However, until satellite advancements can couple decreased latency with drastically increased capacity, there will still be limitations in how much data can be rerouted from a damaged subsea cable to satellite networks.

SLAs and satellite solutions

With current satellite infrastructure limited to carrying only a portion of cable, prioritizing data becomes a first-line option. Luckily, there is already precedent in the telecom industry for this.

“…the idea of there being backup paths available for your network has existed for at least a few decades in terrestrial networks,” said Mishra. “That problem is solved by offering differentiated services to the customer. If they were willing to pay more, they could get access to a service that had priority on a backup terrestrial network.”

A similar business model could be used to back up terrestrial networks and subsea cables with satellite networks.

“Some operators have tested an on-demand pricing model that has been very successful. Should there be a critical failure in a big part of the infrastructure, they give customers immediate access to backup infrastructure and pathways at eye-bleedingly expensive prices,” said Mishra. “It will more than likely end up being the same sort of a solution for backup with satellite.”

Fortunately, advancements in technology could eliminate the need to prioritize data, and make it so that all data on a subsea cable could be backed up by satellites – not just the data from the highest bidder.

More capacity on the horizon

While today’s satellites offer limited capacity, numerous satellite payload manufacturers and operators are looking to change that.

In April this year, SES announced that its O3b mPOWER service was operational. This satellite constellation offers hundreds of Gbps per satellite with lower latency due to its position in Medium Earth Orbit (MEO). However, each O3b mPOWER satellite can still carry just a small fraction of the traffic that a single subsea cable can transmit.

Satellite constellations in LEO, including SpaceX’s Starlink, can deliver 20 Gbps per satellite and incredibly low latency thanks to their proximity to the Earth. However, considering that the recently-installed MAREA cable connecting Bilbao, Spain, to Virginia Beach, VA, is capable of carrying 224 Tbps, even the next generation of Starlink satellite, the Starlink V2 Mini, will offer just a fraction of a subsea cable’s capacity.

These new, advanced services can back up some of a subsea cable’s capacity, but not all. However, a new satellite technology that offers similar throughputs and latency as a subsea cable could be introduced within the next half-decade.

Leveraging a new generation of optical satellites that use lasers to receive and transmit information between the ground and space – and between satellites – several satellite companies are looking to eliminate the capacity restrictions that keep satellites from effectively and efficiently serving as backups to subsea cables.

“Constellations at LEO and MEO have brought satellites closer to Earth, reducing that gap in latency. The introduction of optical communication systems takes that to a whole new level…multiplying the speeds and throughputs of traditional radio frequency (RF) communication by a minimum of ten times,” explained Younis. “This technology has already been demonstrated successfully. It has not been commercialized yet.”

If satellite throughputs could begin to compete with the throughputs of subsea cables, there would be no need to prioritize data, and satellites could more effectively serve as a backup for damaged or destroyed subsea cables.

“In the past, the amount of research and development that happened for optical transmission over physical media was more substantial than the investment in transmission over air,” said Mishra. “It was only very recently that we started getting to a point where [we could] transmit really high data rates that are comparable to optical fiber at the distances that would allow you to relay through a satellite. It is now becoming possible to reconstitute fiber networks via satellite if you have a failure.”

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