When Nicole Robinson, President of DataPath, reflects on the sentiment around optical ground terminals just one year ago, she recalls that the satellite community viewed the technology as still in its infancy. “Advance the clock one year to today, now everyone thinks we’re late and need to hurry up,” Robinson said during a Defense in Space Conference (DiSC) panel this past October, where she was joined by Jean-Francois Morizur, CEO of Cailabs, and Hugh Keane, SES Space & Defense’s Senior Director of Defense Networks.
The desire to make optical ground terminals widely available is understandable, given the benefits the technology will deliver for global militaries. And since optical lasers are already successfully deployed for satellite-to-satellite communications in orbit, Morizur noted that widespread adoption of optical ground is within reach. “Let’s keep in mind that lasers in space are a reality,” said Morizur. “It’s not science fiction anymore. It’s already there.”
So, what exactly are the key advantages optical technologies will have in the satellite-to-ground game? And if optical ground is the next natural step for the technology’s development, what are the remaining challenges that stand in the way of fully realizing its benefits?
Providing Greater Security, Increased Data Rates Through Optical Lasers
For Morizur, the need for higher throughputs is one of the top reasons why global militaries will want to shift away from traditional RF and towards optical for space-to-ground communications. Morizur explained that government and miltary users leverage satellites to carry increasing amounts of data and require space-to-ground capabilities to accommodate the high volume of data they generate. “[Customers] need higher data rates,” said Morizur. “Optical provides much higher data rates than Ka-Band and Ku-Band.”
In addition to higher data rates, optical space-to-ground comms also provide one of the most critical elements that DoD SATCOM architectures require: greater security. “The most important thing about [optical space-to-ground comms] is it’s difficult to detect, difficult to intercept, and it’s jamming resistant,” said Morizur. Unlike RF, which can be intercepted by adversaries on the ground if they are within a 40-kilometer radius, an optical laser beam’s radius is exceptionally smaller. “The [optical laser’s] spot on the ground is tens of meters,” said Morizur. “That means that if you want to intercept it, you need to be within tens of meters of the ground station.”
Keane agreed with Morizur about the role of optical in providing greater data security on the ground, especially given the evolving nature of warfare over the last several years. “There has been a distinct shift, especially since 2022, from the sort of asymmetric conflicts that we’ve been involved in previously, where you didn’t have to worry about adversary capabilities in terms of jamming,” said Keane. “What we’ve seen come out of Ukraine, and what might be anticipated in other theaters for the future, [makes optical comms] more important. The low probability of intercept/detection (LPI/LPD) characteristics of [optical comms] are significant for those end users.”
In addition to the higher data rates and the LPI/LPD benefits that optical space-to-ground comms provides to DoDs, Robinson pointed out that optical also plays a crucial role in the data path diversity required to support a proliferated space architecture.
“When we think about what’s happening in the last five years, in particular with non-geostationary satellite orbits…and mesh networks that are taking place between those constellations, it’s not just about having multiple orbits, but multi-modalities that are leveraging that data highway,” explained Robinson. “Creating that network in space requires a greater degree of sophistication on the ground in order to receive, process, and make that data most usable to those who are on the front line. When we think about defense end-users, optical is about getting that data down faster and leveraging that…space-to-space, optical highway and being able to bring that data down faster.”
Atmosphere, Contracting, and Transportability Breakthroughs
Though optical comms is already being used for communications between satellites in space, there are still limiting factors that prevent fully realizing the capability’s potential on the ground. The first and primary challenge concerns the fundamental physics of how lasers interact with Earth’s atmosphere.
“People will tell you [the challenge] is about clouds, but it’s not cloud coverage,” said Morizur. “The problem is the atmosphere. We need to deal with the interplay between the laser beam and the atmosphere. This is the main problem.” Morizur explained that through advancements in adaptive optics, those challenges are currently being solved. “It took a long, long time to solve with adaptive optics and different technologies, but we’ve got validation now,” said Morizur. “But it took time for the industry to get there.”
To Keane, one of the main limiting factors in the DoD’s use of optical ground technologies lies in the ability to acquire them. “From our perspective, we need the right contracting mechanisms and other things in place to be able to get this to certain end-users,” he said. “I think we’ve got quite a broad scope on certain things that we already have, but it’s making sure that optical fits and can actually be easily bought by those end-users.”
Keane also pointed to the need for optical terminals that can be leveraged at the tactical edge for different military use cases, noting that Robinson’s company, Data Path, has been making strides in this area. “We’ve got to get [tactical optical terminals] out at the tip of the spear, so people can be sending ISR information back and enabling battlefield decision making,” said Keane. “We also see people wanting smaller and smaller terminals…[DataPath] has already been [working] on [optical terminals] that are much more tactical.”
Robinson explained that the push for tactical, ruggedized optical ground terminals stems from the DoD’s need for operational flexibility and the desire to move away from fixed terminals, citing Iran’s attack on a fixed U.S. terminal in Kuwait last summer. “It’s a powerful example of why it’s important to have operational flexibility and relocation ability, so that you’re not a sitting bullseye,” said Robinson. “This is the defense domain. We have to be clever, flexible, and agile, and move where and when the threat might exist. So, transportability is a huge part of that for us. We’re very excited that we will have the first transportable optical ground station ready by September of next year.”
Optical Ground + RF = Increased Assurance
The panelists agreed that when optical ground terminals operate en masse, they will not completely replace RF technologies. Instead, they will serve as an additional layer and tool that will increase the assurance of data transport and comms for the warfighter. “[Optical] is just going to be another mode of transport, essentially,” explained Keane. “For [SES Space & Defense], we are introducing it into the networks for customers to increase the assurance and availability of what they have. It’s not that we’re going to rely just on optical, but we’re not going to rely just on RF, either. We will continue to integrate [optical] for the end-users as it makes the most sense.”
Robinson agreed with Keane that both RF and optical will be crucial in providing resiliency to the warfighter. “There are few operators better positioned than SES, because they have multiple orbits that they’re working with,” said Robinson. “The core themes of resiliency and redundancy include not relying just on RF or optical, but having a balance of both. Similarly, [we shouldn’t] rely solely on fixed infrastructure on the ground or rely solely on transportable infrastructure. It’s about both. There’s room for both. That’s a really healthy ecosystem for us to be looking toward.”