Since its initial full constellation of 24 satellites became operational in 1993, the Global Positioning Systems (GPS) has evolved into the leading source of position, navigation, and timing (PNT) data for the U.S. government, Department of Defense, and commercial enterprises. Today, GPS is widely known as the satellite signal that powers “turn-by-turn” navigation applications, such as Google Maps, but the PNT data provided by the GPS constellation contributes far more than simple driving directions.

“…GPS has a significant impact on [numerous] sectors, [including] telecommunications, transportation, energy, and finance,” explained Patrick Shannon, the Founder and CEO of TrustPoint, Inc., a company working to develop a commercial PNT alternative in Low Earth Orbit (LEO). “All of our data centers are synchronized to GPS time…to support high-efficiency communication between data centers and between users on the network. Our power grids synchronize to GPS in order to efficiently move electricity from power generation facilities to user markets. GPS is also critical in the use of consumer applications like rideshare apps, gaming, and even dating applications.”

So many users have “swiped right” on the GPS constellation because of its ability to reliably and accurately provide the real-time PNT data and information needed to power modern capabilities and applications. However, the GPS constellation’s importance and popularity come with a fair share of drawbacks.

“With how critical GPS is to everything from economic stability to warfighter capability, its immense value has painted a very large target on its back,” said Brian Manning, Co-Founder and CEO of Xona Space Systems, a company focused on delivering satellite PNT services.

Satellites in the Crosshairs

Unfortunately, the very nature and location of the GPS satellites make them vulnerable to attack. In fact, America’s largest adversaries could degrade or deny GPS PNT data for military and commercial users in numerous ways.

“GPS signals are broadcast from satellites over 20,000 km away,” said Shannon. “This high orbital altitude makes the signals incredibly weak when they arrive on Earth.” Manning confirmed this vulnerability of the GPS constellation: “The signals broadcast from GPS today are incredibly weak; they are even below the noise floor. That means if you aren’t specifically looking for them, you can’t find them.”

The weak GPS signals leave them vulnerable to jamming attacks. As Manning explained, these signals are, “…very easy to overpower and disrupt, and thus most attacks on GPS target the receiver to overpower or jam existing signals.”

While jamming is one of the most frequent attacks on GPS signals, the GPS service’s lack of encryption leaves it vulnerable to another type of attack that could potentially be even more damaging—especially for military GPS users.

“GPS remains one of the last unencrypted services on the planet, next to SMS texting. This lack of encryption makes it possible for many adversaries - not just well-funded nation-state peer adversaries - to spoof the service,” said Shannon. “From the perspective of a GPS receiver, a properly spoofed signal is indistinguishable from the true signals, but the data will have been tampered with to make the resulting time and positioning solution wrong.”

However, jamming and spoofing GPS signals through electronic warfare (EW) are just some of the many ways users can be denied PNT data from GPS. Cyberattacks are another avenue for attack.

“Given that GPS satellites and ground control systems rely on extensive software and communication networks, they are vulnerable to cyberattacks,” said Sean Gorman, the Co-Founder and CEO of Zephr, a developer of next-gen location-based solutions. “These attacks can range from disabling ground control stations to infiltrating satellite communication channels.”

To help protect GPS signals and receivers from jamming and spoofing, the military’s industry partners have developed anti-jam receivers that are capable of securing GPS signals in dense electromagnetic environments and rejecting spoofed GPS signals. However, many of these receivers are for military use cases, not commercial use cases. They also often come in form factors that would not work for the average GPS-enabled device.

“Anti-jam antennas are an incredibly capable technology,” said Shannon. “But, today, they are the size of a dinner plate or even a pizza box, making them incompatible with most GPS users due to their large size and weight.”

The military has also developed a new encrypted GPS signal called M-code that leverages the Modernized Navstar Security Algorithm (MNSA) as its main encryption method. When rolled out as part of a modernized GPS constellation, M-code should provide protection for military GPS users against both jamming and spoofing of military signals.

Unfortunately, as the Government Accountability Office noted in their recent report, “GPS Modernization: Delays Continue in Delivering More Secure Capability for the Warfighter,” the Department of Defense (DOD) has fallen behind in all three segments of its GPS modernization effort - the space segment, ground control segment, and user equipment.

According to the report, “The [DOD] has worked for more than two decades to modernize its GPS with a more secure, jam-resistant, military-specific signal known as M-code. After multiple delays, the Space Force has continued its GPS modernization efforts, but significant work and challenges remain for each segment...”

While the GPS modernization continues to face challenges and delays, adversaries are exploiting vulnerabilities in the GPS system today. “In recent years, we’ve seen instances of large-scale jamming and spoofing from countries like Russia, Iran, and North Korea rise precipitously impacting civil, commercial, and defense users across wide geographic areas,” said Shannon. And the impacts could be significant.

“While GPS is not strictly needed for the day-to-day operations of the internet, removing GPS from the equation will increase network latency and reduce data rates for applications we use on a daily basis,” explained Shannon. “In the transportation sector, GPS denial has ground commercial aviation across Eastern Europe and the Middle East. It has disrupted global maritime trade in the Mediterranean, Baltic, Black, Red, and South China Seas, increasing transportation costs and slowing delivery of critical goods, commodities, and energy products.”

But the loss of the PNT data delivered by the GPS constellation doesn’t just impact critical infrastructure. It could have a hefty price tag for commercial enterprises, as well.

“There are several studies that have looked at the impact of the loss of GPS from a defense and commercial perspective,” said Gorman. “Potentially the most compelling stat is the economy would lose a billion dollars a day if GPS was out of service.”

This is why many in the commercial satellite industry are exploring ways to augment or replace the existing GPS system—potentially with a commercial solution.

Finding an Alternative Source For PNT

Today, there are few viable alternatives for assured PNT (APNT) data aside from the GPS constellation.

“Are there U.S.-owned or operated systems that can provide the same or better capability than GPS? Foreign systems, such as the European Galileo system, have the same general architecture and capabilities as GPS but also carry the same vulnerabilities,” explained Manning. “Outside of that, there are ground-based systems that are very powerful, but scalability becomes a major challenge.”

Companies such as TrustPoint, Inc. and Xona Space Systems are just some of the many companies that are looking to launch PNT satellite constellations into LEO in an attempt to make PNT available for both the government and private enterprises through a commercial provider.

“The U.S. commercial space industry has proven how immensely valuable commercial dual-use technologies are in virtually every aspect of space—from launch to communications to weather monitoring to imaging and more,” said Manning. “Navigation is no different.”

According to Shannon, these constellations would, “use frequencies optimally selected for navigation like L or C-band, be placed in LEO, and address the security, cost and availability issues of the existing L-band services.”

The addition of these commercial PNT satellite solutions is expected to provide additional resiliency for GPS system users, effectively delivering a more assured and reliable source of PNT. But that’s not just a result of increasing the signal strength and engineering more modern solutions to existing GPS vulnerabilities. These commercial constellations could also help protect access to PNT data by confusing an adversary’s targeting calculus.

“…a new commercial system makes the GPS system less of a target for our adversaries, who now know that even if they take out GPS, the U.S. and our allies will still be able to navigate…” said Shannon. “A commercial service…immediately adds frequency diversity given we are moving to C-band. Our constellation in LEO also adds orbital diversity and signal angle of arrival diversity as a user would receive both GPS and [commercial PNT] signals from 15 to 30 satellites instead of the current 6 to 10 satellites.”

However, not everyone believes that deploying commercial PNT alternatives is the sole solution to the problem. Others in the industry think that commercial PNT alternatives coupled with modernized GPS solutions built and managed by the military is the better, more resilient solution for GPS users.

“The best approach is probably a hybrid of the two, depending on the use case. There are many missions where only a DoD managed capability will be viable, like supporting M-code receivers,” said Gorman. “The M-code program, like GPS modernization, is massively behind schedule. For less sensitive missions there are big immediate benefits to be had by moving to multi-constellation Global Navigation Satellite System (GNSS) approaches or support. These commercial alternatives can counterbalance the slow-moving nature of government programs…”

However, all of these considerations are secondary if an alternative PNT satellite constellation can’t get off the ground.

Challenges and Timing

While many companies looking to launch LEO PNT alternatives are making progress, they’re still a few years away from launching their constellations.

According to Shannon, “TrustPoint has a deployment path with early commercial services [being delivered] by the end of 2026, and a full constellation deployed before the end of the decade.”

Xona plans to launch the first of its PNT satellites to LEO next year. The company recently raised $19 million in a Series A funding round led by Future Ventures and Seraphim Space, which Manning claims will, “…be used to accelerate the deployment of Xona’s low Earth orbit satellite network.”

“The industry is still pretty early in developing and adopting GPS alternatives or GPS complementary services, but the demand signals are fully verified and the path to commercial services well understood,” said Shannon. “At this point, it is really about deploying satellites and getting product to market.”

But it’s not just about manufacturing and launching satellites and building ground systems. There also needs to be a robust ecosystem of endpoints, equipment, and devices that can leverage these new commercial PNT solutions.

“What people always overlook with the deployment of any new service is the user equipment,” said Manning. “Putting satellites in space has no value if there isn’t user equipment on the ground to use it.”

Once these solutions have been launched and equipment developed that can utilize them, they’ll need to demonstrate to government and military leaders that they are sustainable, accurate, and reliable.

“The [military will] want to see a high-performing solution [that is different] to what they already have, realistic capital requirements to complete the constellation, and a healthy ecosystem of partners developing user equipment that works with the new system,” Shannon explained.

However, if any alternative PNT companies can overcome these challenges, the nearly seven billion active GPS devices on Earth practically guarantee demand for their services.

“I firmly believe that - within the next five years - the SpaceX of the satellite navigation world will emerge,” said Manning. “The only question is whether or not it will be a US company this time around.”

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