LEO Satellites as Navigation Alternatives: Arctic Circle Research

The Challenge of GPS Vulnerability

• ⚠️ GPS services are facing increasing global disruptions, making them unreliable, especially in safety-critical systems like aviation and military operations.
• 💡 The research explores alternative methods for positioning, navigation, and timing (PNT) as a response to these growing vulnerabilities.

LEO Satellites as a Navigation Solution

• 🚀 Low Earth Orbit (LEO) satellites, such as Starlink and OneWeb, are being investigated as potential reliable navigation alternatives.
• 💡 The initial research began in 2017, exploring constellations like Iridium and Orbcomm, before demonstrating in 2021 that Starlink satellites alone could pinpoint location within approximately 10 meters.
• 🗺️ This concept has been successfully demonstrated on ground vehicles, high-altitude balloons, and unmanned aerial vehicles (UAVs).

Arctic Circle Research Findings

• ❄️ The study focused on the Arctic Circle due to its increasing geopolitical importance and the limited coverage of GPS satellites in polar regions.
• ✨ Surprisingly, LEO satellite signals in the Arctic were not only useful but also described as "more beautiful" than in many other tested locations.
• 🚢 The research demonstrated that a vessel could be navigated using Starlink signals alone or in combination with OneWeb signals, achieving an accuracy of tens of meters over several kilometers.

Technical Aspects of Opportunistic Navigation

• 📡 The research leverages communication signals transmitted by LEO satellites (like OFDM frames similar to 5G/4G) for navigation, rather than dedicated navigation signals.
• 🛰️ A significant challenge is the ephemeris problem: precisely knowing the location of LEO satellites in space, as publicly available data is often course and not always up-to-date.
• 🧠 The team developed a method to reverse-engineer Starlink signals and satellite positions without direct cooperation from the satellite operators, enabling navigation.

Future of Navigation and Opportunistic Approaches

• 🧭 Three schools of thought for future navigation exist: dedicated LEO PNT constellations, dual-purpose LEO constellations, and fully opportunistic navigation.
• ♻️ The opportunistic approach, which the research champions, is highly sustainable for both the space environment and spectrum usage, as it reuses existing signals and infrastructure.
• 🚗 An analogy is drawn to Uber: instead of adding more taxis, repurpose existing cars to meet demand, highlighting the efficiency of leveraging existing LEO communication signals for navigation.
• 🤝 While the approach is novel, some satellite operators are aware of the research, and some even learn about their own systems from the findings.