SpaceX’s Starlink project was initially intended to provide internet access anywhere, anytime. However, researchers have discovered an additional use for these satellites – they could potentially function as a GPS system.
The deployment of Starlink is a remarkable technological and logistical feat. Imagine a fleet of thousands of small satellites coordinating their movements 500 km above us. Each satellite acts as a link in a chain, transmitting data at high speeds through precise and efficient laser connections. The final user receives the signal through a specially designed ground antenna. With over 5,398 satellites launched as of November 2023, Starlink is ahead of its competitors.
But here’s where it gets even more interesting. A researcher from Texas, Todd Humphrey, has discovered that by tinkering with Starlink’s software, it could replace the GPS system in case of any issues. Humphrey and his team analyzed the encrypted signals from Starlink and found that they could be used for location tracking on Earth.
Their research used an ingenious method: analyzing high-definition videos, such as Rafael Nadal tennis matches on YouTube, to study the coded signals using OFDM technology. Decoding these signals revealed a redundancy of synchronization sequences, which opened the door to their potential use for geolocation. Even without SpaceX’s intervention, the system could locate a receiver with an accuracy of 30 meters, which they believe could be improved to 1 meter. For comparison, GPS offers 2 to 9 meters of accuracy with six to eleven satellites in view.
However, this discovery raises security concerns. Mark Psiaki from Virginia Tech warns that the use of predictable and open-source sequences could allow malicious actors to falsify signals, posing a challenge to strengthen signal security against spoofing. This means that individuals with ill intentions could send fake signals and disrupt the system.
It’s worth noting that GPS is no longer the only player in the geo-location field. Other systems, such as Russia’s GLONASS, Europe’s Galileo, and China’s Beidou, already offer similar services. Each system has its own characteristics, but they all operate on the same principle – satellites transmit signals that ground receivers use to determine their position. Additionally, most recent smartphones are compatible with all of these constellations.