How do we find our way across billions of kilometers of void?

Space · Published 23 October 2026 Swipe more like this →

In short: Spacecraft travel for decades across vast distances, requiring split-second timing and precise maneuvers. While we use GPS on Earth, navigating the solar system requires a complex blend of celestial mechanics, deep-space radio signals, and even the rhythmic pulses of dying stars.

Spacecraft navigation is a three-part discipline: mission design creates a planned reference trajectory, orbit determination tracks the actual position, and flight path control executes maneuvers to correct deviations. Because even the subtle pressure of sunlight can push a craft off course, engineers must constantly account for unpredictable disturbances that cause a spacecraft to drift from its intended path.

For deep-space missions, the Deep Space Network (DSN) provides critical data types to maintain control. While early explorers relied on the sun and stars, modern researchers are testing advanced systems like NAVCOM. By utilising radio equipment aboard the International Space Station, this innovation captures timing and location data from reference clocks and ground-based stations, acting similarly to GPS for Mars or Moon expeditions.

One of the most fascinating frontiers is X-ray pulsar navigation. Using the NICER instrument, the SEXTANT investigation demonstrated that pulsars—neutron stars that emit rotating beams of light—can act as cosmic beacons. Because some pulsars pulse with the accuracy of atomic clocks, they can theoretically allow for autonomous, real-time navigation anywhere in the solar system, a feat successfully demonstrated in space in 2017.

Even mechanical backups remain vital. During the Gemini and Apollo missions, crews used hand-held sextants to measure angles between stars and the horizon. Recent tests on the ISS show that with minimal training, crew members can produce quality sightings through station windows, providing a reliable emergency backup for future lunar and Martian exploration.

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