MIT Lincoln Laboratory researchers are developing a satellite system that could provide GPS-like navigation and communications for spacecraft traveling between Earth and the moon. Called Light High-Orbit Utility Signal Emitter, or LightHOUSE, the concept would place a small constellation of satellites in ultrahigh orbits to serve as cooperative optical beacons, tells MIT News.
Spacecraft operating beyond geosynchronous Earth orbit currently rely heavily on NASA’s Deep Space Network, an Earth-based collection of radio antennas. Although highly accurate, the network can support only a limited number of missions simultaneously. Determining the orbit of distant spacecraft can also take hours. LightHOUSE is designed to provide more timely and independent navigation information.
The proposed satellites would exchange timing and communication signals with spacecraft while using stars as a visual reference to calculate a vehicle’s three-dimensional position and velocity. The system would rely on free-space optical communications, using laser links instead of depending solely on radio-frequency technology. Better navigation could reduce corrective maneuvers, conserve spacecraft propellant, and decrease reliance on onboard sensors and ground infrastructure.
LightHOUSE satellites could orbit as high as roughly 1 million miles above Earth. Their locations would provide the angular diversity needed for accurate positioning across cislunar space. They could also maintain communications with spacecraft traveling behind the moon, helping prevent temporary communication blackouts.
Following the philosophy behind GPS, the system would place most technical demands on the beacon satellites. These satellites would carry relatively powerful lasers and large telescopes, allowing user spacecraft to operate with much smaller optical equipment.
Researchers are now refining LightHOUSE through simulations, analysis, and laboratory experiments. Major engineering challenges remain, particularly achieving precise optical measurements across enormous distances. A full-scale system could cost hundreds of millions of dollars, but researchers believe it could eventually make navigation beyond geosynchronous orbit routine and support the growing number of Artemis and other lunar missions.
