Trikon Station

Trikon Station

When placed in orbit, a long skinny object exhibits a peculiar property due to the basic physics of orbital mechanics. Once aligned so that its long axis points towards the center of the Earth, it tends to maintain this attitude. The bottom end (nadir) remains at the bottom and the top end (zenith) remains at the top as the object orbits around the Earth. The forces that cause this phenomenon are called gravity-gradient torques and the object is said to be gravity-gradient stabilized.

As applied to a space station, this means that the modules will always be oriented so that the Earth is « below » or « down » the station in relation to its internal structure. When a space station orbits about 480 kilometers (300 miles) above the Earth’s surface, space is not entirely a vacuum at this altitude. In fact, there is a faint, thin atmosphere composed principally of atomic oxygen. This highly reactive gas can erode the station’s components.

Dark Deep Space Reflective. Credit image © Megan Jorgensen (Elena)

To minimize this erosion and the orbital decay resulting from the slight but real aerodynamic drag, the station’s normal orbital orientation is to fly “edge on”. However, the station’s natural tendency to remain gravity gradient stabilized is not enough to keep it properly functioning. The solar panels must always be oriented toward the sun to collect energy. The radiators must be aimed away from the Sun to discharge waste heat. As the station orbits the Earth, the positions of the solar panels and radiators must be constantly adjusted for the most efficient orientations. Although the station carries gas jet thrusters to make gross changes in its position and to reboost itself to higher orbit when necessary, thrusters are an imprecise and costly method of “fine turning” attitude.

Trikon Station therefore employs a sophisticated system of control moment gyroscopes or CMGs to correct and maintain proper orientation. These gyroscopes are mounted in the external truss of the station’s skeleton.

Trikon Space Station Orientation Manual by Ben Bova and Bill Pogue, The Trikon Deception.