Free drift mode refers to the state of

motion In physics, motion is the phenomenon in which an object changes its position with respect to time. Motion is mathematically described in terms of displacement, distance, velocity, acceleration, speed and frame of reference to an observer and m ...

of an object in

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

whereby constant attitude is not maintained. When attitude is lost, the object is said to be in free drift, thereby relying on its own

inertia Inertia is the idea that an object will continue its current motion until some force causes its speed or direction to change. The term is properly understood as shorthand for "the principle of inertia" as described by Newton in his first law ...

to avoid attitude drift. This mode is often engaged purposefully as it can be useful when modifying, upgrading, or repairing an object in space, such as the

International Space Station The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ( ...

. Additionally, it allows work on areas near the thrusters on the ISS that are generally used to maintain attitude. While in free drift it is not possible to fully use the

solar arrays A photovoltaic system, also PV system or solar power system, is an electric power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to absorb and c ...

on the ISS. This can cause a drop in power generation, requiring the conservation of energy. This may affect many systems that otherwise require a lot of energy.Bertels, 2006. The amount of time that an object such as the ISS can remain safely in free-drift varies depending on moment of inertia, perturbation torques, tidal gradients, etc. The ISS itself generally can last about 45 minutes in this mode.

Notes

References

Bertels, Gaston. November 10, 2006
''Commander Michael Lopez-Alegria talks to Belgian schoolchildren''
ARISS. Retrieved on April 26, 2006. Malik, Tariq. January 21, 2005

Space.com. Retrieved on April 26, 2008. Malik, Tariq. October 26, 2006

Space.com. Retrieved on April 26, 2008.
Celestial mechanics Orbits {{space-stub