Statite
A statite (from the words "static" and "satellite") is a hypothetical type of artificial satellite that employs a solar sail to continuously modify its orbit in ways that gravity alone would not allow. Typically, a statite would use the solar sail to "hover" in a location that would not otherwise be available as a stable geosynchronous orbit. Statites have been proposed that would remain in fixed locations high over Earth's poles, using reflected sunlight to counteract the gravity pulling them down. Statites might also employ their sails to change the shape or velocity of more conventional orbits, depending  upon the purpose of the particular statite. The concept of the statite was invented independently and at about the same time by Robert L. Forward (who coined the term "statite") and Colin McInnes, who used the term "halo orbit" (not to be confused with the type of halo orbit discovered by Robert Farquhar). Subsequently, the terms "non-Keplerian orbit" and "artificial Lagrange point" have been used as a generalization of the above terms. No statites have been deployed to date, as solar sail technology remains in its infancy. NASA's cancelled "Sunjammer" solar sail mission had the stated objective of  flying to an artificial Lagrange point near the Earth/Sun L1 point, to demonstrate the feasibility of the Geostorm geomagnetic storm warning mission concept proposed by NOAA's Patricia Mulligan.