The DY-class is a family of spacecraft designs used by Earth throughout the 21st century and 22nd century. First developed in secret during the 1980s and early 1990s by the Dyson-Yoyodyne Corporation, the DY-100 subclass was intended for use in long-term manned missions to Mars and the Jovian system. However the design proved unpopular following the collapse of the Soviet Union and sudden lack of commercial interest in spaceflight in the mid-1990s.(TOS novel: The Rise and Fall of Khan Noonien Singh, Volume 2, Journal of Applied Technology)