Figure 5: Detecting gravitational waves in space
An interferometer in space can have enormous arm lengths and suffers little interference from unwanted vibrations that plague similar instruments on the ground. Such a device would therefore be sensitive to the lower-frequency gravitational waves produced, for example, by massive black holes, binary white-dwarf stars and tera-scale phase transitions in the early universe. LISA, which is due to launch about 10 years from now, will contain gold–platinum alloy cubes that float inside cavities in three spacecraft (i.e. where only gravitational forces act on them). Lasers will measure subatomic differences between the position of each cube and similar cubes in the other two spacecraft five million kilometres away induced by a passing gravitational wave. Source: ESA.