LISA will consist of three spacecraft separated by 2.5 million km in a triangular formation, following Earth about 50 million km in its orbit around the Sun.
The observatory scans the entire sky from space continuously and, as it follows the Earth in its orbit, gradually improves the localization of the gravitational wave sources it detects.
The proposed orbit for LISA is an Earth-trailing heliocentric orbit between 50 and 65 million km from Earth,
The orbit has been optimised to minimise the key variable parameters of the separation between the scienecraft, breathing angles (fluctuations of vertex angles) and the range rate of the sciencecraft, as both of these drive the complexity of the payload design, while at the same time ensuring the range to the constellation is sufficiently close for communication purposes.