Pre-Phase A Report - Lisa - Nasa

Front cover figure :
Artist’s concept of the LISA configuration. Three spacecraft, each with a
Y-shaped payload, form an equilateral triangle with sides of 5 million km in
length. The two branches of the Y at one corner, together with one branch
each from the spacecraft at the other two corners, form one of up to three
Michelson-type interferometers, operated with infrared laser beams.
The interferometers are designed to measure relative path changes δℓ/ℓ due to
gravitational waves, so-called strains in space, down to 10−23 , for observation
times of the order of 1 year.
The drawing is not to scale, the diameters of the spacecraft are about 2 m, the
distances between them 5×109 m.