The project did not solve the dark matter problem, but placed important upper limits on the fraction of dark matter in MACHOs across a wide range of masses, and achieved several notable discoveries in the field of microlensing, and new results on several classes of variable stars.
Microlensing refers to the special case of lensing where the two images are too close to be seen as separate objects in a telescope, but the time-varying geometry (as the source and lens move) causes the apparent brightness (the sum of the two images) to vary with time; this variation has a characteristic shape which can be calculated theoretically.
The cameras imaged a 42 by 42 arcminute square field of sky in two colours (blue-green and red light) simultaneously.
The project made a number of notable discoveries documented in around 35 scientific papers published between 1993 and 2003: the most important results were firstly, upper limits on the contribution of MACHOs to the dark matter in the Milky Way: no more than xx percent can be composed of MACHOs between xx solar masses () and xx solar masses;[vague][2][3] secondly, confirmation that microlensing occurs as expected, based on large samples of events with the theoretically predicted properties.
The future NASA NGRST space mission (planned launch c. 2027) includes a substantial microlensing planet survey as one of its key projects.