From Halopedia, the Halo wiki
MELAENO was kickstarted by the CMA in 2491, based on the organisation's own keen interest in the Materials Group's Project: HRUNTING. MELAENO was supported by forward-thinking elements of the Office of Naval Intelligence and served as the technical equipment and support partner of the CMA's ORION Project - an effort to create advanced supersoldiers for use in quelling colonial insurrection. The project's successes and failures remain highly classified even as of 2559, though Doctor Catherine Halsey was able to discover the project and strip it of useful information in 2515. This information was used by Halsey to inform the development of the nascent Project: MJOLNIR, with ONI not becoming aware of the security breach until many years later.
MELAENO is most notable for its creation of the Orion Exoframe Load Carrier; a specialised armor system developed for use by ORION candidates which saw limited field-testing before the program's cancellation. The suit's components saw testing during Operation: KALEIDOSCOPE between 2502 and 2507, with other parts being tested on Mars.