OPS 0855

OPS 0855, also designated OV4-3, was an American boilerplate Manned Orbital Laboratory spacecraft launched in 1966. It was flown to demonstrate the launch configuration for future MOL missions. A number of research payloads, designated Manifold were carried aboard it, which were intended to operate for 75 days, however the spacecraft ceased operations after just 30. It was built from a decommissioned HGM-25A Titan I first stage oxidizer tank, bolted to a Transtage. It was part of the MOL and Orbiting Vehicle projects.

The Manifold experimental package consisted of two micrometeoroid detection payloads, a transmitter beacon designated ORBIS-Low, a cell growth experiment, a prototype hydrogen fuel cell, a thermal control experiment, a propellent transfer and monitoring system to investigate fluid dynamics in zero gravity, a prototype attitude control system, an experiment to investigate the reflection of light in space, and an experiment into heat transfer. The spacecraft was painted to allow it to be used as a target for an optical tracking and observation experiment from the ground.