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.