WASHINGTON — NASA is seeking bids to develop a new engine for its Orion spacecraft that will effectively be a plug-in replacement for the shuttle-era engine used on the spacecraft’s initial missions.

NASA published a request for proposals March 19 for the Orion Main Engine with a deadline of June 11. The agency expects to select a company and have it on a firm fixed price contract by Nov. 1 that has a period of performance extending to mid-2031.

The contract will cover the production of new engines for Orion’s European-built service module. That engine is used for major maneuvers by the spacecraft, such as entering and departing lunar orbit, and for some abort scenarios.

Initial Orion missions will use Orbital Maneuvering System (OMS) engines originally built for the space shuttle program by Aerojet Rocketdyne. NASA anticipates that the first five Artemis missions will use those engines, which means that the new engine will not be needed before at least the mid-2020s.

The OMS, and overall Orion propulsion system, has generated some criticism because of its limited performance. That’s driven the use of a near-rectilinear halo orbit for lunar operations, rather than a low lunar orbit that would require a greater change in velocity to both enter and exit.

However, there are no plans to change the engine’s performance, or that of the overall propulsion system in the Orion service module, with this new contract. The request for proposals notes that the new Orion Main Engine much be compatible with interfaces with the service module and ground equipment, and that the engine will be constrained “within the existing [European Service Module] interface, performance, and functional requirements.”

The publication of the request for proposals, which came after a request for information last June and a draft request for proposals in December, does not appear to be significantly altered by the coronavirus pandemic. An industry day briefing about the procurement, which traditionally has been done in-person at a NASA center, will instead be done online April 2.