Discovery receives her replica main engines ahead of final journey

by Chris Bergin

The flagship of the shuttle orbiter fleet has received her three replica main engines, as Discovery prepares for next year’s ferry trip to her final resting place. The three Replica Shuttle Main Engines (RSMEs) are substitutes for the three Space Shuttle Main Engines (SSMEs) she last flew with, as they prepare to live on with the Space Launch System (SLS).

Discovery’s Final Months At KSC:

The veteran orbiter marked the beginning of the end for the orbiter’s role of conducting missions under the NASA call sign, when she returned from the highly successful STS-133 mission. Soon after, Discovery was placed into the Transition and Retirement (T&R) flow, which was always going to result in her being the first orbiter to leave the Kennedy Space Center (KSC) for one final time.

For that final trip, Discovery will be rolled to the Shuttle Landing Facility (SLF), hoisted up by the Mate/Demate Device (MDD), prior to being mated atop of the awaiting Shuttle Carrier Aircraft (SCA), which will fly Discovery to the Smithsonian’s National Air and Space Museum near Washington, D.C.

In fact, Discovery’s T&R flow schedule shows she will be coming to the end of preparations for the trip by the holiday break in late-December 2011,  Those schedules – which are subject to change – show that by January 3, 2012, Discovery will be “ready for ferry”.

Soon after, Discovery will be rolled out of her Orbiter Processing Facility (OPF-1) and into Vehicle Assembly Building (VAB) High Bay 4 (HB4) for storage. She will remain in storage until April 10, when she will be towed to the SLF and hoisted atop the SCA.

The non-official date – based on preliminary internal information – has Discovery departing KSC on April 12, 2012, just as her older sister Columbia did 31 years previously, during the very first Space Shuttle launch.

Discovery’s point of arrival, Dulles Airport, currently believe Discovery is due to arrive around April 16, as much as they do not have a confirmed date. The Smithsonian’s current orbiter, Enterprise, will be moved to a staging point just days ahead of Discovery’s arrival.

This means it may be possible that Discovery and Enterprise will be parked together on the tarmac at Udvar-Hazy for a short period of time for photos and video right after Discovery is wheels-down.

Discovery will be removed from the back of the SCA via cranes and lowered onto the ground at Dulles, a process which has already been practised at KSC’s SLF earlier in the year.

Shortly thereafter, Enterprise will be hoisted on top of the SCA in preparation for her ferry flight to JFK International Airport in New York.

Discovery will still sport her battle scars of re-entry on her Thermal Protection System (TPS) blankets. However, she will be missing some of the hardware she used during her operational life.

To her visitors, she will have a very similar appearance on the surface, but her Orbital Manuevering System (OMS) Pods and Forward Reaction Control System (FRCS) were near-gutted during safing operations at the White Sands facility in New Mexico.

She will also be sporting three RSMEs, as opposed to SSMEs, following the Program Requirements Control Board (PRCB) decision to protect all flight-able SSMEs for the SLS program.

The PRCB Change Request presentation (available on L2) noted direction from the Space Shuttle Program (SSP) to roadmap the ability to keep the engines, and replace them with replicas for when the retired vehicles go on display at their exhibitions.

“Directed by SSP to prepare an integrated approach for an alternative to using flight Space Shuttle Main Engines (SSMEs) on post SSP orbiter displays. To obtain authorization and funding to design, build, deliver, and install nine (9) Replica Shuttle Main Engines (RSMEs) to replace flight SSMEs on orbiters,” noted the presentation.

“To preserve the SSME flight engines for future use, NASA MSFC (Marshall Space Flight Center) / KSC (Kennedy Space Center) / JSC (Johnson Space Center) recommends a replica engine be provided utilizing existing inoperable nozzle assets and an adapter to simulate the SSME for display purposes.”

With the Shuttle Derived (SD) Heavy Lift Launch Vehicle (HLV) utilizing between three and five RS-25 engines on its core stage, the available stock of SSMEs (RS-25Ds) – comprising of three sets from each orbiter, a spare set of three and up to three others located outside of KSC – will be used during the testing and initial launches of the SLS, prior to the switch to the expendable RS-25E version of the engine in the 2020s.

For the orbiters going on display, SSME contractor Pratt & Whitney Rocketdyne (PWR) developed the RSME, of which nine have been fabricated for installation on the vehicles.

While a flight ready SSME consists of large amounts of plumbing, turbopumps and electronics, etc. The RSMEs simply consist of a scrap – but cosmetically repaired – nozzle, with an adaptor to install it into the aft of the retired orbiter.

The internal schedules showed the installation of the RSMEs was scheduled to take place in October, meaning they are behind on the timeline with this week’s completion of the task. However, there is a large amount of flexibility in the flow, given the aforementioned information that Discovery’s schedule allowed for four months between her “ready to ferry” date and her eventual departure from Florida.

With all three RSMEs now installed on Discovery, she is starting to return from her rather sorry looking appearance of a vehicle with no engines, no OMS Pods and no FRCS. This process was required to allow for the complete safing of the vehicle, due to the amount of hazardous substances her powered systems contained after returning from STS-133.

Click here for other T&R Articles:

The T&R plans for Atlantis and Endeavour are currently under embargo, while the Johnson Space Center (JSC) – which missed out on a flown orbiter, are soon to expect delivery of the high-fidelity model which is being dismantled from its current home at the KSC Visitor Complex.

The model is scheduled to be moved to the Turn Basin at 7am (first motion) on Sunday, December 11, with the move requiring removal of light poles and other obstructions – work which will begin on December 9.

The replica External Tank and Solid Rocket Boosters (SRBs) which sat next to the orbiter at the display have also been dismantled and will be placed into temporary storage at KSC.

Ground breaking on a new exhibition facility – which is going to be the eventual home for Atlantis – is expected to start early in the new year.

(Images: Via L2 content and NASA.)

(L2 and NSF are continuing to follow the orbiters through their transitional period. To join L2, click here:

Related Articles