If the space Shuttle Supported Apollo.

The basic Apollo hardware as shown in shuttle support mode. Completely new Trans Lunar Injection stages (TLI) would be required rather than using a Saturn S-IVB stage which is too wide to fit into the shuttle PLB. The TLI stage would be built to utilize a J-2 engine or equivalent. There would be a version without the engine to facilitate SM attachment and allowing clearance for the Apollo SM Service Propulsion System (SPS) engine Two of the engineless versions would be required to support a lunar mission. They would be docked to the engine equipped booster.

 

One of five shuttle launches required to support a single Apollo lunar mission.

 

What if the shuttle were the available launch vehicle during the 1960s for supporting Apollo rather than the Saturn-V? This hypothetical exercise will look at that question. The shuttle was originally rated to carry 32.5 tons of payload to Low Earth Orbit (LEO). This was scaled back post Challenger to around 24 tons. But for the purpose of this article, we will look at the original 32.5 ton to low orbit capacity. The shuttle will be shown as it actually existed with the 60' (18.29m) X 15' (4.57m) Pay Load Bay (PLB). The one difference will be cost. The shuttle was originally planned at $10 million per mission or thereabouts depending on mission parameters. By the mid 1980s, that cost had zoomed to $450 million and by the 1990s, $1 billion. The cost having escalated primarily because of the huge standing army of support personnel required to manage and operate the complex shuttle system.

 

Comparing the payload capacities of the shuttle and Saturn-V.

 

The fully fueled 27.5 ton Apollo Service Module being deployed via tilt table.

 

A typical lunar mission would require the shuttle to lift Apollo hardware to Low Earth Orbit (LEO). The Apollo Command and Service Modules would not require any external mods to fit into the shuttle PLB except for mounting trunnions. The Lunar Module (LM) descent stage would require mods or even a redesign. The total fueled mass of the CSM and LM also have to be accounted for in using the shuttle to lift them. The Service Module (SM) alone has a fueled mass of 55,000 lbs (24,948 kgs). This is just 10,000 lbs short of the total 32.5 ton lift capacity of the shuttle thus not allowing the manifesting of the LM and CM on the same shuttle. This would also be a problem for a Return To Launch Site (RTLS) abort because the return payload capacity for an orbiter on landing is 16 tons. In an emergency, this means the shuttle would have no choice but to execute an RTLS with the possibility of landing long or the fuselage breaking at the mid point of the vehicle. But this is better than loosing the vehicle during RTLS, assuming it does not explode upon crash landing due to residual hazardous propellants on board. In addition, the shuttle would have to execute this maneuver regardless of payload. As for payload manifesting, the CM would have to be sent to LEO with the LM and the LM would then be attached to the SM on orbit. Total LM/CM fueled mass would be about 24 tons. There would still be 8.5 tons remaining for Airborne Support Equipment (ASE) such as a tilt table to mount the SM. Once on orbit, the system would be assembled and attached to three boost stages including one with an engine. The boost stages would not be the SIV-B stage of the Saturn-V because it is presumed the Saturn-V would not have ever existed and the boost stages would have to be designed to fit into the shuttle PLB. Once the hardware is assembled, it is boosted by the three stages through the Trans Lunar Injection (TLI) phase of an Apollo mission. Once the stages are expended, the mission proceeds in much the same way as Apollo missions actually did. This would include the CM re-entry at 24,500 mph which precludes LEO rendezvous with a shuttle for returning the CM to Earth since the CM had no capability to re-enter LEO prior to re-entry into the atmosphere.

 

Three boost stages would be required in order to accommodate enough propellant for the Trans Lunar Injection (TLI) burn. Only one boost stage would require a boost engine such as the J-2 shown, or equivalent. The shuttle itself performs the LEO insertion burn that the Saturn-SIVB performed.

 

Two shuttles in orbit simultaneously. A feat never accomplished in the actual shuttle program. The remote Manipulator Arm (RMS) deploys the CM from Atlantis as Columbia with the deployed SM awaits the CMs attachment to the SM.

 

The images above tell the tale of how the shuttle could have lifted Apollo hardware to orbit fully fueled. The Remote Manipulator System (RMS) arm could have deployed each component and join the CM to the SM. It could have even been used to dock the LM to the CSM. Astronaut EVA could have been used to facilitate any other on orbit tasks if...or as required. Essentially, using the shuttle to support Apollo is basically the old Earth Orbit Rendezvous (EOR) method originally proposed for Apollo before Lunar Orbit Rendezvous (LOR) was chosen. The shuttle is a Saturn class vehicle in terms of thrust and payload. However, most of the payload capacity is the orbiter itself.

 

Five shuttles to do the Saturn-Vs job. Three shuttles are required just to get the TLI propellant filled boost stages to LEO. A Saturn-V launch in todays dollars would be $2.7 billion. On the flip side, a $1 billion dollar shuttle launch would cost $170 million dollars in 1970. Five shuttle flights would cost $850 million in 1970 or nearly twice the cost of a single Saturn-V launch.

 

One of the boost stages (Yellow stripe) and the CSM/LM are in LEO as shuttle Discovery prepares to deploy the long boost stage (Blue stripe). The docked CSM/LM await attachment to the top of a second short boost stage not yet in orbit.

 

Ultimately, it would have required five shuttles to do the same job just one Saturn-V did. Apollo 8 could have been assembled with 4 shuttle missions. Two shuttles would be required to get the CSM to LEO. But the LM could be replaced with a partially fueled boost stage. One of three necessary for the shuttle to support the TLI phase of the mission. All other lunar missions would have required five shuttle flights. Apollo 8 could have used 4 shuttle missions assuming a boost stage could be eliminated. There was no LM on Apollo 8. Apollo 9 would have required no boost stages for TLI because it was a LEO LM test mission therefore, only 2 shuttle missions would  have been required to support it. Apollo's 10 through 17 would have required five shuttle missions each for a total of 40 shuttle missions not counting Apollo 8 and 9 which would bring the total to 46 or 47 depending on the Apollo 8 final assembly mission configuration.

 

Two shuttles with the SM and CM/LM.

 

Just after the TLI burn, the already docked CSM/LM separate as they travel at the 24,500 mph escape velocity imparted by the TLI booster stack. Note the LM legs are fully deployed. Their deployment having occurred in LEO. From this point on, the mission would be the same as Apollo missions actually were. This includes the CM re-entry at mission completion. Note also, a standard LM is shown for illustrative purposes rather than a redesigned one.

 

In the end, the shuttle would have been far to expensive to support Apollo at the $1 billion per mission cost. Considering how Apollo ultimately played out, if shuttle had supported Apollo, that could have limited the Apollo program to as few as two lunar landings. Had the shuttle supported Apollo at it's original $10 million per mission cost, it would have totaled just $50 million per lunar mission. It would have been a bargain compared to the $450 million dollar average cost of a single Saturn-V launch.