After the election of Obama in 2008, it was apparent that the then-major program of NASA, Project Constellation, was not long for the world. Essentially the response of President Bush to the Space Shuttle Columbia disaster, it had become bogged down in ballooning cost estimates and insufficient funding, with all of the major development programs being more or less disasters, and was, of course, a Bush initiative and thus not especially popular with the incoming President. After assembling a blue ribbon commission, as is traditional, Obama went ahead and cancelled the program without really planning for a replacement program of similar scale.
Congress, however, didn't like this, mostly because with the Shuttle winding down and Constellation cancelled a lot of Shuttle-related facilities would also be closing down in the near future, reducing the flow of dollars to their districts. They therefore pushed the administration, which was not really inclined to fight them very much, to begin a new major development program "based on Shuttle" to rectify some of the issues identified with Constellation, which became SLS. Although there were some studies feinting at alternative designs for SLS, there were really only two contenders that had any chance, both of which were essentially versions of the same Shuttle-derived vehicles that had been looked at since the 1970s. One, which was the one we got, took the basic components of the Shuttle design and rearranged them to create an "inline" vehicle, more similar architecturally to other launch vehicles. The other was basically a rehash of Shuttle-C and envisioned instead largely reusing the Shuttle design except with a disposable cargo pod in place of the Orbiter, and was called sidemount.
As I said, we got the first. But from several points of view, the second offers a number of advantages over the SLS we got, mainly because of being even more shuttle-derived. In the first place, it easily covers the Congressional desire to maintain jobs given that Michoud would still be producing external tanks, ATK would still be producing solid rocket boosters, and new jobs would be needed building the cargo pods, not to mention Orion capsules, iCPS upper stages, and other payloads and equipment. Somewhat fewer new jobs would be created, perhaps, since less new infrastructure and equipment throughout the supply chain would be needed, but by the same token costs would also likely be less. The smaller number of changes would also make it more likely that sidemount could get into service in a reasonable period of time than our SLS has proved capable of doing, making it more likely to actually be able to fly missions. The main downside is that growth options were somewhat more complex, but not nonexistent; the main study on the concept proposed that increasing SSME thrust (since they would only be used once, and so could be run at levels that would be incompatible with reuse), stretching the external tank, and perhaps adding five-segment boosters would allow for considerably increased payloads to low Earth orbit, reasonably comparable to OTL's SLS.
Thus, it seems that NASA and Congress embracing (or "embracing") sidemount was reasonable and plausible. What would the consequences have been if, to wave hands a little bit, they had done so? Would SLS have flown by now, with or without Orion? What impact would a somewhat accelerated (and possibly cheaper?) SLS have had on other plans (Artemis...)?
Congress, however, didn't like this, mostly because with the Shuttle winding down and Constellation cancelled a lot of Shuttle-related facilities would also be closing down in the near future, reducing the flow of dollars to their districts. They therefore pushed the administration, which was not really inclined to fight them very much, to begin a new major development program "based on Shuttle" to rectify some of the issues identified with Constellation, which became SLS. Although there were some studies feinting at alternative designs for SLS, there were really only two contenders that had any chance, both of which were essentially versions of the same Shuttle-derived vehicles that had been looked at since the 1970s. One, which was the one we got, took the basic components of the Shuttle design and rearranged them to create an "inline" vehicle, more similar architecturally to other launch vehicles. The other was basically a rehash of Shuttle-C and envisioned instead largely reusing the Shuttle design except with a disposable cargo pod in place of the Orbiter, and was called sidemount.
As I said, we got the first. But from several points of view, the second offers a number of advantages over the SLS we got, mainly because of being even more shuttle-derived. In the first place, it easily covers the Congressional desire to maintain jobs given that Michoud would still be producing external tanks, ATK would still be producing solid rocket boosters, and new jobs would be needed building the cargo pods, not to mention Orion capsules, iCPS upper stages, and other payloads and equipment. Somewhat fewer new jobs would be created, perhaps, since less new infrastructure and equipment throughout the supply chain would be needed, but by the same token costs would also likely be less. The smaller number of changes would also make it more likely that sidemount could get into service in a reasonable period of time than our SLS has proved capable of doing, making it more likely to actually be able to fly missions. The main downside is that growth options were somewhat more complex, but not nonexistent; the main study on the concept proposed that increasing SSME thrust (since they would only be used once, and so could be run at levels that would be incompatible with reuse), stretching the external tank, and perhaps adding five-segment boosters would allow for considerably increased payloads to low Earth orbit, reasonably comparable to OTL's SLS.
Thus, it seems that NASA and Congress embracing (or "embracing") sidemount was reasonable and plausible. What would the consequences have been if, to wave hands a little bit, they had done so? Would SLS have flown by now, with or without Orion? What impact would a somewhat accelerated (and possibly cheaper?) SLS have had on other plans (Artemis...)?
