Fair point, I was thinking of something more basic like cutting in a 72 or 90 inch porthole, but I suspect that would encounter the same issues and problems.
Boldly Going: A History of an American Space Station
- Thread starter e of pi
- Start date
To amplify this a bit, I suspect when originally approved in 1987, ESA's plan for Kepler is to fly on Ariane 44L, but then the push for Kepler-L/Shuttle-C debut and integration complicates European independent preparations as the focus is on getting the lunar variant ready on schedule. By the time they can focus on Kepler-C on Ariane again, it's about 1997 or 1998, and Ariane 4 is on its way out in favor of Ariane 5. Flying on Ariane 5 from the start thus means no need to qualify a second vehicle later, and more margin to boot. Thus, the Ariane 44L plans never get carried out.
Part 25: Shuttle enhancements offer more performance even as Enterprise and the Space Shuttle struggle with transition to the post-assembly era.
Boldly Going Part 25
The new millennium saw NASA facing the challenges arising from its own success. The lunar program had succeeded in meeting the unofficial goal of a return to the moon before the decade was out--and before the thirtieth anniversary of the Apollo 11 landing. The goal had never been officially codified, but the relevant dates had been specifically designed to be reasonably met when President Bush had given the Space Exploration Initiative speech in 1989. Only the delays in the original program authorization and then in fielding the Shuttle-C’s new Liquid Rocket Boosters had cast doubt on the ability of the agency to meet their objectives and lunar schedule. Similarly, the new millennium saw Space Station Enterprise’s largest expansions nearly complete, with only a few more launches remaining to finish the orbital outpost. The availability of sufficient Liquid Rocket Booster engine pods to serve Space Shuttle launches as well as Shuttle-C lunar cargo missions also brought benefits for the Shuttle program, as the safety of the vehicle was increased even while cost and handling times between launches were reduced. The next three to five years of NASA’s future were well in hand, with the reduced costs of Shuttle, the completion of Space Station Enterprise, and the preparations for the first multi-launch lunar missions. However, the success in all of their 90s-era objectives left NASA’s long-term strategic planners eyeing the future and debating what new challenges could come over the horizon.
Though the dual-launch Class-B lunar outpost mission planned for 2000 was hotly anticipated by the public, internally NASA’s Florida operations teams were most focused on the complete phase out of the Solid Rocket Boosters for ordinary Shuttle missions and their replacement with the Liquid Rocket Boosters. The change not only came with improved payload capability and reduced maintenance, but also eliminated major areas of risk, improving performance, safety, and cost. Not only were the new SSME-35 engines easier to shut-down in an emergency than the old SRBs, but the pods’ five-engine design allowed them to launch with 80% throttle. Thus, the new LRBs would be capable of performing a nominal mission even with a single engine out right off the pad. The added thrust of the SSME-35s and the lower mass of the stack also meant that it was possible to reduce the throttle setting on the Orbiter’s SSME-69 engines from the usual 104.5% to “merely” 100% while still increasing the payload of the stack. Another benefit would come from changing how the Space Shuttle stack handled the “thrust bucket,” an aggressive reduction in engine power carried out before and during the time of peak pressure on the rocket to reduce “max-Q.” The maneuver was nick-named for the shape it made in SSME-69 telemetry traces for thrust and other values. The existing SRBs required much of the thrust bucket to be handled by the Orbiter’s three main engines, moving them from 104% of rated power to just over 70% power, then throttling back to 104% at the conclusion of the “bucket”. While the grain structure of the SRBs allowed their thrust profile to be “programmed” geometrically, the new LRB’s ten SSME-35 engines allowed a true throttle back of the boosters. Even with the added stress of a requirement to cycle from 80% thrust to 67% thrust and back during max-Q, the SSME-35’s short firing time during a mission and relatively low throttle setting would be much lower stress than the existing SSME-69 profile. These gentler stresses suggested that the time between overhauls for the pod’s engines should be even higher, and maintenance reduced over even that of the Block II SSME-69 just being introduced [1]. For the SSME-69’s part, eliminating the aggressive “thrust-bucket” throttle-down and throttle-up mid-burn would add to the Block II’s benefits in minimizing maintenance, further reducing costs of the Shuttle for both Enterprise support missions and independent flights to other orbits.
Lockheed Martin, who had inherited the LRB and related Atlas III NSSL program from General Dynamics through the complex aerospace mergers of the post-Cold War drawdown, stood to reap tremendous benefits from NASA’s desire to replace SRBs with LRBs on all future Space Transportation System flights, whether they be Shuttle-C or conventional Space Shuttle missions. However, the DoD had focused many of its low-mass missions onto the ATK Heimdall vehicle. This desire was driven both thanks to a better fit of the Heimdall family’s performance to the missions required (particularly in its single-stick Heimdall 31C configuration) and congressional and internal advocacy for helping to preserve strategic missile development and production capabilities. Lobbyists reasoned that with Shuttle and Shuttle-C supporting it, there was little risk of Atlas III fading away without commercial or DoD support, but solid fueled rocket production continued to be a strategic asset until and unless a new major missile program was begun. The preference for the new partially reusable Atlas III and Heimdall boosters for even NASA missions spoke to new doubts about the Space Transportation System which dominated NASA and DoD thinking during the tail end of the nineties, despite the Space Shuttle program racking up records in support of Enterprise’s rapid expansion and the Shuttle-C debuting for lunar flights. Neither NASA nor the DoD was wholly comfortable having all their eggs in one basket when it came to critical space launchers, and the early months of 2000 helped demonstrate why.
The veteran ground crews at Kennedy Space Center had been running at full tilt throughout the high tempo of operations in 1999, and were ready for more. However, the infrastructure was less capable. Issues with wear on ground support equipment from deferred maintenance resulted in heavy delays to both of the first Space Shuttle launches of the year, with STS-118 being delayed by more than four weeks due to the need to replace both the stack and service structure sides of the newly-installed cryogenic umbilical connector for the portside LRB. Though similar interface issues had been encountered before, the wear of multiple missions and changing weather meant that the umbilical had fallen out of tolerance, resulting in persistent and dangerous hydrogen leaks around the stack. The delays to launches of Enterprise logistics and the remaining station modules helped push the launch of the two Shuttle-C flights required for pre-positioning the cargo element of the first Class-B Habitank outpost into the summer, the first of several delays which would eventually push the crew launch for that mission into 2001.
The Space Shuttles were also showing their age in other ways, both on their own and in comparison to the newer portions of the American launcher stable. The hypergolic Auxiliary Power Units (APUs), OMS engines, and RCS thrusters of the Space Shuttles required major sacrifices in ground handling. The electrically-driven aerodynamic and gimbals and ethalox maneuvering thrusters of the new Shuttle-C engine pods mitigated these issues, making a vehicle safer and easier to work on and around. Moreover, the payload increases for the Space Shuttle came just as the completion of the expansion of Space Station Enterprise rendered such increases less and less relevant--while the logistics payload of the Space Shuttles was increased by the better part of two tons, the large truss and laboratory modules whose design could have benefitted from greater payload were already launched. Routine cargo and crew launches depended more on payload bay size than on launch mass, and the 100-ton mass of the Orbiter was almost overkill for many of the missions it would be called on to support now that its assembly was completed. While the costs of the Space Shuttle were reduced by the LRBs and process improvements to “only” two to three hundred million for each additional flight made in a year, this was still several times the cost of launching a logistics vehicle on other existing launchers like Heimdall or Atlas III--a fact driven home by ESA’s first independent launch of a crewed spacecraft with the Kepler-C capsule Johannes Kepler and a crew of four ESA astronauts to Space Station Enterprise on top of the new Ariane 5 launcher in March, 2000. The four-person crew stayed three weeks onboard the station and assisted in several time-critical EVAs to support outfitting the ESA laboratory’s external payload mounts. The prime purpose of the mission however was a statement that ESA didn’t require NASA assistance in launching crew or cargo to the station--a demonstration of independent launch capacity crucial to ESA’s pride. It did not escape NASA’s notice that despite being less capable than a full Space Shuttle launch, the cost of the mission ran to half that of a Shuttle flight, and there would be times in the coming years where making any logistics flight on time and for a lower cost would be more important than the absolute cargo or crew capacity of that flight.
Space Station Enterprise itself was wrestling with its purpose in the aftermath of its expansion. For almost five years, the space station had been a “self-licking ice cream cone”: the station’s crew had been aboard first for the manual work of outfitting ET-007 LOX Tank habitat, then the installation and outfitting of the expanded solar truss and laboratory facilities. In other words, the raison d'être of the station had been its own expansion and operations. Now, with that expansion completed, the station had to move into an operational phase where every hour of crew time not spent in a laboratory or critical maintenance activities was a drain on the program budget, as NASA tried to excite researchers and commercial partners about sending experiments to fill the station’s labs. The station remained the flagship for humanity’s exploration of space, at least until a permanently-crewed moonbase was constructed. NASA still continued to search for additional applications to help justify its ongoing operations, and for ways in which the station’s capabilities and technologies could be leveraged for the next generation of space development. With the station’s first major expansion complete, NASA was still looking for any way possible to build on its success in the future, particularly in ways which would benefit other programs in Earth orbit and beyond.
One example of this came during the 2001 servicing mission to the Hubble Space Telescope. In addition to carrying up new multi-ton cameras and replacing critical systems such as gyroscopes and star trackers, the crew of STS-125 also installed a new docking ring and optical target on the aft end of the telescope, which would enable it to receive future uncrewed tugs for reboost or orbital adjustments. These plans were about more than maintenance. In the long term, NASA was developing a strategy for an Orbital Maneuvering Vehicle to use this docking ring to push Hubble’s orbital inclination from its original 28.5 degrees to a new 39-degree inclination co-orbital with Space Station Enterprise. This would enable the station to act as an orbital dockyard for Hubble, reducing the need for a separate launch-on-need mission in case of issues, as had been the case for STS-125 and other such flights which went to orbits other than that of the station. Moreover, while Space Shuttle missions would still be needed for replacing the multi-ton primary instruments of the telescope, the planned new orbit would enable crew aboard the station to carry out the repair of any minor issues which might arise. Along with servicing Orbital Maneuvering Vehicles or Orbital Transfer Vehicles, this kind of “orbital dockyard” service would also be of value for NASA’s future long-term plans.
As NASA began to update their 1989-vintage Space Exploration Initiative visions for space exploration to include a new journey to Mars, finding ways for the new program of record to continue to justify supporting Enterprise was not officially a critical factor in architecture selection. Still, when choosing between options which were otherwise equally effective for developing design reference architectures for NASA’s new mars plans, the options which could make use of NASA’s existing orbital assets and experience were favored over those which did not tie into the existing lunar architecture and the massive recent investments in Enterprise. Eventually, this would lead to the last major overhaul of Enterprise’s original legacy STS-37R hardware in the years to come. For the moment, though, Mars plans remained far off, awaiting Congressional approval. In the meantime, NASA had to negotiate scheduling ongoing station operations, Shuttle flight rhythms, and the launch of 2001’s Minerva 3 “cabin-in-the-woods” lunar outpost.
[1] SSME Blocks are complicated. The following is per Jenkins:
SSME First Manned Orbital Flight (FMOF) were used for STS-1 through STS-5, and were rated only to the maximum originally specified for the engine. This number is set as 100% of rated thrust, and future engines were certified for higher.
SSME Phase I were used through Challenger (STS-51L), and were rated at 104%, and in theory 106% to support very heavy payloads (up to 65,000 lbm) and polar missions.
SSME Phase II were used post-Challenger, and retained the earlier rating of 104%, but not 106%. Phase II and prior engines are referred to as RS-25A by Rocketdyne.
SSME Block I first flew in OTL on STS-70 in 1995, and utilized the new Pratt & Whitney High Pressure Oxidizer Turbo-Pump, a two-duct powerhead, and a few other modifications.
SSME Block IA first flew in OTL on STS-73, also in 1995, and was a Block I with a modified main injector and modified temperature sensors. Rocketdyne refers to both Block I and Block IA as RS-25B
Block IIA first flew OTL on STS-89 in January of 1998, and integrated all of the changes planned for the Block II except the new High Pressure Fuel Turbo-Pump (HPFTP). This included the new Large Throat Main Combustion Chamber (LTMCC) that reduced the expansion ratio from 77.5 to 69.5. The corresponding reduction in chamber pressure and ISP was countered by the change from 104% thrust to 104.5% thrust. Rocketdyne designated this configuration the RS-25D
Block II first flew OTL on STS-104 in 2001, and added the HPFTP to the Block IIA design. NASA delays to the HPFTP design (done by Pratt & Whitney) historically slowed this effort. Rocketdyne Designation for the Block II was RS-25C
In this timeline, Block II work is never slowed, and the full suite of Block II changes is introduced around the time of the historical Block IIA. These changes are made in parallel with the introduction of the SSME-35 nozzle and chamber alongside the SSME-69 chamber and nozzle. Here, by 2000, the SSME-35 and SSME-69 in service are both using Block II chambers, turbo-pumps, and probably throats.
A short (and free!) version of SSME history can be found in this NTRS paper, entitled Space Shuttle Main Engine (SSME) Options for the Future Shuttle.
Artwork by @nixonshead (AEB Digital)
The new millennium saw NASA facing the challenges arising from its own success. The lunar program had succeeded in meeting the unofficial goal of a return to the moon before the decade was out--and before the thirtieth anniversary of the Apollo 11 landing. The goal had never been officially codified, but the relevant dates had been specifically designed to be reasonably met when President Bush had given the Space Exploration Initiative speech in 1989. Only the delays in the original program authorization and then in fielding the Shuttle-C’s new Liquid Rocket Boosters had cast doubt on the ability of the agency to meet their objectives and lunar schedule. Similarly, the new millennium saw Space Station Enterprise’s largest expansions nearly complete, with only a few more launches remaining to finish the orbital outpost. The availability of sufficient Liquid Rocket Booster engine pods to serve Space Shuttle launches as well as Shuttle-C lunar cargo missions also brought benefits for the Shuttle program, as the safety of the vehicle was increased even while cost and handling times between launches were reduced. The next three to five years of NASA’s future were well in hand, with the reduced costs of Shuttle, the completion of Space Station Enterprise, and the preparations for the first multi-launch lunar missions. However, the success in all of their 90s-era objectives left NASA’s long-term strategic planners eyeing the future and debating what new challenges could come over the horizon.
Though the dual-launch Class-B lunar outpost mission planned for 2000 was hotly anticipated by the public, internally NASA’s Florida operations teams were most focused on the complete phase out of the Solid Rocket Boosters for ordinary Shuttle missions and their replacement with the Liquid Rocket Boosters. The change not only came with improved payload capability and reduced maintenance, but also eliminated major areas of risk, improving performance, safety, and cost. Not only were the new SSME-35 engines easier to shut-down in an emergency than the old SRBs, but the pods’ five-engine design allowed them to launch with 80% throttle. Thus, the new LRBs would be capable of performing a nominal mission even with a single engine out right off the pad. The added thrust of the SSME-35s and the lower mass of the stack also meant that it was possible to reduce the throttle setting on the Orbiter’s SSME-69 engines from the usual 104.5% to “merely” 100% while still increasing the payload of the stack. Another benefit would come from changing how the Space Shuttle stack handled the “thrust bucket,” an aggressive reduction in engine power carried out before and during the time of peak pressure on the rocket to reduce “max-Q.” The maneuver was nick-named for the shape it made in SSME-69 telemetry traces for thrust and other values. The existing SRBs required much of the thrust bucket to be handled by the Orbiter’s three main engines, moving them from 104% of rated power to just over 70% power, then throttling back to 104% at the conclusion of the “bucket”. While the grain structure of the SRBs allowed their thrust profile to be “programmed” geometrically, the new LRB’s ten SSME-35 engines allowed a true throttle back of the boosters. Even with the added stress of a requirement to cycle from 80% thrust to 67% thrust and back during max-Q, the SSME-35’s short firing time during a mission and relatively low throttle setting would be much lower stress than the existing SSME-69 profile. These gentler stresses suggested that the time between overhauls for the pod’s engines should be even higher, and maintenance reduced over even that of the Block II SSME-69 just being introduced [1]. For the SSME-69’s part, eliminating the aggressive “thrust-bucket” throttle-down and throttle-up mid-burn would add to the Block II’s benefits in minimizing maintenance, further reducing costs of the Shuttle for both Enterprise support missions and independent flights to other orbits.
Lockheed Martin, who had inherited the LRB and related Atlas III NSSL program from General Dynamics through the complex aerospace mergers of the post-Cold War drawdown, stood to reap tremendous benefits from NASA’s desire to replace SRBs with LRBs on all future Space Transportation System flights, whether they be Shuttle-C or conventional Space Shuttle missions. However, the DoD had focused many of its low-mass missions onto the ATK Heimdall vehicle. This desire was driven both thanks to a better fit of the Heimdall family’s performance to the missions required (particularly in its single-stick Heimdall 31C configuration) and congressional and internal advocacy for helping to preserve strategic missile development and production capabilities. Lobbyists reasoned that with Shuttle and Shuttle-C supporting it, there was little risk of Atlas III fading away without commercial or DoD support, but solid fueled rocket production continued to be a strategic asset until and unless a new major missile program was begun. The preference for the new partially reusable Atlas III and Heimdall boosters for even NASA missions spoke to new doubts about the Space Transportation System which dominated NASA and DoD thinking during the tail end of the nineties, despite the Space Shuttle program racking up records in support of Enterprise’s rapid expansion and the Shuttle-C debuting for lunar flights. Neither NASA nor the DoD was wholly comfortable having all their eggs in one basket when it came to critical space launchers, and the early months of 2000 helped demonstrate why.
The veteran ground crews at Kennedy Space Center had been running at full tilt throughout the high tempo of operations in 1999, and were ready for more. However, the infrastructure was less capable. Issues with wear on ground support equipment from deferred maintenance resulted in heavy delays to both of the first Space Shuttle launches of the year, with STS-118 being delayed by more than four weeks due to the need to replace both the stack and service structure sides of the newly-installed cryogenic umbilical connector for the portside LRB. Though similar interface issues had been encountered before, the wear of multiple missions and changing weather meant that the umbilical had fallen out of tolerance, resulting in persistent and dangerous hydrogen leaks around the stack. The delays to launches of Enterprise logistics and the remaining station modules helped push the launch of the two Shuttle-C flights required for pre-positioning the cargo element of the first Class-B Habitank outpost into the summer, the first of several delays which would eventually push the crew launch for that mission into 2001.
The Space Shuttles were also showing their age in other ways, both on their own and in comparison to the newer portions of the American launcher stable. The hypergolic Auxiliary Power Units (APUs), OMS engines, and RCS thrusters of the Space Shuttles required major sacrifices in ground handling. The electrically-driven aerodynamic and gimbals and ethalox maneuvering thrusters of the new Shuttle-C engine pods mitigated these issues, making a vehicle safer and easier to work on and around. Moreover, the payload increases for the Space Shuttle came just as the completion of the expansion of Space Station Enterprise rendered such increases less and less relevant--while the logistics payload of the Space Shuttles was increased by the better part of two tons, the large truss and laboratory modules whose design could have benefitted from greater payload were already launched. Routine cargo and crew launches depended more on payload bay size than on launch mass, and the 100-ton mass of the Orbiter was almost overkill for many of the missions it would be called on to support now that its assembly was completed. While the costs of the Space Shuttle were reduced by the LRBs and process improvements to “only” two to three hundred million for each additional flight made in a year, this was still several times the cost of launching a logistics vehicle on other existing launchers like Heimdall or Atlas III--a fact driven home by ESA’s first independent launch of a crewed spacecraft with the Kepler-C capsule Johannes Kepler and a crew of four ESA astronauts to Space Station Enterprise on top of the new Ariane 5 launcher in March, 2000. The four-person crew stayed three weeks onboard the station and assisted in several time-critical EVAs to support outfitting the ESA laboratory’s external payload mounts. The prime purpose of the mission however was a statement that ESA didn’t require NASA assistance in launching crew or cargo to the station--a demonstration of independent launch capacity crucial to ESA’s pride. It did not escape NASA’s notice that despite being less capable than a full Space Shuttle launch, the cost of the mission ran to half that of a Shuttle flight, and there would be times in the coming years where making any logistics flight on time and for a lower cost would be more important than the absolute cargo or crew capacity of that flight.
Space Station Enterprise itself was wrestling with its purpose in the aftermath of its expansion. For almost five years, the space station had been a “self-licking ice cream cone”: the station’s crew had been aboard first for the manual work of outfitting ET-007 LOX Tank habitat, then the installation and outfitting of the expanded solar truss and laboratory facilities. In other words, the raison d'être of the station had been its own expansion and operations. Now, with that expansion completed, the station had to move into an operational phase where every hour of crew time not spent in a laboratory or critical maintenance activities was a drain on the program budget, as NASA tried to excite researchers and commercial partners about sending experiments to fill the station’s labs. The station remained the flagship for humanity’s exploration of space, at least until a permanently-crewed moonbase was constructed. NASA still continued to search for additional applications to help justify its ongoing operations, and for ways in which the station’s capabilities and technologies could be leveraged for the next generation of space development. With the station’s first major expansion complete, NASA was still looking for any way possible to build on its success in the future, particularly in ways which would benefit other programs in Earth orbit and beyond.
One example of this came during the 2001 servicing mission to the Hubble Space Telescope. In addition to carrying up new multi-ton cameras and replacing critical systems such as gyroscopes and star trackers, the crew of STS-125 also installed a new docking ring and optical target on the aft end of the telescope, which would enable it to receive future uncrewed tugs for reboost or orbital adjustments. These plans were about more than maintenance. In the long term, NASA was developing a strategy for an Orbital Maneuvering Vehicle to use this docking ring to push Hubble’s orbital inclination from its original 28.5 degrees to a new 39-degree inclination co-orbital with Space Station Enterprise. This would enable the station to act as an orbital dockyard for Hubble, reducing the need for a separate launch-on-need mission in case of issues, as had been the case for STS-125 and other such flights which went to orbits other than that of the station. Moreover, while Space Shuttle missions would still be needed for replacing the multi-ton primary instruments of the telescope, the planned new orbit would enable crew aboard the station to carry out the repair of any minor issues which might arise. Along with servicing Orbital Maneuvering Vehicles or Orbital Transfer Vehicles, this kind of “orbital dockyard” service would also be of value for NASA’s future long-term plans.
As NASA began to update their 1989-vintage Space Exploration Initiative visions for space exploration to include a new journey to Mars, finding ways for the new program of record to continue to justify supporting Enterprise was not officially a critical factor in architecture selection. Still, when choosing between options which were otherwise equally effective for developing design reference architectures for NASA’s new mars plans, the options which could make use of NASA’s existing orbital assets and experience were favored over those which did not tie into the existing lunar architecture and the massive recent investments in Enterprise. Eventually, this would lead to the last major overhaul of Enterprise’s original legacy STS-37R hardware in the years to come. For the moment, though, Mars plans remained far off, awaiting Congressional approval. In the meantime, NASA had to negotiate scheduling ongoing station operations, Shuttle flight rhythms, and the launch of 2001’s Minerva 3 “cabin-in-the-woods” lunar outpost.
[1] SSME Blocks are complicated. The following is per Jenkins:
SSME First Manned Orbital Flight (FMOF) were used for STS-1 through STS-5, and were rated only to the maximum originally specified for the engine. This number is set as 100% of rated thrust, and future engines were certified for higher.
SSME Phase I were used through Challenger (STS-51L), and were rated at 104%, and in theory 106% to support very heavy payloads (up to 65,000 lbm) and polar missions.
SSME Phase II were used post-Challenger, and retained the earlier rating of 104%, but not 106%. Phase II and prior engines are referred to as RS-25A by Rocketdyne.
SSME Block I first flew in OTL on STS-70 in 1995, and utilized the new Pratt & Whitney High Pressure Oxidizer Turbo-Pump, a two-duct powerhead, and a few other modifications.
SSME Block IA first flew in OTL on STS-73, also in 1995, and was a Block I with a modified main injector and modified temperature sensors. Rocketdyne refers to both Block I and Block IA as RS-25B
Block IIA first flew OTL on STS-89 in January of 1998, and integrated all of the changes planned for the Block II except the new High Pressure Fuel Turbo-Pump (HPFTP). This included the new Large Throat Main Combustion Chamber (LTMCC) that reduced the expansion ratio from 77.5 to 69.5. The corresponding reduction in chamber pressure and ISP was countered by the change from 104% thrust to 104.5% thrust. Rocketdyne designated this configuration the RS-25D
Block II first flew OTL on STS-104 in 2001, and added the HPFTP to the Block IIA design. NASA delays to the HPFTP design (done by Pratt & Whitney) historically slowed this effort. Rocketdyne Designation for the Block II was RS-25C
In this timeline, Block II work is never slowed, and the full suite of Block II changes is introduced around the time of the historical Block IIA. These changes are made in parallel with the introduction of the SSME-35 nozzle and chamber alongside the SSME-69 chamber and nozzle. Here, by 2000, the SSME-35 and SSME-69 in service are both using Block II chambers, turbo-pumps, and probably throats.
A short (and free!) version of SSME history can be found in this NTRS paper, entitled Space Shuttle Main Engine (SSME) Options for the Future Shuttle.
Artwork by @nixonshead (AEB Digital)
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Figure out how to use an ET as a propellant tank farm. (shades to keep sunlight off, liquifiers and radiators to keep prop liquid.
Then use the extra, currently unused, payload capacity of the shuttle to haul water to the station. Electrolyze the water, liquify the gases, et voila.
Then use the extra, currently unused, payload capacity of the shuttle to haul water to the station. Electrolyze the water, liquify the gases, et voila.
Interesting, is this lack of "purpose" also OTL affected the ISS or is it specific to ITTL SSE ? Is it because it's a NASA, CSA, ESA, JAXA club instead of a true international station ?
Anyway, great update and thread !
Anyway, great update and thread !
The ISS has never moved out of the self-licking ice cream phase. Usually there are five people not doing science, and one person actually running experiments. SSE has 8 people, so it should roughly have twice the science capability (first three dudes needed to keep the thing running, then two are off-shift for every one working)
I'd argue that the ISS is starting to move out of that phase. ComCrew should expand the crew roster enough to double the science output IIRC.
Two big issues with that: how to move cryogenic fluids around in space (there have been many abortive schemes with magnets, surface tension, spin, etc., but none ever flew, and now SpaceX, and Boeing before them, seem to be settling on the simplest, though somewhat inefficient, method of using thrusters to settle the prop), and how to restart an LH2 engine in space.
Very nice art in the update before this of the LRBs!
NASA probably needed a new crop of geologist-astronauts to support future lunar missions--the corps has been short of those since Apollo, so we'll probably see a bunch of new names in the 2000s.
Interesting to see France getting more assertive toward Russia on Mir-II. Curious to see who else might join that program--China, perhaps? Or India?
Err... Worst come to worst, use TWO ETs, and give them a spin.
As for relighting LH2 engines, haven't RL-10s been doing that for ages?
The J-2 as well...Vinci is also restartable. So although it's certainly not trivial it seems to be reasonably achievable.
Ahh, but we're all neglecting to keep track of TTL's REAL up-coming space power! The Italians have already snuck into Kepler but we all KNOW they have much longer range and more insidious plans to replace ALL space launchers with their own ARIES and EAGLE spacecraft!
(https://web.archive.org/web/2007110...t.com/forums/thread-view.asp?tid=2925&start=1, and https://forum.nasaspaceflight.com/index.php?topic=2925.0;all)
ARIES: Alternate Reusable Italian Expandable Spacecraft
EAGLE: European Advanced Gear for Lunar Exploration
Randy
(https://web.archive.org/web/2007110...t.com/forums/thread-view.asp?tid=2925&start=1, and https://forum.nasaspaceflight.com/index.php?topic=2925.0;all)
ARIES: Alternate Reusable Italian Expandable Spacecraft
EAGLE: European Advanced Gear for Lunar Exploration
Randy
I'm unfamiliar with American strong men beyond those already used, but may I propose the names Samson and Herakles for potential OV-203 and OV-204 names?
The mention of issues with deferred maintenance on the launch infrastructure raises the potential for a new launch pad or two being built, perhaps in parallel with 'new build' Shuttles or the start of a 'Shuttle II' program. Time will tell!
The mention of issues with deferred maintenance on the launch infrastructure raises the potential for a new launch pad or two being built, perhaps in parallel with 'new build' Shuttles or the start of a 'Shuttle II' program. Time will tell!
Oh dis gon' be good. Perhaps we've found a use for that huge hydrogen tank volume on Enterprise's ET. I'll grab the Russian Space Pocket Knife to start the cutouts for the hangar doors
At any rate NASA's bumped into its perennial problem for any permanent installation built anywhere. "Now what?". That last paragraph is particularly interesting in the face of that question, and the question of NASA's exploration priorities going forward. I'm not saying it's going to be Red Mars's External Tank derived Ares colony ship (at least at first
), but American station as orbital shipyard is a nice callback to the Reagan era ideas surrounding what an American station would do.That's an interesting point. What exactly is NASA going to do with its ageing Orbiters? Do the Shuttle-C engine pods count as a "Shuttle-II"? The authors make the point that post-Enterprise "completion", ultimately the Orbiters are just expensive and fragile 150 ton mail trucks reusable or not. Even with the demands of supporting STS flights, I suspect there's room on the Atlas production line for one or two vehicles a year to dedicate to launching a tin can up to Enterprise to keep the thing topped off on consumables. And if there's going to be one supply tin can design flying, I also suspect in that case NASA would also contract for a second for assured capability reasons.
Which then begs the question. If we can launch sufficient cargo aboard STS derived lifters, and the Europeans have shown they can launch crew aboard something other than an Orbiter, why do we even need the Orbiter in the first place to launch crew?
And finally with regards to this chapter's artwork, I'm just gonna link two images which I think say all that needs to be said. As always keep em coming and great work!
With threadmarks, if you turn on reader mode (upper right corner of the thread) it will show only the thread-marked posts--it turns this thread into the story-only thread!
Boldly Going: A History of an American Space Station
Good morning everyone! This year, @TimothyC and I have gotten a very special present for you all for Boxing Day. We hope you'll enjoy it. Thanks go out to both the usual suspects for editing and image assistance: @nixonshead, @Workable Goblin, @Brainbin, @Usili, and a few unusual suspects too...
www.alternatehistory.com
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It's important to remember that while this LRB Shuttle is safer than the OTL one it's still fundamentally unsafe so it's a question of when not if a major accident occurs. Now with Shuttle-C the overarching STS program is going to continue but if you permanently ground and then remove the orbiters from service after another tragedy, and with Shuttle C and Kepler the argument to remove it from service is much stronger, NASA won't have an American crewed spacecraft. They'll be less unhappy to rely on the ESA than the Russians but it won't be acceptable for anything other than the short term.
Which means some sort of mid 2000's crew transport program is highly likely. The options as I see them are:
Kepler clone mounted on Shuttle C which is already man rated. Cheap to design though not operate and it meets the basic requirement but you lose the servicing capability. Also while the Shuttle C and capsule combo should be safer than the Shuttle any side mounted design is structurally dangerous.
Evolved block 2 Shuttle. Retains commonality with Shuttle C and should be safer but still side mounted and the closer it sticks to the Block 1 legacy the more dangerous it is. Also unlikely to be that much cheaper.
Clean sheet Shuttle II. Expensive and risky design phase and you might end with something dangerous and expensive. Or you could do it right side up and get a Space X starship a decade plus early. The underlying technology is mostly there. Best case scenario if it works but you could get an Ares like disaster.
Commercial Crew. With a successful "in house" system the push for commercial is going to be much weaker, in OTL you needed successive NASA managed programs to fail to make it possible, here NASA's rep is better so this is a very difficult sell.
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While an interesting idea, it runs into the problem that the front of Kepler capsule, and it's OTL antecedent the MRC, have their radar and main propulsion on the nose. This means that such a configuration would have to duplicate not only the docking port, but also all of the other systems. This would get very expensive very quickly. A much more likely solution would be to use use a 'caboose' made out of a SYLDA, that remains attached to the Kepler-C until the later is docked to the station. At that point, the cargo vehicle would be removed and berthed to either Space Station Enterprise or MIR-II. The upside is that we've got a nice side-access path for late-load on the pad. The downside is that the capsule is in a new place on the rocket, and the ground infrastructure would have to change.
Most notably, the engine used on the EDS is the RL60, and explicitly designed for on-orbit restart and reuse.
It's not so much launching of crew that the orbiter is best at, but doing that while offering pressurized and unpressurized upmass and downmass on the same flight. NASA/ESA have been able to use a fleet of just four Kepler-E lifeboats for nearly five years at this point, with each lifeboat having an-orbit life of a year. Using the shuttle to bring Kepler back down, combined with MPLM flights certainly makes logistics a lot easier for SSE than it has been for ISS over the last decade.
It is amazing.
NASA, ITTL, has plans to put a Kepler on an Atlas III, which while it doesn't offer a full backup (either in vehicle - It would be the same Kepler capsule that ESA flies, just an American one), or in engine (Atlas III differs from the LRB primarily in tank structures, not in P/A module), it would be a sort-of backup US crew vehicle....
One thing that we mentioned more or less in passing, is that the work for the Enterprise "Heavyweight" "Moonraker" external tank led NASA to solutions for the foam-shedding problems. This dramatically reduces the risks from being side-mounted at launch...