Eyes Turned Skyward, Part IV: Finale
In the late 60s, at the height of the Apollo program, NASA had conceived of a grandiose vision for the future, the “Integrated Program Plan”. This plan, in several variations, had amounted to a wish-list for the agency’s future, based on the assumption of a budget continuing at or above that of the Apollo-era peak. In these visions, reusable spaceplanes and large Saturn boosters would have been used to access Earth orbit, supporting a fleet of nuclear-powered orbital tugs, space stations, and depots, which would have enabled ongoing exploration of the Moon and even missions to Mars. The drawdown of funding in the wake of Apollo 11 was a hard reality check for these ideas, and under Administrator George M. Low, the agency had instead followed a cheaper program focused on just one aspect of the integrated plan, the orbital space stations--a decision that lead directly to Skylab, Spacelab, and Space Station Freedom. However, less than half a century after that grand vision, Low’s policy of a largely conservative, incremental development of capability combined with the unanticipated explosion of private spaceflight has seen many of the lofty hopes of the Integrated Program Plan become a reality. Through incremental development, ongoing advocacy, and more than a little luck, the agency that started with just one leg of the Integrated Program Plan has achieved almost all of what those planners envisioned and more.
In the late 60s, perhaps the most anticipated element of the Integrated Program Plan was one that was common in almost every piece of science fiction--the reusable space shuttle. In the Integrated Program Plan, such a vehicle would loft satellites, space tugs, propellant, space station modules, logistics cargo, and even crew to orbit cheaply and regularly before returning to its launch site for another mission. At the time, the potential for such a “space shuttle” had made its continuation, rather than that of the space station program, a strong contender for Low’s recommendation as the primary direction of the agency if only one path was to be followed. However, skepticism about the cost of technology development and the necessary flight rates lead to pressure from the OMB and White House to seek more cost-effective development paths. The dream of a fully reusable, multi-purpose space shuttle, though, is one that never truly died. With the Star Launch Thunderbolt L2 system joining the Lockheed Starclipper and the ongoing testing of the European Aquila, fully reusable launchers are driving the cost of access to space below what would have been wild dreams just a few short decades prior. Supplemented by NASA’s next-generation partially-reusable Saturn II, the ability of these reusable vehicles to launch spacecraft, cargo, logistics, and propellant is key to the current boom in spacecraft launches and the ongoing preparations and support of Armstrong Base at Shackleton Crater and the launch of Space Station Discovery. Given the necessary flight rates from launch pads in Matagorda, Wallops, and Florida, the sight of one of these reusable “shuttles” rising on a tail of fire can be seen at least monthly from nearly anywhere on the East or Gulf coasts.
In orbit, the Integrated Program Plan envisioned at least one large “Space Base,” augmented as necessary by smaller platforms in other orbits, as well as an assortment of depots and tugs. This was the main element of the Plan’s vision that survived cancellation in the 60s, but even though Space Station Discovery and the Gateway depots at LEO and EML-2 may be seen as just a continuation of of this legacy, there are differences. Unlike its predecessor Freedom, Discovery isn’t designed to ever truly be “complete”. Instead, it consists of a core group of modules for supporting the station’s ten to fifteen-strong crew and a variety of outlying lab modules. With the European Aquila and Lockheed Starclipper, the proposal is that these subsidiary modules can be returned from orbit as necessary for refurbishment or reconfiguration to support new scientific objectives of the station before being relaunched. The creators of the Integrated Plan also likely would not have anticipated the variety of origins of the various other stations circling the planet, from the partially commercially operated Mir-II to the Chinese Tianjia program. The commercial heritage of the Northrop Centaur-derived TransOrbital depot and its cousins, the Pegasus-derived Gateway 1 in LEO and the Centaur-derived Gateway 2 at EML-2 would also be surprising, as might the flights of orbital tourists to Mir-II and (in some proposals) on specially-fitted “L3” Thunderbolts or Starclipper shuttles. In the era of the IPP, that anyone but NASA would lead in space infrastructure development or crewed flights would have been unimaginable, where today it is commonplace for NASA to rely on commercially-developed vehicles and technologies for its space launch needs. While Saturn and Apollo are still core elements of space exploration, they too have changed with the times.
One major element of the Integrated Program Plan of the 1960s that has not materialized and seems unlikely to do so is the “nuclear shuttle”--a reusable nuclear thermal transfer stage which the IPP envisioned being used to transfer payloads between Earth orbit, geosynchronous orbit, the Moon, and beyond. While nuclear power is slowly recovering from damage done to its reputation in the 70s on the ground, concerns over launching even RTGs to orbit make the prospect of a full-scale orbital reactor dim, much less a nuclear rocket. However, the IPP’s nuclear shuttle does have a direct analogue: its role as an interorbital tug has fallen to the Northrop Centaur, NASA Pegasus, and the planned ESA Prometheus cryogenic tugs. Though less efficient than their nuclear-powered inspiration, once paired with the Gateway and TransOrbital depot network, this fleet of more than half a dozen orbiting tugs is capable of easily moving propellant, cargo, and even crew around LEO and cislunar space, and even to Earth escape.
Of course, one of the key tasks for this tug network is the support of crew, logistics, and cargo flights to the new Armstrong Base at Shackleton Crater. As the Oasis program sees Orion’s “soonbase” grow into a fully-operational outpost permanently crewed by four astronauts, the depot and tug network has already been hard at work transferring the base modules launched by Saturn II as far as lunar orbit, and crew are soon to follow. The house-sized trio of main modules, as well as the experimental semi-buried inflatable greenhouse and new rovers, represent a true outpost on humanity’s nearest neighbor. From the base at Shackleton, crews are planned to stage traverses of as much as 500 kilometers around the poles, exploring nearby craters and mountains, and conducting a wide variety of scientific investigations including preliminary small-scale experiments with excavating and extracting water ice for the base’s own use and possible electrolysis into propellant. In addition, Shackleton already plays host to the Lunar Infrared Tracking Telescope, the FROST-II radio telescopes, and the growing scattering of omnidirectional surface-mounted antennas that make up the Lunar Low Frequency Observatory. While the four-person outpost may not currently live up in scale to the dreams of some in the 60s, Armstrong certainly lives up to the vision of a lunar base, and seems likely to continue to expand in the coming decades.
It is certainly in the level of beyond-Earth exploration that the Integrated Program Plan of the late 60s diverges most from the reality of the present. Currently, lunar exploration is confined to a several-hundred-kilometer radius around the lunar South Pole, and the IPP’s sketch of a nuclear-powered Mars mission in the 1980s is still far from being achieved. However, in both cases, planning and advocacy is already in place in several places to see these deficiencies rectified as the next stage of NASA’s exploration plans. The most basic of these suggestions is the further expansion of development at Armstrong, expanding the base and its permanent staff. Given that thanks to the LEO RLVs and the Gateway and TransOrbital depot and tug network, the total cost of a single seat on a 6-month rotation to Armstrong is lower than the cost sustained for Spacelab and Freedom using entirely expendable vehicle, this seems likely to occur as a minimum conservative estimate. More advanced concepts envision the development of a replacement for the nearly twenty-year-old Artemis lander design, incorporating reusability and depot-connection features. Such a design, combined with a Centaur or Pegasus used as a reusable “uncrasher” stage to transfer it to a lunar suborbital trajectory, could further decrease the cost of logistics and crew flights to Armstrong. A more ambitious proposal calls for a similar but larger vehicle using the same architecture for a reusable remote sortie architecture, landing a reusable “minibase” science station the size of the original Orion outpost for a few months at any point on the lunar surface before dusting off for orbit, returning to the wide-ranging exploration of Apollo and Artemis but with the vastly improved scientific capacity and decreased cost of Orion and Armstrong expeditions.
However, while the further exploration of the Moon beckons to selenologists and members of O'Neill's Lunar Society, there is a strong drive to see the remaining destination in the Integrated Program Plan explored: Mars. Since the era of Apollo, Mars has been seen as the natural successor to the Moon for exploration and development, and the Red Planet’s attractions have only been boosted by television programs like Exodus and the ceaseless support of Robert Zubrin and his On to Mars! group. There is a strong case to be made--as it has been in both Zubrin and NASA-funded studies on mission concepts--that with NASA’s current Gateway network and experience with long duration spaceflight, Mars requires little more development than a renewed program of sortie “minibases’ with a reusable lander would on the Moon: one or two new vehicles, and a re-allocation or expansion of spending on human spaceflight. After all, a reusable Pegasus tug departing fully-fueled from an upgraded Gateway-2 station at EML-2 would be able to push a Saturn II-Heavy’s entire LEO payload to Earth escape, potentially enabling as much as 50 tons to be landed on the surface of Mars for less than half a billion dollars--a capability which makes expansive multi-launch Mars flights seem far more practical and less expensive than they were in the 1960s, when serious plans of Mars were almost certainly a step too far. Whether it is the Moon, Mars, or perhaps both which see the next phase of human exploration of space, the decreased costs and increased capacity of orbital infrastructure seem to suggest that the boundaries of Earth orbit shall not re-assert themselves any time soon.
However, the current boom in commercial spaceflight means that NASA aren’t the only ones carving out their own plans and aspirations, nor are the additional plans limited to those of other traditional players like Europe, Russia, Japan, China, or India. As shown by the developing Korean program and recent announcements by Brazil and some of the Gulf States, the dropping price of launch and democratization of space access has enabled many nations to consider space exploration who previously were unable to do so. Moreover, this democratization of spaceflight isn’t limited just to governmental organizations, as shown by NEOSearch’s establishment of the first non-governmental space telescope for asteroid research and the success of semi-commercial tourist flights to Mir-II by Roscosmos. It remains to be seen if some of the ambitious schemes proposed for more extensive commercial spaceflight prove to be more than pipe dreams, from specialized “space hotels” for orbital tourists launched on second or third-generation reusables, asteroid resource extraction, privately-organized flights to the Moon or beyond, the development of lunar resources, or the construction of orbital power stations.
Like the Integrated Program Plan of the past and like NASA’s own Moon and Mars aspirations of the present, these dreams are all within the realm of technical feasibility. The question of which, if any, may come to pass depends on political will and economic realities, as they have throughout the history of the space program. However, just as been true throughout history, there will no doubt be those who will find their inspiration with their eyes turned skyward.