The Value of the Moon

by Paul D. Spudis

  Looking back from our vantage point of having an operational ISS, it is easy to forget what a monumental engineering and programmatic challenge that was. We had never assembled a giant, distributed-system satellite in space. The assembly of complex equipment and facilities in space would require techniques that had not yet been developed and were only vaguely understood. The assembly robots had not yet been conceived, let alone built, and a managerial structure had to be formulated that could adapt to changing budgets, module delivery schedules, weather delays, and pad availability. From their mid-1980s vantage point, those tasked with the challenge of assembling the station knew that many more unknowns than certainties lay ahead.

  Having a large space station in low Earth orbit would offer more than just a laboratory for experiments: If properly constructed and configured, it could become the transit node for missions beyond low Earth orbit to the Moon and on to the planets. This idea still held sway in the minds of shuttle architects who took the moniker Space Transportation System literally. The von Braun architecture, laid out in the famous Collier’s articles of the early 1950s,8 envisioned first a space station, then an orbital transfer vehicle, a Moon tug and lander, and finally an interplanetary spacecraft. This incremental, building block approach had been abandoned when the political imperative of beating the Soviets to the Moon had taken center stage, but it was an approach to which the space agency wanted to return.

  President Ronald Reagan announced plans for the new space station program in his 1984 State of the Union speech.9 It would be called Freedom and would serve a variety of purposes, including laboratory research and observing the Earth and the universe, as well as serving as a transportation node. In its latter role, Freedom would be equipped with a servicing bay for satellite repair and serve as a departure point for missions from low Earth orbit to high orbits typically occupied by commercial communications and other satellites. Such transport required a reusable, refuelable vehicle, one that could move from low orbits to geosynchronous orbit (GEO), a circular, equatorial orbit about 22,000 miles (36,000 km) high. At this altitude, satellites orbit once every twenty-four hours and thus appear stationary or trace elongated, figure-eight loops in the sky. Any ground station on the hemisphere below the satellite in GEO is always in radio view. GEO is extremely important real estate for global communications, weather monitoring, and remote sensing.

  A rocket launched from the surface of the Earth expends virtually all of its fuel to achieve low Earth orbit. But in terms of orbital energy, this is only about halfway to geosynchronous orbit. To get satellites to GEO, the rocket would have to carry an upper stage for the final orbital transfer, thus limiting the size, and therefore capacity, of a satellite in GEO. Additionally, a satellite in high GEO would not be accessible by the shuttle, or any other human spacecraft to date. When a high orbit satellite malfunctions, typically it is abandoned and deorbited, whereupon an entirely new satellite must be built and launched.

  Having a spacecraft stationed at the low orbit space station would solve this dilemma. It would permit crews to travel routinely to and from the high orbits that these satellites occupy to service or replace them. But more significantly, crews could build satellite systems that would be much larger and more capable than any that could be launched on a single existing or planned launch vehicle. If the building of Freedom were successful, it would teach us how to build large, distributed systems in space. These techniques could then be applied to complex satellites in high orbits, presuming that there would be a way to get crews and repair facilities to that high orbit.

  A key piece of the evolving STS, the projected orbital transfer vehicle (OTV), was designed to be berthed at Freedom and available to transport people and equipment to higher orbits when needed. The OTV was to be fueled by liquid hydrogen and oxygen brought up from Earth, at least initially. The vehicle also carried a heat shield, allowing it to use the friction of Earth’s atmosphere to slow down the vehicle during close approach on return to LEO, thus requiring only a minimal amount of maneuvering capability. This strategy made the vehicle smaller and more efficient. Development of an OTV would be the next link in creating a genuinely space-based transportation system—and a vehicle that could routinely reach GEO could also go to the Moon.10 Despite its many potential benefits, an OTV was never built.

  The Lunar Base Movement (1983–93)

  In 1983, two scientists from the Johnson Space Center, Michael Duke and Wendell Mendell, realized that if NASA developed the OTV as part of the shuttle-station architecture, we would possess the means to return to the Moon. Along with physicist Paul Keaton from Los Alamos National Laboratories, they organized a small workshop, which was followed by a major conference at the National Academy of Sciences in Washington.11 That conference drew a large and enthusiastic attendance of engineers, scientists, and space visionaries. Over the course of three days, they discussed and pondered the implications of a lunar return. The scope of the meeting varied widely, with such topics discussed as extended exploration of the Moon, habitation and life support, mining and use of local materials for oxygen and construction, and orbit-to-surface transportation and fueling depots.

  This meeting initiated a large community movement dedicated to lunar return. Enthusiasts and advocates studied and improved their knowledge of the lunar surface and materials in preparation of a return, not in the temporary, sortie mode of Apollo, but for longer, more permanent stays. A series of meetings, workshops, and conferences over the next few years fleshed out possible scenarios for lunar return. Much attention was paid to the possible use of lunar resources to support extended human presence on the Moon and elsewhere in space.12 These schemes tended to focus primarily on the production of oxygen; lunar soil is about 45 percent by weight oxygen, although extracting it and converting it into its free, gaseous form was found to be a very energy intensive activity. Moreover, the environment of the low latitude regions of the Moon requires a long-lived source of electrical power in order to survive the fourteen-Earth-day-long lunar night. Thus, studies of power generation mechanisms needed at lunar outposts to keep equipment and people warm during the bone-chilling lunar night, revolved around the development of nuclear reactors, which would provide steady, constant electrical power and heat.

  All these studies concluded that while lunar habitation was possible, it would require several expensive technical developments. Once again, space dreams ran up against the cold realities of fiscal constraints. The response to this realization tended to focus on justifying lunar return in terms of some high-value benefit, such that billions of dollars of investment would be worthwhile. Such benefits typically involved the production of clean electrical energy for the Earth. One idea was to make solar cells in situ on the lunar surface and create kilometer-sized photovoltaic arrays whose power output could be transmitted to Earth via microwave or laser. An alternative concept was to harvest the lunar regolith for a rare isotope of helium, 3He, which could fuel a “clean” fusion reaction, i.e., one that produces no harmful radioactive by-products.13 Although 3He is present on Earth as a trace component of natural gas, it is found in extremely minute quantities, inadequate to fuel a commercial electrical generating industry. However, the Sun streams energetic particles continuously. This is the solar wind, which bypasses the Earth due to our global magnetic field but is implanted on lunar dust grains. Although still present in relatively minute amounts in the lunar soil (about twenty parts per billion), studies indicate that such concentrations are large enough such that 3He could be harvested from the Moon. This idea caught the imagination of both the public and the lunar return community when it was first proposed. However, several significant technical prerequisites remain before we have power generation systems that use 3He, most significantly, the need for a reactor design in which to burn the helium fuel.

  A major activity of the lunar science community in the 1980s was an effort to send a robotic mission to orbit the Moon. This mission concept first emerged in the mid-1970s under t
he name Lunar Polar Orbiter (LPO), a perfect descriptor. Because the plane of an orbit is fixed in inertial space, a satellite in polar orbit will view the entire surface as the planet or moon slowly rotates on its axis. Such a spacecraft could be configured with nadir-pointing instruments to measure a variety of chemical, mineralogical, and physical properties of the Moon. All of the Apollo missions flew in near-equatorial orbits, so only about 20 percent of the lunar surface was overflown and mapped with compositional remote sensors from the orbiting Command-Service Modules. Both of the Lunar Orbiter IV and V spacecraft were placed in polar orbits and completed a global survey of the Moon, documenting their value.

  Figure 3.1. Lighting maps of the north (left) and south (right) poles of the Moon. On these composite images, bright areas are in sunlight for extended periods while black areas are in permanent darkness. This relation (caused by the 1.6° obliquity of the Moon) makes cold traps that have accumulated significant amounts of water ice over geological time. The sunlit areas permit electrical power to be generated nearly continuously. (Credit 3.1)

  One critical piece of information about the Moon was much debated in the years following Apollo. No evidence for water—past or present, on the surface or inside the Moon—was found in the lunar samples, a finding that led to the dogma that the Moon was bone-dry and that it had always been so. As such, this made the task of living on the Moon much more formidable and challenging. However, before the advent of the Space Age, we knew that the poles of the Moon had some unique properties. Because the spin axis of the Moon is nearly perpendicular (88.4°) to the plane of the ecliptic (the plane in which the Earth-Moon system orbits the Sun), the Sun always appears on or close to the horizon at the lunar poles. If you were on a peak, you could be bathed in constant sunlight. Conversely, if you were in a hole (crater) at the poles, you might never see the Sun (see figure 3.1). These dark areas would be extremely cold, since the only heat they receive comes from the extremely low quantities of heat flowing from the interior of the Moon itself.

  Several studies suggested that these properties could have some dramatic consequences. We had evidence that the Moon has been bombarded by water-bearing objects—namely, comets and meteorites—over its history. Most of this water would be lost to space or dissociated in the high temperature vacuum of the lunar surface. However, if water somehow found its way into a dark “cold trap” near the poles, it would remain there forever, and no known natural process could extract it. Much speculation was expended on how much ice might be in the polar regions of the Moon, but we could not know if it was there until we went looking for it.14 A polar orbiting, remote sensing satellite (e.g., LPO) was needed to detect what might be in those dark areas.

  Despite its appeal on scientific grounds, and its obvious importance as a precursor for eventual human return to the Moon, the LPO mission was repeatedly passed over for other missions throughout the twenty years following Apollo. In January 1986, the space shuttle Challenger exploded shortly after liftoff, killing all seven of its crew, including Christa McAuliffe, who was not an astronaut but instead the first teacher in space. The shock of this tragedy was a public relations disaster for the agency, followed by a wrenching period of introspection and soul-searching about its vision and purpose, along with the accompanying technical reviews called up to fix the problem and restart the shuttle program. In addition to agency chaos after the Challenger accident, the Freedom project was also in turmoil, having undergone two complete redesigns before the shuttle accident, followed by another redesign a year later. Because of the major disruption of the loss of a shuttle, serious concerns were raised about the viability of the space station program.

  Two reports were issued during the manned spaceflight hiatus of the late 1980s. The Rogers Commission, named after its chairman, former Secretary of State William Rogers, was chartered to identify the cause or causes of the Challenger accident and to recommend policies and procedures to fix the problem.15 The other commission had a broader task: The National Commission on Space (NCOS), also called the Paine commission after its chairman, former NASA Administrator Thomas Paine, was asked to devise a set of long-range goals for space and to identify some of the strategies needed to attain them.16 The NCOS work was near completion when the Challenger accident occurred, and because of this unfortunate timing, its report was largely ignored when released. However, the Paine Commission report was very thorough and complete. It identified a systematic, incremental, and affordable expansion of humanity into space, for all the reasons we have identified over the years—the NCOS vision prominently featured space resource utilization in addition to exploration and science. It anticipated almost all of the current arguments for space goals and destinations, and suggested that because all are desirable in the objective sense and have their own constituencies, each can and should be pursued via a program that incrementally develops a wide range of capabilities.

  The agency responded to the Paine report with a series of studies and workshops throughout the hiatus period in human spaceflight, culminating with a report issued in August 1987 by an internal study group led by astronaut Sally Ride. The Ride Report identified four mission concentration areas: Earth system science from space, unmanned space science exploration, a lunar outpost, and a human Mars mission.17 The report did not advocate or choose any of the four but instead focused on what benefits and spacefaring legacies each one would give us. It suggested that a heavy lift launch vehicle would enable many of these activities and that a new HLV, using shuttle-derived hardware, could be developed quickly and inexpensively.

  Rise and Fall of the Space Exploration Initiative (1989–93)

  Problems with the shuttle solid rocket booster joints (identified by the Rogers Commission) were corrected and the vehicle returned to flight in September 1988. Armed with a renewed capability to get humans to and from orbit and with reports from three blue-ribbon study groups, President George H. W. Bush made the decision to announce a new major direction for America’s space program. Much speculation has been expended on the origins of the subsequent Space Exploration Initiative (SEI).18 My interpretation is simple: at the end of the 1980s and the beginning of the 1990s, as the Cold War was winding down in our favor, concern had developed about the erosion of our national technical capabilities—the enormous defense industrial infrastructure that won the struggle against the Soviet Union. President Bush and his advisors were well aware of this issue and the need to maintain a level of advanced technical infrastructure in the absence of the Cold War political imperative. The space program had served that purpose before and thus, an expanded space program—made affordable by the easing of defense requirements—could maintain a keen technological edge at a fraction of the level of Cold War defense expenditures. Curiously, the members of the Bush administration responsible for space policy never made this point publicly, but I know from discussions with some of them that many in the White House were well aware of its dimensions and implications.

  In a special speech delivered on the steps of the National Air and Space Museum in Washington DC, President Bush announced the new initiative on the twentieth anniversary of the Apollo 11 Moon landing.19 The SEI was what space enthusiasts had been wanting since the Apollo program: a presidential declaration on ambitious space goals. It called for the completion of space station Freedom, a return to the Moon (“this time to stay”), and a human mission to Mars. The president did not set forth deadlines for each milestone, except that space station Freedom should be completed within the next decade and that missions to the other destinations were tasks for the new millennium. The president asked his own White House National Space Council to examine and define the technologies and architectures needed to implement his new space initiative. Naturally, the Space Council turned to NASA for assistance in this new task.

  Teams from NASA Headquarters and the field centers were quickly assembled and charged with defining the steps, and the missions and pieces of the new program. They were tasked to report to the White
House within ninety days. The “90-Day Study” soon became infamous as the death certificate of the SEI, although in hindsight, it is not nearly as nefarious as widely reported and believed, and in fact, contains much good engineering sense and many clever ideas.20 In short, the main problem was that NASA was barely being funded at an adequate level to run the space shuttle program and to build Freedom. Naturally, it would require additional funding if additional major tasks were added to its agenda. Such logic was forgotten or ignored in an orgy of self-righteous indignation over the “pedestrian and bloated approach” of the 90-Day Study. Five alternative “reference approaches” were outlined, with each building outward from the shuttle/station in incremental steps while varying the rate of development and the amount of activity according to selectable levels of effort.

  The biggest problem with the 90-Day Study was not the report itself, but what happened behind the scenes. The report deliberately did not include budget information. Estimated costs were prepared so that policymakers could evaluate differences among the approaches. As one might expect, once these cost numbers were leaked to the press, the chattering classes inside the Beltway were aghast: the new SEI was expected to cost upward of $500 billion! What was always left out of these stories was that this cost number was the aggregate budget of the agency spread over the course of thirty years, a metric against which few federal agencies would stand up well under scrutiny. And given the national security dimension of the new SEI, such sums were a mere fraction of the national defense budget over the same period. Nonetheless, this number was widely circulated. It quickly became “canonical” and was used to discredit and disparage the whole idea of the SEI.