America’s Return to the Moon: A Foothold, Not Just Footprints

Our return to the Moon will not be like the Apollo-style sorties of the old Constellation project. This new approach calls for true lunar habitation—our first foothold on another world. The sooner we understand what is needed to get started, the better.

The Trump administration’s national policy directive (via its Space Council) calls for the return of humans to the lunar surface to use its resources. Since NASA has previously been tasked with this near-term space goal—lunar return—understanding the significance of the goal will go a long way toward completing a vital mission that has faltered and failed twice before.

Lunar return is often interpreted in various ways, from merely orbiting the Moon at some great distance (“look but don’t touch”) to surface operations that create a permanent human and robotic presence. Those are vastly different points of view, proving yet again that the devil is in the details. Clearly, which “lunar presence” we get depends entirely on how the people selected to guide this important, national policy-directed goal of human return interpret that term.

Let’s step back for a moment and examine some possible drawbacks and benefits of different modes of lunar return. Simply touching the lunar surface, and possibly setting up a few experiments or returning samples, does not begin to address or tap into the potential value of permanent lunar return. Over the past two decades (yes, decades) we’ve learned that the Moon contains both material and energy resources, including water—resources that will permit long-term residence and use. By establishing such a presence (as directed by the Trump administration and actively pursued by other nations), we have an unequalled opportunity to realize the Moon’s full potential—to learn how to use these space resources in establishing a true long-term capability, one that spurs innovative commercial enterprise while enabling a long-term space journey beyond the Moon.

A critical aspect of lunar presence is having enough reliable electrical power to support surface activities, including human facilities and habitations, and the build-up of an extensible surface infrastructure and space resource architecture. Power is critical in space (necessary for even the most simple application); so having useful energy available from local sources is huge in any attempt to enable the establishment of new and innovative systems.

Because the spin axis of the Moon is oriented near-vertically to the plane of its orbit around the Sun, its poles are unique areas possessing almost continuous sunlight. Instead of rising and setting like it does on Earth, the sun continuously appears and circles around the Moon’s polar horizons. This simple, yet vital difference caused by the Moon’s orientation addresses a critical need: Previous studies show lunar habitation placement near equatorial sites is severely penalized due to the limitation of available sunlight and subsequent accompanying temperature swings when one lunar day has 14 days of sunlight (-100° to 150° C) followed by 14 days of darkness (-250° C). Some type of reliable power source is required to permit habitation during the 14-day lunar night at the equator.

By comparison, conditions at the poles are practically benign, at -50° C! Using data from LRO (the hardworking lunar robotic orbiter), we’ve identified regions of near-permanent sunlight in the Moon’s polar regions—the prime real estate where a permanent presence on the Moon is possible.

Since the Moon’s poles possess unique features and deposits, what advantage should we draw from their relationship? With permanent presence enabled by near-constant solar power, we can begin to map, prospect and harvest the ice deposits and other volatile elements present at the poles. Water is a rare commodity in near-Earth space; we now know that significant quantities of frozen water have built up in the permanently dark craters at the poles. Water has a great many uses in space—aside from its obvious use to support human life, water can also serve as a medium of energy storage. It can be broken into its component hydrogen and oxygen using solar power, then recombined back into water, generating reliable electrical power as a byproduct.

The alert reader will have noticed that the preceding discussion is leading to a major conclusion—that our return to the lunar surface should be permanent, and that the mission is to learn how to use what the Moon has to offer to create new spacefaring capability. Although this is not a wholly new concept in terms of mission objectives, it is the first time that we recognize such a goal is not only feasible, but has the potential to be revolutionary.

Our examination of newly discovered facts about the lunar poles leads to several conclusions. First, we go to the Moon to experiment and to learn how to extract useful products from lunar materials—termed ISRU (in situ resource utilization). Because our initial, experimental efforts are likely to be fraught with difficulties and failed approaches, we need sufficient equipment and capabilities in order to understand their magnitude and adapt. (This does not mean massive factories).

Adopting this mode of operation actually simplifies our choices. First, we establish an outpost, a permanent facility whose location does not change (note that there are limited polar locales where the conditions of permanent sunlight and local volatiles are available). Although there is value in conducting sortie missions to specific sites of scientific or utilization interest, it makes sense to stage your sortie mission from a centralized outpost. By identifying and confirming the value of locating operations near the poles’ quasi-permanent sunlight in order to generate electrical power and access the water, stakeholders in the new space economy are assured that resources needed for ordinary surface operations will be constantly available. An outpost can be used in a variety of modes, but the fact that it is permanent makes it an “anchoring” facility on the lunar surface attracting more players.

Although resource processing is largely focused on the harvesting of water ice, the use of other material resources such as building aggregate, along with metal reduction, are also important. Once established, the outpost facility can become not only a processing facility, but also an experimental laboratory, where different resource processing streams can be tested and evaluated.

The problem still remains though, that while this approach contributes to obtaining the strategic knowledge necessary for establishing a permanent presence, at present, such planning appears to remain unfocused, making any coordination likely to be fortuitous, rather than planned. Though early lunar robotic payloads are likely to be small, an integrated architecture must include both robotic and human flights. Beyond being precursors, robotic missions need to remain an ongoing requirement of missions designed to assist and aid human crews on the Moon. Initial robotic missions will likely consist of simple measurements and characterization, but later robotic flights will emplace infrastructure (habitation, electrical power systems, mining machines and processing equipment). Such missions are needed indefinitely and continuously, thus an integrated plan to assure continuity—an architecture that focuses on integrating all of these parts (not merely create a wish list)—must begin now and begin in earnest.

In order to achieve this lunar return directive and have a good chance of success (this third time around “charm”), a separate, independent authority—one designed to focus solely on the requirements of a sustained lunar presence—is required. This program office needs a manager with experience in both robotic and human missions. It should not be operated like the typical Mission Directorate office that selects and flies individual payloads, and whose operations are largely self-contained and independent. Instead, each lunar mission and piece of equipment should become part of a larger mosaic of asset deployment, infrastructure, and operational capabilities. It is imperative we understand what pieces go together (be they commercial, national or international assets)—placed in a proper sequence; this requires drawing up a properly thought out architecture that still permits adjustments, with enough flexibility to enhance its viability and assure long-term success.

It is critical at the outset that the purpose of lunar return be fully understood and subscribed to. Our goals include establishing a sustainable human presence on the Moon, with the ultimate objective of learning how to use what the Moon has to offer in order to create new spacefaring capabilities. While the setup of ice mining serves many of these purposes, the Moon is rich enough in material and research opportunities that new processes can be undertaken on an experiential basis. Habitation can be achieved by covering habitat modules at the poles using the Moon’s abundant, loose surface regolith—creating places where humans are protected from hard radiation exposure, while still being able to monitor and control teleoperated machines. Solar energy can melt the surface regolith into roads, and provide material for solar panels. Potential opportunities for expansion and the involvement of commercial, science and transportation investment is limitless.

So we go to the Moon—permanently. We begin by occupying a single space on the Moon, not only to consolidate our resources for maximum leverage, but also to learn how to exploit the environmental factors necessary for rapid production. Surface operations will expand as we begin to understand how to achieve maximum leverage and can pass this knowledge on to those with new ideas—entrepreneurs eager to join and invest in a growing space economy.

Paul D. Spudis | READ MORE

Paul D. Spudis (1952-2018) was a senior staff scientist at the Lunar and Planetary Institute in Houston, Texas, and a prolific author on the subject of the moon. His books include The Value of the Moon: How to Explore, Live, and Prosper in Space Using the Moon's Resources.