Why we are going back to the Moon


Paul D. Spudis


The recent release of the details of NASA’s proposed plans for human return to the Moon in response to President Bush’s new Vision for Space Exploration of last year has drawn much comment:  some positive, some negative, and some simply perplexed. 


Although the reasons for undertaking the new Vision were clearly articulated in the President’s speech, it is important to re-examine why the Moon is the cornerstone of the Vision and what we hope to achieve by returning there.


The Moon is important for three reasons – science, inspiration, and resources.  All three aspects are directly served by the new lunar return architecture.  Implementation of this program has the potential to make significant contributions to our national economy and welfare.


The Moon is a scientific laboratory of extraordinary facility, richness, and benefit.  The history of our corner of the Solar System for the last 4 billion years is preserved and readable in the ancient dust of the lunar surface.  This record is lost on the dynamic and ever changing surface of the Earth.  Other planets do not record the same events affecting Earth and the Moon, including impacts, space particles, and the detailed history of our Sun.  The recovery of this record will let us better understand the impact hazard in the Earth-Moon system as well as unravel the processes and evolution of our Sun, the major driver of climate and life on Earth.


The Moon is a stable platform to observe the universe. The far side of the Moon is the only known place in the solar system permanently shielded from the radio noise of the Earth.  That uniqueness allows observation of the sky at radio wavelengths never before seen.  Every time we open a new spectral window on the universe, we find unexpected  and astounding phenomena; there is no reason to expect anything different from the opening of new windows on the universe from the surface of the Moon.


The Moon is close in space (only three days away) yet a separate world filled with mysteries, landscapes and treasures.  By embracing the inspiring and difficult task of living and working on the Moon, we can learn how to explore a planetary surface and how the combined efforts of both humans and machines enable new levels of productive exploration.


In 21st century America, our existence depends on an educated, technically literate workforce, motivated and schooled in complex scientific disciplines.  Tackling the challenges of creating a functioning society off-planet will require not only the best technical knowledge we can muster, but also the best imaginations.  One cannot develop a creative imagination, the renewable resource of a vibrant society, without confronting and surmounting unknowns and challenges on new frontiers.


Although of fairly ordinary composition, the Moon contains the resources of material and energy that we need to both survive and operate in space.  With its resources and proximity to Earth, the Moon is a natural logistics and supply base, an offshore island of useful commodities for use on the Moon, in space, and ultimately, back on Earth.


Water is an extremely valuable commodity in space – in its liquid form, it supports human life and it can be broken down into its two components, hydrogen and oxygen.  These elements make the highest energy chemical rocket propellant known.  Water exists in the dark and cold regions near the poles of the Moon.  Scientists estimate that each pole contains more than 10 billion tons of water, enough to launch a fully fueled Space Shuttle once a day, every day for over 39 years.  The ability to make fuel on the Moon will allow routine access to Earth-Moon space, the zone in which all of our space assets reside.


The Moon’s slow rotation, unclouded skies, and abundant local materials make it possible to build installations specifically designed to harvest solar energy on the Moon.  Solar power, collected on the Moon and beamed to the Earth and throughout Earth-Moon space, provides a clean and reliable energy source not only for space-based applications, but ultimately, for users on the Earth as well.  Lunar solar power solves the apparent “show stopper” of other space-based solar power systems – the high cost of getting the solar arrays into space.  Instead of launching arrays from the deep gravity well of Earth, we will use the local soil and make hundreds of tons of solar panels on the Moon.


Living on the Moon will expand the sphere of human and robotic activity in space beyond low Earth orbit.  To become a multi-planet species, we must master the skills of extracting local resources, build capability to journey and explore in hostile regions, and create new reservoirs of human culture and experience.  That long journey begins on the Moon – the staging ground, supply station, and classroom for our voyage into the universe.





Spudis Lunar Resources was created by renowned planetary geologist Paul D. Spudis (1952-2018) and is archived by the National Space Society with the kind permission of the Spudis family.

National Space Society