AirSpaceMag.com

Resource map of the north pole of the Moon (from Spudis and Lavoie, in press)

We are almost at the end of a year that has seen major changes in our space program.  We have in hand a report from a “blue ribbon” Presidential committee that concluded that Project Constellation, the architecture NASA had chosen to implement the Vision for Space Exploration, was not affordable at current funding levels but might be accomplished with an increase in the agency’s budget, on the order of an additional $3 billion per year.  The committee presented architectural alternatives to Project Constellation, one of which eliminated the Moon in favor of a “flexible path” that allowed human missions to other destinations (e.g., an L-point, an asteroid) beyond low Earth orbit.

I take issue with several points in the Augustine report and have commented on them at length in several previous posts of this blog.  But now that the dust has settled and we have a “new direction” for our space program, its two principal deficiencies are evident.  First, by discarding the clear strategic direction provided by the VSE, we have entered an era of uncertainty and aimlessness of purpose in our space program.  This institutional drift is reflected in nearly daily stories about NASA – new missions studies, new launch vehicles, the endless personal backbiting amongst the space internet cognoscenti.  Second, the assertion of the report that return to the Moon is “unaffordable” is simply wrong.  How you go to the Moon and what your mission is there determines cost and all the committee looked at were cost models for the existing program and minor variants on it.

I have made both of these points here and elsewhere and many were quick to challenge me to show how we could go back to the Moon under the conditions and assumptions of the Augustine committee.  Rather than shut up, I now put up.  I have submitted a paper for publication in the Proceedings of Space Manufacturing 14, the conference in late October sponsored by the Space Studies Institute.  My co-author Tony Lavoie and I have developed an architecture that returns America to the Moon with a specific mission in an affordable way.  Our paper has now been accepted for publication, so I am posting a pre-print of it on my web site and will summarize our findings here.

One of the biggest problems with NASA’s implementation of the VSE was that they never understood why we were going to the Moon.  I base this assertion on their own statements, actions and publications.  Early workshops were held by the agency to develop a rationale for lunar return.  The Exploration Directorate issued a poster showing six “themes” for lunar return, but no one at the agency could state their mission in one sentence.  At a Congressional hearing in 2009, the acting administrator of NASA said the he did not understand what “return to the Moon” meant in terms of mission objectives and activities.

The agency took the position that they were merely transportation agents – that it was up to the various “user” communities to decide that activities were to be undertaken on the Moon.  As a matter of fact, the Vision itself very specifically laid out what was to be done on the Moon and even how to approach it.  The purpose of lunar return is to learn the skills and develop the technologies we need to live on another world.  The Vision specifically mentions that one skill we need to acquire is the use of extraterrestrial resources to make both exploration and human presence permanent and sustainable.

NASA ignored this direction.  There are many reasons why they did this, but I believe that the main one was they did not know how to create sustainable human presence on the Moon using its resources and were concerned that such a thing might not be possible.  But building large rockets is certainly possible – history documented that.  So the VSE morphed into a rocket-building program, an Apollo Redux because that’s what the agency (allegedly) knew how to do.  The only problem was that we do not live in the Apollo era and the space program no longer gets 7% of the federal budget.

The approach we take in our new architecture is to: 1) define the mission clearly and directly; and 2) design an architecture that accomplishes the mission in small, incremental and cumulative steps.  These last three adjectives are important:  Steps must be small to be affordable, not only under existing budgetary constraints but also under possible lower budgets that could be necessitated by national economic conditions in the future.  The steps should be incremental, meaning that each step adds some asset or capability and must work in tandem with previous equipment and operations.  Finally, the steps must interlock such that the whole is greater than the sum of the parts.  The architecture cumulatively increases features and capabilities with time.

We take as our mission the original Vision for Space Exploration.  We go to the Moon to establish a permanent human presence there and a reusable, refuelable, and extensible transportation system to support such presence.  Once established, we will have a space faring system that can not only routinely access the Moon, but all other points in cislunar space and beyond, including the L-points and near-Earth asteroids.

How do we accomplish all this?  One of the principal advantages of the Moon as our first goal beyond LEO is that: 1) it has the material and energy resources we need; and 2) it is both close and accessible.  This latter set of attributes is more important than you might think.  The closeness of the Moon allows us to directly control and operate robots on the lunar surface; the time-lag between action on Earth and execution on the Moon is only a bit over one second.  We can operate machines on the Moon in near real-time.  Additionally, we can send space vehicles to the Moon at virtually any time.  No other space destination is so easily and readily accessible.

The key to making all this work is the use of teleoperated robotic machines.  We go to the Moon robotically first and later with people.  These robots are controlled by people on the Earth.  They prospect for resources, test techniques, evaluate product yields, set up processing plants, and begin harvesting lunar resources almost immediately.  The extracted products are cached on the surface for future use.  The entire lunar outpost is set-up and made operational by these robotic machines.

Our architecture is designed so that time is a free variable.  We make constant, steady progress toward our goal; in fiscally lean times, we go slower, but we can accelerate the schedule if more money is available.  Making individual steps small and incremental permits this approach – we are not waiting for the development or advent of some “magic carpet” piece of equipment to fill a major hole in our plan.

So what’s the bottom line?  Our plan creates a fully functional, operating lunar resource outpost capable of manufacturing 150 metric tonnes of water per year.  In addition, we develop a reusable space faring system, one fueled by lunar propellant and expandable to support missions to the planets and destinations throughout cislunar space.  We do all of this under the budget guidelines provided to the Augustine committee by NASA; total aggregate funding for this program is less than $88 billion (real-year dollars), with peak funding of $7.1 B in Year 11.  Although schedule is flexible, we achieve our primary mission goals by the end of year 16.  We have had our assumptions, mass estimates and costing examined, reviewed and validated by a variety of space experts, including the Engineering Directorate Mission Analysis Group at NASA’s Marshall Space Flight Center.  This program architecture does what Project Constellation did not: it returns America to the Moon with a legacy of real and permanent space faring infrastructure.

In contrast to the current drift of our space program, the original Vision for Space Exploration set a strategic direction and path that made sense, giving us an expanding sphere of human reach beyond low Earth orbit.  The idea that America cannot afford space is ludicrous – we have the world’s largest economy and the amount we spend on space is now less than one-half of one percent of the federal budget.  But whatever we spend on space, we should expect to get something in return.  A lunar outpost and space transportation system gives us a return on our investment; a program of one-off, stunt missions does not.

The path forward into the future is still open to us.

LROC composite image of the south pole, showing quasi-permanent sunlit areas (LROC Ariz. State Univ.)

A new image released this week by the Lunar Reconnaissance Orbiter Camera Team shows the lighting conditions of the south pole of the Moon.  This new data supports the conclusions of many previous studies that areas exist on the Moon that are illuminated by the sun for more than one-half the lunar day (the time it takes the Moon to rotate once on its axis, a bit more than 29 Earth days or about 708 hours).

Why do such areas exist and why are they important?  Most locations on the Moon experience a day/night cycle, albeit one of an Earth month duration.  But unlike the Earth, the spin axis of the Moon is nearly perpendicular (off from the vertical by 1.5°) to the plane of its orbit around the Sun (the Moon orbits the Earth, but as the Earth orbits the Sun, the Moon can be said to do the same).  This means that at the poles, the Sun is always close to the horizon.  As the Moon slowly rotates during the course of a lunar day, the Sun tracks a 360° circle around the pole, sometimes just above the horizon, sometimes dipping just below it.

Or rather, it would do that if the Moon were a smooth sphere.  But as we all know, the Moon is not smooth – deep craters and basin make rims, peaks and holes that complicate the picture.  The deep interiors of craters may never see any sunlight at all.  These areas are extremely cold; we’ve learned from new orbital data that some of these cold traps are only a couple of tens of degrees above absolute zero.  It is for this reason that we find water ice and other volatiles near the poles – they are stable in the permanently dark, cold areas here.

On the other hand, if some bit of terrain near the pole is topographically high, it may stick up into the sunlight for a much longer time than other spots on the Moon.  This concept was first postulated in 1837 by German astronomers Wilhelm Beer and Johann Mädler and popularized in 1879 by French astronomer Camille Flammarion, who dubbed these areas pics de lumière éternelle (peaks of eternal light).  If such an area could be found near one of the lunar poles, the only time it would not be in sunlight would be during a lunar eclipse, which occur infrequently and last only a few hours.

We got our first good look at the lunar poles in 1994 with the global mapping obtained by the Clementine spacecraft.  Although Clementine only orbited the Moon for 71 days, we were able to determine that no peaks of “eternal light” existed at the south pole.  However, we did find small areas near the south pole that are lit more than 70% of the lunar day, and this was during the southern “winter” season (the 1.5° obliquity of the Moon provides some small seasonal variation).  We also found locations that are lit 100% of the day at the north pole.  These images were taken during mid-summer, when the north pole receives maximum solar illumination.

Lighting at the poles is primarily dependent on local topographic relief.  Because Clementine did not get laser topography for latitudes greater than 70°, we had a poor understanding of polar topography until the Japanese Kaguya mission flew in 2008.  The Kaguya spacecraft made a detailed laser altimetry map of the entire Moon, including both poles.  From this precision topographic data, we made a simulated relief model of the poles and illuminated it as the real Moon would be illuminated by the Sun over the course of a year.  Our new results suggest at least four areas near the south pole are in sunlight for large fractions of the lunar day.  One location (B) is illuminated more than 82% of the lunar day and is only 10 km from another point (A) that is lit 81% of the day.  Moreover, these two points are complementary in that the dark times at one corresponds to sunlit times at the other.  The four topographically high sunlight points are collectively illuminated 100% of the time during the lunar seasons.

The new composite image from LROC confirms the inferences from the illumination model we devised from the Kaguya altimetry.  The four high points (A-D) correspond to bright zones on the illumination map (see image above), indicating that they are sunlit most of the time.  These areas of “quasi-permanent” sunlight are the closest things we have found to correspond to Flammarion’s imagined pics de lumière éternelle. Although not “eternal” in the original sense, they are sunlit for extended periods, well beyond the typical lunar day-night cycle.

What is the significance of such features?  Permanently lit areas of the Moon are important for future habitation and use of the Moon for two principal reasons.  First, these sunlit areas are prime locations for the establishment of solar photovoltaic arrays.  The constant sunlight here means continuous generation of electrical power using solar panels.  This solves one of the most difficult problems of lunar habitation, survival during the 354-hour lunar night.  Prior to the discovery of the quasi-permanently lit areas, we imagined that the only feasible power source to survive this long night was nuclear reactors.  Such a power system does not exist and would require several tens of billions of dollars to develop.  So sunlit zones allow us to go to the Moon and stay there without this expense and technology development.

The second advantage of a sunlit area is that it is thermally benign.  The surface temperatures at the lunar equator and mid-latitudes depend almost entirely upon incident solar illumination and range from less than -150° to over 100° C, a 250° temperature-swing over the course of a day.  In contrast, the surface temperature of these quasi-permanent lit areas is nearly constant – a nice, toasty -50° ± 10° C.  This simplifies the thermal design of surface habitats and equipment and greatly relieves the energy required for thermal control at an outpost.

The sunlit areas of the poles occur in close proximity to high concentrations of water ice and other volatiles at the poles of the Moon.  Their presence indicates the lunar poles are the best places we have found off-planet for human habitation.  Constant sunlight, benign temperatures, near the water and a great view – that’s prime real estate.

Ralph Baldwin (photo by J. Wood from U. B. Marvin, 2003)

I learned that a titan of lunar science passed away last month.  Dr. Ralph Belknap Baldwin (1912-2010) was a rare specimen – a gentleman scholar, businessman and pioneering student of the Moon.  Beyond the impact of his books and papers, he influenced space history in several profound ways.

Baldwin, an astronomer by training, noticed the spectacular images of the Moon displayed in Chicago’s Adler Planetarium while giving public lectures there.  Those images showed a system of grooves and lineations that seemed to radiate from the center of Mare Imbrium (a large dark region on the lunar near side).  Upon investigation of the literature, Baldwin was surprised to find no good explanation for these patterns.  In fact, to astronomers, the Moon was an unattractive target for their attentions.  The biggest influence the Moon had on their work was that its bright, reflected light shining in the night sky often ruined observations of the faint star field that lay beyond.

The prevailing wisdom in the 1940s held that lunar craters were primarily produced by volcanism and Baldwin quickly discovered that no one was particularly interested in his new observation.  However, he persisted wondering what could have produced such a global pattern. He noted that the largest volcanic eruption in recorded history on Earth (Tambora in 1815) had left a crater a mere 4 km in diameter.  He reasoned that such a process – especially on the smaller and presumably cooler Moon – could not possibly have produced the “crater” the size of the Imbrium basin, a depression over 1000 km in diameter.  In his mind, the only alternative was that it formed by the impact of a large asteroid or comet.

Today we take the process of impact for granted but it was quite controversial before the space age.  Geologists hated the concept of impact because it smacked of catastrophism (the doctrine that singular, large-scale events could create landforms) and as that battle of ideas had been fought for over a hundred years, they resisted the idea that catastrophes may happen.  Astronomers ignored the concept completely, feeling that anything dealing with the planets (and certainly the Earth and Moon) was outside their purview.  So by championing the impact origin of lunar craters and attributing scientific importance to the Moon, Baldwin gained the distinction of being a double heretic.

Baldwin used his collected observations of the Moon, terrestrial impact craters such as Meteor crater in Arizona, and aerial images of bomb craters (created during the recently ended war) to argue that the vast bulk of lunar craters were formed by the collision of solid objects with the Moon’s surface.  He believed that impacts were explosive events that threw enormous amounts of debris across the surface of the Moon and, in the case of Imbrium, created the radial “sculpture” that dominates portions of the near side.  His book, The Face of the Moon, published by the University of Chicago Press in 1949 was widely ignored by most but not all.

During a party, Nobel laureate Harold Urey, a chemist who had worked on the Manhattan Project, picked up Baldwin’s book.  He consumed it in one sitting.  The idea of impact fascinated him and he became convinced the Moon was the critical object to understanding the origin of the Solar System.  As Urey’s opinion was considered important, the scientific stature of the Moon rose.  Researchers like Eugene Shoemaker, a young geologist with dreams of flying to the Moon, combed the literature for information about it.   The Face of the Moon was one of the few geologically insightful works available at that time.  Shoemaker went on to become a renowned lunar scientist and cratering expert, instrumental in assuring that astronauts going to the Moon conducted lunar field geology.  Although he never made the journey to the Moon in his lifetime  (some of his ashes were sent to the Moon on the Lunar Prospector mission in 1998), he trained the Apollo astronauts how to observe and collect samples on the Moon – samples that demonstrated the importance of impact on our history.

Ralph Baldwin (whose day job was Vice President of Oliver Machinery Corporation of Grand Rapids Michigan, the family business) was a gentlemen scholar who studied the Moon simply because he loved it.  His two principal books (he wrote an extension and revision of his book in 1963 entitled The Measure of the Moon) got the lunar story correct.  Almost all lunar craters were formed by impact.  The largest craters on the Moon are the gigantic, multi-ringed basins that contain the dark maria of the Moon.  The maria are volcanic lava flows, unrelated to the basins that contain them and erupted on the Moon long after the basins were created by impact.  The Moon’s surface features are very old; we don’t find large numbers of craters on the Earth because they formed mostly during the early history of the planets and have been erased from the Earth’s surface by active geological processes.  Baldwin had found his niche, achieving an important understanding of the Moon at a time when most of the scientific community was preoccupied with virtually any problem except the Moon.

I was fortunate to meet Ralph Baldwin in 1981 at a special conference on the origin of multi-ring basins (my dissertation topic).  I remember standing in front of a wall-sized enlargement of the lunar near side with him, looking at basin rings.  He was surprised and pleased to find out that I agreed with him on the existence of a very old, vaguely expressed basin in the central highlands.  We talked mostly about the Nectaris basin, a key feature in lunar history.  A couple of years later, while I working at the U. S. Geological Survey in Flagstaff, my boss Larry Soderblom gave me a paper by Baldwin on the topography of the Nectaris basin that he had been sent to review.  Baldwin believed that basins had relaxed through viscous flow of their topographic relief.  Since rocks have finite physical strength, given enough time, they will deform plastically.  High peaks or deep holes slowly will be erased as the rocks flow and relax under their own weight.  Baldwin had collected data that (he thought) demonstrated this effect occurred in lunar basins.  While this is undoubtedly possible, the degree to which it occurs on the Moon is still fiercely debated.

I read Baldwin’s paper in detail and made extensive notes.  I collected new measurements of the Nectaris basin using topographic maps that Baldwin apparently did not have.  I wrote all this up in a ten-page memo and sent it to Larry for his use in reviewing Baldwin’s paper.  To my initial horror, Larry simply sent my comments directly to Baldwin.  My fear was that he would be offended by an upstart student, questioning his data and conclusions.  To my delight and surprise, Baldwin phoned to thank me for my review efforts and asked for copies of the newly made topographic maps.  He later wrote me a very courteous and kind letter, thanking me for all of my review efforts and data collection on his behalf.  To me, this episode demonstrated the mark of the true scientist, one who is willing to consider valid criticism from wherever it may come.

As it turned out, Baldwin retained his original hypothesis, regardless of my own (and others) criticisms.  It is very human to hold to one’s own ideas.   Scientists must strive to discard useless or wrong concepts as new data or insight becomes available (something we regularly do, though sometimes reluctantly).  I too have felt the tendency to hold on to an idea, even when overwhelming new evidence shows it to be wrong, or at least, incomplete.  As in many other fields of endeavor, scientific research is a very human experience.  Scientists get intensely involved in their research and personally invested their ideas – more Vincent Van Gogh than Mr. Spock.

With little background in geology, except that which he taught himself, Baldwin deciphered most of the geological story of the Moon.  Moreover, his scientific work was done in his spare time and largely alone, as opportunities to discuss his work with other interested parties was rare. It is astounding to leaf through the 1949 The Face of the Moon today and realize how his insight – much of it completely intuitive – is still pertinent.  One of my personal favorites:  Baldwin suggests that extinction events in the fossil record might be caused by the impact of large meteorites and comets (page 155).  This suggestion, a throw-away line in a chapter about the frequency of large body impact, was proven correct in 1980 with the discovery of a large impact at the end of the Cretaceous, causing the extinction of dinosaurs and many other fossil families.

After all is said and done, I’ll let my own mentor in lunar science, Don Wilhelms, have the last word.  In the dedication of his excellent history of lunar science, To a Rocky Moon: A Geologist’s History of Lunar Exploration, he wrote:

“Dedicated to the amazing Ralph Baldwin, who got so much so right so early.”