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Neil walks on the Moon, July 1969

Memorial Day weekend is upon us, so thoughts of heroes and remembering them are foremost in my mind.  As a kid growing up in the Sixties, I saw a lot of change in our country. There was upheaval and tension here at home and around the world but the U.S. space program was a shining light that inspired many of us.  America was going to the Moon.  My friends and I dreamed of going and did the next best thing by launching rockets in vacant fields, excited and inspired by the idea of going into space and to the Moon.  Astronauts who flew into space, braving certain death in exploding rockets to fight the Soviets for control of the heavens, were our heroes.

The decade following was disappointing in many respects, but none more so than our apparent retreat from space.  In my exuberant but ignorant youth, I did not realize that Apollo wasn’t about space but rather about geopolitics right here on Earth.  America had won the war of space supremacy.  Unaware of the implications of what that reality meant to manned space exploration, we pressed on, eagerly preparing for a future that simply was not to be.  But our feelings for those men who braved the unknowns of space remained true.  They blazed the trail, setting us on our course, and they hold a special place in our hearts and memories.

The Apollo astronauts were a varied lot and all of us had our favorites — and a few we didn’t particularly care for.  But we admired all of them.  They did much more than simply play Russian roulette with rockets.  All of them were technically trained people, keen sharp guys with thorough educations and long experience in handling, managing and using advanced technology.  The Apollo astronauts were intimately involved with the design of their spacecraft; they were not “button-pushers” or “appliance jockeys,” or “spam in a can.”  They knew the principles of how their systems worked and could adapt and improvise when things went wrong. They had the “Right Stuff.”

Listening to Neil Armstrong, the first man on the Moon, testifying before the House Space Subcommittee the other day brought back so many memories.  Although I know many of the Apollo astronauts personally, I have only met Neil Armstrong once, very briefly at a technical meeting.  I was struck by his testimony during this House committee hearing.  His words rang so familiar and true.  I have said many of these things myself over the years and most recently argued for them in this blog.

Neil Armstrong is not only a famous, experimental test pilot, he has decades of experience in aerospace engineering and in the management of complex technical projects.  He faced critical life-and-death decisions on both of his spaceflights.  In 1966, his Gemini spacecraft malfunctioned, sending him and co-pilot Dave Scott tumbling end over end, out-of-control while they were near another space vehicle in Earth orbit.  His piloting skills brought the vehicle under control, ending the mission early but saving his and Dave’s lives.  Three years later, as his Lunar Module continually rang out with program alarms of unknown origin, he coolly guided his vehicle over a crater full of large boulders before making a soft touchdown on the Moon for the first time in history – all with less than 20 seconds worth of fuel to spare!  Because his training and experience gave him the ability to decisively, competently and quickly weigh his options, his corrective actions saved the mission.

His testimony before Congress reflects a grave concern over the “new direction” proposed for NASA.  He believes it is a mistake to abandon the Moon and the Vision for Space Exploration without a thorough review of all options and alternatives.  He makes the case that the Augustine committee, whose report allegedly is the basis of the new direction, was configured and given terms of reference in such a way as to assure that some options would be found untenable.  Specifically, that the cost estimates provided by The Aerospace Corporation and used by the Augustine committee to support the case for commercial transportation are unjustified and unsupported by serious analysis, a critical point that others have also made.

Armstrong is particularly mystified by the President’s casual and unconsidered dismissal of lunar return on the grounds that “we’ve been there.”  And oh yes, he is also very aware that “Buzz has been there” – he was there with him.  Armstrong made an analogy about this change in direction, using the example of courts of Europe in the early 1500s dismissing new trips to the Americas on the ludicrous grounds that, “We’ve been there.”

The Moon is a continent-sized landmass, where we have touched only six spots near the equator on the front side.  Moreover, we have found that the polar areas of the Moon are even more interesting and useful than we had ever imagined or hoped for.  The water found in the polar cold traps could enable the building of an extensible space transportation system, giving us access to all of our space assets in cislunar space, as well as taking us to the planets.  We need to return to the Moon for fundamentally the same reasons Europe returned to the New World – for prosperity, knowledge and the expansion of our civilization – the very reasons so many other space faring countries are currently working toward building a base on the Moon.

Neil Armstrong had a distinguished career serving his country in space on his Gemini and Apollo missions.  He seldom speaks out on public policy, so his emergence in this debate on our national space program is thus significant.  By coming forward to warn us how this proposed new direction will eliminate our nation’s space faring capabilities and leadership in space, he is once again striving to hold a steady course for the good of our country.  This warning comes from someone with considerable experience in space engineering, as well as a former employee of an agency that he knows well, for both its strengths and its weaknesses.  We should reflect on and consider his counsel carefully.  He is a tried and true American hero.

Flatlined -- in every sense of the word (Gallup Polls)

Those of us in favor of human lunar return have been called “dinosaurs” because, as it’s being told, we want to repeat what this nation already did 40 years ago.  If that were our mission objective, such a characterization might be valid.  But who really is the dinosaur?

At a recent Senate hearing, Norm Augustine told anecdotal stories in regard to lunar return, of how “our committee received many informal inputs, particularly from young people, questioning why we would have a space program whose centerpiece is something that was accomplished over a half-century earlier.”  NASA Administrator Charles Bolden states publicly that trips to new (non-lunar) destinations is exciting, while there are already “six American flags on the Moon.”  The President himself, referring to our efforts to return to the Moon, remarks with disdain, “we’ve been there,” the implication being that only new destinations in space are sufficiently exciting for the American public.

The administration’s new direction calls on NASA’s manned space program to: 1) stop what they are doing; 2) transition into technology study groups with a window of five years for sketching out the hardware and roadmap that NASA will follow for visiting a variety of new and ever-more-distant destinations; and 3) as soon as a rocket is built, commence with the objective – a series of intermittent (though spectacular) space “firsts” (as they believe this formula is needed to recreate the emotional pull Apollo had on our nation) that will eventually lead to a human setting foot on something beyond LEO. The “new” direction requires that we launch everything we need on these voyages directly from the surface of the Earth.  Afterwards, the small vehicle that returns the crew to Earth will be all that remains of the mission hardware. Then comes the next challenge: a more distant destination to keep a paying (but not going) public “engaged and excited.”  The “new” template is nothing more than a very old one – keep the Roman public amused with circuses and gladiatorial shows.

In contrast, those of us who support the Vision for Space Exploration (VSE) want to return to the Moon to use its abundant resources to incrementally create a sustainable, permanent human presence in cislunar space.  We want reusable, extensible, maintainable and affordable systems in space.  We want to unlock and harvest the enormous wealth of the Solar System for the benefit of all humanity.  We want to do what has never before been done – extend our civilization into the universe.  In place of one-off stunt missions, we want to create something of value – lasting and continuous access to space and its resources to expand our economy and create new wealth.  Instead of repeating Apollo, the VSE is an engraved invitation that will encourage participation from the paying (and probably going) public.  We want to build a real space economy.

The concept that our space program should excite people is a long-held faith in many space policy circles.  Several annoying facts remain though, suggesting that regardless of their desire for public excitement, its existence (or lack thereof) does not historically track with our national space program.  President Kennedy did not assemble a focus group or enlist a write-in campaign to gauge and prompt support for his call for a lunar landing program.  In fact, he himself wanted to find another venue for Soviet-American competition, one that would produce more tangible and practical benefits, such as desalination of seawater.

Ever since it ended, NASA has doggedly tried to re-create the Apollo program.  But the facts do not bear out their collective rosy memories of those days.  Polls taken before and during the Apollo missions to the Moon, found, at best, a plurality of public opinion in support of the lunar landing effort.  Many polls found a majority against the effort.  Media interest was intense for the first landing (Would anyone expect otherwise?) but tailed off afterwards.  During the totality of NASA’s existence, public support of the space program has hovered around 50-50 favor/oppose, regardless of what the agency was doing at the time.  My conclusion from these results is that, in broad terms, people don’t really care that much about space; they do not oppose it, but they are not wildly enthusiastic about it either.  Perhaps they can’t picture a time when they will move beyond their current role as mere spectators.

There is a belief in space circles that public excitement is a critical and driving factor in selecting goals and objectives in space. Threads on various space forums repeatedly argue for or against some path forward on the grounds that a certain program or effort will excite people.  This belief is closely related to its corollary belief that excitement equals political support and hence, more funding for space efforts.  There are two issues with this kind of thinking.  First, regardless of the excitement factor, one cannot set goals and objectives that are technically impossible.  For example, if the public decided tomorrow that only interstellar voyages were their hearts’ desire, we would not set that as a goal because we don’t know how to do it.  More seriously, excitement does not necessarily correlate with value.  We all buy and pay for many things that are exciting, such as watching or participating in sporting events, but after they are over, they are over.  They may have some long-term value in improving our own health or satisfying a need to be entertained, but eventually, we turn away from them and go back to attending to the necessities of our daily lives.  As adults, we need to spend time and money on practical matters as we plan and prepare for our futures.

In other words, it’s not excitement that we need from our space program, it’s value for the money spent.  Many in the space community (and even many inside the agency itself) parrot the falsehood that lunar return under the VSE was all about repeating Apollo.  In contrast to the trite “been there, done that” formulation of such misdirected thinking, the real purpose of return to the Moon under the VSE was to learn how to create sustainable human presence off the Earth, including learning how to harvest and use its material and energy resources.  Such an objective has never been attempted.  In fact, we’re not even certain that it can be done – that’s why it was given to an agency reputed to be our premier technical problem-solving agency – NASA.

So, who is the dinosaur here?

Last week, the Science Team of the Mini-RF imaging radar experiment aboard the Lunar Reconnaissance Orbiter (LRO) mission, met in Flagstaff, Arizona.  We were there to conduct field studies of some interesting lunar analogs that occur in this area. Scientists study the planets through a variety of means, including images, remote-sensing, and sample return. One technique involves studying the processes and deposits of the Earth as a guide or analog to understanding similar features on the Moon and other bodies.  Analogs have been studied since the beginning of the space program and have been essential to unraveling the complex histories of rocky objects in the Solar System.

The team gathered early Wednesday morning north of Flagstaff.  Our field guides pictured the three  areas we would spend the day visiting, along with geologically similar features found on the Moon. Our technique used airborne radar images of our targets: The SP cone and lava flow, Sunset Crater National Monument and Meteor Crater.  Each site offers specific features that one can observe and walk across, using it as a guide toward understanding the same processes that have shaped our Moon.  Our field trip illuminated the radar data in a “real world” environment, assisting us as we continue to explore and map with our instrument now orbiting the Moon.

SP cone and flow, a very rough, fresh volcanic feature in northern Arizona. Radar image courtesy of L. Carter, Smithsonian Inst. (click to enlarge)

The SP cone and flow is one of the most remarkable volcanic features in the region, with a beautifully symmetrical cinder cone and an extremely rough, blocky lava flow (Fig. 1; for full resolution versions of the surface pictures, click here: a, b, c). As viewed from the ground, the lava flow is blocky and extremely rough at the scale of the L-band radar wavelength (about 25 cm, or almost a foot).  Steep flow fronts of blocky lava lie directly upon a smooth plateau of flat-lying sedimentary rocks.  These remarkable flow fronts can be up to 50 m high (over 150 feet) and their rubbly, rugged fronts provide a spectacular contrast to the featureless plain upon which they rest. In the radar image, the lava flow is extremely bright, indicating high radar returns and its circular polarization ratio (CPR), one measure of its surface roughness at wavelength scales, is very high.

The lunar crater Gerasimovich D, showing an outflow of impact melt rock with high CPR. This relation is similar to the high CPR seen in the SP lava flow (click to enlarge)

The relations seen at the SP flow indicate the very high CPR features on the Moon could likewise represent very rough, block-rich surfaces.  An example of such is the unusual flow of shock impact melt (not volcanic lava, although quite similar in terms of its physical properties) seen emanating from the far side crater Gerasimovich D (22°S, 122°W, 26 km diameter; Fig. 2).  Both of these lobate flows (volcanic lava on the Earth, impact melt on the Moon) show high CPR, indicating the surface of the flow on the Moon probably has similar properties to the SP flow north of Flagstaff.  One exception is that the mean block size on the Moon may be smaller, as the Mini-RF S-band radar has a shorter wavelength (12.6 cm or about 5 inches) than the longer wavelength AIRSAR L-band image (23 cm wavelength) of SP crater.

Sunset crater lava flow (high CPR) and ash deposits (low CPR). Radar image courtesy of L. Carter, Smithsonian Inst. (click to enlarge)

Fifteen miles away from the SP flow, an instructive set of geologic relations are seen at Sunset Crater National Monument (Fig. 3; for full resolution versions of the surface pictures, click here: d, e).  At this feature, the extremely rough lava surface of the Bonito flow is in direct contact with smooth, ash mantled hills of the same age.  This contact is shown by the sharp boundary between high CPR lava and the extremely low CPR ash-covered hills in the radar image.  Such a relation is also evident on the Moon, where regional dark mantle deposits of lunar volcanic ash (such as the Sulpicius Gallus dark mantle on the rim of Mare Serenitatis) show low CPR, exactly as does its terrestrial counterpart.  Once again, the Earth example allows us to better interpret our remote-sensing data for the Moon.

Meteor crater, showing blocky, rough exterior rim deposits, wall outcrop, and fine-grained floor materials. AIRSAR radar image (click to enlarge)

The Moon is covered with millions of impact craters and we were anxious to visit and compare the radar data of Meteor crater, the world’s first proven impact structure, with surface conditions within and near the crater rim to better understand the surface of the Moon.  The rugged, blocky ejecta of rocks thrown out of the crater is evident by the radar bright halo surrounding Meteor crater (Fig. 4; for full resolution versions of the surface pictures, click here: g,h,i,j).  On the ground, this is manifested by abundant boulders of rock, strewn about the outer rim of the crater.  The crater interior is filled with ancient lake bed sediments.  This fine-grained material results in lower radar echoes for the floor of Meteor crater than for its rocky walls and rim.  Similar features are found in certain lunar craters where fine-grained material, moved downhill by gravity, partly fills the crater interiors.  The afternoon’s hike down into and across the floor of Meteor crater gave all of us a better appreciation for the surface topography and conditions on the Moon.  The climb back up to the rim, capped off our long day of field work.

Many of the geological features seen in radar images of the Earth are also seen in the radar images from the Moon.  As we continue to map the Moon with the Mini-RF radar, the sometimes puzzling relations seen in the lunar data are understood better by comparison with Earth analogs.  Our entire team acquired valuable insight into how the Moon works and what the surface is like from our day in the field.  For a geologist, there is simply no substitute for directly observed field data to fully comprehend the complex history and processes of the Moon.

Equally interesting and important will be the insight and knowledge gained when we sample the Moon in more detail.   The Moon has been described as a “dead planet” because compared to the Earth, which has rapid, dynamic processes of erosion, the Moon remains unchanged for millions of years.  However, for its ability to retain the ancient historical record of the Earth-Moon system, advantage goes to the Moon.  The multi-billion year records of impact and solar wind embedded in the lunar surface awaits our recovery, and will tell us about both the past and possible future of our home planet.

Earth over the north pole of the Moon as seen from Clementine, 1994

The Moon is constantly bombarded by the solid debris of the Solar System. Comets, asteroids and interplanetary dust, all containing varying amounts of water, have pounded the lunar surface for billions of years. Yet until recently, the Moon was considered to be barren and bone-dry. Rock and soil samples returned by the Apollo missions lacked any hydrous mineral phases or water-bearing weathering products. Since water is not stable on the Moon under ordinary conditions, what happens to it?

New studies of lunar samples, along with results from several missions in recent years, have given us a revolutionary new picture of water on the Moon. Study of volcanic glass from the Apollo 15 landing site in 2008 demonstrated that tiny amounts of water (about 50 parts per million) are present in the interiors of these glasses, suggesting that the lunar mantle (whence they came) contains about ten times this amount. This was a startling result, considering the extreme dryness of other lunar samples.

Because the Moon’s spin axis is nearly perpendicular (1.5° from vertical) to the ecliptic plane, the Sun is always on the horizon at the poles, keeping the floors of deep craters in permanent shadow. These dark areas only receive heat from the interior of the Moon and are extremely cold; recent measurements by the DIVINER instrument on the Lunar Reconnaissance Orbiter (LRO) spacecraft indicate temperatures as cold as 25-35° C above absolute zero. Water molecules are trapped by the cold as soon as they find their way into these craters. Over the more than 4.5 billion years of lunar history, significant amounts of water could accumulate in many of these crater “cold traps” at the Moon’s poles.

The first hint of water ice in these polar cold traps came from a radio experiment aboard the 1994 Clementine mapping mission orbiting the Moon. The polarization characteristics of echoes from the south pole were consistent with the presence of ice in the crater Shackleton. Four years later, the Lunar Prospector (LP) spacecraft carried an instrument designed to measure the amount and energy of neutrons given off the Moon’s surface. Hydrogen absorbs neutrons, so when LP investigators saw a decrease in the flux of medium-energy neutrons near the lunar poles, they concluded that excess amounts of hydrogen were present there. Although this observation is consistent with the presence of polar ice, neutron data alone do not tell us what form the hydrogen is in, and it was alternatively postulated that this enhancement was caused by excess solar wind hydrogen.

The Moon Mineralogy Mapper (M3) instrument on the 2008-09 Indian Chandrayaan-1 mission collected reflectance spectra for most of the Moon. It found both water (H2O) and hydroxyl (OH) molecules, present either as a monolayer on lunar dust grains or bound into the mineral structures in surface materials, poleward of about 65° latitude at both poles. Moreover, the abundance of this surface water varies with time, being present in greater quantity in both local early morning and late evening and it increases in abundance with increasing latitude. These results were verified by observations from the Cassini and EPOXI spacecraft during separate flybys of the Moon. The new observations indicate significant quantities of water moving towards areas with lower mean surface temperatures and increasing in abundance with latitude. Taken all together, the results mean that water is being deposited (e.g., by comet impact) and/or created (e.g., by reduction of metal oxides in the surface by solar wind protons) and then transported to the poles. By this process, significant quantities of water ice could accumulate at the poles over geological time.

Last October, the companion satellite to LRO, LCROSS, slammed the upper stage of its launch vehicle into the Moon’s south pole and observed the ejected material. Results show that both water vapor and ice particles were ejected from the LCROSS impact crater; initial analyses indicate that water is present at about the 5-10 wt.% level. The LCROSS impact site exhibits no anomalous radar behavior, suggesting that such an amount of water ice cannot be detected by radar. However, the results do indicate that significant amounts of lunar polar water may be present even in the absence of specific radar evidence for it. Spectra from this impact event show evidence for other volatile substances, including ammonia and simple carbon compounds. The presence of such material may indicate a cometary source for these volatile materials.

Both poles were covered by radar images from the Mini-SAR instrument on Chandrayaan-1. Much of the north polar region displays backscattering properties typical for the ordinary Moon, but one group of craters in the region show elevated polarization enhancements in their interiors, but not in deposits exterior to their rims. Almost all of these anomalous craters are in permanent sun shadow and correlate with proposed locations of ice modeled on the basis of the Lunar Prospector neutron data. These relations suggest that the interiors of these craters contain nearly pure water ice, with approximately 600 million metric tonnes of ice present in over 40 small craters within 10 degrees of the pole. The south polar region shows similar relations, except that it has fewer anomalous craters than the north pole. Small areas of polarization enhancement are found in some craters, notably Shoemaker, Haworth and Faustini; these areas might be deposits of water ice.

So water on the Moon is present in large quantity in at least four different “flavors.” Water was in the deep lunar interior 3.3 billion years ago, at concentration levels of a few hundred parts per million. This water would have been released during the eruption of lunar magma and could have made its way into the polar cold traps. Water is either being made or being deposited nearly continuously by impact all over the Moon. Most of this water is subsequently lost to space (e.g., by sputtering, ionization or thermal escape) but some is retained on the Moon. Any water arriving at a cold trap near the pole will be captured. Water, once in the polar areas, is stable as ice in the permanent darkness or where sublimation is prevented when buried by a thin layer of soil. Significant quantities of water may accumulate there; the LCROSS results suggest several to tens of weight percent water ice may exist in the polar soils. Finally, some of this migrating water apparently collects at rates high enough so that significant soil cannot mix with it during normal impact bombardment, as shown by the presence of relatively “pure” water ice deposits in selected lunar craters imaged by radar.

A significant amount of water at the poles of the Moon is present, with many billions of metric tonnes at each pole (detailed estimates of the water reserves are in progress). Such an amount is more than enough to support both permanent, sustainable human presence on the Moon and for export to cislunar space. Water is useful as rocket fuel and energy storage (hydrogen and oxygen are the two most powerful chemical propellants known) and for life support (water and oxygen) in space. These new discoveries fundamentally alter our understanding of the Moon’s processes and history and highlight both it’s scientific value and utilization potential. The Moon is on the critical path to human expansion into the Solar System.

Addendum. In the comments below, reader Pradeep Mohandas reminds me about the findings of the Moon Impact Probe, released from Chandrayaan-1, which discovered water vapor in very small concentrations in the space just above the Moon during its descent to the south pole.  This exospheric water (i.e., water in extremely small concentrations) may be related to the time-variable water seen in the spectral data from M3, Cassini, and EPOXI — in other words, it may represent water molecules in motion, migrating toward the poles.  Work on the nature and processes of the lunar hydrosphere continues and I will keep you up to date on the latest research results on this new and exciting subtopic of lunar science.