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Luis and Walter Alvarez at the KT boundary. Dinosaurs on the bottom right; little critters on the top left.

There is a brief but vociferous debate about the value of human spaceflight over at Space Politics, under a discussion of the new NASA proposed budget.  An often expressed opinion is that in general, humans contribute little to the scientific exploration of space.  Indeed, my scientific colleagues often make this argument, largely in the hope that some cancelled human space program cash will magically work its way into their programs.

I’m sometimes asked what we learned by going to the Moon with Apollo (1969-1972).  People vaguely remember that we brought back some rocks and maybe some remember that  experiments were laid out on the surface of the Moon.  But they don’t remember any great discovery on the Moon, like mountains of solid platinum or the uncovering of some new “unobtainium” element with anti-gravity properties.

Indeed, such was not found on the Moon.  The Moon is rather ordinary in composition.  It’s made of the same elements found in Earth rocks, although there are some interesting differences, such as the lunar samples are depleted in the so-called “volatile” elements, i.e., those with very low boiling temperatures.  So the conventional wisdom is that we  found nothing of value on the Moon.

In truth, we found true scientific gold.  The rocks brought back from the Moon told us the story of the Solar System’s early history, details both surprising and astonishing.  It was a time when planets collided and giant asteroids blew holes in planetary crusts hundreds to thousands of kilometers across.  The outer part of the Moon completely melted, forming a global ocean of liquid rock.  Our ideas about planetary formation and evolution had to be re-written from scratch after Apollo.

What does this have to do with human exploration?  Because people went to the Moon, we now have a completely different view of how life has evolved on Earth.  That’s a bold assertion, but I believe it to be true.

The lunar rocks are shaped by the process of hypervelocity impact and shock wave mechanics.  These events leave tell-tale physical and chemical signs, learned through extensive laboratory experiments, field studies of terrestrial impact sites (like Meteor Crater, Arizona), and complex numerical modeling.  Because we had done this work before Apollo, when the lunar rocks were returned, we knew how to read and interpret these signatures.

Now fast-forward to the early 1980’s.  Geologist Walter Alvarez studies sediments in Italy, trying to figure out the rates at which limestone accumulates.  Luis Alvarez, his father and Nobel-prize winning physicist, suggests to his son that he should use the concentration of the element iridium, which is rare in the Earth’s crust but common in meteorites, as a sedimentation “clock.”  Because meteorites constantly rain down on Earth’s surface (including oceans) at a known rate, this meteoritic “sedimentation” is  used to measure how fast the limestone accumulated.

When they applied this technique to the rocks, the Alvarezes got a big surprise.  A huge spike in iridium concentration was found at the boundary (formed 65 million years ago), between the older Cretaceous rocks and the overlying Tertiary rocks, a boundary coincident with the extinction of more than half of all fossil species, including most famously, the dinosaurs.

To everyone’s astonishment, the iridium spike at this boundary is found worldwide.  But the story gets even better: other iridium spikes are found elsewhere around the world at other rock sequence boundaries and many, if not all, are associated with mass extinctions, as evidenced in the fossil record.  In fact, impact mass extinctions  are a driving mechanism of evolution, as the disappearance of species opens an ecological niche for their replacement by new creatures, such as the rise of the mammals after the Cretaceous-Tertiary extinction of the dinosaurs.

What does all this mean?  The lunar rocks melted by impact show enhanced amounts of certain iron-loving elements, including iridium.  These elements are added to the rock during high velocity impact.  It took years of painstaking study by geologists, chemists, and physicists to understand these distinctive features and diagnostic properties of the impact process.  This knowledge was first applied to the Apollo lunar samples, which led to deciphering the impact history of the Moon.  Later, this experience allowed us to uncover a wholly new and unexpected page in Earth’s geological history.

By going to the Moon, we gained a new perspective on the history of life on Earth and new insight into how the process of evolution actually works.  Not a bad scientific return from a program whose real motivations were geopolitical, not scientific.

Why couldn’t this have been done with robot spacecraft?  There are lots of answers to this question, but fundamentally, it boils down to the fact that we would never have gone to the Moon strictly for science.  However, because we went to the Moon for other socially compelling reasons, exploration enabled science.  Only human explorers, trained in the methods of terrestrial field science, were capable of finding and selecting geologically controlled samples, rocks for which we could reconstruct a context that made their stories understandable.

I’m not done with this topic.  Next time, I want to look at the value of human spaceflight from a philosophical perspective.

How interested in space exploration are we?

There seems to be no end of new “strategic plans” designed to “save” our nation’s space program from the purgatory of mediocrity.  The latest entry into the strategic planning sweepstakes comes from the Baker Institute at Rice University.  Originally, I had planned to say nothing about this report, out of deference to my old friend from the Stafford Synthesis Group, George Abbey, who is listed as an author.  But recently, another author (Neal Lane) has made some public statements that are so egregiously ignorant that I cannot remain silent.

Briefly, the Abbey/Lane report urges the new administration to direct NASA to: 1) continue flying the Shuttle until 2015; 2) abandon the Moon as a goal because, “People don’t care about going back to the Moon and there’s no rationale for going back to the Moon”; and 3) focus NASA research on energy development and global climate change.

Aside from the idea of continuing to fly the Space Shuttle (not a very good idea for many reasons), none of this is particularly new but rather a re-statement of the Apollo-era meme that, “If we can go to the Moon, we can solve the (fill-in-the-blank) crisis.”  Since energy and climate change are the current crises du jour, some seek to capitalize on the public’s fondness for the NASA of old (“The Right Stuff”) with the frantic cry that it should be redirected to make these “fixes.”

Although there are good reasons to question the Apollo problem-solving template, I want to focus here on the argument Lane makes that people don’t care about the Moon.  It may surprise you to learn that I agree in part with his assessment but believe it is irrelevant to the determination of national space goals.

When I was on the Aldridge Commission, we received a presentation from NASA Public Affairs  which showed 50 years of polling data on the question, “Do you support the American space program?”  The numbers on this question have bounced around through the years, ranging from as high as about 60 to as low as around 40.  Surprisingly, no matter what the agency was doing, how it was faring, what disasters it endured or triumphs it achieved, the typical breakdown was roughly 50-50, plus or minus 10.  This result is as rock-solid as almost any polling number in existence over a similar time span.

Needless to say, NASA wrings its hands endlessly over this result:  “How can we excite the people?  If we could just come up with the correct PR plan, the public and Congress will shower us with money and support!”

I think we should look at these numbers differently.  If your poll results are always around 50-50, then in a fundamental sense, people are “indifferent” about what you’re doing.  So, in one sense, Lane is right – the public really doesn’t “care” about going to the Moon.  What he leaves unspoken is the fact that at least half of the country doesn’t really “care” about anything NASA does.  True enough, many do have a fascination with spaceflight; attendance at the National Air and Space Museum is consistently the highest of all the museums on the Mall in Washington DC.  But as with any museum visit, their curiosity is easily satiated and few dwell on national strategic goals and objectives in space.

Although NASA sees 50-50 polling as a problem, I see it as an opportunity.  In broad and vague terms, people support our space program – they don’t want to see NASA on the chopping block.  They like the idea of going to new places and making new discoveries – they just don’t focus and orient their lives around the  “sausage making” of space policy, like we in the business do.  What they want from their government is a space program that does interesting things (and not too many dumb things) with programs that will make and keep the country smarter, inspired, proud and hopeful.

Given such an attitude and with a funding level almost literally in the noise compared with other federal programs (at less than 1% of the federal budget, much smaller than most believe it to be), what should NASA’s strategic direction be?  I think that it should be the incremental build-up of our capability to go farther, stay longer, and to develop and increase human “reach” beyond low Earth orbit, first into cislunar (where so many national assets reside) and then into interplanetary space.

So what does this have to do with the Moon?  The Vision for Space Exploration (VSE) has exactly these objectives.  The plan is to fund NASA at a politically sustainable level (in constant dollars, the agency’s current budget has been at more or less the same level for the last 30 years) and give it the authority to create a growing spacefaring capability, assembled in small, incremental, cumulative steps.  Our Moon plays a key role as it is the first place beyond low Earth orbit with the building block resources needed to develop and expand our spacefaring capability.  Initially, this means oxygen and hydrogen, which provide consumables to support human presence and rocket propellant for re-fueling spacecraft.

Lane claims that the public doesn’t “care” about the Moon and he may be right.  However, I note with some amusement that in a recent poll on critical issues the public was worried about, concern for man-made global warming came in dead last.  Maybe turning NASA into EPA in orbit isn’t any better at inspiring people than creating new capabilities to explore ever more distant reaches of space.

The Vision has the promise to give us the flexibility to pursue a set of long-term goals in space that ultimately will allow us to go anywhere, for any amount of time, to do almost any job we can imagine, as well as many more that we can not yet imagine.   Is this not why we have a national space program?

Magnetic field strength on the near side of the Moon

We’ve known since the beginning of the space age that the Moon has no global magnetic field. Before we returned samples from the Moon, this was thought to be well understood – compared to Earth, the Moon is a small body (1% the mass) and it rotates very slowly (almost 30 times slower). The large magnetic field of Earth is generated in its very large, rapidly rotating, molten nickel-iron core. This process, called a core dynamo, is thought to be the principal explanation for global magnetic fields in planets throughout the Solar System. Thus, it’s not surprising that the Moon has no global field; for surface navigation, you can forget about packing a compass.

Rocks formed from cooling lava retain a memory of the strength and orientation of any magnetic field existing during their solidification. The magnetic domains in minerals align themselves with the direction of the prevailing magnetic field. As the rock cools below a critical point (the Curie point), the magnetic field is recorded as something called thermal remnant magnetism, which can be measured in the laboratory. Determination of remnant magnetism in Earth rocks has documented the existence of plate tectonics (continental drift), contributed to the unraveling of complex geological histories, and enabled the solution of many problems in terrestrial geology.

So it was quite the surprise to find that although there is no magnetic field around the Moon now, apparently there was one over 3 billion years ago. The Apollo samples were studied by every known technique, so measuring their remnant magnetism was one of many tests to which each sample was subjected. To everyone’s amazement, some of the lunar rocks were quite intensely magnetized – they cooled in the presence of a strong, steady oriented field. At first we thought this result simply must be wrong; perhaps the rock acquired it’s magnetism by traveling back from the Moon, through the strong magnetic fields that surround the Earth and give rise to its radiation belts and polar aurora. We even took one lunar sample back to the Moon, to be sure that its magnetism was not induced by the transport to Earth.

In conjunction with these sample results, some very strong local magnetic fields were recorded in place on the Moon’s surface by instruments carried by the Apollo astronauts and measured from orbit by robotic missions. John Young, Commander of the Apollo 16 mission, measured one of the strongest magnetic fields near his Descartes landing site, about one-hundredth the strength of Earth’s global field. It wasn’t until the flight of Lunar Prospector more than 26 years later that we found that his Descartes landing site is one of the strongest magnetic anomalies on the Moon. These magnetic anomalies have no clear or obvious distribution on the Moon, except many of them are associated with unusual bright swirls that appear to drape themselves over the landscape of the Moon.

Recently, a team from MIT has found remnant magnetism in a very old (almost 4.3 billion years) lunar rock. This rock is not a surface sample, created by impact and its associated shock, but rather, a deep-seated igneous rock, formed by the slow cooling of a magma at many kilometers depth within the Moon. The presence of a magnetic field in such a rock argues for 1) a stable, constant field, not likely to be achieved by impact; and 2) this field was in place early in lunar history. Both observations support the idea of a lunar core dynamo, one that somehow started early (sometime in the first few hundred million years of the Moon’s existence), operated for awhile, and then quit (around 3.5 billion years ago.) Is it really plausible for a body as small as the Moon to have had a molten core, generating a global field?

To say that this is scientifically troubling is an understatement. Scientists typically don’t like these “Just So” stories because they are simply contrivances that fit the presently known facts, and have little or no predictive power. A useful hypothesis not only explains the phenomena in question, it also has specific implications or predictions that can be explored and tested. If subsequent work shows the idea to be a false one, it is discarded. In fact, we need some mechanism to discard useless hypotheses, lest we be drowned in worthless trivia.

We appear to have a non-magnetic Moon, made up (at least in part) of magnetized rocks. In theory, there is no reason why a magnetic field should start, then abruptly stop operating. On Earth, reconstructing the magnetic story requires hundreds of carefully selected, oriented bedrock samples, something which we totally lack for the Moon. Resolving the paradox of the origin of lunar magnetism will be a high priority of lunar return.