Keep in mind that it’s not over, until it’s over. The Falcon 9 launched successfully. The Dragon orbiting module separated successfully and deployed its solar arrays. It still must dock successfully with the ISS and deliver its 544 Kg of supplies, which is planned for Friday, May 25. Thereafter, SpaceX and its competitors must repeat successful missions (flights) often enough so that the effort becomes profitable. That is, after all, what private/commercial space is about. This won’t happen if the record of the launches, orbiting and docking isn’t good enough. Right now the ‘private’ space efforts are heavily subsidized, for example, the launch facility at Cape Canaveral in Florida was renovated by NASA, the American space agency, to accommodate the SpaceX launch. Presumably such subsidy won’t go on forever.

Many people say that commercial space operation is inevitable. That it will be attempted is inevitable; that it will be profitable, not so much.

The race to put a man on the Moon between the United States and the Soviet Union is long over. NASA got there first, national glory was achieved and then NASA and the American public lost interest in the Moon. The Russians’ all out space effort collapsed with the Soviet Union and is slowly rebuilding with intermittently successful commercial rocketry. In the follow-up to the Moon as the Next Big Thing, the International Space Station (ISS) is ‘completed’ and doing far less science, or anything else, than was expected. The NASA shuttle craft that were to establish healthy trade between Earth and the ISS – are finished, history, already on their way to becoming museum pieces. These days, the squabbles over mission priorities and budgets at NASA are tawdry and dispiriting. Budgets for space are riddled with cuts and complex politics in most of the other countries that have a presence in space – except China. China appears to be gung ho about space (if the right expression is gung ho, which in the original Chinese are the two words, ‘work’ and ‘together’); but strangely there’s hardly any reaction to China’s space achievements from governments, the media or otherwise. It appears there will be no space race with China. It’s as if we – the professionals, enthusiasts and the non-space engaged public – have mostly lost interest.

What seems to be missing is motivation, a real and powerful motivation to once again garner the attention and interest of the public in exploring space. With the exception of the Chinese, national pride seems to be out of the picture. Science, for all its true value, has never produced much general passion. There is always economics, but so far the exploration of space is a massive loss operation – as if it had any serious economic intention to begin with. Now that could change, perhaps in a big way.

Enter these gentlemen, multi-multi-millionaires and billionaires all: Larry Page, K. Ram Shiram, and Eric Schmidt (Google), James Cameron (film director), Ross Perot Jr. (Perot Systems), Charles Simonyi, Paul Allen (Microsoft), Peter Diamandis (X-Prize), Burt Rutan (aerospace engineer), Eric Anderson (Space Adventures). They have aligned with a company called Planetary Resources, Inc. that has the express purpose of exploring about 1,500 of the 9,000 or so Near-Earth Asteroids (NEA) with the intention of extracting from them valuable resources such as water and platinum. The company predicts that the value of such extraction will be measured in trillions (dollars, presumably).

Although the company was founded in 2009 by Peter Diamandis (a key figure in the personal space flight industry) and Eric C. Anderson (co-founded Space Adventures with Diamandis), the public launch was a rather eagerly anticipated formal announcement made from the home base in Seattle (Washington, USA) on April 24, 2012. In the years since 2009, the company’s narrative has been developed and more importantly the impressive list of names was added to the support roster. The announcement made a relatively big splash in the news for a company that as yet has far more plans than product. So, what have we here?

First, a disclaimer: Three years ago I wrote a novel precisely about the subject of commercial resource extraction from Near-Earth Asteroids, which means I’ve done some homework and have a bias in the direction of thinking the company’s plans are reasonable and feasible. That said, I’m aware that Planetary Resource’s notion of ‘mining asteroids’ is borderline fodder for late-night comedy. Some say it is crazy; et cetera.

I would say that for most people the idea of mining asteroids is brand new, and I use the word ‘brand’ intentionally. As a rule of thumb, most people know about exploring the Moon; most people are aware of plans to reach Mars – but the asteroids? The notion of reaching asteroids with orbits in the neighborhood of Earth has been a fringe idea. There is an important exception: In 2009, a report by the NASA commissioned blue-ribbon committee, the so-called Augustine Report, examined the future of the American humans in space program and recommended that NASA make reaching an NEA a priority. The recommendation was generally disregarded. The choice of a mission to reach an NEA, compared to return to the Moon or a major deep-space mission to Mars has had little or no constituency. However, some of the people involved with Planetary Resources noticed the Augustine Report recommendation.

To explain all the comparative reasoning behind an NEA versus other missions would require a book; I won’t attempt much here except some key points.

Ease of access: Some of the asteroids that have orbits approaching Earth are at their nearest point relatively as close to Earth as the Moon. Although the navigation is more complicated, reaching these asteroids is not much more difficult or time consuming than reaching the Moon. The major factor is that asteroids have no significant gravity. Unlike the Moon, which has one-sixth the gravity of Earth, there is no gravity well to fight on the way onto or off an asteroid. This is a huge savings in energy and simplifies local maneuvering.

Resources: There are many kinds of asteroids, three are the most common. Some are composed primarily of metals (M-type), mostly nickel-iron, mixed with stone and other metals and minerals. Others are composed mostly of carbon-based materials (C-type) including complex hydrocarbons (e.g. methane, ethane, etc.) and materials containing water. More than 75% of asteroids are C-type. Then there are asteroids composed mainly of stony material, often high in silicon mixed with a wide range of minerals. All types of asteroids contain material of commercial-industrial value, but the two materials that are singled out are water and precious metals. Water is arguably the most important because of its potential as a source of rocket fuel (hydrogen and oxygen), and oh yes, life requires it. Water is unfortunately quite heavy, and lifting it off the Earth’s surface is very expensive. The Moon has some water in deep polar craters, but from what we know; it is not available in industrial quantities and would still have to be lifted out of the Moon’s gravity well.

Precious metals – gold, silver, platinum, palladium, ruthenium, rhodium, osmium, and iridium – are of high commercial value, relatively compact for value, and are present in asteroids in what are believed to be accessible conditions. That is, unlike the Moon, the concentrations are relatively high – possibly high-grade ores – that can be extracted and potentially processed on site. Of course the big draw here is these metals are of extreme value on Earth for cosmetic or industrial uses. A thousand kilos of platinum is worth about $50 million at today’s spot price. Lifting quantities such as that from an asteroid for transportation back to Earth is feasible and potentially profitable.

That’s where Planetary Resources, Inc. comes into the picture.

A single 500-meter platinum-rich asteroid contains the equivalent of all the Platinum Group Metals mined in history. “Many of the scarce metals and minerals on Earth are in near-infinite quantities in space. As access to these materials increases, not only will the cost of everything from microelectronics to energy storage be reduced, but new applications for these abundant elements will result in important and novel applications.”
[Source: Planetary Resources press release]

In short, extracting water especially for rocket fuel and human environment supply and mining of valuable ores is the core of Planetary Resource’s plans. Sounds pretty good, but of course how this is to be done – that’s the thing isn’t it? The good news here, which you would expect from people who are both visionary and carefully rich, is that the company isn’t planning a gold rush. Contrary to some of the gushing media coverage, the program spans many years, perhaps decades, and takes everything step-by-step. The first step is to select, explore and analyze candidate NEAs for their commercial value. This will be done by robotic probes – asteroid prospectors. Planetary Resources is already building the first of these probes called the Arkyd-100 Series, which will orbit Earth and participate in the study of NEA candidates. A follow-up series, Arkyd-300, will journey to the target asteroids to conduct on-site exploration. Launch of the first robotics will be in 2013-2014 aboard various rockets.

Common intuition would caution not to minimize the technical difficulty of what Planetary Resources proposes to do. Launching expensive probes is never a sure thing. Getting them to their targets is not trivial. The technology for gathering the appropriate information, especially material samples, is still largely experimental. Returning samples to the Earth is also difficult. Then there comes the whole business of seriously extracting material from the asteroids – the technology for which exists only in Earth-based experience and the imagination of engineers. Let’s put it another way, the path to profitability is very long and uncertain. Why then are the quite intelligent and successful people who support Planetary Resources willing to put up their name and their cash?

Some of them have spoken about it, but I’ll summarize and extrapolate. In a nutshell: The vision of mining asteroids combines some of the romance of space exploration and development of the human race with the notion of making a great deal of money. It replaces the fading motivations of nationalism, the semi-obscure goals of science, and the abstract ideas about building things for Earth in space with something tangible and lucrative. I suppose one could kvetch about greed and profit motive as a mass motivator for developing our solar system, but few who have thought about it would argue that it would, sooner or later, become the ongoing driver.

Meanwhile, the Planetary Resources program will probably have a couple of important effects: It will provide a continuing story that can be followed by the media and the public. It will also require – and put pressure on – governments and space agencies to collaborate with and support the effort. It’s no secret that Planetary Resources will need to work with the science, technology, expertise and funding of academic and government sources. These folks may be rich, but not that rich. So, the effort to reach the asteroids and develop extraction techniques will be a massive joint effort – or it won’t work at all.

I have no idea whether this will happen. I hope so. In a sense, Planetary Resources, Inc. represents the human race getting off its collective butt and once again trying to do something really ‘out there’ – difficult, challenging, and at least in the long run exciting. There’s no need to romanticize the development of space to make it exciting, making a lot of money will do.

If this had happened, say, thirty years ago; it would have been an occasion for great nationalistic clucking and crowing. These days, people notice the irony, perhaps. More likely, with the tightening of budgets for space everywhere, the loss of any major expedition is viewed with dismay.

Mars is a difficult target. More than one-half of the missions have failed, some like the recent Russian Fobos-Grunt project fail even before leaving Earth orbit. Others, such as the NASA Mars Polar Lander crashed into the Martian surface. It’s known as the Mars Curse, but in truth it’s the complexity of the journey and the various requirements of landing on a major planet that demand near perfection in every detail, which is difficult to achieve.

Mars is often cited as the most important destination for human space exploration. Conceptually, this is certainly so; Mars has more to offer humanity – including possible colonization – than any other planet or moon. However, Mars Curse or not, it’s clear that Mars is logistically very difficult – beyond our means (money and technology) at least for the time being. What I just wrote can be vociferously disputed, but I wouldn’t take any bets on a manned Mars mission happening within two decades.

Zircon is a very common trace mineral in many kinds of rocks and soils. It’s relatively hard, crystalline material that, among other things, often contains trace amounts of radioactive elements uranium or thorium. The radioactivity has made it possible to date zircon with considerable precision, leading to the discovery that some zircons were formed about 4.4 billion years ago, the oldest known minerals.

Scientists at the New York Center for Astrobiology at Renssalaer Polytechnic Institute reasoned that zircon might also be used to determine what kind of gasses were present in the magma that formed the zircons. That, in turn, could reveal what gasses were escaping from magma that reached the Earth’s surface and were contributing to the formation of the atmosphere. Their results, published in Nature [30 November 2011, paywalled, The oxidation state of Hadean magmas and implications for early Earth’s atmosphere] may overturn fundamental assumptions about Earth’s early atmosphere.

The heart of the research was to create zircons in the laboratory, in essence making lava with various compositions and particularly with various levels of oxygen. The key to the research was using a rare earth metal, cerium, as a component of the zircon. Cerium is found in two oxidation states (containing different quantities of oxygen molecules). The more of the cerium with higher oxygen content found in zircon, the more likely the zircon was formed in magma with higher oxygen content. Since it is a long-standing hypothesis that most of Earth’s atmosphere was formed by outgassing from magma at the surface; demonstration that magmas of higher oxygen content would produce atmosphere with more oxygen could change long held beliefs about the early Earth atmosphere.

According to the Renssalaer researchers, Dustin Trail, E. Bruce Watson and Nicholas Tailby, zircon with the higher oxygen content was prevalent during the Hadean eon (4.7 – 3.8 billion years ago), and by their calculations this indicates that Earth’s atmosphere at the time contained more oxygen than previously thought. If it holds up under further testing, this is a significant finding that could change how astrobiologists view the conditions for the formation of life. Oxygen is a key component of organic material, and in the current notion of primordial atmosphere it was in short supply. It has long been assumed that the early atmosphere was mostly methane, carbon monoxide, hydrogen sulphide and ammonia – not the best mix for life. Now with the possibility that there was far more oxygen available in the crust of the Earth and in the atmosphere, the view on the formation of water and life could be pushed much closer to the origin of the Earth. As researcher Bruce Watson put it:

“Our planet is the stage on which all of life has played out,” Watson said. “We can’t even begin to talk about life on Earth until we know what that stage is. And oxygen conditions were vitally important because of how they affect the types of organic molecules that can be formed.”

Despite being the atmosphere that life currently breathes, lives, and thrives on, our current oxidized atmosphere is not currently understood to be a great starting point for life. Methane and its oxygen-poor counterparts have much more biologic potential to jump from inorganic compounds to life-supporting amino acids and DNA. As such, Watson thinks the discovery of his group may reinvigorate theories that perhaps those building blocks for life were not created on Earth, but delivered from elsewhere in the galaxy.

[Source: EurekAlert]

This sort of hypothesis will be controversial, but as is the case with novel but plausible research, it will be tested.

November 9, 2011: It was a reminder for the neighborhood (Earth and Moon) that strangers pass in the night. Night being metaphorical in this case because the asteroid 2005 YU55 actually took about three days to orbit through the vicinity of the Earth and Moon. As asteroids go, YU55 is fairly large, about 400 meters (1300 ft) wide, what Americans would call a city block. If it collided with Earth it would make a helluva bang, on the order of many megatons of TNT, roughly a nuclear bomb that would make a crater 6.4 km (4 miles) across and 518 meters (1700 ft) deep. Of course, it didn’t this time and probably won’t collide with the Earth in the future; so it serves as a reminder that such asteroids are around and collisions can happen. In fact, because 2005 YU55 also passes close to Venus and Mars during its long orbit, it is subject to gravitational and other forces that can alter its path. Current calculations indicate that despite changes caused by Mars or Venus, the asteroid still will not be anywhere near collision course with Earth when it comes back around 2041, however, there is a margin of error.

First seen in 2005 (hence the provisional name, 2005 YU55), this particular asteroid passes between the Earth and Moon with 319,000 kilometers (198,000 miles) to spare at its closest point to the Earth. It’s too far away and too small to be seen by the naked eye, but professional and amateur astronomers will have a day in the field spotting, tracking and studying the relatively infrequent event. The next such ‘near miss’ (to put it with as much dramatic spin as possible) will be in 2028 when asteroid 2001 WN5 swings by for a passing visit.

These passing asteroids, part of a group known as the Near Earth Asteroids are also the subject of a NASA mandate for a human landing. 2005 YU55 might, in fact, be a candidate. Asteroids present an interesting opportunity to ‘hitch a ride’ through the solar system, while at the same time extracting metals and minerals too heavy to be lifted in quantity from Earth. Since asteroids have negligible gravity, it would in theory be easier to ship heavy material from them than to fight the gravity well of any planet or moon.

It was, as so many jokingly put it, a real down-to-earth mission to Mars. As in, the mission never left Earth. Beginning June 3, 2010 and ending November 4, 2011, the Mars 500 mission took place in a facility at the Russian Academy of Science Institute of Biomedical Problems near Moscow, as a joint project of the European and Russian space agencies. Joking is easy but try looking at it this way: How would you like to step into a windowless room about as big as a studio apartment (12×66 ft or 3.6×20 m) and spend the next 520 days (18 months) with five other people, in this case all men, who until this experiment you’ve never met in your life?

Actually I’m not sure why this story was often treated by the media as something of a joke. Other than the obvious and unavoidable fiction of space travel while remaining on the ground, this was a serious experiment that cost over $15 million. The specially constructed facility, which included a simulated Mars Lander and an ‘external area’ that simulated the surface of Mars, was designed to maintain the isolation and confinement that would actually occur on a 500 day mission. The program included over 100 experiments, some requiring the use of spacesuits and there were many simulated ‘events’ that would typically be encountered by a real space flight. The six cosmonauts maintained communications with Earth, including with their families, but a transmission lag of up to 25 minutes was created, just as it would be on the 54 million kilometer flight.

It was not easy. In fact, all of the other attempts at doing something like this, including the expensive and widely hyped Biosphere II in Arizona (USA) were failures. Whether a mission to Mars was faked or you just put six people into a small space for a long time, the experience is grueling and potentially violent. It is already known that jealousy over workload and contact with loved ones was a problem among this crew.

It will be interesting to read what was learned from the experiment. We know that part of conquering the vast distances involved with interplanetary travel is overcoming boredom and the inevitable stresses of living in close quarters. Much has been learned from the navies of the world, especially those on submarine duty, but the situation in space – and especially the very long duration of travel in an unrelenting and extremely hostile environment – is different. How different, we have yet to learn. This experiment was part of the process of learning, for example, fatigue and lack of motivation were part of the difficulties encountered.

It is not accidental that the Russians spearheaded Mars 500. Almost from the beginning of the so-called ‘space race’ with the United States back in the 1950’s, the Russians placed greater emphasis on the human aspects than their counterparts at the U.S. space agency, NASA. This included, early on, extensive experiments and observation of psychological factors and later with social and cultural factors. Outside of weightlessness (microgravity) and the dangers of radiation in space, psychological and physical problems may be the most important in these long flights.

The six men who participated, three Russian, and one each Italian, French and Chinese were paid $100,000 for the duration. They also spent over a year in preparation. When they stepped out of the facility modules on November 4, they were pale but healthy. Officially, they said they were ready to go on the next mission. The next mission may well be even more ambitious – a similar experiment aboard the International Space Station, where microgravity is real.

The Global Warming controversy is ended. Right.

Take a look at the graph above. It shows the results of global temperature measurements over a span of some 100-200 years as compiled by four groups: NASA Goddard Institute for Space Studies, NOAA (National Oceanic and Atmospheric Administration), United Kingdom Meteorology Office Climatic Research Unit (hadCRU), and the Berkeley Earth Surface Temperature Project. Notice that the graph lines are almost identical and they all show a strong trend in global warming.

This is not exactly news, is it? No, but one line in the graph of particular interest is from a report that is making its way toward official release. It’s important because the data for that line on the graph is from those skeptical of scientific measurement of global warming. The Berkeley Earth Surface Temperature Project was begun by University of California physics professor Richard Muller, a man highly critical of the manner in which climate scientists were gathering and manipulating their data. Initial project funding included sources that generally contribute to climate change denial. Muller’ stated goal was to establish an independent source of climate data that would be thoroughly vetted for bias and error.

The Berkeley team, ten scientists led by Robert Rohde, a specialist in climatology with large data sets, included Saul Perlmutter, this year’s Nobelist in physics. The goal was to assemble a merged set of climate data from surface weather stations, check it for various errors, bias, or other distortions, analyze it with new and existing statistical methods, and provide public access to all the data and results. The result of the multi-year project is a database of 1.6 billion records of climate data, and a report that is now available at the website [Berkeley Earth Surface Temperature], which is heading for peer review and publication. Though not final, this is the official report.

The report is based on data collected from about 40,000 weather stations around the world. It will be difficult to impugn the source, as the Berkeley project explicitly stated that the quality of weather station reporting was sufficiently reliable and more importantly did not reflect the contention that modern ‘urban heat islands’ (the heat generated by cities and roads) affected a significant number of measurements. I would say that this data was also subjected to scrupulous statistical analysis, although that will have to wait for the peer review process to be validated. The essential results, in the words of Dr. Muller:

“Our biggest surprise was that the new results agreed so closely with the warming values published previously by other teams in the US and the UK,” said Professor Muller. “This confirms that these studies were done carefully and that potential biases identified by climate change sceptics did not seriously affect their conclusions.”

[Source: BBC News]

The findings of the Berkeley project agree that the global temperature has increased 1 degree Celsius since 1950 and the trend is up. In short, global warming is real.

So here we are in 2011, more than twenty years after the first warnings about the rise in global temperatures, and most people in the United States still think there is no global warming. The Republican Party has virtually enshrined climate change denial as part of its platform. At the same time, the U.S. military is planning for the effects of global warming on world politics and conflict. The energy industry is preparing a full-scale development of the Arctic petrochemical fields as the ice recedes, and plans are already in motion for shipping routes through the Arctic seas. Many countries, especially island states around the world, are making plans for rising coastal waters. This is what some like to call cognitive dissonance, the discrepancy between what people choose to believe and what is actually happening around them.

Will the addition of one more global warming report, albeit from a group inclined to be skeptics, have an impact? Watch your favorite media outlets. Will the results be highlighted? Will they be mentioned even once? Then judge for yourself.

Most western media have commented on the political (PR) aspects of this event. All such space efforts are political, in China or elsewhere. This project is interesting because of the contrast to the International Space Station (ISS), the decades-long effort by a consortium of countries. In this case China is following a resolutely go-it-alone approach. Although the program relies heavily on Russian space technology, there is nothing collaborative about it.

What’s more interesting is that the Chinese space effort is not being used in an organized way to flagellate the public into support for NASA or other western space agencies. There’s no Sputnik effect. Why?

One possibility is that experience with the ISS has taught NASA and others that until the problem of costly and dangerous transport between station and Earth surface is more than marginally improved, large permanent space facilities are not worth it. The amount and quality of research produced by the ISS is nowhere near what was expected. The Russians, in their blunt fashion, suggested that the ISS consortium let the $100 billion station fall into the ocean in 2020. So if the Chinese wish to build their own albatross for prestige purposes…let them have at it.

There is also speculation that the Chinese have military purposes in mind. However, space platforms such as the ISS are too public, too complicated and inconveniently multipurpose to be very appealing for the military. I wouldn’t rule it out, but it’s more likely the Chinese military will use specialized and highly secret satellites, just like the military elsewhere.

It’s most likely that the Chinese have chosen their space program to mark their national ascendency in science, technology and wealth. The U.S. and Soviet Union did that for a while, but the Russian economy collapsed and the Americans lost focus. Now we get to watch what the Chinese can do when faced with the same problems.

Earth has lots of liquid water, like oceans of it – though salty. Why would people be excited by briny water on Mars? However, for those intrepid, dreaming human beings who think of traveling to Mars and one day pitching camp there, the news from the NASA Mars Reconnaissance Orbiter (MRO) and reported in the journal Science [04 August 2011, paywalled, Seasonal flows on warm Martian slopes] is almost surprising: There may be, at times, running water on Mars.

Far and away most of the Martian planetary surface is too cold for water, liquid or frozen. With a mean temperature of -63 degrees Celsius, surface water or ice quickly sublimates in the cold dry atmosphere. It has long been thought, and then shown by satellite instruments, that water exists on Mars but only as subsurface ice. Now it looks like there may be exceptions.

Mars has seasons, much like Earth. It can get surprisingly warm at the height of summer in the middle latitudes, around 20 degrees Celsius (68F). It is there, in an area of the Southern hemisphere, where the MRO has taken a seasonal series of pictures of a slope with dark streaks, from .5 to 5 meters wide and hundreds of meters long, that appear with the Martian spring, grow bigger with the summer, and disappear with the coming of winter. There are several possible explanations (called hypotheses for scientists), for example the change could be caused by melting carbon dioxide; but the temperatures are too high to sustain CO2. At this point the one hypothesis that makes the most sense is liquid, salty water. Salty because the temperatures in the area during the ‘warm’ seasons are still too cold for pure water (it would freeze). However, the slopes where this occurs are struck directly by the summer sun and while the water may not be gushing, it is probably at or near the surface.

Probably. As with most science at this distance, the images and explanations are the best shot with the given evidence. That doesn’t mean it might not be something altogether different – a chemical reaction or the fluid motion of some other geologic material. In fact, there is already an interesting problem with the water hypothesis. The area of the flows was surveyed for the presence of water by the MRO’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) – none was found. This might mean the water is (mostly) subsurface. Then there is the dark color of the flows, which changes with the seasons. There are many possible explanations ranging from chemical reaction with water to the angle of light reflection. Such inconsistencies are the bread and butter of experimental science. The problem now goes to the laboratory where scientists will try to recreate the circumstances of the Martian flows. Someday, commitment to scientific budgets allowing, there may be direct sampling of the Martian soil and the mysteries will be resolved.

Meanwhile, there is provisional evidence of liquid water on Mars. This is not too surprising, really, given that by some estimates there are oceans of frozen water at or near the Martian polar caps. What may be causing the stir is that water in any form promises the possibility of life. This is especially true for liquid water, whether at the surface or deep underground in aquifers. The possibility of sustaining liquid water also increases the potential of Mars for human habitation – yes, the fabled Mars colonies.

Martian colonies are still very much science fiction. For now, science is doing its thing by following the water:

[SciTechStory: Mars water: What’s all the fuss?]
[SciTechStory: On the Moon or elsewhere, follow the water]

It’s been known for decades that there are striking differences between the surface of the Moon on the near side (the side we see from Earth), which is relatively smooth, low and flat, and the far side, which is high, mountainous and has a much thicker crust, about 50 kilometers (30 miles) thicker. It’s also widely accepted that something about the size of Mars slammed into the Earth about 4.5 billion years ago and ejected material that eventually coalesced into the Moon. The new hypothesis, as simulated by computer, proposes that two moons were created at about that time with the second roughly 1/30th (about 4%) the mass of the larger moon. The second moon shared the same orbit for about 100 million years but at some point it collided – not with a huge high velocity bang, but more likely a slower velocity “splat.”

The relatively slow impact caused neither a huge crater nor much volcanic activity, but added a deep layer of rock – a kind of mountain building from the sky – to one side of the Moon. Because of the Earth-Moon tides, the heavier, thicker side automatically became the dark-side, the one not visible from Earth. The model helps to explain the composition of the Moon’s crust, which on the near-side is dominated by potassium, rare-earth metals and phosphorus (the so-called KREEP composition). This could have been caused by displacement of ‘old crust’ from the far-side to the near-side during the collision.

Now here’s the key point: This is a model, which makes a hypothesis. It’s not the only model out there. In fact, Jutzi and Asphaug have colleagues at U.C. Santa Cruz that developed a model explaining the far-side geology as a result of the much stronger tides of the early Moon, when it was only about 80,000 miles from Earth. There are other models and other explanations, some of which have already been displaced by data returned from various Moon missions (e.g. the Moon is not made of green cheese).

The next step, as it is with any true scientific hypothesis, is to test it – to find evidence that confirms or disputes the conclusion. Data collected by NASA’s LRO (Lunar Reconnaissance Orbiter) may help, but the real kicker would be to collect rock samples from the far-side. Meanwhile, scientists will do what they usually do – argue – and try to knock down the two moon hypothesis, or replace it with a better one. Eventually, it is likely there will be enough evidence in this case to settle the argument, and science will move on. Splat, indeed.