Ask a random sampling of people if they think we will have colonized space in 500 years, and I expect it will be a while before you run into someone who says it’s unlikely. Our migration from this planet is a seductive vision of the future that has been given almost tangible reality by our entertainment industry. We are attracted to the narrative that our primitive progenitors crawled out of the ocean, just as we’ll crawl off our home planet (en masse) some day.

I’m not going to claim that this vision is false: how could I know that? But I will point out a few of the unappreciated difficulties with this view. The subtext is that space fantasies can prevent us from tackling mundane problems whose denial could result in a backward slide. When driving, fixing your gaze on the gleaming horizon is likely to result in your crashing into a stopped car ahead of you, so that your car is no longer capable of reaching the promised land ahead. We have to pay attention to the stupid stuff right in front of us, as it might well stand between us and a smart future.

I was completely astonished by the prevalence of the “space” reaction to the inaugural Do the Math post on galactic-scale energy. The post illustrated that continuing growth of our physical scale (energy) is not viable on a number of fronts—not the least of which is that Earth’s surface would reach the boiling point of water in a mere 400 years, based purely on thermodynamic arguments, and independent of which energy technology is employed. Many comments on the internets chided this view as being hopelessly unrealistic in its willful ignorance of the great space migration to come.

The connotation is that we should not heed repeated warnings about our current collision course with a finite world when—by some clairvoyant means that eludes me—we know we are destined to colonize the infinite void beyond. Space is therefore seen as an escape hatch for the human endeavor and from our arguably botched track record on Earth. Escapism may be more accurate.

Survey Says…

Before we get going on practical matters, let me share the results of a survey question I have posed to college students in my classes. Let’s see how you fare, imagining yourself to be in the same age bracket of 18–22:

Approximately how far have humans traveled from the surface of the Earth in your lifetime? [e.g., since 1980 or so]

  • a) 600 km (low Earth orbit, 0.1 times the Earth radius)
  • b) 6,000 km (about the radius of the Earth)
  • c) 36,000 km (geosynchronous orbit; about 6 Earth radii)
  • d) 385,000 km (about the distance to the Moon; 60 Earth radii)
  • e) beyond the Moon

I make the question visual, which you can do as well. Start with a standard Earth globe (12 inch or 30 cm diameter). The first answer is 1.2 inches (3 cm) from the surface, followed by 6 inches (15 cm), then a yard (meter), then 30 feet (9 m) for the Moon. Take a minute to picture this.

Earth-Moon system to scale, with response distances indicated

Out of a total of 109 students responding (one group in 2006, another in 2010), only 11% got the right answer: low Earth orbit. 52% thought humans had been as far as the Moon since the 1980′s, and 20% thought we had been farther than the Moon. Some were indignant on learning the truth: “What do we use the space shuttle for, if not to go to the Moon?!” I can only guess that some students imagined the International Space Station as a remote outpost, certainly beyond the Moon, and likely strategically located next to a wormhole. How disappointing it must be to learn that it merely hugs the globe.

I could easily get sidetracked on this astounding result. But I’ll just point out that the idea that we are no longer able to accomplish feats we once could do (like travel to the Moon) clashes with the prevailing narrative that we march forever forward. Not only can’t we get to the Moon at present, but the U.S. no longer has a space shuttle program—originally envisioned to make space travel as routine as air travel. And for that matter, I no longer have the option to purchase a ticket to fly trans-Atlantic at supersonic speeds on the Concorde. Narratives can break. I’ll leave it at that.

A Moment of Silence

A recent article in the Economist about the end of the space age—besides generating howls of protest—noted that, short of signs of life turning up on Mars, public interest in the surviving unmanned space program will wane. I think this is especially insightful given my survey of what young folks assume we’re already doing. It would be hard to sell this upcoming generation on an expensive plan to return to the Moon when the act of announcing the plan will backfire in angst that lunar trips are not already a routine part of NASA’s activities. Travel to Mars, carrying a multi-hundred-billion dollar price tag, is even less likely to see support.

John Michael Greer followed this piece with a delightfully well-written elegy lamenting the end of our space ambitions. Many of my sentiments are perfectly captured in this article, and I highly recommend the read.

Surely the termination of the NASA shuttle program has forced us to accept setbacks in our dreams of space. But this does not have to be a predictor of the future. After all, we could have decided to keep the shuttle program alive if economic and political winds had favored doing so, and we do not lack the know-how for going back to the Moon if it became a priority. Perhaps, then, we are looking at only a temporary bump in the road.

Down to Brass Tacks

However, there are practical realities to consider. If we extend our solar system model using the standard-size Earth globe as our reference, the Moon is 30 ft (9 m) away, and is about the size of an apple. The sun is 2.2 miles (3.6 km) away. Mars is sometimes as close as 0.8 mi (1.3 km) and sometimes as far as 6 mi (10 km). Light travels at a sprinting speed of 16 m.p.h. (26 kph) in this scale, but an energetically feasible transfer orbit to Mars would take 8.5 months, effectively traveling slower than a snail.

First, reflect on the vastly different scale in travel to the Moon vs. Mars. In our model, you could toss a rock to the Moon. But getting something to Mars is a whole different ballgame. Not even a slingshot would be up to the task. In practical terms, a three-day lunar journey becomes 260 days to Mars: almost 100 times as long. The closest star to the Sun, in this model, is about a million kilometers distant: 2.5 times farther than the actual Earth-Moon distance. On a separate model scale—compressed 17,000 times compared to our previous model scale—the density of stars in the local Milky Way (one star per 100 cubic light years) is analogous to grains of sand 50 km apart! Can you imagine this? Mostly empty, empty space, folks.

I often travel to the Apache Point Observatory in southern New Mexico to tend to my lunar ranging experiment. On a recent trip, I was excited to find a newly-installed solar system model consisting of planet signs positioned along highway 6563 (named by nerds after the wavelength of the hydrogen-alpha emission line of great importance in solar, stellar, and galactic astronomy). Even traveling at 15 times the speed of light, or 40 m.p.h., the scale is daunting (although, considering relativistic time dilation, a traveler would experience this pace if traveling at 0.998 times the speed of light). If you’ll forgive me, it really drives home the isolation even within the local oasis we call the solar system.

Space is no Luxury Cruise

Space is a hostile place for humans. It’s mostly empty, though not lacking in deadly ionizing radiation and cosmic rays. What few resources exist are so mind-blowingly scattered that they would seem to be utterly absent to the casual observer. Some point out that the open ocean is also hostile to human life, and conjure the image of a luxury ocean liner placidly plying the waters, oblivious to the surrounding harshness. If we can picture that, why is it such a stretch to imagine a luxury liner in space? It’s a gripping image, and would seem to counter worries about the cruelty of space. But let’s look at the oh-so-many ways the two situations cannot compare.

If the ship sinks, and you have a life raft, you stand some chance of rescue. The ocean is vast, but it’s a two-dimensional vastness teeming with human activity (compared to any realistic vision of 3-d space inhabitation even within the confines of our solar system). People have survived for months on the open ocean, subsisting on the elements around them. Running out of air is not a problem. Fresh water falls out of the sky as rain. Critters that are attracted to the cover of your life raft provide a source of food. I recommend the book 117 Days Adrift for a gripping account of a British couple who survived such an ordeal. Sometimes edible fish would actually jump into their dinghy. By contrast, a hamburger has never slammed into the side of the space shuttle in orbit, and I very much doubt that chicken nuggets are going to float up seeking the shelter of your space rescue pod!

If you fall overboard in the ocean, you can conceivably survive for a day or more depending on water temperature. I have actually met a guy who twice survived being stranded overnight treading water in the ocean—once in Indonesia and another time in Australia! In space, you’re dealing with a life expectancy of about one minute, unless you’re lucky enough to be suited up for the unexpected accident—in which case you have a perhaps a few hours to enjoy the view.

If the ship springs a leak, you can pump out water indefinitely, and that magical, life-supporting air fills in the void: it surrounds the ship, which is open to the air above. In space, a leak must be replaced with air brought on board (presumably in pressurized containers), but cannot be counted on to last indefinitely. A submarine is therefore a more apt analogy, but even then, the safety of the surface is never more than “walking distance” away.

And let’s not forget: ships take us to places that are naturally habitable. Where are the space versions of cruise-ship submarines going to take us? I, for one, would hope back to Earth!

No, the ability to picture a luxury liner in the hostile open ocean is hopelessly insufficient for me to extend the analogy to space. We’ll see our oceans teeming with people-laden vessels or inhabitation of the ocean floor before we see a population explode into space. These options are just so much easier, and carry some hope of acquiring vital resources.

Failure of a Narrative

This brings us back to the compelling narrative that our evolutionary ancestors finned their way out of the water, so it is only natural—nay, inevitable—that we will wing our way off the planet. When creatures crawled out of the water to inhabit the land, it was to reap the unbelievable vegetative bounty of the land, free of the threat of predation. No bounty of food or sense of safety tugs us into space. It’s quite the opposite on both fronts, in fact. We live on the bounty right now.

Ideas of terraforming Mars must be seen in a new light given the challenge revealed by global warming. Compared to pre-industrial levels, we have a 100 part-per-million (0.01%) CO2 problem in our atmosphere that has us completely stymied. Crudely speaking, Mars has a one-million part-per-million (100%) problem with its atmosphere. As much trouble as we are having mitigating climate change with unfettered access to all the resources on Earth, what hope would we have of turning around a place like Mars with no infrastructure to rely upon?

Likewise, attempts to create a self-contained biosphere to support human life have so far been failures—despite having the overwhelming advantage of being set up in an otherwise habitable environment with unencumbered access for construction and provisioning efforts. Making something work in the harshness of space, far from any Home Depot, would represent a challenge many orders-of-magnitude harder still.

Despite this, and the winding-down of the NASA shuttle program, the optimism of many space enthusiasts is not fazed. They look forward to future mining operations on asteroids and on the Moon. I would think we would tear up the much closer ocean floor first, given the comparative convenience and cheapness of such operations.

Insider Out!

Having said all of this, it may come as a surprise when I say that I am a proponent of the space program. As a teenager, I fell in love with the movie The Right Stuff. I cherished visits to the nearby space museum in Huntsville, Alabama, and was thrilled to see Chuck Yeager in person at the National Air and Space Museum. Inspired by the passage of Halley’s Comet, I built a telescope and through it saw all nine planets in one night—when there were nine!. I saw a quasar over 2 billion light years away, and a supernova rivaling the brightness of its host galaxy 36 million light years away in Leo. My eyes have been out there, in some sense (and I never saw any food).

Just after college, I worked on analysis of a ring-laser gyroscope camera that flew on the space shuttle, and learned in the process that I was better at identifying stars than were the astronauts. I shot lasers at satellites (with permission!). I witnessed a shuttle launch and felt the percussion on my proud chest. I was supported by NASA during part of my graduate school days to study merging galaxies. My current project uses the reflectors left on the Moon by the Apollo astronauts: I feel I have touched the reflectors on my own (and discovered them to be dusty). My team and I found the reflector on the lost Soviet Lunokhod 1 rover after forty years of silence. Half of my project funding comes from NASA (they won’t read this, will they?).

APOLLO in action. Credit: Dan LongAPOLLO in action. Credit: Dan LongIn other words, I’m an insider—and a supporter. I whole-heartedly believe that space offers tremendous scientific promise. If we decide to return to the Moon (with or without people), I am enthusiastic about placing next-generation reflectors on the lunar surface, allowing us to drill deeper into the mysteries of gravity. Radio observations from the quiet far side can peer into the “dark ages” of the universe as the very first stars were forming. I am super-excited about the LISA gravitational wave observatory that I hope someday will get the funding and the green light to launch, assuredly revolutionizing our view of the universe. And to the extent that human spaceflight inspires youngsters to pursue a career of exploration and science, I’m all for it.

But I want to caution against harboring illusions of space as the answer to our collision course of growth on a finite planet. We live at a special time. We have enjoyed spending our inheritance of fossil fuels, and are feeling rather heady about our technological prowess. For many generations now, we have ridden an exponential growth track, conditioning ourselves to believe that our upward trajectory is an eternal constant of our existence. We’ll see. When we cross to the down-slope of fossil fuel availability—beginning with oil—we’ll see how timeless the growth phase seems to be, and whether we can afford a continued presence in space. We should be mature enough to admit that we have no context in which to evaluate how successfully the human race will navigate this unprecedented transition.

Some professional athletes are smart about their earnings. They know that they will long outlive their athletic prowess, spending and investing modestly and smartly in preparation for the long haul. Others live large, assuming that the future will always be bigger—as has so far been true for their whole lives. We have not yet known a modern existence without an ever greater scale of fossil fuels, and it is their availability that has catalyzed our progress. This century, we will enter a new phase, untested by humanity. Dismissing the challenge this presents by looking beyond to a future in space is one of the best ways to ensure that such a future never comes to pass. All athletes know better than to take their eye off the ball.