When you think about it, so much of science involves putting our instruments into the right place at the right time. The transit of Venus across the Sun in 1769 was an opportunity to use triangulation from opposite sides of the Earth to calculate the distance to the Sun more accurately. That effort took James Cook to Tahiti, and though the experiment failed, it remains an inspiring example of the human intellect trying to solve questions by exploration, determination and hard work.

We saw yesterday that if we put instruments into much further places, we may be able to identify oceanic worlds and perhaps map their continents. Peter McCullough (Space Telescope Science Institute) wrote the most recent paper on this concept and presented it at a conference on missions that could be enabled by a return to the Moon. But the Moon itself may not be the best venue for the instruments in question, as McCullough noted in an e-mail after reading yesterday’s entry:

“I might comment (in anticipation of your coverage of the speculative digressions in that same paper) that the polarization-measuring telescope probably would be best as a free-flyer (e.g. at L2 like JWST) instead of on the lunar surface, although the infrastructure to get payloads to the moon will be very helpful for getting large telescopes to L2, which I think was a common theme of the conference held here at STScI…”

So we’re looking at a mission that is enabled by the infrastructure that will boost large payloads to the Moon and other destinations, but which will itself be best placed in a ‘halo’ orbit around the L2 Lagrange point, approximately 1.5 million kilometers from Earth. That’s outside the Moon’s orbit, but it’s clear that tuning up the technologies for lunar missions will make operating at L2 that much easier. The James Webb Space Telescope, as McCullough notes, is already slated for L2.

But even a project as ambitious as tracing the outline of continents on distant exoplanets pales in comparison to the deeper motivations for building up our space infrastructure. Can a lunar base help solve some of Earth’s deepest problems? One possibility is that it could lead by example. A sustainable presence on another world won’t power itself with fossil fuels. It will rely on nuclear and solar power and doubtless develop countless new insights into conservation. All of this returns to Earth in the form of practical technology to preserve our ecosystem.

A lunar colony offers all the benefits of learning to live off the land. The harsh environment forces the issue in ways that can pay off for the home planet. Let me quote McCullough again on this point because I think he has it exactly right:

…solar power is readily and abundantly available on the lunar surface, and a large, slow ?ywheel utilizing compacted regolith for mass could provide for the variable power demands of human habitation and/or store power through the lunar night away from the poles. An alternative approach would be to bring from Earth a high-speed, precision ?ywheel of relatively small mass or a chemical battery, but those are antithetical to the strategic bene?t of utilizing lunar resources. From the opposite perspective, utilizing any water ice mined from lunar craters, for human consumption and/or rocket fuel, could be myopic exploitation and destruction of an important scienti?c resource.

Those of us who find ourselves in front of audiences trying to justify space exploration would do well to review McCullough’s arguments with care. Here’s another, which speaks to the objection that the money we spend on space could better be applied to solving problems here on Earth. Weigh NASA and its expenses against what goes on on Wall Street. The pharmaceutical company Pfizer had a 2005 annual revenue of $51 billion, spending some $7 billion on research and development.

By contrast, NASA’s 2005 budget as allocated by Congress was $16 billion. In other words, the NASA budget that year was less than one-third the annual revenue of a single company of the thirty that make up the Dow Jones Industrial Average. Nobody is saying that Pfizer isn’t huge, or that $16 billion is a small amount of money. But the idea that diverting NASA’s budget will solve global warming or shelter the world’s homeless is a fantasy. Whereas exploration properly conducted may provide benefits far outreaching what might be accomplished by keeping those dollars here on Earth.

McCullough quotes Freeman Dyson on the nature of exploration, a passage he draws from George Dyson’s wonderful Project Orion: The True Story of the Atomic Spaceship:

We shall know what we go to Mars for, only after we get there…. You might as well ask Columbus why he wasted his time discovering America when he could have been improving the methods of Spanish sheep-farming. It is lucky that the U.S. Government like Queen Isabella is willing to pay for the ships.

Of course, paying for the ships is always problematic, and remains so today given the eternally fluctuating budgetary situation. It may be that getting us back to the Moon and continuing our work on a space-based infrastructure will take prompting from China’s determination to do the same — competition is always a sure driver, as it was during the Apollo days. Whatever the trigger, though, the benefits of space exploration are tangible if all too rarely part of current discourse. Consider McCullough’s paper a short primer marshaling many of the needed arguments.