Mark Whittington’s commentary in the Jan. 14 Tribune praises the idea of planting a human colony on the moon.

In support of this idea he says, “Water and ice at the lunar poles can be mined and refined to rocket fuel,” and also, “Access to the moon and its abundant resources will be of benefit to the United States.”

Both of these ideas form the basis of entertaining science fiction, e.g. “The Martian.” But the moon (and Mars), as far as we know, do not supply visitors with air, drinking water, food or fuel. Visitors to the moon (or Mars) must bring all of those with them.

As with the international space station, visitors to the moon and Mars may only ever leave their closed capsules wearing space suits with contained air. The (speculative, not actually seen) water on the moon is apparently locked as ice crystals, mixed with the soil and in minerals. With large and powerful mining and processing equipment it may be possible to separate it and use it for drinking and/or other uses, e.g. growing food.

On earth, with abundant electric power and major industrial infrastructure, it is possible to electrically split water into hydrogen and oxygen, and then convert these gases to liquids, which can be then used to propel conventional rockets. Similarly, on the moon, with abundant electric power we could convert water, (if we can separate it from the soil) to oxygen to breathe (mixed with nitrogen which we cannot easily produce on the moon).

The greenhouses that grow our food would require water (to be found on the moon), fertilizer (from earth) and carbon dioxide (freely available on Mars but not on the moon), which presumably would have to come from earth and be recycled by collecting and processing our out-going breaths and excreta. The moon’s extreme temperature swings would require that the greenhouses (and living quarters) be cooled at lunar noon and heated at lunar midnight.

So far lunar exploration has not shown that there are “abundant natural resources”, on the moon, and to date there are none whose value on earth (e.g. gold or platinum) would justify the cost of bringing them to earth, even if those resources cost nothing to find and extract from the moon’s surface (or interior, as most earthly gold and platinum is). There is no evidence that the fossil fuels or mineral deposits that life on earth depends on were ever formed by lunar geology and biology, as geology and biology has formed them on earth.

The international space station can keep its crew alive by strenuous recycling (urine-to -drinking water, etc.) and regular visits by supply ships. To have a self-sustaining moon colony whose survival did not depend on frequent visits from supply ships from earth, the colonists would have to begin with a major power source, most likely nuclear. (Solar is possible, but would require major batteries for the lunar night. Burning fuels for heat or power requires an oxygen-rich atmosphere.) The power infrastructure would have to be up and running before a reliable water source was in place. Unless we find water already collected in tanks with pumps and pipelines from the poles to our station, we would have to import those facilities and their power source from earth.

On earth, with freely available air and water, inexpensive food and fuel, and an advanced industrial infrastructure, we can perform all the tasks we would need to survive on the moon or Mars. But none of those conditions will exist on the moon or Mars until we put them there.

In the past 150 years we have made amazing technological and scientific advances on earth, allowing us to do things that seemed like science fiction 150 years ago (e.g. fly in airplanes, utilize electronics in many ways, cure many diseases, put humans on the moon and rovers on Mars.)

The next 150 years may be equally productive, and with the new, currently unknown technologies we may indeed put self-sustaining colonies on the moon and/or Mars. But, with currently known science and technology, such colonies remain the subject of science fiction.