From time to time I wear my spleen on my sleeve over issues of scientific priority. Orbiting Mars are imaging devices whose data, if they were of the Earth’s surface, would cost geoscientists the proverbial arm and a leg.  ‘Astrogeologists’ get those from Mars for nothing. The latest result explains why I get annoyed; and I hope many others do as well (Milazzo, M.P. and a great many others 2009. Discovery of columnar jointing on Mars. Geology, v. 37, p. 171-174). The High Resolution Imaging Science Experiment (HiRISE) aboard the Mars Reconnaissance Orbiter, can resolve pixels 30 cm across (about the same as the best, classified military data of Earth from spy satellites). It has stereoscopic capacity capable of producing not only stunningly informative 3-D visualisations but also topographic elevation data sufficiently precise that they could be used ‘at home’ for large-scale civil engineering, for instance routing water pipelines. The US Department of Defence vetoes access by scientists to near-global SRTM DEMs with even a 30 m resolution, the degraded 90 m version being freely available. Sub-metre DEMs can be produced from aircraft for the Earth’s surface, but at very high cost.

The paper reports one of the most common features exhibited by thick lava flows and other tabular bodies of igneous rock that cooled slowly. Visit the Giant’s Causeway in Antrim to see columnar joints, and put your child on one for scale. In fact there are thousands of such sights on Earth, and any planet that has a volcanic history will have columnar joints. Similar quality data is awaited from the Moon, and you can bet your intimate garments that some bright spark will report much the same. Meanwhile, there are over a billion people drinking hazardous water when geologists armed with data this good – and the inclination – could find safe supplies in the rocks beneath them.