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Mars Orbiter Beams Back Images of Comet's Surprisingly Tiny Nucleus
astroengine writes The High-Resolution Imaging Science Experiment (HiRISE) camera on board NASA's Mars Reconnaissance Orbiter (MRO) has become the first instrument orbiting Mars to beam back images of comet Siding Spring's nucleus and coma. And by default, it has also become the first ever mission to photograph a long-period comet's pristine nucleus on its first foray into the inner solar system. Interestingly, through analysis of these first HiRISE observations, astronomers have determined that the icy nucleus at the comet's core is much smaller than originally thought. "Telescopic observers had modeled the size of the nucleus as about half a mile, or one kilometer, wide," writes a NASA Jet Propulsion Laboratory news release. "However, the best HiRISE images show only two to three pixels across the brightest feature, probably the nucleus, suggesting a size less than half that estimate."
don't link to Discovery.com for TFA. The last time I tried to load a page there, the NoScript menu got half a mile long. Every domain I enabled trying to get the site to display correctly, added 5 more script domains to the list. You end up downloading half the Internet just to display one page.
Comets are named after whoever spots it first. Siding Spring is an observatory in Australia.
Without a planetary magnetic field to speak of, any atmosphere created by comet or terraforming would be temporary. If humans are to colonize Mars someday, we would need a steady stream of comets to fire at the planet to replenish the atmosphere swept away by the solar winds. Somehow, dropping comets on a planet for the sole purpose of supporting a permanent settlement seems....odd?
There is no water coming out of comets. What is detected are OH- ions, that are believed to be derived from water - which is not there
This is flat out wrong in the sense that water, as opposed to OH-groups, have been confirmed. This includes the v2 bending mode and v3 asymmetric stretching mode ~1600 cm^1 and ~3750 cm^-1, plus other combination vibration modes such as v1+v3. These modes do not exist in just the OH ion, and involve frequencies specific to water (although some combination modes overlap with other detected vibration modes). This stuff has been seen since at least the 80s.