(Jon sez:) Mars would lose air to space more quickly than Earth or Venus because its surface gravity is much less than Earth's and because its current atmosphere has no way to stop the hydrogen in water from being lost to space. Mars' gravity is four-tenths the gravity of Earth, or about half the gravity of Venus. Heavier gases like carbon dioxide and argon make up the majority of the atmosphere of Mars because these heavier gases are less able to escape the planet's gravity over geologic ages. Mars also needs a method to force water to condense out of the air and rain back to the surface before it can get high into the atmosphere and be decomposed by ultraviolet light into hydrogen and oxygen. If the water decomposes, much of the hydrogen is lost to space, and the free oxygen will be unable to "find" hydrogen to bond with again and reform water. At the moment, water on Mars would evaporate, then eventually work its way to the top of the atmosphere and decompose. The current atmosphere on Mars is at less than ten millibars of pressure, which is less than one percent of the pressure at Earth's surface. While Mars can probably hold onto a thick, Earth-like atmosphere for millions of years, it would eventually lose that atmosphere again without some proactive steps by the terraformers. Terraforming Mars, if we want to stay there for the long haul, will require more than dropping a few comets on it to raise the water table...	(Mark sez:) I like Caprice's expression in the fourth panel. Benjamin's bad enough when he's being pushy and impatient, but when he gets to feeling sorry for himself he's just intolerable.