The high point of the August long weekend must be the successful landing of the Mars rover Curiosity on the Red Planet. Making the event even more dramatic, the Mars Reconnaissance Orbiter was passing overhead during the landing and photographed the rover hanging from its parachute, on its way to a successful landing in Gale Crater.
About the size of a Mini Cooper and weighing about a tonne, Curiosity is the largest thing we have ever landed on Mars. This was a challenge. In the thin Martian atmosphere, parachutes cannot slow you down enough for a soft landing. One solution used in the past was to embed the lander in partially-inflated balls that act as shock absorbers. When the rolling and bouncing has stopped, they can be discarded. This method works well, but not for big, heavy things, such as Curiosity, and eventually, for the first manned landing on Mars. The “sky crane” approach, lowering Curiosity on cables from a rocket-equipped platform, made sure Curiosity did not end up sitting in the middle of melted, blasted ground, contaminated by rocket exhaust. This mission will tell us a lot more about many aspects of the Red Planet, but one of the main objectives is the search for life, present or extinct.
Studies of the gas and dust clouds making up much of our galaxy and many others show they contain the ingredients for the sort of carbon-based chemistry that is the foundation of life as we know it. Which in turn suggests that carbon-based life will have what it needs to get started on any suitable planet. Mars is remarkably like the Earth and both planets share similar histories. Both worlds were born about 4.5 billion years ago, along with the Sun and other bodies of the Solar System.
The earliest signs of life on Earth occur in rocks about three billion years old. Results from previous Mars landers suggest that around that time conditions on Mars were similar to conditions on Earth: a dense atmosphere, mild temperatures, and rivers, lakes and oceans. However, being smaller than the Earth and lacking our strong magnetic field, Mars was less able to hang onto its atmosphere. So it became the cold, dry body we see today, and whatever living things existed either became extinct or took refuge underground. However, even if Martian life is long-gone, there should be trace chemicals in the soils and rocks that will show that life existed.
Part of the equipment for this search for life is “Made in Canada”, by the University of Guelph and the Canadian Space Agency. It will be used to detect chemical traces in rocks and soils. Curiosity is landed in a crater, where a meteoric impact has stirred up the rocks, revealing outcrops not otherwise reachable and making sampling easier.
It is a mark of our progress in exploring Mars that we can actually buy books about Martian geology. However, if I were you I would hold off heading for the bookstore for a while. We could be expecting a new and updated edition, quite soon.
Mars, Saturn and the star Spica are close together low in the southwest after dark. Venus and Jupiter shine brightly in the eastern sky in the early hours. You might glimpse Mercury, low in the dawn sky. The Moon will be new on the 17th.
Ken Tapping is an astronomer with the National Research Council’s Dominion Radio Astro-physical Observatory, Penticton.