As we reach the end of the season here at Quirks & Quarks and head off to parts unknown for the summer, keep your eye out for the next landing on Mars in early August.

Curiosity, the largest robot ever sent to Mars, will land on August 5 with a scheduled mission to roam the surface for years, looking for signs of life - and it carries a Canadian instrument.

The six-wheeled rover, about the size of a Mini and weighing more than a metric tonne, must execute the most complicated powered landing, in the roughest area,

that a robotic lander has ever attempted on Mars.

The landing site is Gale Crater, 155 kilometres across, with a mountain rising 5 km from its centre. Curiosity is aiming for a pinpoint landing on the crater floor, right at the base of the mountain.

In the thin Martian air, parachutes only work at high velocities after they first enter the atmosphere. The air is not dense enough to slow the heavy spacecraft down for a safe landing. 

So, for the final descent to the surface, a set of rocket motors attached to a rig above the lander will fire. Then a cable system will lower Curiosity from the rig like a sky crane and gently bring it to the ground. As soon as wheels touch down, the cables are cut, the sky crane flies off and crashes at a safe distance, and Curiosity opens its eyes on an alien world. (Watch a video simulation of the landing here.)

Curiosity will begin by exploring the lower slopes of the mountain, named Mt. Sharp after a NASA geologist. It will spend two years climbing its lower slopes, looking for signs of ancient water activity and possible Martian life.

One of the instruments that will analyze the chemical composition of the Martian rocks is Canadian, an Alpha Particle X-Ray Spectrometer, with Dr.Ralf Gellert from the University of Guelph as the principle investigator.

An on-board mini-laboratory will analyze soil samples to look for chemical signatures of past or present life, an elusive search that has been ongoing since astronomers first looked at Mars through telescopes and thought they saw artificial canals. Perhaps this mission will finally answer the fundamental question of whether or not we are alone in the universe.

Curiosity's mission is planned for two years, but there is an excellent chance it will run far longer than that.  Its two predecessors, Spirit and Opportunity, landed in 2004 and one of them is still running today. Those landers are half the size of Curiosity and solar powered, so Curiosity should better that record, thanks to a small nuclear reactor that powers its drive motors and scientific instruments. 

Radioisotope Thermoelectric Generators, or RTGs, have been used on spacecraft since the Moon missions. They have no moving parts and use a small amount of nuclear material to provide heat, which is turned directly into electricity.

This type of long-running generator has enabled robotic spacecraft to reach beyond Mars, where sunlight is too dim to feed solar panels.  Voyager, which left Earth in 1977 and still running, is currently well beyond all the planets and about to leave our solar system entirely, making it the first human-made object to wander among the stars.  That crossover into the interstellar medium should also happen this summer.

For the Mars mission, NASA is putting all of its eggs in Curiosity's basket.  There is no backup if the landing goes badly.  But if it succeeds, we could be getting daily reports from Mars for the next decade.

Of course, the other science stories to watch out for this summer are the Best of Quirks & Quarks,  which is your chance to catch up on items from our past season that you may have missed or listen to your favourites once again.

Have a great science summer.