On 6 August, while many of us are enjoying the Olympics, staff at NASA’s Jet Propulsion Laboratory will be nervously watching their monitors, waiting for a message from Mars.If all goes well, their Mars Science Laboratory spacecraft will scream through the tenuous Martian atmosphere, until its parachute cracks open, followed a little later by a solid-fuel rocket’s brief orange flare.Lowered by a revolutionary skycrane landing system, the Curiosity rover will gently descend to the dusty surface in Gale Crater, then the Mini-sized robot will call home to report its safe arrival. At JPL the tension will break and the champagne corks can be popped. Then the real work can begin.
Gale Crater lies just south of the Martian equator in the planet’s eastern hemisphere.This side of the planet is noticeably smoother than the western hemisphere, perhaps lava flows once obliterated the more rugged terrain, or possibly this was the seabed of a long-vanished ocean.Both possibilities intrigue planetary scientists.Gale Crater is 154 km (96 miles) in diameter (so you could easily fit Northern Ireland inside it) and believed to be about 3.5 to 3.8 billion years old, about the same age as life on Earth.The crater is named after Walter Frederick Gale (1865-1945), an Australian amateur astronomer who observed Mars in the late 19th century and (of course) confirmed dear old Percival Lowell’s canals. Gale is distinguished from many other craters on Mars by the large interior mound called Aeolis Mons (which NASA calls Mount Sharp) which at 5.5 km high is actually taller than the crater’s rim. Orbital views show that Aeolis Mons is stratified, that is to say made of layers. These rock layers probably took millions of years to be laid down by wind or water within the crater, then more time to be eroded to make them visible. As such they are a detailed record of the Martian past waiting to read.
During a mission planned to last a Martian year (nearly two of our years) after landing, Curiosity will use its instruments to investigate whether this area of Mars has ever enjoyed conditions suitable for life, especially the presence of liquid water.Lower layers of Aeolis Mons could reveal there was once a lake within Gale Crater long ago.But this is just the beginning of what Curiosity can investigate, it will scan the soil for biosignatures, chemicals associated with living organisms.The plan is that Curiosity will make a wandering tour of the crater floor to the foothills of Aeolis Mons.What a strange wild ride this will be!
(Article by Colin Johnston)