Curiosity’s mission roves on
THERE has been a lot of interest in the three launches to Mars that took place recently.
The United Arab Emirates’ Hope mission, an orbiter, was launched from Japan; China launched its orbiter-rover combination; and NASA sent its next rover, Perseverance, on its way. Travelling with Perseverance is the first helicopter ever to be sent to Mars. Called Ingenuity, the little flying machine is a test of the technology so that future, larger, helicopters can be used.
Amid all of the excitement of the three missions, which will arrive at the Red Planet in early 2021, it’s important to remember that there is an operational rover that has been working for the past eight years – the Curiosity rover, which has been exploring a huge feature on Mars known as Gale Crater.
I have taken a great interest in the activities of spacecraft that have landed on the Martian surface, and Curiosity is no exception. I was fortunate to be at the Jet Propulsion Laboratory in Pasadena, California, in 2008 to spend some time watching the assembly of the craft. It was being put together in a ‘clean room’ — a room with mostly white walls and fittings, and staff with white coats. The great care was taken in order to avoid, as much as possible, contamination of craft being sent to other planets.
This procedure dates back to the 1960s, when NASA sent its Ranger craft to the Moon. Because they were designed to crash into the Moon, it was imperative to avoid contaminating the Moon with biological material from Earth, and this desire has continued to this day. NASA estimated that Curiosity launched with fewer than 300,000 bacteria spores. It is an amount that allows scientists to classify Curiosity as ‘extremely clean’.
Curiosity’s mission is called the Mars Science Laboratory, and ‘science’ is certainly a key word in its title.
Landing on Mars took place on August 6, 2012, and since then the rover has sent back some major findings from its close examination of the Martian surface.
Building on the results of other spacecraft, especially the twin rovers Spirit and Opportunity, Curiosity has provided further evidence of past liquid water on the Red Planet’s surface. This has been particularly clear at Mount Sharp — the tall, central mountain peak near the middle of the crater — where Curiosity examined vertical rock, hundreds of metres tall, that NASA assessed as having ‘formed originally as mud at the bottom of a series of shallow lakes’. I like that vivid description, as it certainly paints a picture of a different surface in Mars’ distant past.
More than just the evidence for ancient liquid water, Curiosity has also found, by drilling into the mudstone, that the chemistry of the surface was the right kind to have supported the existence of any primitive life that existed. The sample showed many ingredients important for life, including sulphur, carbon, oxygen, phosphorus and nitrogen. It’s important to note, however, that Curiosity has not actually found direct evidence of present or past life. That is something that future missions will investigate, especially the European Space Agency’s ExoMars 2022 mission, which will arrive at Mars in 2023.
Despite all the successes of Curiosity, the Martian environment is taking its toll on the rover. A particular point of interest is the condition of its wheels. As they have rolled across the Martian surface, they have experienced ‘punctures’, although not the same kind of punctures that we all experience from time to time in our car tyres!
The six wheels, made of aluminium and about 50cm in diameter, are often inspected by the rover’s camera, and it can provide quite interesting views! Clearly visible are a number of holes, which have been made as the wheels have rolled across jagged material on the surface. Although this is of some concern, it is considered that the wheels should be able to operate for quite some time to come. A degree of wear and tear can be expected after being on Mars for eight years, and driving over 20km across the surface!