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After some downtime to enable a software upgrade, the Curiosity rover on Mars has got straight back to work by drilling into a rock.

The robot sank the latest shallow mini-test hole in a target called Mojave2.

An earlier attempt this month at the same activity resulted in a nearby slab splitting into several chunks.

Curiosity needs a stable rock to drill down the full 6cm to acquire a sample for analysis in its onboard labs. Mojave2 looks like it will oblige.

If all goes to plan, this task should be completed shortly. It would be the fifth drill sample picked up by the machine for ingestion.

The Nasa robot is currently investigating the lower layers of Mount Sharp, the big mountain at the centre of Gale Crater, which is the deep depression where it landed in 2012.

Recent accomplishments include finding evidence for how that mountain was built billions of years ago by river and lake sediments.

The mission also hit the headlines in December for identifying methane and other, more complex carbon molecules in Gale.

Methane on the Red Planet is intriguing because here on Earth, 95% of the gas in the atmosphere comes from the activity of microbial organisms, such as the bacteria in the digestive tracts of animals.

Researchers have hung on to the hope that the molecule's signature at Mars might also indicate a life presence - although any such connection at the Red Planet is purely speculative at the moment.

Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: