Mercury shows off its colourful side

Scientists working on Nasa's Messenger probe to Mercury have shown off a stunning new colour map of the planet.

It comprises thousands of images acquired by the spacecraft during its first year in orbit.

This is not how we would see Mercury, which would look like a dull, brownish-grey globe to our eyes.

Rather, the map represents an exaggerated view of the planet that is intended to highlight variations in the composition of its rock.

"Messenger's camera has filters that go from the blue to the near-infrared of the spectrum, and we are able to use computer processing to enhance the very subtle but real colour differences that are present on Mercury's surface," explained Dr David Blewett from the Johns Hopkins University Applied Physics Lab.

In addition, the probe's instruments have detected relatively high abundances of sulphur and potassium in surface materials.

These are volatile elements that should not really be present on such a scale on a planet that orbits so close to the Sun with its searing heat.

But these elements may help explain many puzzles, like the nature of those opaque terrains. These could get their dark hue from the presence of sulphides.

Messenger is in great shape should Nasa management agree to a mission extension. The probe is thought to have enough fuel to operate until 2015.

And by then, new spacecraft will be on their way to Mercury. Under a joint venture known as BepiColombo, Europe and Japan are sending two satellites that should arrive at the innermost world in 2022.