With scorching temperatures of up to 400 degrees Celsius by day and a frigid -170 degrees by night, Mercury is no place for the ill-prepared! Nonetheless, this has not stopped a joint European and Japanese consortium from designing one of the most robust spacecraft ever made in order to brave these extreme conditions and get a close-up look at the ‘iron planet’. Known as BepiColombo, the mission is set for launch next year and aims to spend four Mercury years unlocking the secrets of this unique planet.
Mercury, the smallest and innermost planet of the Solar System, lives the paradox of being one of the closest planets to Earth and yet one of the least known - out of the eight planets of the Solar System, only the faraway Uranus and Neptune have been less explored.
This is not due to lack of interest, as the ‘iron planet’ has some unique and intriguing features: it is the second-densest planet in the Solar System after Earth, and the only other inner planet besides Earth to have a significant magnetic field. This is a key parameter in allowing life to take hold on a planet, as without its shielding Earth would receive a significant amount of dangerous radiation from the Sun thus making conditions difficult for biological life to develop and persist.
Nonetheless, despite its modest gravity, Mercury also has an atmosphere, albeit very tenuous, which is constantly replenished in a way yet to be clarified, and its craters may hold more ice than the Moon.
Not surprisingly, there is a lot of scope for scientific exploration. However, many technical challenges exist in trying to get a spacecraft in orbit around Mercury. This is due to the gravitational pull of the Sun which tends to accelerate any spacecraft approaching it. Conversely, to be inserted in to an orbit a spacecraft needs to be slowed down, therefore a lot of fuel needs to be carried for the manoeuvres – in fact going to Mercury requires more fuel than going to Pluto!
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