THE EXPLORATION OF MERCURY

To date, Mercury has only been visited by one spacecraft.

Launched on 3 November 1973, Mariner 10 was the first mission to try and visit two planets. It flew past Venus on February 5, 1974 using Venus’s gravity to accelerate its onward journey to Mercury.

Mariner 10 was the first spacecraft to be equipped with an imaging system. The spacecraft’s trajectory allowed it to perform three flybys of Mercury, on 29 March 1974, 21 September 1974, and 16 March 1975. Mariner 10 acquired 10,000 pictures covering approximately half of the surface of Mercury.

Temperatures were recorded that ranged between 187°C on the day side and -183°C on the night side. No atmosphere was detected but there was evidence of a weak magnetic field.

Mariner 10 is now in orbit round the Sun.

The next Mercury bound spacecraft is NASA's MESSENGER. MESSENGER, which is an acronym of MErcury Surface, Space ENvironment, GEochemistry, and Ranging mission, is scheduled for launch in 2004. The spacecraft will orbit Mercury and collect the first images of the entire surface, it will study the composition of surface materials and enable researchers to explore the structure and geological history of the planet. MESSENGER will be equipped to study the tenuous atmosphere Mercury is now thought to possess, and its active magnetosphere. En route, MESSENGER (like Mariner) is to make flybys of VENUS in 2004 and 2006, arriving at Mercury in 2009

The European and Japanese Space Agencies are also working on a Mercury mission, they plan a bold joint project which will comprise two orbiters: a Mercury Planetary Orbiter (MPO), a Mercury Magnetospheric Orbiter (MMO), and possibly a small lander - the Mercury Surface Element (MSE). The mission, named BepiColombo after Giuseppe (Bepi) Colombo an Italian mathematician and engineer, is planned for launch in 2011 or 2012 and will take about three years to arrive.

Mercury MESSENGER and BepiColombo should fill large gaps in our knowledge of Mercury - one of the solar system's least known planets, and shed more light on the formation, and evolution of the inner terrestrial planets, including Earth.