Mercury

The closest planet to the Sun yet its is smaller than moons like Ganymede and Titan.

Because it lacks a viable atmosphere, Mercury has no way to retain the heat from the Sun. As a result of this and its high eccentricity, the planet experiences considerable variations in temperature. Whereas the side that faces the Sun can reach temperatures of up to 700 K (427° C), while the side in shadow dips down to 100 K (-173° C).

Mercury (Messenger probe)

With a mean radius of 2440 km and a mass of 3.3022×10²³ kg, Mercury is the smallest planet in our Solar System – equivalent in size to 0.38 Earths.

Mercury’s density (at 5.427 g/cm³) is the second highest in the Solar System, only slightly less than Earth’s (5.515 g/cm³).

Mercury is tidally or gravitationally locked with the Sun in a 3:2 resonance, and rotates in a way that is unique in the Solar System. As seen relative to the fixed stars, it rotates on its axis exactly three times for every two revolutions it makes around the Sun.

Exploration

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) probe.

Launched on 3 August 2004. It made a fly-by of Earth in August 2005, and of Venus in October 2006 and June 2007 to place it onto the correct trajectory to reach an orbit around Mercury. A first fly-by of Mercury occurred on January 14, 2008, a second on October 6, 2008, and a third on September 29, 2009. Most of the hemisphere not imaged by Mariner 10 was mapped during these fly-bys. The probe successfully entered an elliptical orbit around the planet on March 18, 2011. The first orbital image of Mercury was obtained on March 29, 2011.

Messenger finished a one-year mapping mission,and then entered extended mission until it was ordered to impact Mercury on 30 April 2015 forming a new crater.

BepiColombo

Two satellites developed in Europe and Japan are on their way to Mercury, known as BepiColombo, left Earth on an Ariane rocket on 19th October 2018 to arrive in 2025.

bepicolombo mission to mercury

Colonizing Mercury