Mission to Mercury

A false colour image of Mercury, captured by Messenger, using several  filters (6 October 2008). Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Arizona State University/Carnegie Institute of Washington. Image Source: Space.com.

For weeks now, space-exploration-related Websites have been anticipating the entry of NASA's Messenger craft into Mercury's Orbit today. The craft has a heat shield made of ceramic cloth to shield Messenger from temperature extremes as high as 425 degrees Celcius and -185 degrees Celcius.  The cloth keeps the instruments consistently at room temperature.  It has taken more than six years for Messenger to travel to Mercury and line it up so that it enters the planet's orbit.

The planet was previously fleetingly photographed by Mariner 10 (1974-1975), and by Messenger itself during a fly-by in 2008. Machines Like Us reports that the Deputy Project Scientist, Louise Prockter's reflected on the mission as follows:

On receipt of ... early images of Mercury, Prockter writes: "How often in your life do you get to see something completely unexplored?...My first feeling was one of complete joy and disbelief – a perfect, beautiful, gibbous Mercury filled the screen, showing an incredible level of detail."

This mission will bring unprecedented photographs of the planet, which is slightly larger than our Moon, to public attention over the coming months.

Size comparison of the four inner Terrestrial planets: Mercury, Venus, Earth, Mars. Image Source: NASA via Wiki.

Mercury has several mysteries, such a volcanoes and an irregular depression that is characterized by a strange bright spot on the planetary surface. Mercury has no moon. Space.com has an initial gallery here. NASA's main page for the mission is here.

One of Messenger's previous photographs of Mercury, distance 11,000 miles (14 January 2008). Image Credit: NASA/JHUAPL/CIW. Image Source: Space.com.

Mercury's size compared to the Sun (2006). Image Credit: Mila Zinkova. Image Source: Wiki.

Caption for the above photograph: The Historical Transit of Mercury on November 8,2006. Please note that sunspot #923, which is just below the equator at the left-hand side, is much bigger than Mercury is. You can also see two more sunspots at the right-hand side at the equator. You can see Mercury as a small black dot in the lower middle of the solar disk.

Culturally, we grant the planet the symbolic and astrological connotations of speed and communication.  Wiki:

Mercury is the ruling planet of Gemini and Virgo, and is exalted in the latter and possibly in Aquarius. In Roman mythology, Mercury is the messenger of the gods, noted for his speed and swiftness. Echoing this, the scorching, airless world Mercury circles the Sun on the fastest orbit of any planet. Mercury takes only 88 days to orbit the Sun, spending about 7.33 days in each sign of the zodiac. Mercury is so close to the Sun that only a brief period exists after the Sun has set where it can be seen with the naked eye, before following the Sun beyond the horizon.

Astrologically, Mercury represents the principles of communication, mentality, thinking patterns, rationality and reasoning, and adaptability and variability. Mercury governs schooling and education; the immediate environment of neighbors, siblings and cousins; transport over short distances; messages and forms of communication such as post, email and telephone; newspapers, journalism and writing, information gathering skills, and physical dexterity. The 1st-century poet Manilius described Mercury as an inconstant, vivacious, and curious planet. In medicine, Mercury is associated with the nervous system, the brain, the respiratory system, the thyroid, and the sense organs. It is traditionally held to be essentially cold and dry, but variable in temperament, according to its placement in the zodiac and in any aspects to other planets. It is linked to the animal spirits, alongside the Moon.