Messenger y Mariner 10

Messenger

MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) flew Mercury September 29, 2009. The first spacecraft to have visited Mercury was Mariner 10 sent November 3, 1973 by NASA to study Venus.
NASA decides to modify the program to fly over Mercury by Mariner 10 and 3 flights were made in 1974 and 1975. After 3 500 photos of the sunny side of Mercury, the probe failed fuel and the mission was terminated. The Messenger probe took the baton and flew Mercury from January 14, 2008. Its objective is the study of Mercury's surface to meet a number of questions about its density, its atmosphere, its geological history, the structure of its nucleus, its huge cloud of sodium, its magnetic field...
Messenger was launched August 2, 2004 at 06H16 UTC from Cape Canaveral by the Delta II Boeing. The Messenger probe used the gravity assist from Earth and Venus, who hastened to each pass over these planets to reach Mercury in January 2008.
Three flybys of the planet at altitudes of about 200 kilometers before it needs to go into orbit around Mercury, March 18, 2011.
Then it photographed the area plunged into darkness when the Mariner 10 flybys.

On Mercury, the surface temperature can reach over 400 ° Celsius and down, at night -170 ° Celsius. Messenger designed to withstand huge temperature fluctuations has a large sun shield and covered with a protective ceramic. Some regions of the planet nearest the sun were unknown until October 6, 2008, when the Messenger spacecraft came brushing Mercury for the second time. In 2009, the spacecraft has completed almost three quarters of its travel 7.8 billion miles to enter orbit around Mercury. The entire trip will include more than 15 trips around the sun.
In addition to fly Mercury, the spacecraft passed close to Earth in August 2005 and Venus in October 2006 and June 2007. The probe will enter orbit around Mercury in 2011 to observe the polar regions, only areas of the unknown planet.

Image: Mercury: an impact basin double ring of approximately 290 kilometers wide. "This double ring basin, seen in detail for the first time, is remarkably well preserved," notes Brett Denevi, a team member of the imaging probe and a researcher at Arizona State University in Tempe. Credit NASA.

Mariner 10

Mercury, the planet nearest the sun is hidden in the glare of the sun, it is a difficult target for a terrestrial observer. The first spacecraft to explore Mercury was Mariner 10, which made three flybys of Mercury in 1974 and 1975, revealing approximately 45% of its surface. Mariner 10, the last spacecraft in the Mariner program, was sent by NASA November 3, 1973 to study the planets Venus and Mercury. This is the first spacecraft to be photographed before the overflight Mercury Mercury Messenger probe by January 14, 2008. Mariner 10 took a total of 4165 pictures of Venus to gather important scientific data on its magnetic field, rotation, atmosphere...
It was also the first to implement the principle of solar sailing. During a failure on the attitude control, the engineers decided to reposition the solar panels for use of solar sail. The trajectory of the probe was corrected and then that his mission was to fly over Venus, engineers at NASA, after some adjustments, sent in March 1974, the spacecraft to Mercury. Mariner 10 was also the first spacecraft to use the gravitational pull of a planet to reach another.

The first encounter with Mercury occurred at 703 kilometers altitude, March 29, 1974.
The probe used the pressure on its solar panels to control his altitude and visit again the Planet, September 21, 1974 at a distance of 48069 km.
A third encounter with Mercury, was held March 16, 1975 at an altitude of 327 kilometers.
Out of fuel, contact with the probe was arrested March 24, 1975.

Image: A restatement helped reconstruct the mosaic frightening. As the Moon, Mercury's surface shows the scars of ancient impact craters.
The smooth vertical band and patches visible on the surface represent areas where no information was available in 1996. Credit: NASA