Following the successful encounters with the gas giants, attention was turned back toward the innermost planets. Mariner 10 set sail for Venus in November 1973. On its way it took this look back at the Earth and Moon.
Robot Explorers: US Unmanned Space Missions: page 8 |
Following the successful encounters with the gas giants, attention was turned back toward the innermost planets. Mariner 10 set sail for Venus in November 1973. On its way it took this look back at the Earth and Moon. |
|
| After visiting Venus, Mariner 10 continued on its course and by using the gravity assist method reached Mercury nearly two months later. In three successful flybys, Mariner 10 was able to image half of Mercury. Until that time, very little was known about the planet. Because Mercury is so close to the Sun it is usually lost in the solar glare. Even the best telescopic views from Earth showed it as an indistinct object lacking any surface detail. | |
|
|
|
But the photos that were radioed back to Earth revealed a heavily cratered surface, similar in appearance to our own Moon. There are cliffs as high as 2 miles and as long as 300 miles, criss-crossing the planet. Instruments on board the spacecraft found that Mercury has a weak magnetic field and a trace of an atmosphere -- a trillionth the density of the Earth's atmosphere. When Mercury's orbit takes it closest to the Sun, surface temperatures range from 872 degrees Fahrenheit on the sunlit side, to minus 298 degrees Fahrenheit on the dark side. This range in surface temperature, 1170 degrees, is the largest for a single body in the entire solar system. Mercury is literally being baked and frozen at the same time! |
 |
Copyright ©2004 Colleen Gino |
Images courtesy JPL and NASA. |
|
