Planets
All About Mars
(Contd. from page 2...)But the famous "canals" "seen" by Lowell and others were, unfortunately, just as imaginary as Barsoomian princesses. Viking 2 Landing Site Pathfinder Landing Site The first spacecraft to visit Mars was Mariner 4 in 1965. Several others followed including Mars 2, the first spacecraft to land on Mars and the two Viking landers in 1976. Ending a long 20 year hiatus, Mars Pathfinder landed successfully on Mars on 1997 July 4. In 2004 the Mars Expedition Rovers "Spirit" and "Opportunity" landed on Mars sending back geologic data and many pictures; they are still operating after more than a year on Mars. Three Mars orbiters (Mars Global Surveyor, Mars Odyssey, and Mars Express) are also currently in operation. Mars' orbit is significantly elliptical. One result of this is a temperature variation of about 30 C at the subsolar point between aphelion and perihelion. This has a major influence on Mars' climate. While the average temperature on Mars is about 218 K (-55 C, -67 F), Martian surface temperatures range widely from as little as 140 K (-133 C, -207 F) at the winter pole to almost 300 K (27 C, 80 F) on the day side during summer. Though Mars is much smaller than Earth, its surface area is about the same as the land surface area of Earth. Olympus Mons Mars has some of the most highly varied and interesting terrain of any of the terrestrial planets, some of it quite spectacular: Olympus Mons: the largest mountain in the Solar System rising 24 km (78,000 ft.) above the surrounding plain.