Have all the planets been visited by space probes?
Have all the planets been visited by space probes?
The planet closest to the Sun, Mercury has so far had only one visitor from Earth, the American Mariner 10 space
probe in 1974. A second visitor, also American- the Messenger space probe-is due to arrive at Mercury in January
2008. The European Venus Express is at present orbiting Venus, and Mars is being observed by an entire fleet of
probes which include the European Mars Express and the American Mars Reconnaissance Orbiter. The last probe
to visit Jupiter was the American Galileo craft, which burnt up in the giant planet's atmosphere in September 2003.
Saturn is currently being orbited by the American probe Cassini, and the American Voyager 2 probe flew past Uranus
and Neptune in 1986 and 1989 respectively. Hence, every planet in the solar system has had a visit from at least
one terrestrial space probe.
Which was the first planetary probe?
After their success with Sputnik 1. the Soviet Union attempted to beat the USA in the race to send unmanned
space probes to investigate the planets. However, in October 1960, two Mars probe launches failed. Although
an initial venus probe was successfully launched in February 1961, it didn't get beyond Earth's orbit because
the final rocket stage failed to ignite. A second attempt several days later was more successful, but only seven
days after the launch, radio contact with the probe was lost. Then, in July 1962, the USA made their first attempt
to send a probe to Mars, but the launch failed. The next Soviet attempt to reach Mars, also in 1962, failed.
Then an another Venus probe failed to leave Earth's orbit.
In the end, it was the Americans who 'won' when, on 27 August 1962, they launched Mariner 2. In December
that same year it flew within 34 773 km of Venus and into the history books as humankind's first successful
planetary probe. It was another four years before the Soviet Union celebrated a successful planetary mission,
when Venera 3 crashed into Venus in 1966.
