OUR knowlege of Mars got a major boost with the arrival of NASA’s two American Viking missions to Mars in 1976. Each put a spacecraft into orbit and put a lander on the surface, Viking 1 touching down on 20 July and Viking 2 on 3 September. The two missions sent home more than 50,000 photos including the first spectacular views from the surface. The landers also carried out analysis of the Martian atmosphere and soil.
The great success of the Vikings was followed by disappointment in 1988 and 1989 when the Russian probes Phobos 1 and Phobos 2 were both lost – the first en route to the planet and the second when it was approaching its moon Phobos. Then in 1992 contact was lost with the US probe Mars Observer shortly before it reached the planet.
Mars Global Surveyor achieved more success for the US, arriving in September 1997 to begin a comprehensive programme to map Mars. It produced spectacular views, including that of the volcano Olympus Mons, seen right, and operated successfully until November 2006 when all contact was lost.
But there was failure for Russia in November 1996 when Mars 96 failed soon after launch. The main rocket crashed into the Pacific but the probe itself came come down between Chile and Bolvia.
Another stunning success for the US was the relatively low-cost Mars Pathfinder mission. The probe used airbags to bounce to a landing on Independence Day, 4 July, 1997. Then it sent a little robot rover called Sojourner to explore nearby features.
The Japanese Nozomi (Planet-B) probe was launched in July 1998 for a rendezvous with Mars in October 1999 – the longer than usual flight time due to a complex route due using flypasts of the Moon and Earth to gain momentum. Things did not go according to plan and the probe was re-routed to reach Mars in late December 2003 – but failed to get there.
After its great successes, the US tasted failure when it lost two probes. Mars Climate Orbiter, launched in December 1998, was destroyed in the Martian atmosphere in September 1999 after radio commands were sent to the craft in imperial rather than metric units.
A companion probe, the Mars Polar Lander, was also lost and crashed on the planet in December 1999. Contact was also lost with two Deep Space 2 probes that were designed to break free from the lander and spear themselves into the surface of Mars.
These setbacks were followed by another major success for the US – the Mars Odyssey mission which reached Mars in October 2001 and is still studying the planet.