A Delta II rocket lit up the early morning sky over Cape Canaveral Air Force Station in Florida as it carried the Phoenix spacecraft on the first leg of its journey to Mars. The powerful three-stage rocket with nine solid rocket motors lifted off at 5:36am local time.
Credit: NASA
WASHINGTON DC: A NASA space probe began a long journey to Mars on Saturday, where it will land and dig through freezing Martian soil.
The Phoenix Mars Lander successfully separated from a U.S. space agency Delta II rocket after blasting off into the dark sky at 5:26am local time (9:26am GMT) from the Kennedy Space Centre in Cape Canaveral, Florida.
Power by solar panels, Phoenix – whose launch was delayed by one day following bad weather – is scheduled to land on Mars on May 25, 2008, after travelling 680 million kilometres through space.
Polar lander
NASA hopes to land the probe on flat ground with few or no rocks at a northern Martian latitude equivalent to Alaska on Earth.
During its three-month mission, the lander will pierce through soil in the planet's arctic region amid freezing temperatures ranging from minus 73°C to minus 33°C.
The solar-powered craft is equipped with a 2.35-metre robotic arm that will enter vertically into the soil to break the icy crust believed to lie within a few inches of the surface. The robotic arm will lift samples onto the lander's deck and use instruments to check for water and carbon-based chemicals, considered essential building blocks for life, and analyse the soil chemistry to look for clues of past or present life.
With its two solar panels deployed, the lander, built by U.S. aerospace firm Lockheed Martin, measures 5.5 by 1.5 m, weighs 350 kg and carries 55 kg of scientific equipment.
"Our instruments are specially designed to find evidence for periodic melting of the ice and to assess whether this large region represents a habitable environment for Martian microbes," said Phoenix Principal Investigator Peter Smith of the University of Arizona in Tucson.
Phoenix also has a weather station that will measure water and dust content in the atmosphere.
Many scientists have seen signs of ancient rivers and oceans on the arid and sterile surface of Mars, and believe the planet may once have harboured some forms of life.
Water, water, everywhere
In 2002, the NASA probe Mars Odyssey detected huge quantities of hydrogen on the Martian surface; a likely sign there could be ice at a depth of less than one meter.
NASA's roving robots Spirit and Opportunity have also found signs of past water while rolling across the Martian landscape since 2004.
Unlike the rovers, the US$420 million (A$490 million) Phoenix lander will stay put in one location during its mission. It will also have a softer arrival on Mars than the rovers, which made a bouncy landing inside huge air bags.
As with previous missions, Phoenix will deploy a heat shield to slow its high-speed entry into the Martian atmosphere. It will then open a supersonic parachute that will cut its speed to about 217 kph.
The lander then separates from the parachute and fires pulsed descent rocket engines to slow the craft to about nine kilometres per hour before landing on its three legs. Fifteen minutes after landing, the probe's solar panels will deploy and power up its instruments.
But landing on Mars has been a fifty-fifty proposition for past missions to the Red Planet: Half of the 14 missions sent by Russian, Japanese, American and European space agencies since 1988 have failed.
