The mission will establish if there is water on the Red Planet, writes Dick Ahlstrom, Science Editor.
THE PHOENIX Mars Landerhas begun beaming back spectacular images from the polar regions of the Red Planet. More importantly, today may be the day scientists can confirm the discovery of ice in this cold, desiccated wasteland.
The lander's arrival on the planet's surface late on Sunday night went according to plan, with its three legs touching down at 12.38pm Irish time.
Proof that the Phoenix Landerhad landed safety reached Nasa 15 minutes later in a radio message sent by the spacecraft. Even before that message arrived, the lander began a pre-set sequence of activities, including deployment of its solar arrays, the hoisting of its weather mast, stereo camera system and the transmission of an image showing it was up and running.
While mission control was happy to receive the pictures, confirmation that the solar panels were producing electricity and that its three-month mission on the planet was formally under way, the real test of the lander will likely come today.
All going well, Phoenix'scontrollers at Nasa's Jet Propulsion Laboratory in Pasadena, California, Lockheed Martin Space Systems in Denver and the University of Arizona will deploy the lander's 2.35m robotic arm to dig into soil and deliver absolute proof that water exists on Mars.
The spacecraft was sent far north into the Martian Arctic, where there is a high likelihood of discovering frozen water beneath the surface.
It now sits in a region called Vastitas Borealis at 68 degrees north latitude. The equivalent latitude on Earth skirts the Arctic Ocean, tracking along the northern fringes of Alaska, Canada and Russia.
The location was carefully scouted by orbiting satellites, chosen as much for its smooth, relatively rock-free surface as for its polar position. Satellite images have revealed the surface soil there is formed into irregular polygonal shapes, and the first striking images from Phoenix confirm this.
This same patterning is seen in ground in the arctic regions of Earth, where water is known to exist just beneath the surface.
"We see the lack of rocks that we expected, we see the polygons that we saw from space, we don't see ice on the surface, but we think we will see it beneath the surface. It looks great to me," Peter Smith of the University of Arizona, Tucson, and principal investigator for the Phoenix Lander mission said yesterday.
Concerns about the spacecraft were well-founded, given that only five of the 11 landers sent to Mars so far have actually arrived in one piece. The others crashed or disappeared without trace after equipment failures.
With a long 703 million kilometre journey behind it, the lander now begins a busy three months as it deploys various experiments, takes images and initiates its search for water.
Almost as importantly, it will also taste and sniff the polar soil and any ice samples found for chemical compounds which could carry a signature for life on the Red Planet.
While it will not establish the existence of past or present life there, the presence of specific complex carbon molecules could indicate the potential for life to have existed on Mars.
The lander will use the robot arm to scoop up ice and soil samples, cooking them in tiny on-board ovens and then analysing the chemicals given off to test for substances that could have helped sustain life.
Nasa's delight that the Phoenix Lander arrived safely was echoed by astronomers and astrophysicists here. "It is tremendous the spacecraft has landed successfully," said Prof Mark Bailey, director of the Armagh Observatory.
"The most important thing will be to see whether it finds hospitable conditions for life and that is what we will be waiting to hear in the coming weeks and months."
"The Phoenix Landeris the next step in the great endeavour to find evidence for water on Mars," said astronomer Dr Paul Callanan at University College Cork.
"The fact that they have got it down in one piece is a fantastic achievement."
Prof Luke Drury of the School of Cosmic Physics at the Dublin Institute for Advanced Studies described the landing as an "impressive piece of engineering".
It will also finally settle the question about water on Mars, he added.
"Everyone thinks there is water on Mars but it is another thing to actually find it."