US probe to attempt perilous landing on Martian arctic

WASHINGTON (AFP) - US space scientists were to attempt Sunday to land a 420-million-dollar spacecraft near Mars's frigid north pole, but were concerned that the odds for success were less than 50 percent.
"I'm a little nervous on the inside ... This is not an easy thing to do," scientist Peter Smith said Saturday of the planned landing of the Phoenix probe due late the following day.
"There's a lot of uncertainties left," added Doug McCuistion, Mars Exploration Program Director. "Mars is always there to throw those uncertainties at us."
Mission specialists were reviewing data to decide whether a course-correction manoeuvre would be needed eight hours ahead of touch-down to keep the Phoenix on track for landing in a relatively rock-free, flat region in the Mars arctic after its 679-million-kilometer (422-million-mile) journey from Earth.
An earlier trajectory correction was scrubbed Saturday because "Phoenix is so well on course for its Sunday-evening landing on an arctic Martian plain that the team decided it was not necessary," NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, which controls the mission, said on its website.
Phoenix will enter the Martian atmosphere at around 2331 GMT Sunday at about 21,000 km per hour and rely on its thermal shield, then a parachute followed by a bank of pulse thrusters, to slow down to a mere eight kph (five mph) ahead of touchdown on the circumpolar region known as Vastitas Borealis — akin to northern Canada in Earth's latitude.
Phoenix will become the first spacecraft to land on the Martian arctic surface, digging into the polar ice in a new three-month mission searching for signs of life. "We are going to a place on the planet that is unexplored and very exciting," Smith, Phoenix principal investigator at the University of Arizona, told reporters Saturday.
"Getting a scoop full of that icy soil is our goal" in searching for a habitable zone, he said.