NASA scientists readied for the landing of the 420-million-dollar Phoenix spacecraft near Mar's frigid north pole. Phoenix will enter the Martian atmosphere at around 2331 GMT Sunday at about 21,000 kilometers (13,000 miles) 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. "I'm a little nervous on the inside. ... This is not an easy thing to do," said Phoenix scientist Peter Smith of the landing planned for late Sunday. "There's a lot of uncertainties left. ... Mars is always there to throw those uncertainties at us," added Doug McCuistion, Mars Exploration Program Director, of what NASA calls "the scariest seven minutes of the mission" -- the period of hyper-deceleration and descent onto the Red Planet.