It was like a party to which the iceman refused to come. Some 300 fidgety school kids and fans of the red planet turned out yesterday for Seattle MarsFest ’99, hoping to catch a new glimpse of Mars soon after the Polar Lander touched down. “The aliens are coming and they are US!” extolled a special edition of “Mini Sojourner,” the newsletter of the local chapter of the National Space Society and the Mars Society Puget Sound.