Astronauts bound for orbit this week will dabble in science fiction, assembling a "monstrous" two-armed space station robot that will rise like Frankenstein from its transport bed. Putting together Dextre, the robot, will be one of the main jobs for the seven Endeavour astronauts, who are scheduled to blast off at 2:28 a.m. Tuesday, less than three weeks after the last shuttle flight. Their mission is to last for 16 days. The launch countdown began Saturday. The shuttle's seven astronauts arrived early in the morning and the countdown clocks began ticking. Good weather is expected; forecasters put the odds at 90 percent. The crew are also delivering the first piece of Japan's massive Kibo space station lab, a float-in closet for storing tools, experiments and spare parts. For the first time, each of the five major international space station partners will own a piece of the real estate.