T isn’t exactly your typical modular home. The astronauts now working to assemble the 500-ton station — which will eventually provide long-term living space for up to seven crew members — are faced with some unusually challenging conditions. Temperatures at the job site range from a sweltering 150°F on the sunny side to a numbing 100°F below in the shade. All the work must be done with cumbersome, pressurized space-suit gloves. In the zero-gravity environment, a dropped object instantly becomes an irrecoverable piece of space junk. As you would expect, the job involves some highly sophisticated tools and equipment. They include a 55-foot robotic arm capable of “inchworming” jacket” that enables an accidentally untethered astronaut to jet back to safety,