How do space suits keep astronauts alive?

The answer

A modern EVA (extravehicular activity) space suit is essentially a personal spacecraft. It maintains internal pressure at about one-third of an atmosphere, provides pure oxygen for breathing, removes carbon dioxide, and regulates temperature between the extreme heat of direct sunlight (+120°C) and the cold of shadow (−160°C) using a water-cooling system woven into an undergarment. Multiple layers of Kevlar and Mylar protect against micrometeorite impacts. Each suit costs approximately $12 million and weighs about 127 kg on Earth - though astronauts feel none of that weight in orbit.