WARNING: The following contains spoilers from Star Wars #17, on sale now from Marvel Comics.
"War of the Bounty Hunters" is forcing many of the main players in the Star Wars universe to collide in dangerous and unexpected ways. One of the most tense confrontations in this crossover event is a battle currently taking place between father and son. Luke Skywalker and Darth Vader were in the middle of a fierce dog fight in Star Wars: Darth Vader #16 which almost resulted in Luke's defeat, if not for some unexpected help from the Empire.
As the dog fight comes to a crashing end and a victor seems all but declared, another of Vader's secrets is revealed in Star Wars #17, by Charles Soule, Ramon Rosanas, Rachelle Rosenberg and VC's Clayton Cowles. As Luke notes that the water on this barren planet freezes almost instantaneously, he has an idea. Luring Vader into a trap, he flies low, kicking up lots of water, and makes a sharp turn. This turn results in a large ice barrier being created. Vader, having followed closely behind the Rebel X-Wing has little time to react to the new obstacle and crashes into it.
With smoke rising from the wreckage, Vader's destroyed TIE Fighter seems irreparable. One wing is severely damaged and the wiring in the cockpit lays loose and sparking. Even if the Sith Lord could mend all that, there is one thing he can't mend - the cockpit window. The glass is smashed to pieces and he had to force the broken window frame off to exit his fighter.
Assuming the Sith Lord is stranded, Luke flies away rather than engage the marooned Vader with his X-Wing. He tells the Falcon that he'll be with them shortly now that he's shaken off his father...but he is sorely mistaken. Vader proves that the fight is far from over, as his battered TIE Fighter rises from the clouds to continue his pursuit of the X-Wing into space again.
Vader was able to get the ship into a position where it could take to the skies once more using the force and his engineering prowess. However he was unable to fix the cockpit window. This leads to the horrifying revelation that Darth Vader can survive in the vacuum of space.
After his fateful duel with Obi-Wan Kenobi on Mustafar, Emperor Palpatine rebuilt Anakin Skywalker as his indestructible mechanical enforcer Darth Vader. Although his life support armor has certain limitations (for example, its added weight forced him to change his lightsaber style) there's a reason it is feared throughout the galaxy.
The Sith Lord's armor not only protects his damaged body but also enables him to survive harsh conditions. It regulates his body temperature and adjusts his vision to compensate for his injuries, and this aids him in extreme temperatures and darkness. If it wasn't clear from the iconic sound of his breathing, it helps his respiratory system as well. His lenses are already reinforced to survive the vacuum of space and it appears that his breathing apparatus also adjusts for this.
Even though this startling ability comes from simple enhancements that improve Vader's quality of life, it also adds to the menace of his legend. Luke assumed he was safe after downing his father, and the fact that Vader can relentlessly pursue Skywalker in the vacuum of space is terrifying. The possibilities this creates are also unsettling. Darth Vader could ideally stand atop a Star Destroyer in deep space and take on the Rebellion with only the force and his lightsaber and would have a pretty good chance of emerging victorious. This proves beyond the shadow of a doubt that the galaxy is wise to fear the power of Darth Vader.