The UFO is a large spacecraft used by The Thing as its only means of transportation to other planets. The UFO's appearance resembles the Flying Saucer.
The UFO crashed in Antarctica 100,000 years ago, and became buried under several millenia's worth of ice and snow. The UFO is first seen in the opening credits entering Earth's atmosphere, in such a disoriented manner that it is implied that it was not even attempting to land, but had completely lost control, possibly due to the actions of The Thing on board.
The Thing crawled out of the ship a short distance, but was unable to withstand the harsh cold weather and subsequently froze. It was buried in ice along with the UFO, only to be discovered in the modern day.
During the winter of 1982, a Norwegian crew discovered the UFO buried in the ice near their outpost and the frozen remains of the assumed passenger of the spacecraft. A simple lab test on the remains of the unknown creature resulted in its revival from its long slumber, killing off the crew one by one and assimilated them, causing chaos. The creature mutated into grotesque monstrosities, and the crew were able to fend them off by killing them with fire. In a dire situation, the crew did its best and destroyed most of the camp in hopes of killing the creature, however the creature survived (now assimilated an Alaskan Malamute) and fled from the remains of the outpost.
Two survivors pursued the creature to stop it once and for all, however both survivors were killed before the succeeded in killing the creature, the creature was then found by the crew of a nearby outpost, who would later suffer the same fate. Like before, the creature began to assimilate the crew, causing paranoia among the crew. The creature tried to build a miniature UFO out of parts from the base's helicopter and tractor, but the survivors destroyed the UFO, and the creature.
- There are many theories that has been commented with the fans regarding the UFO whether or not it being actually constructed by the Thing or that it belonged to one of the Thing's previous hosts before heading towards Earth. These are the following speculations that has been discussed.
- The first idea would imply that the ship belonged to the Thing’s own race. Things were the ones who built and piloted the vehicle. For whatever reason, not many fans seem drawn to this notion. They tend to gravitate towards the more sinister possibilities. However, it is interesting to note that Susan Turner, the one who originally built the saucer model, makes an off-the-cuff remark on the DVD’s Terror Takes Shape documentary. There, she refers to the saucer’s central dome as the place “where presumably the creature is steering the ship.” What supports this theory is that one of the things, an infected Blair to be specific, was building a small UFO under the ice.
- The second notion of the Thing being one of the ship’s passengers is even less popular. For whatever reason, no one has seriously defended this option. Perhaps it’s because people find it difficult to imagine the Thing as just a harmless passenger sitting in an interstellar "cruise liner" of sorts, comfortably sharing its cabin area with other space-going races. Given that the Thing has shown considerable intelligence, as well as the fact that other alien races could easily be immune to it (like silicone-based life forms), it's not at all unlikely.
- The third idea of a Thing stowaway seems to be more attractive among the film’s fans. Perhaps the ship visited other places before coming to our Solar System, and on one of these planets it inadvertently picked up a Thing. Or maybe the Thing had gained access to the ship by assimilating one of its crew or passengers.
- Surprisingly enough, the fourth possibility of having the Thing as part of the ship’s cargo or equipment is not without its supporters. Maybe the ship was on a scientific expedition to gather specimens from other star systems, and the Thing was collected from its own home world. Or even more: what if the Thing was part of the ship’s armament? The idea here is that the Thing was a biological weapon created by the race that built and operated the ship. Perhaps the craft was a military vessel equipped with the Thing as part of its standard weaponry. Maybe Earth itself had become a target for planetary invasion. But, as with all biological weapons, the creation ultimately turned against the creators.
- The 2011 prequel some how support the fourth possibility and chose to show that the ship was not constructed by the Thing itself but was the ship of its previous hosts. The sequences involving the ship were subjected to drastic cuts as the studio increasingly pressured for a "leaner and meaner" film that cut many of the tension-building and exposition scenes. A full animatronic prop was even built for the alien pilots of the ship, but this sequence was cut (though it appears in behind-the-scenes featurettes). In various interviews, the cast & crew explained that there were scenes on the ship showing containers or chambers which The Thing had broken out of (which also do not appear in the final cut of the film). The implication was that the aliens were picking up animals from many different planets as part of a zoological study, and brought The Thing aboard without realizing its true nature. Other descriptions of these unfinished scenes lean more towards the position that it was a biological weapon created by the aliens themselves, but broke out of its transport container.