Enemy Mine

In the late 21st century, an interstellar war between the humans (associated as the Bilateral Terran Alliance, or BTA) and the Dracs (a sentient, bipedal reptilian humanoid race) is fought. Battles are periodically fought between fighter spacecraft, and no human pilot hates the Dracs more than Willis E. Davidge (Dennis Quaid). During one such battle, Davidge and Drac pilot Jeriba Shigan (Louis Gossett, Jr.) engage in a dogfight which results in both crash-landing on Fyrine IV, an alien world uninhabited by intelligent life, with two moons, a breathable atmosphere, water, native fauna, and a hostile environment.
After initial hostilities, the two eventually learn to cooperate to survive. They work together to build a shelter for protection against meteorite storms, a natural phenomenon that periodically strikes the planet. Over the next three years, they overcome their differences, become friends and learn each other's languages and cultures. Each saves the other's life several times.
Davidge, haunted by dreams of spaceships landing on the planet, leaves in search of help. He finds evidence of humans, but learns that the planet has only been periodically visited by human miners known as "Scavengers", who use Dracs as slave labor. He returns to warn Jeriba, (nicknamed "Jerry"), only to discover that Jeriba is pregnant. It is revealed that Dracs reproduce asexually.
A blizzard and an attack by an indigenous predator forces Davidge and Jeriba to flee their shelter. To pass the time Jeriba teaches Davidge his full lineage. Jeriba later slowly dies in childbirth, but not before making Davidge swear to take the child back to the Drac homeworld and recite his full ancestry, so that he can join Drac society. Davidge raises the child Zammis (Bumper Robinson). Davidge and Zammis form a very close bond and the young Drac loves Davidge as any sentient child loves a parent, despite referring to Davidge as "uncle".
One day a ship flies overhead and Davidge goes to investigate. However, Zammis is curious and follows. He is discovered by a pair of Scavengers. Davidge attacks the men, but Zammis inadvertently stands between Davidge and one miner, and Davidge is gunned down. Later, a BTA patrol ship finds Davidge apparently dead, and returns him to his base space station.
On the station during an impersonal funeral ceremony, Davidge suddenly awakens when a disposal technician tries to steal the book Jerry gave him years before to learn the Drac language. Davidge's old team vouch for his loyalty, even after they find he speaks the enemy's language fluently. Davidge is later reinstated to duty, but not as a pilot, as his superiors want to make sure he has not been brainwashed by the Dracs. Unable to get help in rescuing Zammis, Davidge steals a spaceship to find the child by himself. He manages to find the Scavenger ship and sneak aboard. Davidge speaks to the Drac slaves in their own language as he searches for Zammis. The slaves know who Zammis is and realize that Davidge is "uncle". Davidge enters the facility and fights with one miner after another as he searches for Zammis. In the confusion caused by Davidge, the slaves revolt against the miners. Towards the end of the battle, Davidge is assisted by the BTA crew who pursued the stolen ship. They realize that whatever it was he experienced while missing in action (MIA) has made him more human; he no longer hates Dracs.
In the epilogue, Davidge and Zammis return to the Drac homeworld of Dracon for Zammis's heritage ceremony before the Drac Holy Council. As he promised Jerry, Davidge recounts the complete Jeriba ancestry before the Holy Council in the traditional ritual as he was taught. The narrator explains that when "in the fullness of time, Zammis brought its own child before the Holy Council, the name of 'Willis Davidge' was added to the line of Jeriba."

Question: What does Davidge steal?
Answer: Spaceship