In 1958, two ambitious U.S. Air Force pilots, William "Hawk" Hawkins (Tommy Lee Jones) and Frank Corvin (Clint Eastwood), find themselves testing a modified Bell X-2 after Hawk boldly decides to break a soaring altitude record. Unfortunately, the aircraft stalls, forcing them to eject just in time to avoid a Boeing B-50 Superfortress that is piloted by navigator "Tank" Sullivan (James Garner). Once on solid ground, a heated confrontation ensues where Frank confronts Hawk over his reckless actions, nearly jeopardizing his own career. Their quarrel is swiftly interrupted by flight engineer Jerry O'Neill (Donald Sutherland). Their superior, Bob Gerson (James Cromwell), reprimands Hawk and soon brings them to a press conference revealing that the newly established NASA, instead of the USAF, will carry out the upcoming space flight tests, including sending a chimp into space as the first American in orbit. This shocking announcement effectively crushes their dreams of moon travel.
Fast forward to the present day, NASA faces an urgent challenge: they must prevent the Soviet satellite IKON from falling out of orbit and crashing to Earth, with its systems failing rapidly and only 35 to 40 days left. Sara Holland (Marcia Gay Harden) serves as the mission director, guided by Flight Director Eugene "Gene" Davis (William Devane). The Soviets, led by General Vostov (Rade Serbedzija), are unexpectedly adamant about preventing the satellite's re-entry, prompting the White House to push NASA for all possible assistance.
The vintage electronics of the satellite bear a striking resemblance to those developed by Frank in the past. Bob, now in a position of authority at NASA, seeks Frank's expertise once again, enlisting Sara to bring him back into the fold. Frank advises that capturing the massive satellite using the space shuttle is impractical, insisting the problem must be addressed from space itself. Although Frank loathes Bob for past grievances, he agrees to participate only if he can reunite with the old crew, known as "Team Daedalus," which includes Hawk, Tank, and Jerry.
The crew's return to space preparation sees them confronting various medical evaluations and tests to ensure they are fit for the mission—one highlight being Frank's comedic bet with Hawk regarding who will faint first on the G simulator. Meanwhile, Sara develops a crush on Hawk, who aspires to pilot the shuttle but struggles with the tendency to disengage the autopilot, leading to dangerous maneuvers.
As the older astronauts mentor the younger team members, chemistry begins to blossom, although tensions grow as the younger astronaut, Ethan Glance (Loren Dean), grows frustrated with Frank's refusal to mentor him. When news of Frank's team breaks to the media, the Vice President pressures Bob into including them on the mission for public relations, leading to a heart-wrenching revelation: Hawk has been diagnosed with cancer. Frank adamantly refuses to embark on the journey without Hawk aboard, leading Bob to agree to have Hawk join the mission despite his illness.
Upon reaching the satellite, it is discovered that it contains not communications technology, but six nuclear missiles—a remnant of the Cold War that defies the Outer Space Treaty. Frank learns that the KGB pilfered classified control systems from Bob’s files, now threatening to launch the missiles if the satellite loses contact or drifts out of orbit. With the team's focus set on using payload-assist rockets to cast the satellite into deep space, a mishap occurs when Ethan, acting on orders from Bob, attempts to stabilize the satellite's orbit himself, resulting in catastrophic consequences: the satellite collides with the shuttle, disabling critical systems and accelerating their impending crash.
While Tank and Jerry care for the injured Roger Hines (Courtney B. Vance), Frank and Hawk must embark on a spacewalk to activate a booster rocket to slow the satellite's descent. In a moment of profound sacrifice, Hawk, motivated by his terminal diagnosis and long-held dream of lunar landing, chooses to ride the satellite, igniting its engines in a selfless act to ensure it is launched into deep space.
Post-handover of the shuttle for water landing, Frank and his team find themselves battling against the odds, facing a challenging descent without any automated systems. After safely ejecting the surviving younger astronauts, Tank and Jerry refuse to leave Frank's side as they all risk their lives to navigate the shuttle back home. Recalling Hawk's prior technique for landing, Frank opts to stall the shuttle—an instinctive maneuver that ultimately ensures a safe landing.
The film concludes poignantly with the classic tune "Fly Me to the Moon," as viewers are treated to a breathtaking view of the Moon's surface, confirming that Hawk achieved his dream before his passing.
