Deep space interplanetary mission spacecraft is becoming real

Mission Commander Marina Barnett, biologist David Kim, and medical researcher Zoe Levenson lift off aboard MTS-42, on a two-year mission to Mars. Once underway, the upper stage of their launch vehicle is connected by 450-meter tethers to the ship's main hull, acting as a counterweight for inertia-based artificial gravity.[3] Shortly after takeoff, Barnett discovers launch support engineer Michael Adams, an accidental stowaway, unconscious between two modules, entangled with a device that scrubs carbon dioxide from the air on the ship. As he falls, the device is inadvertently destroyed. The crew is forced to use emergency lithium hydroxide canisters to scrub CO2 from the air. Unfortunately, the canisters cannot sustain the extra load. Barnett orders David to immediately cultivate his algae experiment on the ship, rather than at the Martian colony as planned. Only half of the algae survive, providing just enough oxygen for a third crew member. Without another oxygen supply, the crew of four will asphyxiate weeks before reaching Mars. Barnett asks mission control for a solution that will save all four passengers, but the only option—an untested EVA (spacewalk) to climb the tethers and recover liquid oxygen from the spent upper stage rocket—is deemed too risky. Barnett and David begin to come to terms with sacrificing Michael, but Zoe convinces them to wait ten days for mission control to think of another solution. After three days, David breaks rank to explain the situation to Michael, offering him a painless lethal injection. Michael nearly takes his own life, but Zoe stops him and convinces him to hold out for a while longer. She insists on climbing the tethers to retrieve the liquid oxygen. David reveals that the rest of the algae has died, leaving only enough oxygen for two. Now facing the death of two passengers, he agrees to join her on the climb. Zoe and David perform the EVA and jury rig a solution to fill two cylinders, enough to sustain two more passengers. However, deadly radiation from a high-energy solar flare—a coronal mass ejection—forces them to leave one of the cylinders behind.[4] They make it back to the ship, but due to a critical equipment failure, the single oxygen cylinder is lost. After regrouping, they realize that the large tank continues to leak oxygen due to the improvised connection, and that if one person exposes themselves to the lethal radiation to retrieve the cylinder left behind on the first attempt, the other three can survive. Marina must survive to pilot the ship, but the other three all volunteer to make the sacrifice. As Michael is untrained and both he and David have families back home, Zoe ultimately insists on doing it herself. She manages to fill and return the cylinder to the ship before succumbing to radiation poisoning. She spends her final moments outside the ship, gazing at a faint Mars amongst the stars.