50 years in the future, Earth's Sun is dying.
Why it is hard sci-fi
The Icarus II mission carries a stellar bomb to reignite a dying Sun. The first half is procedurally rigorous. Heat shielding, radiation budgets, oxygen management, a rendezvous with the lost Icarus I, and a debate about whether to take the second bomb when the timing of the rendezvous compromises the budget. The films science discipline collapses in the third act when a horror element takes over, but the first hour is one of the cleanest near-future spacecraft films ever made.
Science inside it
Solar sail-style heat shielding, oxygen recycling under combat-damage conditions, the orbital mechanics of a rendezvous, the energetics of a Q-ball as a stellar reignition device, and the psychology of a small crew on a one-way mission. The Q-ball is fictional physics borrowed from Brian Cox who advised on the science.