"The Invincible" (Niezwyciężony) is a novel by Stanisław Lem describing the mission by the titular spaceship to find out what happened to its sister vessel, Condor. Condor vanished after landing on a desert planet of Regis III, sending a single distress signal mere hours after landing. The crew quickly discovers strange metallic ruins on the surface of the planet, which don't look like anything in particular, be that machines or buildings. During exploration, they stumble upon the cause of Condor's sad fate, losing several crewmembers. As attempts to learn more about the phenomenon or destroy it cause increasing damage and loss of life, the protagonists have to come to terms with the fact that there is nothing really left for them to do on Regis III. Nothing but make sure every man - alive or dead - is accounted for. Which leads to one last venture into the desert...
Unmarked spoilers ahead.
This work includes examples of:
- Absent Aliens: Justified: the only other known alien civilization - the Lyrans - have been destroyed millenia ago when their home star went supernova. However, protagonists speculate that living machines of Regis III might have descended from some kind of autonomous robots crewing a crashed Lyran colony ship.
- Artistic License Chemistry: Atmosphere of Regis III contains significant quantities of oxygen and methane, which normally would make it an immense bomb just waiting to go off. When the captain points that out, it's explained that the methane here has different chemical bond energy, making it much less reactive.
- Cool Starship: The Invincible is capable of interstellar travel, generating protective forcefields capable of surviving a close nuclear detonation, and can return it in kind. The fact that equally powerful Condor had met its end on Regis III is not lost to the crew.
- Deflector Shields: Of disintegrator variety, employed by both humans and "the clouds", for various purposes and to various degrees of success. Come in all sizes: from kilometer-wide starship shield, to man-portable variants. A plot-important flaw is that they cannot be shaped arbitrarily... and don't shield from any electromagnetic waves.
- Desolation Shot: The Condor, once it's found, looks like "it's been attacked by a horde of mad monkeys", with tools, book and personal belongings laying all over the ship and surrounding area.
- Enmity with an Object: Rohan at one point explicitly compares plans to destroy the resident Microbot Swarm to Xerxes whipping the ocean.
- Foreshadowing: During an expedition to the ocean shore, protagonists manage to catch a native fish. It turns out to have some kind of bilogical magnetic sensor, which causes confusion as to why would it need this sense.
- Gradual Grinder: The way "the clouds" destroy hostile machines is to either overheat them, slowly grind them down using tiny forcefields, or destroy their programming via electronic interference.
- Hover Tank: The Cyclops, the mightiest vehicle in the arsenal of Indestructable. "The clouds" never manage to put a dent in its armor, but it's control computer is another matter...
- In the End, You Are on Your Own: A variation. Rohan has to scout the area where one of the previous expeditions was lost, to find out what happened to the lost crewmembers. He has to do it alone, mostly on foot, since bringing in vehicles would attract unwanted attention.
- It Can Think: Discussed and mostly dismissed. One of the scientist points out that truly sentient "clouds" would be able to easily circumvent Invinicible's forcefield.
- Laser-Guided Amnesia: Inverted. The clouds' electromagnetic attack utterly destroys higher brain functions of animals, including humans. It does the same to computer-controlled machines, too.
- Mechanical Lifeforms: The only lifeforms on the surface of Regis III. All biological life has been driven into the ocean.
- Microbot Swarm: Dubbed "the clouds" by the crewmember and "necrosphere" by the science section, they effectiveley killed the crew of Condor, and crippled nearly a half of the crew of Invincible. The strengths and weaknesses of such swarms are discussed (and shown) at length.
- Single-Biome Planet: Partially averted. The text mentions polar caps, and there is an expedition to the ocean shore, but all we see of Regis III continents is endless desert.
- Sleeper Starship: The novel starts with the crew waking up from hibernation.
- Subspace Ansible: Of sorts. Some kind of relays, or beacons, are mentioned as means to establish interstellar communication, but the timeframe of their operation is never established firmly.
- The Chains of Commanding: Horpah, the captain of the Invincible, usually maintains his steely facade. When it slips during a private conversation with Rohan, the latter is shocked, despite having served with Horpah for years.
- Title Drop: Done as the very last word of the novel, no less.