Civilization X needs to explore nearby exoplanets using nanobots. These nanobots are made of singular (relatively large) molecules. These react with common gases in the atmosphere, acting as a catalyst and making more nanobots. This reaction leaves behind oxygen and consumes toxic gases, eventually making the planet habitable to humans. This reaction only proceeds at liquid water temperatures, and also leaves unique 'marker' chemicals, allowing members of X to see potential destinations for interstellar flight using spectroscopy.
These nanobots are deployed by packing them into a shell around a chemical/nuclear/antimatter bomb and detonating it, releasing vast quantities at well past escape velocity of the small star that Civilization X orbits.
How could the nanobots survive the extreme temperatures (and radiation, if using nuclear/antimatter bombs) of the explosion?
Rules:
- No indestructible/unrealistically strong materials
- At least 1% of the bots must survive.
- The bots must make it to an exoplanet.
- The nanobots must be distributed uniformly, making a sphere shape.