Realistic Planetkillers

[Clockwork_werewolf]

Idea 1: solar sail and solar panels. Drop the temperature of the planet enough with the shadow to cause starvation and mass extinction. The panels are there to power a medium laser to destroy anything they send up to destroy the "winter sail". Minus is you now have a dead ice world , they could find a way to destroy your sail and it would take a few years.

Idea 2: Targeted virus, airborne and easily spread with a week incubation. Expect 95% casualty rate. Then wait two months while they fight over food and band together. Then use orbital lasers and land based robots to clean up. Plus point with this is mostly intact resources and infrastructure. Minus is the robot army cost.

Idea 3: Doomsday device. Pack a few large nukes with something like cobalt around them, this when radioactive has a half-life of 5 years meaning only those in underground bunkers could survive the radiation. Then is a simple mop up of (if earth like) maybe 50-1000 bunkers, but these should be easy to find and neutralise. Minus is the radiation and the time it would take.

Idea 4: If you want the planet totally gone (I have no idea why) then just make and fire a big enough black hole at the planet to absorb it all. Minus is no goldilocks zone planet with breathable atmosphere, life resources, cultures, usable building space, workforce, and everything that comes with what even in our present exoplanet gold-rush seems very rare indeed.

[Rhidian]

1) Make a giant planetary size mirror

2) Position mirror between their star and the planet (L1 Lagrange point maybe) so that all light from the star doesn't reach the planet

3) ???

4) Profit