I'm writing a book, and I am trying to develop a massive weapon of mass destruction. This particular weapon can detect particular strains of DNA or particular organisms (so like, any and all organisms sharing a high similarity to human DNA) and can eliminate any particular organism and any like it, with a very high rate of success (essentially a genocide weapon) I need some ideas, but I would like it to be something that at least is not in contact with the ground (so flying or hovering) and is energy based. I would like it to be as scientifically accurate as possible, but a few corners can be cut!
To "detect particular strains of DNA" you need to go "close and personal"; I cannot imagine being able to do it from orbit.
You are asking for genotype (as opposed to phenotype) detection and that is best addressed with some kind of genetic-aware weapon such as a virus.
You can, if your plot requires that, actually combine the two things:
- have a virus (or a nano-robot) to infect targets with no ill side-effect (if infected being doesn't have the needed "trigger" DNA strand it just disable itself).
- after a suitable time (to ensure pandemic infection) send some signal the "virus" will respond to (either actively or beacon-like) and start targeting with orbital laser all exposed targets.
In this schema "virus" would act as contrast-enhancer for the long-range sensors (probably in microwave range).
I think your requirements are not feasible.
- Stays above the atmosphere means that it has to affect people at about 100 km distance, through near vacuum for part of the way. That makes me think of an orbital laser cannon, or perhaps kinetic bombardment. A weapon with enough energy to penetrate the atmosphere would likely cause collateral damage where it hits.
- DNA-specific targeting means a very complicated analysis. It isn't enough to target bipeds in the 2-metre-range, or even bipeds with a specific skin color.
It might be possible to target individuals from high altitude after they have been identified by electronic emissions, like drone strikes at the owner of a certain mobile phone or the drivers of certain styles of SUV. But that would target visible behaviour, not DNA.
Only way I can think of to do this is to slowly and subtly build up 2 things:
1: A database of people’s faces, personal details and DNA (say it’s to help law enforcement) 2: A ubiquitous surveillance network (ditto)
Then you can make (with your super villian genius):
3: An AI capable of identifying and tracking everyone in the world simultaneously 4: An orbital laser cannon
Use the DNA database to identify targets, the AI to find them using the surveillance grid, and the orbital weapon to kill them.
A quick note: this is pretty much the plot of Captain America: Winter Soldier, but targeting specific genetic markers.