A scenario occurred to me recently where the Chinese space program decided to go all-in on Mars sample return, and their schedule was such that it would happen before the NASA/ESA mission was scheduled to return a sample in 2032 (that hopefully won't crash land and disperse into the environment).
- Planetary Society: NASA, ESA Officials Outline Latest Mars Sample Return Plans
Suppose an impulsive billionaire decided step in and step around the government bureaucracy associated with planning, approving and funding NASA missions and just go get some soil and bring it back ASAP in order to prevent China's being the first country to return a Mars sample.
Would that billionaire need explicit permission from the US government to bring martian soil samples to Earth, or could they pretty much just do this by only complying with regulations associated with launches and landings and communications?
Would it matter if the recovery was on a ship built elsewhere and driven to international waters for recovery?