Wow, I didn't realize helicopters can't go that high. I was wondering why it wasn't a simple helicopter extraction job, there you go.
On Mars atmosphere is about 1%, or close. Still helicopter did fly. Correctly saying 'helicopters designed for dense atmosphere cannot fly in thin'.
It is possible to build a drone specifically for these cases. Which will be able to lift 200kg off Everest. With long, wide blades. It's not that expensive and not a rocket science onymore.