If there is life, then I believe we should do nothing to disturb that life. Mars then, belongs to the Martians, even if they are microbes.
The moral of it is this: If you are of any account, stay at home and make your way by faithful diligence; but if you are 'no account,' go away from home, and then you will have to work, whether you want to or not. Thus you become a blessing to your friends by ceasing to be a nuisance to them-if the people you go among suffer by the operation.