Earlier quoted context omitted.
All this terror about "contaminating" other objects in the solar system with terran life is just misguided. We should all hope to get some terran life established on them. Heck, we need to build probes full of selected terran extremophiles and spray them into the Martian atmosphere.
1. Any existing life there is, at this point, highly improbable 2. If there is any, how could terran life be competitive with it if the existing life has evolved to match the local environment over billions of years? 3. If there is existing life, how could a biologist not be able to easily distinguish it from terran life? 4. If the life there is ancient and now extinct, terran life isn't going to interfere with that
To answer part 3: We're still discovering new kingdoms of life on Earth (though it's unlikely we'll discover new domains). If localized panspermia exists within our solar system (from meteor impacts or the like) it's possible martian life and terrestrial life are related enough for the martian life to fit within the already existing family tree of terrestrial life. https://astronomy.com/news/2021/05/did-life-on-earth-come-fr...