I don't see why we're obliged to care about the sanctity of Martian life. It's not an ethical question, because it doesn't involve harming any sentient being: living species don't have any inherent right to exist. Species go extinct on Earth all the time, and we aren't obliged to resurrect them.
Making humans better off (through advancing science, off-world colonization or mining) is an absolute good, and it should always take precedence over the possible extinction of non-sentient species.
Making humans better off (through advancing science, off-world colonization or mining) is an absolute good, and it should always take precedence over the possible extinction of non-sentient species.