WHAT NONSENSE it is all!!
It all comes out of assuming that "life as we know it" is the thing to search = which, of course, is utter nonsense by itself. In search for life on other planets we do, essentially, search for life as we do NOT yet know it. Some modesty would be to understand, that we by no means represent some "necessary universal example" of what life actually IS, or can be. We are just one specific, totally random case, of life as evolved here TO BEFIT THE GIVEN CONDITIONS HERE. First there were the conditions = a G-type mid-size yellow star, a rocky planet ~150 million KM from it, comets bringing many basic elements to it, during its formative stage… so, we evolved to fit these conditions. For US, liquid water and ~20 degrees Celsius are ideal.
Now, in all likelihood, an astrophysicist born on Saturn's moon Titan would define his "goldilock zone" as the area where METHANE AND NITROGEN may exist at liquid form and, if he is as lacking in imagination as NASA people evidently are, shall laugh at the very concept, that ANY life could POSSIBLY evolved on the burning hell that is third, blue planet. "Suppose you landed on the third planet, Bluey", he would say. "If the intense radiation from the Sun would not instantly kill you off, the insanely high temperatures = keeping 'water' [their water = liquid Methane] at gaseous state and the rocks [their rocks: Ice-7] as oceans of molten lava – combined with the poisonous gases (such as Oxygen) are bound to. No life, could possibly evolve there! It's an actual planet hell!!"
So, to summarize:
"Life as we know it" exist ONLY on Earth, and even here, it is by no means "ALL forms of Life"; throughout the Universe, most probably EVERYWHERE, there are Life as we do NOT yet know it.
Limiting our minds and closing them, is bound to prevent us from ever noticing such Life-forms, when we shall, finally, meet them face to… well, whatever-they-might-have.
"The Habitable Zone" is bullshit – unless we'd restyle it to be named "The HUMAN Habitable Zone, which is most likely hosting local life-forms, just as ANY OTHER REGION OF SPACE MOST PROBABLY DOES".