When Will We Find Another Earth?

I've been thinking about the Fermi Paradox and Great Filters a lot lately. People think that there must be Earth like planets and life, based on the sheer numbers of stars and planets in the universe. But, I think the importance of our moon and Earth's iron core are underestimated with regard to the development of life. Our moon regulates the tides on Earth, creating regularity in the biological and chemical evolution of life - critical to allowing experimental continuity in life's formation. The magnetic field from the iron core protects life from deadly radiation from the sun. Without both of these I don't think life would exist, and I think both of these are not common. Perhaps there are planets with large moons like ours, and planets with iron cores like ours, but are there many planets with both requirements? Couple these requirements with the fact that there must also be liquid water in the habitable zone, and the chances of life on another planet could be much lower than commonly believed, even given the sheer numbers of stars and planets. I hope i'm wrong. Meanwhile, my home computer is cranking away on Seti@home data, keeping the hope alive.

About 2020 perhaps with 20/20 vision. More likely by 2027 just 70 years after the first Sputnik.

Terran Nebula sounds about right to me.