Toward Alternative Earths' Habitability of Solar System Bodies at Earth's Orbit

This paper presents the first structured evaluation of Solar System bodies hypothetically relocated to Earth orbit (1 AU) to assess their potential as alternative habitats. Using comparative criteria, planetary size and gravity, atmospheric retention, volatile accessibility, weather system potential, soil development feasibility, and orbital transfer cost. We find that most bodies are unsuitable. Mercury and the Moon lack volatiles and atmospheres, while gas and ice giants offer no solid surfaces. Venus, despite strong atmospheric retention, remains constrained by extreme greenhouse forcing. Mars emerges as the most viable candidate, balancing accessibility and volatile resources. Titan provides a conditional long-term promise, with a dense atmosphere and rich organics that could transition to a water-based cycle at 1 AU. These findings highlight new pathways for planetary engineering and long-term human survival.