The current atmospheric conditions on both Venus and Mars present significant challenges for human habitation, and they would require extensive modifications and technological advancements to make them suitable for long-term human presence. Here's an overview of the conditions on each planet:
Venus: Venus has a thick atmosphere composed mainly of carbon dioxide with extremely high pressure and temperature. The surface temperature averages around 900 degrees Fahrenheit (475 degrees Celsius), hotter than the surface of Mercury despite being farther from the Sun. The atmosphere also contains sulfuric acid clouds and experiences intense greenhouse effect, making the surface inhospitable for humans. Additionally, Venus has no breathable oxygen, and the atmospheric pressure is about 92 times that of Earth at sea level. The extreme conditions on Venus make it currently unsuitable for human habitation without significant terraforming efforts.
Mars: Mars has a thin atmosphere composed mostly of carbon dioxide, with a surface pressure about 0.6% of Earth's atmospheric pressure. The average surface temperature on Mars is around -80 degrees Fahrenheit (-62 degrees Celsius), much colder than Earth's average temperature. The thin atmosphere also means that Mars lacks a significant greenhouse effect, resulting in low average temperatures. Furthermore, Mars has no breathable oxygen, and the atmosphere offers little protection from radiation. However, Mars' conditions are relatively more favorable for human habitation compared to Venus. Future colonization efforts would require extensive life-support systems, protective habitats against radiation, and the ability to grow food in controlled environments.
In order to make these planets habitable for humans, various technologies and processes would need to be developed, such as terraforming to modify the atmosphere, creating artificial habitats, generating sustainable food and water sources, and providing protection from radiation. These endeavors would require significant scientific advancements, engineering capabilities, and long-term planning.
It's worth noting that current missions to Mars, such as those by NASA and private space companies, are focused on exploration and studying the potential for past or present microbial life. The prospect of human habitation on Mars or Venus remains a complex and challenging goal for the distant future.