“We often assume that Earth is a model of habitability, but if you look at it in isolation – we don’t know where the boundaries and limits are,” says Stephen Kane of the University of California, Riverside. “Venus makes it possible for us.”
A new study compiles a large amount of known information about Earth and Venus. It also describes Venus as a foothold for better understanding the conditions that make life impossible around other stars, writes Phys.org.
Although it has a pressure cooker-like atmosphere that would crush a human in an instant, Earth and Venus share some similarities. They have roughly the same mass and the same radius. Given its proximity to that planet, it’s natural to wonder why Earth is so different.
Many scientists believe that the insolation flux, the amount of energy Venus receives from the Sun, caused the runaway greenhouse effect that ruined the planet.
Venus receives almost twice as much solar energy as Earth. Many think that is why she is different. However, Venus does not have a moon, which gives Earth phenomena such as ocean tides and affects the amount of water, Kane says.
Aside from some known differences, scientists don’t know the size of its core, how it got to its current, relatively slow rotation, how its magnetic field has changed over time, or anything about the chemistry of its lower atmosphere.
“Venus has no detectable magnetic field.” It may be related to the size of the core. The size of the core also tells us how the planet cools itself. Earth has a core mantle that circulates its heat. “We don’t know what’s going on inside Venus,” Kane says.
The interior of a terrestrial planet also affects its atmosphere. This is the case with Earth, where our atmosphere is largely the result of volcanic release of gases.
NASA is planning missions to Venus for the end of this decade. The DAVINCI mission will probe the acidic atmosphere to measure noble gases and other chemical elements. Measurements will be made from the top to the bottom of the atmosphere, helping to build new climate models and predict such atmospheres elsewhere, including on Earth, as we increase carbon dioxide.
The VERITAS mission, led by the Jet Propulsion Laboratory, will not land on the surface, but will allow scientists to make detailed 3D reconstructions of the terrain, revealing the existence of active plate tectonics or volcanoes. Maps of Venus are currently incomplete. It is very different to know how active a surface is and how much it has changed over time. We need both types of information, Kane says.
One of the reasons for these missions is the ability, with better data, to use Venus to confirm conclusions about life on distant planets. We will never have in situ data for an exoplanet. That’s why we need to understand Earth-sized planets that we can visit, and Venus gives us that chance.
Another reason to explore Venus is that it provides a glimpse into what Earth’s future might look like.
“We have to protect the future of our planet.” There are lessons to be learned from studying the processes that made today’s Venus, especially if Venus had a milder past that is now destroyed. It can happen to us too. The question is how and when,” says Kane.
(Telegraph Science/Phys.org)
