Is water enough to find alien life? New research reveals phosphorus and nitrogen are crucial. Discover the 'chemical Goldilocks zone' that makes a planet truly habitable.
For many years, scientists looking for signs of alien life have mainly focused on finding planets that have water. Water has often been considered a key element needed for life to exist. However, some researchers now believe that this approach might not be enough. They suggest that even a planet with large oceans could still be lifeless if it is missing certain important chemicals.
Essential Elements
New research shows that phosphorus and nitrogen might be even more important than water alone. These elements are essential for life on Earth. Phosphorus is necessary for building DNA and RNA, which store and transmit genetic information. Nitrogen is a vital part of proteins, which help form and operate all living cells. Without these elements, life as we know it cannot develop.
Chemical Goldilocks Zone
The scientists have identified a narrow “chemical Goldilocks zone.” This doesn’t just mean being at the right distance from a star to have liquid water. It also means having the correct chemical balance inside the planet. In particular, the amount of oxygen present when a planet first forms is very important.
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Planetary Formation Balance
When a young planet cools down from a molten state, heavy elements like iron sink toward the core, and lighter materials form the outer layers. If there is too much oxygen, phosphorus can become trapped deep within the planet, while nitrogen may escape into the atmosphere and be lost to space. If there is too little oxygen, phosphorus can be pulled down into the core along with heavy metals. In both situations, these life-supporting elements are no longer available near the surface, where life needs them.
Rare Habitable Worlds
Using computer models, the researchers discovered that only a very narrow range of conditions allows both phosphorus and nitrogen to stay accessible in the planet’s outer layers. Earth seems to fit within this rare chemical balance. This could mean that truly habitable planets are far less common than previously believed, possibly only a small portion of what was once thought.
Implications for Exploration
These findings might also influence how we explore space. A planet with lots of oxygen and water might still be unsuitable for farming or colonisation if it lacks phosphorus. Closer to home, Mars has enough phosphorus but not enough nitrogen at the surface, and its soil contains harmful salts, which makes it unsuitable for life as it exists today.
In the future, scientists may need to pay more attention to the chemical composition of distant planets. One way to get clues is by studying the stars they orbit, as planets and stars form from the same material. Systems with stars similar to our Sun might offer the best chance of finding life elsewhere in the universe.
Source: Daily Mail - Science & Tech
