Sugar, spice, and everything nice. Those are the ingredients that Professor X use to bring the Powerpuff girls into life. According to Johns Hopkins researchers, they discovered that sulfur is indeed a 'spice' that can point to signs of life.

Evidence of life on other planets

Lab simulations reveal that sulfur can meaningfully affect planetary observations, especially those planets that are beyond our solar system. These findings imply the use of sulfur as a sign of life on another planet, as well as its effects on the researchers' method in interpreting data of planetary atmospheres.

The researchers published their findings today in the Nature Astronomy journal.

Chao He, an assistant research scientist in the Department of Earth and Planetary Sciences at The Johns Hopkins University and the study's first author, said, "We found that just a small presence of sulfur in the atmosphere, less than 2%, can have major impacts on what, and how many, haze particles are formed."

These findings entirely change what things the researchers should focus their search on and what to expect on planets beyond our solar system.

The discovery of the presence of the sulfur in other planets is unique as its presence in Earth, Venus, and Jupiter is known by many and how it influences the photochemistry of those planets. Its role is an essential element for life on Earth, and researchers propose using sulfur such as those from plants and bacteria to use in the search for life beyond Earth.

Simulating planetary atmospheres

Researchers have already performed studies simulating planetary atmospheres with sulfur inside the laboratory since it has high reactivity and challenging to clean up after the experiment. The primary purpose of the first-lab run simulation is to study further the sulfur's role in the exoplanet atmospheres.

Chao and his colleagues conducted two sets of experiments utilizing carbon dioxide, carbon monoxide, hydrogen, water, nitrogen, and helium to guide their initial gas mixtures. In one experiment, they included 1.6% sulfur, and the other one did not.

The team exposed the gas mixture to one of two energy sources once it is already inside the chamber. These two energy sources are plasma from an alternating current glow discharge and an ultraviolet lamp.

Plasma is an energy source that is stronger than the ultraviolet light. It can simulate electrical activities such as lightning. On the other hand, the main driver of chemical reactions in planetary atmospheres like Earth is the ultraviolet light.

The researchers then analyze solid particles and gas formed during the experiment. They found that the mixture with sulfur has three times more haze particles, and most of it is organic sulfur rather than sulfuric acid or octasulfur, which previously believed would make up the majority of sulfur particles on an exoplanet.

This truly would change the researchers' explanation of spectra they see, according to Chao. Likewise, it should also direct researchers to expect more haze particles in observing exoplanets with sulfur and is also critical for future studies on exoplanets.

But the major implication of the study's findings is for the scientists to take caution and rule out photochemically-produced sulfur before suggesting that the presence of sulfur is a sign for life.

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