'Strange guests' from another planet carry the same thing as on Earth

Objects that once passed through Earth's skies could represent "life trains" billions of years ago.

Earth was born in the Solar System's "Goldilocks zone ," the perfect temperature for liquid water. But how water got to Earth remains a mystery.

A "strange visitor" called 67P/Churyumov-Gerasimenko , first spotted in the skies more than half a century ago, may hold the clue.

67P/Churyumov-Geramenko with ESA's Philae lander on the surface, a daughter of Rosetta on the mission that revealed the comet's special relationship with Earth - (Graphic: ESA).

A study recently published in the scientific journal Science Advances shows that 67P/Churyumov-Gerasimenko, a comet in the Jupiter family, possesses water with molecular characteristics similar to water on Earth.

Comets of the Jupiter family are short-orbit comets that, instead of traveling in a large loop from the Oort Cloud to the region near the Sun - which is also near Earth - are captured by Jupiter in a narrow orbit.

Narrow orbits allow them to return to us more frequently and provide excellent research opportunities.

According to Sci-News, to determine the origin of water on space objects, scientists often look for the ratio between deuterium (D) and normal hydrogen (H) in water.

In 2014, 67P/Churyumov-Gerasimenko was eliminated by scientists as a potential water-bearing "spaceship" when the European Space Agency's (ESA) Rosetta mission in 2014 showed that its D-H ratio is three times that of Earth's oceans.

But this time, a team led by Dr. Kathleen Mandt from NASA's Goddard Space Flight Center showed that comet dust had thrown those initial calculations off.

They used an advanced statistical computing technique to automate the process of isolating deuterium-rich water from more than 16,000 Rosetta measurements.

When the confounding factor of deuterium-rich comet dust was eliminated , the scientists showed that the actual water from the comet body was much lower in deuterium and had a D-H ratio similar to Earth's.

Therefore, they believe that this comet and other Jupiter-family comets represent the ships that contributed to building the life-filled world on Earth.

According to increasingly widely accepted theories supported by a growing body of evidence, the early Earth did not have all the ingredients for life to arise.

Over time, however, many comets, asteroids, and other small meteorites acted as "life carriers ," delivering the ingredients needed to create today's ecosystems.

These elements include water, prebiotic molecules, as well as other chemical components that facilitated the reactions that produced the first life.