“Where did life come from?” is one of those questions that keeps people awake at night, and no matter the many plausible ideas, we have not solved this problem yet. An interesting step forward comes from an international team of researchers who have shown that the building blocks of life can form in space.

The team constructed an artificial comet at the Institut d’Astrophsique Spatiale in Paris and then simulated the conditions of interstellar ice in the early Solar System. They discovered the formation of several sugars, including ribose, a fundamental building block of DNA, and thus life.

The artificial comet was created by placing a mixture of water, methanol and ammonia in a vacuum chamber at -200°C (-328°F). The sample was first exposed to ultraviolet light and then warmed up to room temperature, recreating what a comet approaching the young Sun would experience. The findings were published in Science.

This discovery is the first sign that ribose can form in space but it’s not the first evidence of organic matter in asteroids and comets. Even Philae, the European Space Agency comet lander, was able to detect, in its short life, organic material on Comet 67P/Churyumov-Gerasimenko.

Sugars, and ribose in particular, are fundamental for life. Ribose is the subunit in RNA, which could have been the first complex life molecule to form, and from which the DNA in every living organism has evolved.

The findings strengthen the idea that life formed elsewhere in the universe, and it was seeded by comets in Earth’s past. But they also suggest that the elements for life might be a lot more common if important sugars can be formed in protoplanetary nebulae.

Panspermia, the idea that comets spread life, is one of the many possibilities put forward for how life started on Earth. Underwater volcanic vents, lightning, ice or clay beds are the potential other mechanisms that allowed the first organic molecules to form and subsequently thrive.