Which building blocks of life have been found in space, and which haven't?

Scientists have discovered the basic ingredients for life in asteroids and meteorites , on Mars , and around young stars .

All of those findings have come in the past few years, and upcoming missions aim to search for these building blocks of life.

But how many building blocks of life have we found in space so far? First, it's important to define what we mean by the building blocks of life.

Scientists are looking for molecules that look like those found in life on Earth, including proteins; RNA ; and lipids, the fatty molecules that make up cell membranes.

We’ve found many on sample-return missions.

The asteroid Bennu, brought back to Earth in 2023, contained all five nucleobases of DNA and RNA , along with 14 of the 20 amino acids used by living organisms.

Its sibling asteroid Ryugu also yielded all five nucleobases, including uracil , which is found in RNA.

Other techniques, like radio astronomy, look for these building blocks in distant regions of space.

Astronomers categorize the molecules they find by complexity, starting with a broad group called "complex organic molecules" (COM).

These are carbon-containing molecules with six or more atoms .

Of the 350 molecules of any kind discovered in space so far, "about 180 of them qualify as COMs," Sergio Ioppolo , an astrochemist and an associate professor in the Department of Physics and Astronomy at Aarhus University in Denmark, told Live Science.

"That cutoff is an operational convention rather than a fundamental definition of complexity." Sign up for our newsletter (Image credit: Marilyn Perkins / Future) Sign up for our weekly Life's Little Mysteries newsletter to get the latest mysteries before they appear online.

Not all COMs are building blocks of life, but some of them are.

A subgroup within COMs is a "prebiotic" molecule that scientists think may have played some role in the origin of life.