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 ...