Assuming that comets brought life to Earth, some ask whether it could have started on Mars. Steven Benner, chemist at the Westheimer Institute for Science and Technology, pursues this lead because, he admits, the chances of life forming on Earth are poor:

The molecules that combined to form genetic material are far more complex than the primordial “pre-biotic” soup of organic (carbon-based) chemicals thought to have existed on the Earth more than three billion years ago, and RNA (ribonucleic acid) is thought to have been the first of them to appear.

Simply adding energy such as heat or light to the more basic organic molecules in the “soup” does not generate RNA. Instead, it generates tar.

Generally, the public learns about problems like these when a radically new research emphasis is proposed. More.