In Search of Panspermia
When scientists approach the question of how life began on Earth, or elsewhere, their efforts generally involve attempts to understand how non-biological molecules bonded, became increasingly complex, and eventually reached the point where they could replicate or could use sources of energy to make things happen. Ultimately, of course, life needed both.
Researchers have been working for some time to understand this very long and winding process, and some have sought to make synthetic life out of selected components and energy. Some startling progress has been made in both of these endeavors, but many unexplained mysteries remain at the heart of the processes. And nobody is expecting the origin of life on Earth (or elsewhere) to be fully understood anytime soon.
To further complicate the picture, the history of early Earth is one of extreme heat caused by meteorite bombardment and, most importantly, the enormous impact some 4.5 billion years of the Mars-sized planet that became our moon. As a result, many early Earth researchers think the planet was uninhabitable until about 4 billion years ago.
Yet some argue that signs of Earth life 3.8 billion years ago have been detected in the rock record, and lifeforms were certainly present 3.5 billion years ago. Considering the painfully slow pace of early evolution — the planet, after all, supported only single-cell life for several billion years before multicellular life emerged — some researchers are skeptical about the likelihood of DNA-based life evolving in the relatively short window between when Earth became cool enough to support life and the earliest evidence of actual life.
So what else, from a scientific as opposed to a religious perspective, might have set into motion the process that made life out of non-life?
One long considered yet generally quickly dismissed answer is getting new attention and a little more respect. It invokes panspermia, the sharing of life via meteorites from one planet to another, or delivery by comet.
In this context, the question generally raised is whether Earth might have been seeded by early Martian life (if it existed). Mars, it is becoming increasingly accepted, was probably more habitable in its early period than Earth. But panspermia inherently could go the other way as well, or possibly even between solar systems.
A team of prominent scientists at MIT and Harvard are sufficiently convinced in the plausibility of panspermia that they have spent a decade, and a fair amount of NASA and other funding, to design and produce an instrument that can be sent to Mars and potentially detect DNA or more primitive RNA.
In other words, life not only similar to that on Earth, but actually delivered long ago from Earth. It’s called the The Search for Extraterrestrial Genomes, or SETG.