The fog of discovery
When I first heard about the methane observations a while back, I thought they were pretty amazing. I could not figure out why people were not making a bigger deal out of the story. In fact it is hard to imagine another possible methane source besides living organisms like terrestrial methanogenic bacteria. (On the other hand, our failure of imagination is no proof that Mars has not thought up an alternate, wholly non-biological process to produce it!)
So, is there life on Mars? It is maddeningly hard to say, even now! I had always imagined that if life did indeed exist there, then there would be a particular moment, a revelation, a "Eureka!" But maybe it won't happen that way at all. Maybe we will later realize that we've been seeing the growing evidence for years:
- The still-perplexing (to me, anyway) Labeled Release experiment results from the Viking landers in 1976;
- The controversial microscopic and chemical evidence from Martian meteorite ALH 84001;
- The increasingly understood history of flowing and standing water on the ancient Martian surface;
- And now the queerly variable methane content of the present-day atmosphere.