New data from Mars suggest that it may have been hospitable to life in the past. Haven't we heard this before?
Sedimentary rock on Mars as viewed and analyzed by the Curiosity rover (NASA).
The news of the day is abuzz with the new and astounding discoveries from the Curiosity rover that Mars once had an environment conducive to life. Once it was warmer, wetter, more hospitable. Water flowed over its surface. The chemicals necessary for life’s emergence and development are present on Mars, suggesting that life may have arisen there in the distant past. So why do I have this sense of déjà vu? Perhaps because this new “result” gets trumpeted anew every few years.
The fixation on the possibility of martian life has been a constant throughout the history of the space program, starting before the first planetary mission to Mars in 1965 (Mariner 4) and then waxing and waning in likelihood every few years. Mariner 4 showed us a moon-like Mars, with a rough, cratered surface and thin cold atmosphere. The stock for martian life fell accordingly. A few years later, the twin probes Mariners 6 and 7 flew by Mars, again returning pictures of a cratered ...