Instead, at best NASA can hope to find signs of extremely basic or single-celled life.
The space agency said: “Among our discoveries about Mars, one stands out above all others: the possible presence of liquid water on Mars, either in its ancient past or preserved in the subsurface today.
“Water is key because almost everywhere we find water on Earth, we find life.
“If Mars once had liquid water, or still does today, it is compelling to ask whether any microscopic life forms could have developed on its surface.”
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