Recent research confirms that water existed on Mars as far back as 4.5 billion years ago, with ice still present beneath the surface today. However, the burning question remains: Did Mars once ...
More than 3 billion years ago, Mars intermittently had liquid water on its surface. After the planet lost much of its ...
Johnson reports the crater can be seen today only in a 35-mile wide dome that marks exactly where the asteroid impacted.
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