Photo: The Viking Project/NASA
NASA has been trying to dampen expectations for an upcoming Mars announcement after rumours abounded that the agency’s Curiosity rover discovered something big.”rumours and speculation that there are major new findings from the mission at this early stage are incorrect,” NASA officials wrote in a statement on Thursday (Nov. 29). “The news conference will be an update about first use of the rover’s full array of analytical instruments to investigate a drift of sandy soil.”
The announcement will be made at the Fall Meeting of the American Geophysical Union in San Francisco on Monday (Dec. 3).
In light of this latest saga, we took a look back at the five most overhyped Mars discoveries in years past.
On June 22, 2000, NASA announced it had found evidence for liquid water currently flowing on the surface of Mars.
The news, based on photos of gullies etched across the Martian surface taken by NASA's Mars Global Surveyor, made a big splash.
The gullies seemed to have been formed by flowing water, and debris and mud deposits nearby suggested liquid water as well.
What's more, researchers at the time judged the structures to be freshly formed, implying that liquid water exists on Mars today.
However, in the more than 10 years since the announcement, scientists have yet to confirm the gullies are caused by flowing water, or offer definitive proof of water on Mars today.
While experts mostly agree that water ran over Mars' surface in the ancient past, there is lingering disagreement over the present day.
A small piece of Mars landed in Antarctica about 13,000 years ago in the form of meteorite, which was discovered in 1984 and called ALH84001.
This rock was subsequently found to contain a mineral called magnetite, which on Earth is associated with the presence of microorganisms.
Carbonate materials in the meteorite also indicate that liquid water was present when it formed, at least 16 million years ago.
Taken together, some construed these findings as evidence that Mars once had microbial life.
However, most scientists caution that the magnetite may not have a biological connection, and that the rock doesn't offer any solid proof.
Additionally, claims that small structures inside the meteorite appear to be fossilized nanobacteria have met with scepticism, and stirred more controversy.
NASA's first-to-Mars landers, Viking 1 and 2, which touched down on the Red Planet in 1976, were sent explicitly to look for life.
One experiment did appear to find evidence for metabolic reactions, which its leaders announced as proof of life on Mars.
The claim was big news, but many other scientists rejected the life interpretation, suggesting instead that the reactions were caused by nonliving agents in the Martian dirt.
In the ensuing years, the Viking life-detection experimenters Gilbert Levin and Patricia Ann Straat have stood by their claims, but no rock-solid evidence for microbes on Mars has ever been found.
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