The subject of water on Mars is one of the most highly debated in planetary science; various missions have provided ample evidence that the planet used to be a lot wetter than it is now, with rivers, lakes and maybe even oceans. Most scientists now generally agree on this, but as to how much water there was, how long it lasted and how warm the environment was, is another question. There have been apparent conflicting lines of evidence, and now findings from the Curiosity rover have only added to the mystery. Curiosity has revealed a paradox of sorts – it has found abundant evidence for ancient lakes in now-dry Gale crater, but at the same time has not found evidence for a previous thicker atmosphere with more carbon dioxide, which normally would be needed for water to remain liquid on the surface. These two lines of evidence seem to contradict each other, so how to resolve this puzzle?
Thirteen years. That is how long NASA’s Opportunity rover has now been exploring Meridiani Planum on Mars; not bad for a robot which was designed with a hoped-for nominal 90-day mission. Today marks the 13th anniversary of the landing of Opportunity, on Jan. 24, 2004 PST (Jan. 25, 2004 UTC). The mission since then has been nothing short of incredible, as Opportunity soon found evidence that Meridiani Planum used to be a much wetter place than it is now. It was a place where microbial life could have existed; whether it actually did or not is still unknown but Opportunity continues to provide more clues as it continues exploring vast sandy plains and mountainous crater rims.
The Curiosity rover has now resumed its journey toward Mount Sharp after experiencing some delays due to a faulty drill mechanism. The rover conducted a short drive over the past weekend toward a new location with “plenty of science targets to choose from.” Being on the road again is of course a relief to mission engineers and scientists, although the problems with the drill are still being diagnosed. As has come to be expected, Curiosity again made some exciting science observations in 2016, which continue to show that this region on Mars was once a lot more habitable in the ancient past, and perhaps bringing us closer to answering the question of whether life ever actually did exist there.
NASA held another press briefing this week about the latest findings from the Curiosity rover on Mars, detailing new evidence that this former lake environment was once quite hospitable for possible life. The findings were announced from the fall meeting of the American Geophysical Union in San Francisco. In a related development, there is also new evidence from Curiosity that organics have not only been definitively found by the rover, but that they may be more widespread on Mars than previously thought.
Water on Mars is one of the most talked about and controversial subjects in planetary science. It is now well-known that Mars used to be a much wetter place than it is now, although just how much water there was, and how long it lasted, is still a matter of considerable debate. Direct evidence from rovers, landers, and orbiters, including observations of ancient riverbeds, gullies, and lakes, has shown how at one time Mars was much more Earth-like than it is today. Rovers like Curiosity, Opportunity, and Spirit have actually driven over long-dried-up lakebeds, salty playa lakes, and regions of ancient geothermal activity such as hot steam vents. Now, the Opportunity rover is going to visit another feature not yet explored by any other rover or lander: a gully thought to have been carved by water millions or billions of years ago.