View of terrain near Viking 1 lander on Mars, with trenches dug in the soil for the life-detection experiments. Credit: NASA/JPL

The question of whether or not the Viking landers found evidence of microbial life on Mars in the 1970s is one of the most hotly debated issues in space exploration and continues to this day. Most scientists concluded that the seemingly positive results of the Labeled Release (LR) life-detection experiments were the result of unusual chemical activity in the soil instead of life, based largely on the lack of organics found in the soil samples. This was the single biggest argument against the life hypothesis, as any microbes would need to be composed of organic material.

Results from the Phoenix mission which landed on Mars in 2008 indicated that perchlorates in the soil could explain the apparently missing organics, which would destroy any organic material. Other Earth-based studies have also shown that the Viking experiments may not have been sensitive enough to find organics at very low levels, similar to those found in soil in Antarctica or the Atacama desert, the most Mars-like places on Earth.

Now, another new study conducted over the past six years has concluded that Viking did indeed find life in the Martian soil, based on an updated anaysis of the results using mathematical complexity. The level of complexity found was similar to that in biological systems on Earth. Non-biological processes have a naturally less complex degree of order to them.

The study was published in the International Journal of Aeronautical and Space Sciences.

“On the basis of what we’ve done so far, I’d say I’m 99 percent sure there’s life there,” said Joseph Miller, from the University of Southern California Keck School of Medicine. He adds: “To paraphrase an old saying, if it looks like a microbe and acts like a microbe, then it probably is a microbe. The presence of circadian rhythmicity and a high degree of mathematical complexity or order in the LR data most likely means Viking discovered microbial life on Mars over 35 years ago.”

The data is compelling, if not definitive yet. Further results are expected to be announced next August, according to Discovery News.

The paper is available here (PDF).

This article was first published on Examiner.com.

Artist's conception of the TiME probe floating in the Ligeia Mare sea on Titan. Credit: JHU APL / Lockheed Martin

What would it be like to go sailing on one of Titan’s lakes or seas? Apart from the fact that they are composed of liquid methane/ethane instead of water in the much colder environment, they share a lot of physical similarities to their earthly counterparts. Radar images taken by the Cassini orbiter (to see through the thick, perpetually hazy atmosphere) show that they look just like lakes and seas on Earth, although they are concentrated near the moon’s poles, the north pole in particular.

If you were able to go out in a boat, it would also be a similar experience to sailing on Earth, other than the intense cold and smoggy-looking orangish sky overhead. It might also be safer though, in terms of “rough waters” – the lakes and seas on Titan have so far been found to be smoother than those on Earth, with much less wave activity, according to a new study to be published in Icarus.

With typically weak surface winds on Titan, it was determined that waves on Ligeia Mare, a large sea about 400 kilometres (250 miles) wide, wouldn’t reach any more than about a foot high under normal conditions. According to Ralph Lorenz at Johns Hopkins University Applied Physics Laboratory, “You’d notice 0.2-meter waves if you were in a rowboat, but they wouldn’t get surfers excited.”

As it turns out, we may not have to wait too long to go sailing there – a new mission, the Titan Mare Explorer (TiME), is being planned for a possible landing in Ligeia Mare in 2023. The robotic probe would drift around while taking measurement and photographs of this Titanian sea. The previous, and only probe to land on Titan so far was Huygens, which touched down in a desert region near the equator in 2005.

TiME is one of three Discovery missions being considered by NASA, with final selection scheduled for later this year. The other two are Comet Hopper, which would land on a comet multiple times and InSight, which would study the interior of Mars. Both are interesting in themselves, but if I had to choose, I’d rather go sailing on Titan; I mean how often do you get a chance to explore an alien sea?

This article was first published on Examiner.com.

Credit: NASA/JPL/University of Arizona

The Mars Reconnaissance Orbiter has taken incredible images of another giant dust devil, similar to one photographed in February, but much larger. This one, in Amazonis Planitia, is about 20 kilometres (12 miles) tall! That’s also a lot bigger than typical dust devils on Earth, more like the size of a terrestrial tornado.

There are also two animations, here and here.

Example of recurring slope lineae (RSL) in Horowitz crater on Mars. Credit: NASA/JPL/University of Arizona

Is there still liquid water on Mars? That has been one of the longest-running and most debated questions about the Red Planet. Mars has tons of water, but it is frozen in the polar ice caps and in extensive regions of permafrost underground around the planet. The thin atmosphere does contain water vapour – enough for clouds, fog, frost and snow, but it is too thin and cold for liquid water to exist on the surface.

There might be one exception however. It’s been postulated that small amounts of salty liquid water brines could persist on the surface for short periods of time. The salts allow the water to remain liquid despite the thin atmosphere (and less atmospheric pressure) and cold temperatures. Experiments on Earth have supported this idea.

They may have even been observed directly by the Phoenix lander which landed in the Martian arctic near the north pole – small droplets were seen forming on one of the lander’s legs after landing which had the appearance of water droplets. They grew, merged and slowly moved down the leg before sublimating. Phoenix wasn’t able to analyze them directly, but they looked and behaved like briny water droplets, and the soil, like in other places on Mars, was found to contain both water ice and salts. The theory is that heat from the spacecraft caused the droplets to form, possibly from the exhaust during the landing itself.

Last year, other possible evidence for such brines was found in photographs taken from orbit by the Mars Reconnaissance Orbiter spacecraft. Dark linear markings on slopes which looked a lot like liquid flowing downhill. Unlike some other streaks which might be explained by dry processes such as landslides, these ones appear during warmer months on slopes which face the equator and recur seasonally. They move downhill as dark streaks before eventually fading, as water would be expected to do.

Last week, scientists provided an update on these tantalizing features at the Lunar and Planetary Science Conference in Texas; they have not been able to come up with an explanation that doesn’t involve briny water. The number of known locations of these “recurring slope lineae” (RSL) has more than doubled, up to 15 from the previous seven. There are also currently 23 other candidates, although they haven’t yet been shown to recur; that will require further observations.

On Earth, there are similar features in Antarctica, where salty groundwater seeps downhill through the soil. According to Joe Levy of Oregon State University, ”The RSL and the [Antarctic] water tracks are both flowing like water through sediment. If it moves like water, it may very well be water.”

The evidence suggests that water may indeed still flow on Mars, albeit in small amounts. If true, it adds to our understanding of how Mars is similar to Earth in some ways (and, based on other evidence, used to be much more so in the past).

This article was first published on Examiner.com.