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Posts Tagged ‘Alien Life’

As those of you following my blog will know, I am currently on a cruise around New Zealand, giving astronomy talks. One of my six talks is about our current understanding of whether there is (or was) life on Mars. I try to only talk about objects which are visible during the cruise, and Mars is currently visible in the evening sky, albeit a lot fainter than it was in May when it was at opposition.

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One of the talks I am giving on this cruise is our current understanding of whether there is (or was) life on Mars.

The question of whether there is life on Mars, or whether there ever has been in its history, is a fascinating one. I thought I would do a series of blogs to explore the question. But, I have to begin by saying that ANY search for life beyond Earth is predicated by our understanding of life on Earth. The only thing, it would seem, required by all forms of life which we have found on earth is water. Extremophiles show that life can exist without oxygen, without light, at high pressure, in radioactive environments; in fact in all sorts of environments which humans would find impossible. But, none of the life so far found on Earth can exist without water.

As a consequence, all searches for life in our Solar System tend to begin with the search for water. Now, it may be that life beyond Earth could have evolved to exist without the need for water. I am no chemist, but I don’t think there is anything particularly unique about water in its chemistry which makes it impossible for living cells to use some other substance. Water is the only substance on Earth which can exist in all three forms naturally (solid, liquid and gas), so it does occupy an unique place in the environment found on Earth. But, on Titan for example, methane seems to exist in all three forms. Maybe life has evolved on Titan to metabolise using methane in the same way that life on Earth has evolved to metabolise using water. We don’t know.

So, I thought I would start this series of blogs with the big news in the 1890s, that Martians had built canals on the red planet!

Schiaparelli and Martian ‘canali’

The Schiaparelli space probe which ESA sadly failed to land on Mars recently was named after Italian astronomer Giovanni Schiaparelli. In the late 1880s he reported seeing ‘canali’ on the surface of Mars. Although this means ‘channels’, it got mis-translated to ‘canals’, and led to a flurry of excitement that this was evidence of an intelligent civilisation on Mars.

The idea grew that Martians had built canals to transport water from the “wet” regions near the poles to the arid equatorial regions. The ice caps of Mars are easily visible through a small telescope, so astronomers had known for decades that Mars had ice caps which they assumed were similar to the ice caps on Earth.

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Giovanni Schiaparelli’s map of ‘canali’ on Mars, from 1888.

One person who became particularly taken with this idea of canals on Mars was American Percival Lowell. Lowell came from a rich Bostonian family, and had enough personal wealth to build an observatory in Flagstaff, Arizona. He set about proving the existence of life on Mars, writing several books on the subject. He published Mars (1895), Mars and Its Canals (1906), and Mars As the Abode of Life (1908). But, by 1909 the 60-inch telescope at Mount Wilson Observatory had shown that the ‘canali’ were natural features, and Lowell was forced to abandon his ideas that intelligent life existed on Mars.

However, his Flagstaff Observatory was to go on and make important contributions to astronomy. In the 1910s Vesto Slipher was the first person to show that nearly all spiral nebulae (spiral galaxies as we now call them) showed a redshift, the first bit of observational evidence that the Universe is expanding. And, in 1930 Clyde Tombaugh discovered Pluto at Flagstaff Observatory.

In part 2 of this blog, next week, I will talk about the first space probes sent to Mars, and the first images taken of Mars by a space probe which successfully orbited the planet, Mariner 4.

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Earlier this week it was announced that NASA’s Hubble Space Telescope had observed evidence for water geysers shooting from the surface of Europa, one of Jupiter’s larger moons. Here is a link to NASA’s press release. I was on BBC TV talking briefly about this on Tuesday (27 September), the day after NASA’s announcement.

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NASA has announced that the Hubble Space Telescope has observed water geysers emanating from the south pole of Jupiter’s moon Europa.

In fact, this announcement was additional evidence to add to a finding which had first been announced in 2013. In December 2012, astronomers used a spectroscope on Hubble to look in ultraviolet wavelengths at Europa. They found auroral activity near the moon’s south pole, and upon analysis of the spectrum of the UV emission from this auroral activity they found the spectral signatures of hydrogen and oxygen, the constituents of water.

Those 2012 observations have since been followed up using a different method. This time astronomers have observed how the Sun’s light, which is reflected from Jupiter, is affected as it passes Europa. As Europa transited in front of its parent planet, astronomers looked for signs of absorption of this light near the limb of the moon, which would be due to gases associated with Europa. Such a technique can, for example, be used to find and study the atmosphere of an extra-solar planet as it passes in front of its parent star.

Whilst not finding any evidence that Europa has an atmosphere, what the team found was that absorption features were seen near the moon’s south pole. When they calculated the amount and extent of material required to produce these absorption features they found that their results were consistent with the 2012 finding. They calculate that water jets are spewing out from the surface of Europa and erupting to a height of about 160 km from the moon’s surface.

We have had evidence since the Voyager mission in the 1980s that Europa has an ocean of water below its icy surface. This evidence was further enhanced during the Galileo mission in the 1990s. Where there is water there may be life, so it is possible that Europa’s ocean is teeming with microbial life. To find out, we need to directly study the water in this sub-surface ocean.

Unfortunately, due to the thickness of the icy crust covering its ocean, studying this water directly poses a huge challenge. We currently don’t have the capability to drill through such a large thickness of ice, although it is certainly something we would hope to do in the future. This discovery of water jets provides a much easier way to sample the water directly, and so it is quite feasible that NASA and/or ESA could send a probe to fly through the jet, take a sample of the water, and analyse it to see whether there are any signs of microbial life. This is very exciting, and is why this discovery of water geysers erupting on Europa is so important.

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This story in New Scientist Magazine caught my attention several weeks ago – “Hunting for Mars-like life a kilometre below Earth’s surface”.  Here is a link to the original story. Scientists are using the extreme environment of Boulby mine, a working salt mine in north-east England to look for extremophiles, the kinds of organisms which are able to live (and even flourish) in environments which we human beings would simply find impossible.

Scientists believe that the environment found in Boulby mine could be similar to environments found on Mars, so studying the extremophiles found deep underground in Boulby mine should help us in our quest to find evidence for life on other planets. This work will help NASA’s various rovers (both present and future ones) look in the most promising places for alien-life on the red planet.

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A few weeks ago I was asked to talk on the evening radio news about the firing of a penetrator into a large block of ice in Pendine, West Wales, which I did not know about until the BBC called me.


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The basic idea of the test was to determine some important parameters for the hoped-for one day penetration of the ice sheet of Jupiter’s moon Europa. Europa, one of the four Galilean moons of Jupiter, is thought to be one of the most likely places in our Solar System to be supporting life. This is because we know that, below a sheet of ice, there is a liquid ocean. As water is synonymous with life in our Earth-centric view of what is necessary for life, Europa is at the top of most likely places to find extra-terrestrial life.


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hello there, waht is this we have here


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