h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Should we assume that alien life would be cell based?

Mars is chemically inert, (AFAIK). The Earth isn't, due to the presence of life. In a James Lovelock 'Gaia' book he said this is evidence that Mars doesn't have life on it at all. There's no available energy for them to use. (That doesn't mean there *wasn't*, of course..)

Everybody seems convinced that there were once great oceans on Mars and Mississippi sized flowing rivers. So where does that leave us on the life question?

"Everybody seems convinced that there were once great oceans on Mars and Mississippi sized flowing rivers."

Who is everybody? Not any science I've ever heard about.

Come on Arnie - just google Oceans on Mars or something like that and you'll find loads of sources. And we've all seen those photos of the dry river beds. Maybe they were taken in the Grand Canyon do you think?

Yes that is quite a surreal statement! Has Lucky been reading a copy of Astronomy Now from an alternate dimension? or maybe the mistake has been made of attempting to extract facts from a tabloid newspaper.

All i remember reading about these gullies was that they were possibly caused by a flowing liquid underground, causing disturbance of the soil above. But as already stated, there are also other explanations.

OK. duly Googled. From here (first link i found)http://www.spacedaily.com/reports/Scientist_Posits_Non_Water_Source_For_Some_Martian_Gullies.html

"A planetary scientist said Thursday that some gullies lining the sides of impact craters on Mars may have been caused by dry landslides, not running water."

and

"The Martian gullies also resemble gullies on Earth that were formed by water, she noted. "My point is that you can't just look at the Mars gullies and assume they were formed by water. It may be, or may be not. We need another test to know."

So, not quite 'everybody knows' then...

I must be taking the wrong tabloids.

OK, well more reliably perhaps from New Scientist http://space.newscientist.com/article/dn10740-water-flows-on-mars-before-our-very-eyes.html

"Allan Treiman of the Lunar and Planetary Institute in Houston, Texas, US, agrees that something flowed recently to make the observed changes.
But he is not convinced that water was involved. "There is no direct evidence of water in the images – only that something flowed downhill. My money is on sand and dust, because there's lots and lots of sand and dust on Mars."

and

"The researchers suggest the deposits were made by liquid water flowing out from beneath the surface. The researchers estimate that each flow would have involved 5 to 10 swimming pools' worth of water. "


So very much in dispute i would say.. Take your bets please..

Or maybe you're just taking them on an empty stomach. Remember to follow directions carefully when swallowing tabloids

Lucky, you come on. I can google "astrology" and get some 38,000,000 hits. So that means you're going to swear by astrology now?

And the frequency of flows is completely different from the conditions you're talking about. Even the scientists who think there are water flows think that it bursts to the surfaces, travels briefly, then freezes and evaporates.

And then the Martian canals - Didn't one 'expert' actually looked through a telescope and drew a picture of them.

I think we can presume most of the water is underground caverns?

On a slightly different tack, where did all that sand come from and do they really have sandstorms on Mars do you reckon?

Sand in deserts comes from rock being exposed to intense heat during the day and cold at night. The expansion and contraction causes the rock to crack and break into small pieces, eventually ending up as sands.

Yes, they have huge dust storms on Mars, big enough to see with amateur telescopes from Earth.

Giovanni Schiaperelli 'discovered' canals on Mars. Although I think he named them 'canali' in Italian, which translates as 'channels' rather than canals.


http://www.solarsystem.org.uk/mars/ mentions the dust-storms.

Lucky, the 'expert' was Giovanni Schiaparelli in the late 19th century using some of the first telescopes. The word canal was also a mis-translation of 'channels', the word he used, so there was never an implication of vast artificial waterways.

Simulpost...

Check this out: a martian dust devil passing very close to the Spirit rover.

http://www.lpl.arizona.edu/~lemmon/mer_dd/dd_enhanced_486a.gif

Winnoch, you're a genius, so you are.

Thanks Woodpigeon, that's the first photo I've ever seen of a real live Martian!
But where does all the wind come from to make a Martian devil or a dust storm? Must be quite a bit moving air about mustn't there?
Don't suppose there's much chance of some tumbleweed or the odd cactus?

the rover did find some spent .45 shells, implying there was a large old-western style gunfight at the OK canali.