Saturday 16 June 2012

Moebius, Major Gruber, and Rusps (Rusps II /Archives V)

Click to enlarge; copyright Casterman 1995

Click to enlarge; copyright Casterman 1995

Click to enlarge; copyright Casterman 1995

Jean Giraud (also known as Moebius or Gir) died on March 10 this year. I first encountered his work in the seventies, probably in the magazine 'Métal Hurlant'. I do not think anyone disputes that he was a Grand Master of what the French call the Ninth Art ('Neuvième Art'): 'bandes dessinées', or 'comics'. You might that, regardless of his qualities, his work does not really belong here; while he did draw alien animals and plants, you could see that they were never meant to be realistic. The ones above prove that point, I think, while also underlining the facility with which he drew. To get another view of that, here is a YouTube take of him at work.

Click to enlarge; copyright holder unknown to me

The image above appeared on the cover of Métal Hurlant in 1976. Such images came as a welcome shock at the time. The way had perhaps been prepared by underground comics, but there still was else nothing like it; remember that science fiction films were not mainstream at all, and that computer-generated imagery was in fact science fiction. The cover impressed me so much that it stayed in memory to the present day. Major Gruber, the main character, just exudes character (stiff upper lip anyone?), as does his alien assistant. But look at that 'wall' behind him: it is part of the head of an animal slain by the 'great human hunter' Major Gruber. You cannot see the head well, partly because it is such a large animal, and partly because it is obscured by lettering, which does not hurt the design. This seems to be a magnificent example of telling a better story by not telling all of it.

So when does the major meet rusps? Well, he doesn't really, but just wait. Once rusps had evolved their imaginary existence, their place in the ecosystem required attention, so specialised armoured predators started ramming their way through the rusps' carapaces, keeping their heads tucked away below their bodies to avoid being blinded or decapitated by the rusp's whips. But after imagining this first onslaught, the question came up why rusps would stand still while attacked in this way? Could even a troupe of such predators bring a rusp to its many knees? Perhaps, but the losses to the predators would probably be unacceptable. An obvious solution would be to introduce a mega-predator, so large and strong that it could attack an adult rusp and expect to win. For reasons unclear to me I do not find that concept appealing; for now, adult rusps do not suffer from predation. But rusps die anyway, and a dead rusp constitutes a mountain of succulent meat.

Click to enlarge; copyright Gert van Dijk

Above is my first image of an animal working its way into a rusp carcass, at left. The right panel shows a specialised rusp predator, or perhaps a scavenger. It is not fast but very sturdy, and its two 'raptorial appendages' have developed into two different shapes. The left one is the prototypical blunt instrument, while the right is more useful as a scraper, to reach those parts where other scavengers cannot.

Click to enlarge; copyright Gert van Dijk

My sketchbooks show more versions of this particular scene, in between a variety of other topics. Here are three different versions from different periods. Do you see the influence of Moebius' scene in the back of my mind? The scavenger looks back towards the camera in the same way as the major looks into it. As for the dead rusp, I contemplated showing it as a wall of carapax over a tangle of collapsed legs, directly facing the camera; but would anyone understand what they were looking at? In Moebius' case, the wall was recognisable as a head. The three-quarter views represent moments where I thought I should provide more clues, while the straight-on views were more daring in this respect: the viewer would not know what kind of animal was dead here.

Click to enlarge; copyright Gert van Dijk

I later felt that perhaps the perspective of the predator was too complex. To see if I could improve on the sketches, I recently did a quick rough sculpt of such an animal in Sculptris (above).

Click to enlarge; copyright Gert van Dijk

I then imported the model into Vue Infinite (left), and exported the image into Painter 12 to paint over. Some very rough brush strokes indicate the structure and legs of the rusp. It is not too bad, but still definitely needs more work; perhaps the design works better on a square canvas. Once I feel that I can do the idea justice I will finally paint that scene, and I will be glad and than to have been inspired, as have many others, by Jean Giraud / Gir / Moebius.

Click to enlarge; from 'Faune de Mars'; copyright Moebius.
This is from a small book only available through Moebius' official site here.

Saturday 2 June 2012

The black, black grass of home...

Black? I hoped that by substituting 'green' with 'black' in the title of this evergreen ('everblack'?), your mind would create an image in which plants are suddenly no longer green but black. Plants hardly ever feature as more than background material in science fiction. SF artists may try to come up with odd plant shapes, but the general colour of your generic SF plant is green. Personally, I also often used green plants in my Furahan paintings without conscious thought.

Click to enlarge; copyright Gert van Dijk

What you see here are 'blackgrasses' on Furaha. In effect, they are largely brownish, but in this case at least I did not fall for the 'plants are green' trap. There are exceptions to ubiquitous greenery though, and the best-known one is probably Well's Martian 'red weed'. Anyway, perhaps it is time to think a bit harder about the colour of plants, first on Earth, then elsewhere. This post will be a bit technical; sorry for that. For more thoughts on this issue, see here and here.

The 'green, green grass of Earth' may trigger associations chlorophyll and photosynthesis ('chloro' means 'green' and 'phyll' is derived from 'leaf' in classical Greek, so it means 'green leaf stuff'). Photosynthesis concerns the trick of capturing the energy in light and transferring it to chemical energy (ATP), and chlorophyll is at the centre of that trick: it captures a photon, setting loose an electron that sets a cascade of motions going. As Chlorophyll is green, you might think that a green colour is good for photosynthesis. It is not: green light is almost useless for photosynthesis using chlorophyll.

Click to enlarge; from Wikipedia

Remember that what we call white light is a composite of a range of wavelengths in the electromagnetic spectrum, ranging from deep purple through blue, green, yellow and red to deep red. It is no coincidence that we call that portion 'visible light'. When light falls on an object some wavelengths are absorbed, while others are reflected. If an object looks green to us, that means that green light is reflected, meaning it is NOT used by photosynthesis. Above is an image of the absorption spectrum of two chlorophyll variants. A peak at a specific wavelength means that light at that wavelength is absorbed and used by chlorophyll. There are peaks in the red and blue parts of the spectrum, but not in the green portion of the spectrum. Does that matter? The answer depends on whether there is in fact a lot of light in that part of the spectrum, so let's compare the absorption spectrum of chlorophyll with the light output of the sun.

Click to enlarge; from Wikipedia

The atmosphere selectively absorbs some wavelengths, so what is relevant is how much of each wavelength reaches the Earth's surface. That is shown above. Try to find the visible part of the spectrum , from about 350 to 750 nanometer. You will see that there is a lot of light there.

Click to enlarge; from here

Here is a graph combining all the previous information. Note that the title states that chlorphyl is well-adapted to use solar energy. Well, yes, in the sense that it is roughly sensitive to light in the area where there is most energy. However, there is this big conspicuous gap, meaning that lots of light is unused by plants, mostly of the green variety. In fact, Earth plants would get on quite well if the sun did not emit all that energy at green wavelengths. (We would not like that though, as there would be about 40% less light to see with, and our ability to see details would be harmed as that depends to a large extent on green light; but that is another matter).

All this suggests that chlorophyll is not the best of all possible light absorbers on Earth. To make the most of sunlight, you would want a molecule that is responsive to a much broader part of the spectrum. Such a molecule would reflect very little light, so it would be black or at least very dark. You can also argue that, if chlorophyll can get away with using just part of the spectrum, so could another molecule. In fact, chlorophyll is not the only molecule used in photosynthesis.

Click to enlarge; taken from this site

'Bacteriorhodopsin' is a well-known example, occurring in some bacteria. Above is a graph in which its spectrum is overlaid on that of chlorophyll. This pigment has a rather broad absorption spectrum, but with a peak at precisely the spot where you would want it, meaning where the sun puts out much light: in the green / yellow parts of the spectrum. As a result, it looks reddish. There is a theory that these bacteria formed mats overlying the very first plants. The only light they let through was at wavelengths the bacteria did not use, so chlorophyll evolved to pick up just those wavelengths. This is a fascinating idea, but one thing that has me worried is the following: if chlorophyll could evolve such a detailed sensitivity to particular wavelengths, why did it stop evolving once plants outgrew those bacteria? Wouldn't it have made sense to retune it afterwards? If it would be sensitive to green light as well we would have black plants, and if it would be mostly responsive to green light plants would be purple.

I have no idea how easily evolution can tinker with light-sensitive molecules to shift their absorption spectrum. Still, light-sensitive pigments occur in vision as well as in photosynthesis, and there is an astonishing variety of pigments for colour vision in the animal kingdom. It seems that such pigments can evolve readily. But chlorophyll seems just to be sitting there, blind to all that glorious green light. Adding insult to injury, the chemical steps following chlorophyll are also singularly inefficient. Part of the problem seems to be that there is very little CO2 in the atmosphere, and that the molecule that takes in CO2 to strip the carbon from it leaving O2, quite readily works in the wrong direction, so the work is partly undone. After all this, the calculated efficiency of chlorophyll photosynthesis is on the order of 4-7%. Seeing how life on Earth depends on photosynthesis, that is a bit worrying.

In summary, the blindness of chlorophyll to green light suggests that other molecules with a different absorption spectrum could be just as efficient (or inefficient). It also suggests that you cannot tell the colour of plants well from the spectrum of the sun in their solar system. If you apply that reasoning on Earth, you will proclaim that Earth's plants are purple...

click to enlarge; copyright Chris Webb or Scientific American

In order to show something besides graphs, I will show a nice image used on the cover of Scientific American. I found it on the website of the artist (Chris Webb) right here.

In another post I may go into the consequences of all this for alien plants. For now, just consider some parallel evolution going on, resulting in different groups of 'plants' using different pigments. Forests on such planets need not show shades of green only, but could sport a riot of colours. Ah! The green, blue, yellow, purple grass of home...