The intriguing mounds of Juventae Chasma revealed by Mars Express
Intriguing mounds of light-toned layered deposits sit inside Juventae Chasma, surrounded by a bed of soft sand and dust.
The origin of the chasma is linked to faulting associated with volcanic activity more than 3 billion years ago, causing the chasma walls to collapse and slump inwards, as seen in the blocky terrain in the right-hand side of this image.
At the same time, fracturing and faulting allowed subsurface water to spill out and pool in the newly formed chasm. Observations by ESA’s Mars Express and NASA’s Mars Reconnaissance Orbiter show that the large mounds inside the chasma consist of sulphate-rich materials, an indication that the rocks were indeed altered by water.
The mounds contain numerous layers that were most likely built up as lake-deposits during the Chasma’s wet epoch. But ice-laden dust raining out from the atmosphere – a phenomenon observed at the poles of Mars – may also have contributed to the formation of the layers.
While the water has long gone, wind erosion prevails, etching grooves into the exposed surfaces of the mounds and whipping up the surrounding dust into ripples.
The image was taken by the high-resolution stereo camera on ESA’s Mars Express on 4 November 2013 (orbit 12 508), with a ground resolution of 16 m per pixel. The image centre is at about 4°S / 298°E.Credits: ESA/DLR/FU Berlin (G. Neukum)
The 2013 Geminid meteor shower peaks today! (and on the nights of December 13-14)
Although the Geminid shower favors the Northern Hemisphere, it’s visible from the Southern Hemisphere, too. The Geminids start streaking the sky by mid-evening in the Northern Hemisphere, but people at temperate latitudes in the Southern Hemisphere may have to wait until late evening, or close to midnight, to see the beginning of the meteor shower. (More information. Full video.)
Clear sky to everyone!
Comet ISON above Canary Islands by Juan Carlos Casado
Ring Around the Sun
From New Zealand’s Aoraki Mt. Cook National Park a glorious halo circled the sun over the snowcapped and cloud-shrouded mountains of the rugged Southern Alps.
Such beautiful celestial displays occur when tiny ice crystals form in the Earth’s upper atmosphere and refract and reflect sunlight in a ring 44 degrees across. - Dennis Mammana
Oxygen: The Molecule That Made The World | Personal Notations
I highly recommend this book to anyone who is interested in well, all things science. Chemistry, physics, astrophysics, astrobiology, geology, paleontology, zoology, biodiversity, marine biology, glaciology, oceanography, entomology, micro/biology, archaeology, paleobiology, genetics, neuroscience/biology - it’s all here.
"The working assumption has always been that we must make the best of limited resources, invested over a probable lifespan in the wild. Neither of these conditions - limited resources or probable mortality in the wild from predation, starvation, infection and accident - is the same now as it was for our first human ancestors."
Author Nick Lane, a biochemist whose focus was on oxygen free-radicals and metabolic function in organ transplants, is responsible for developing interactive approaches to medical education.
I don’t want to develop too long of a post about this but I’ve been meaning to share this with all of you because it’s extremely relevant regarding: principles of science/scientific literacy, the search for life elsewhere in the cosmos/Earth itself, ageing, auto-immunse diseases, cancer, biodiversity throughout Earth’s history, antioxidants/free radicals and the present theme throughout the book - oxidative stress.
Nick Lane takes you back to the beginning, 4 billion years back, to delve into the various climactic, biological, atmospheric and cosmic events responsible for the oxygenic turbulence our planet has endured, why it matters that we study atmospheres other than our own in the solar system/universe, how the lack of or abundance of oxygen has radically shaped life on Earth, and why we should care about the period of time we’re presently living in pertaining to the amount of oxygen we breathe and how important it is that we do not tip that scale.
In the sense that animals and plants have fixed lifespans, longevity is obviously written in the genes. This does not mean there is a formal genetic programme, any more than a car is programmed to become obsolete over 20 years. In the case of a car, the parts are designed rom the beginning to last for only so long, and the fact that they wear out simultaneously is no evidence of the workings of a hidden programme. An apocryphal story tells of Henry Ford looking at a junkyard filled with Model Ts. "Is there anything that never goes wrong with any of these cars?" he asked. Yes, he was told, the steering column never fails. "Then go and redesign it," he said to his chief engineer. "If it never breaks we must be spending too much on it."
Natural selection works in the same way. If an organ works well enough for its deficiencies not to constitute an adverse selective pressure, then natural selection has no way to improve on it. Conversely, if an organ works better than required (in new circumstances), the random accumulation of negative mutations over generations will gradually degrade its performance to that required, at which point selection pressure will maintain the standard. For this reason, animals that have adapted recently (in evolutionary terms) to permanent darkness in a cave or at the bottom of the ocean often have vestigial eyes that are no longer functional. Degradation to a common denominator is alone sufficient to explain the apparently synchronous wearing out of organ systems as we age. As John Maynard Smith put it, “synchronous collapse does not imply a single mechanism of senescence (ageing).”
With a copyright date of 2002, we’ve learned much since the writing of this book, certainly, but Oxygen: The Molecule That Made The World is as current as any. To appreciate the present ongoings of genetic and molecular research, it’s important to understand the arduous history that this influential molecule has had on our fragile spaceship Earth.
Oxygen = (Greek) “acid former” in the mistaken belief that oxygen was necessary for the formation of all acids: sulfuric/nitric, not hydrochloric; prolonged exposure results in death
+ Oxygen toxicity discovered by SCUBA (self-contained underwater breathing apparatus) divers in the later 19th century
+ Pure oxygen below 8m/26ft causes seizures similar to an epileptic grand-mal
+ (1942) The term “Oxygen Pete” originated by the British Royal Navy as oxygen poisoning became referred to by divers as “getting a Pete”
“Unique events are best described by singular circumstances.”
ATP (adenosine triphosphate) = “energy currency” of all cells
Rubisco = binds carbon dioxide into carbohydrate in photosynthesis
+ Most abundant/important enzyme in the world (works for and against)
Catalase = getting rid of hydrogen peroxide
Carnitine = shuttles fats into mitochondria for use as fuel along with removing leftover organic acids, which Vitamin C synthesizes
SOD (superoxide dismutase) = enzyme that eliminates free radicals
+ (1969): Most important discovery in all of biology by James McCord and Irwin Fridovich
Photorespiration = stunts plant growth if atmospheric oxygen levels are high
Senescence aka “ageing” = the loss of function over the years
Antagonizing Pleiotropy = our genes are out of step with our lifestyle
Paul Bert (French physiologist, 1878)
+ discovered barometric pressure, invented the hyperbolic chamber, tested pressure on animals
James Lorrian Smith (Pathologist, 1899)
+ Discovered lower levels of oxygen pressure = death
+ 75%+ pressure = inflammation
+ Royal Navy
+ Subjected himself to experiments of varied oxygen concentrations
+ Responsible for discovering nitrox mixtures to lower oxygen toxicity and nitrogen narcosis, otherwise known as “the bends”
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+ astronauts were breathing in 33% pure oxygen via the adjustment to the atmospheric pressure in space
+ on ground, the capsule was pressurized higher and ventilated with pure oxygen = 130% pure oxygen
+ the spark in the capsule ignited a fire which accelerated temperatures up to 2,500 degrees (C)
Black Sea aka “the Euxine” (foul-smelling)
+ Largest body of poorly oxygenated water in the world, developed 7,500 years ago
+ Isolated in its own basin by a land bridge across the Bosphorous, which collapsed due to natural geologic processes
+ “Noah’s flood” was the result of this collapse, pouring into the Mediterranean at 10 cubic miles (42 million cubic meters) per day = 130 times greater than Niagra Falls
+ Black Sea and Mediterranean water mixed, resulting in extreme salinity whereby salt sank to the bottom, restricting oxygen and providing an environment for anaerobic (oxygen-hating) bacteria to flourish
+ Anaerobic bacteria generate hydrogen sulphide as waste = hydrogen sulfide reacting with any trickling down of oxygen, resulting in sustainability
Principle of mass balance = what is buried below the ground cannot be found above ground
+ Carbon decay rates (-12, -13, -14) determine geologic age and oxygen levels/presence
Glaciation/plate tectonics provided oxygen via non-biological factors for PreCambrian life = Cambrian explosion
+ biological activity betrayed by enrichment of carbon -12 buried in organic matter (coal) and enrichment of cabron -13 in carbonate rocks (limestone)
+ 90% of coal reserves date to a period of time less than 2% of Earth’s history; rate of coal burial = 600X faster than average of all time
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LUCA = “Last Universal Common Ancestor”
+ resilient to oxygen toxicity before oxygen/photosynthesis was present
+ Discovered splitting of water by radiation
Henry John Horstman Fenton = (1890) developed “Fenton Reaction”
+ Hydrogen peroxide and iron catalyst used to oxidize contaminants/destroy organic compounds, prohibiting or restraining oxygen surplus
+ Discovered radioactivity via uranium, first developing polonium and radium
"There are said to be more molecules in a single glass of water than there are glasses of water in all the oceans. We should not be too surprised to discover, then, that 100 billion molecules of hydrogen peroxide weigh about 56 thousand billionths of a gram. To put these numbers into some sort of perspective, Kasting calculates that dissolved hydrogen peroxide, which is much more soluble than oxygen, accounts for between 1 and 6 percent of the total oxidant concentration in rainwater today. There is no reason why the amount of hydrogen peroxide in rainwater should have been any less 3 billion years ago, and it may well have been higher, as the intensity of ultraviolet radiation was more than 30 times greater."
Viewing evolution through the prism of oxygen gives us some surprising perspectives on our own lives and deaths. If water is the foundation of life, then oxygen is its engine. Without oxygen, life on Earth would never have got beyond a slime in the oceans, and the Earth would probably have ended its days in the sterility of Mars or Venus. With oxygen, life has flourished in all its wonderful variety: animals, plants, sex, sexes, consciousness itself. With it, too, came the evolution of ageing and death.
We cannot hope to understand the complex degenerative diseases of old age unless we have an evolutionary grasp of their cause. Evolutionary theory can take us so far, but will fail unless backed by empirical evidence. In the same way, the sixteenth-century scientist Francis Bacon famously argued that philosophy could never answer the great questions of life and death without the guiding light of experiments. We should not forget that science was born from philosophy, in other words from a system of ideas about the world. Experiments allow us to weigh the value of competing ideas that cannot be discriminated on a logical basis; but for science to be meaningful, experiments must be conducted within the framework of an idea - a hypothesis - about how the world works. Science does not work by induction - by trawling piles of miscellaneous data in the hope of finding patterns or facts - but by hypothesis and refutation.