Prospects of colonising the Red Planet are truly dire (1)
Kelly and Zach Weinersmith consider challenges to living on Mars. Fictional futures sometimes improve the Martian climate by moving the planet closer to the sun, but the more I learn, the less plausible these scenarios seem (16 November, p 48).
Back-of-the-envelope calculations suggest that moving Mars into Earth’s orbit would require energy equivalent to three full days of the sun’s total output. If we could afford at some point in the future to devote one year’s worth of global energy production to the task, at the current rate of growth we will have to wait for 12 trillion years. I won’t be holding my breath.
Prospects of colonising the Red Planet are truly dire (2)
I fear Mars would be a dreadful destination for colonising for all the reasons stated, plus the planet-wide dust storms that would kill any hope of photosynthesis for periods and interrupt solar power. And what about surviving the maddening isolation? At least on the ISS one can look out of the window at the beauty of Earth below and imagine all the other life with which we share the planet. Mars isn’t just hostile, but lethal, a place for which we have no evolutionary adaptation.
Here's why Shackleton wreck is so pristine
Reader Gerald Legg asks why the wreck of Ernest Shackleton’s ship Endurance, found at the bottom of the Weddell Sea in Antarctica, looks so good (Letters, 16 November).
There are several reasons. The cold water temperatures (-1.8掳C; 28掳F), total darkness, low oxygen and lack of sedimentation, together with the ship’s strong wooden construction, have all contributed to preserve the ship. But the most important reason for the lack of decay is the absence of any shipworms. These bore into and eat wood in other oceans and destroy wooden shipwrecks, unless the timbers are covered rapidly by mud and sediments. Shipworms aren’t found in the Weddell Sea as the water is too cold for them to survive and there is no wood for them to eat.
Those fascinated by Endurance can read more about its incredible condition in the book Endurance: The discovery of Shackleton’s legendary ship, by me and my colleague Nico Vincent.
Let's also hear it for the Bamboo Age (1)
Your article “The Botanic Age” gives welcome space to the subject of pre-Stone Age advances. It would seem important to also mention the Bamboo Age. Bamboo is nature’s fast growing construction material and it can be modified to make anything from a knife to a source of ignition, cooking pot or twisted thread. It is also a lightweight but structurally supreme material to build a raft, boat or major construction (9 November, p 32).
Let's also hear it for the Bamboo Age (2)
As a hobby willow-basket maker, I have often observed that no tools are required. A sharp knife is useful, but not necessary. Likewise, textiles and grass-fibre baskets require no tools to create.
The notion that early humans or prehumans waited for stone tools to be invented before developing other technologies is absurd. Our ancestors were smart enough to weave baskets, shelters, blankets and so on from plant fibres and sew hides with plant fibres with no durable tools required. On a cold night, a crude blanket is better than none.
Soil decline is a major threat to future farming
Neither your article on the impact of food production on the planet nor the editorial that accompanied it mentions the health and maintenance of the largest biome bar the ocean: soil. It is unlikely that wheat yields could increase by 18 per cent by 2100 if farmers keep doing what they are doing unless you could coax a crop from something that will, by then, resemble Martian regolith. A healthy soil structure is essential, if nothing else, for management of water retention and drainage (16 November, Leader and p 44).
On closer inspection, myopia is a mixed bag (1)
As a myope and optometrist, I find the term “disease” for myopia misleading. Axial length of the eye is a continuum; people whose eyes don’t grow long enough have hypermetropia/long-sight. No one says this is a disease, but it also requires spectacle correction (16 November, p 40).
On closer inspection, myopia is a mixed bag (2)
When it comes to myopia, there is a mystery that has long plagued me. After illness kept me at home for a few days, I returned to school to find I could no longer make out writing on the blackboard. A lifetime of spectacles and contact lenses to correct “short-sightedness” ensued. My mother always insisted it was scarlet fever that damaged my eyes, but others have pooh-poohed the idea, saying it was more likely to have been measles. I would like to know one way or the other.
On closer inspection, myopia is a mixed bag (3)
Myopia isn’t all bad news. Reading small print or seeing fine detail is easy even as an adult, when this acuity can otherwise fade. Perhaps an evolutionary advantage arose after fine craftsmanship became an essential survival skill.
See the moon in all its globular glory
For most of my life, my brain rendered the moon as a flat disc or crescent in the diamond-studded canvas of the night sky. However, I discovered that if I think of the moon as spherical while I look at it, it pops out that way. Instead of a flat object, I see it for what it is: a 3500-kilometre-wide globe floating beside us in space and considered by some a twin planet rather than a satellite (16 November, p 52).
Could clothes be why dogs bite faces of dead owners?
On the issue of whether grief motivates a pet dog to bite the face of a dead owner, I have seen a few human bodies that have been partly eaten by animals. I suspect most target the face because it isn’t clothed and there are easy routes to the soft interior, such as eyes, ears, nose and mouth. I doubt whether emotions play much part. Domestic pets may have more complex motivations, but clothing may be a factor for them, too (16 November, p 29).