"Magic number" for space pioneers calculated

The "magic number" of people needed to create a viable population for multi-generational space travel has been calculated by researchers. It is about the size of a small village - 160. But with some social engineering it might even be possible to halve this to 80.

Anthropologist John Moore from University of Florida tackled the problem as part of a combined effort with space scientists to determine how in future humans might successfully undertake century-long journeys out into space.

In the past, attention has been focused on cryogenics, sperm banks and military-style modes of operation, says Moore, but "the 'right stuff' for a journey into space is the family - a million-year-old institution designed to assist reproduction."

Moore has previously studied small migrating populations of early humans and has developed simulation software - called Ethnopop - for analysing the viability of small groups.

Marriage partners

For a space trip of 200 years, perhaps eight to 10 generations, his calculations suggest a minimum number of 160 people are needed to maintain a stable population.

This would produce around 10 potential marriage partners per person, he says, and if this seems a small number, "think about how many people you dated before you got married".

Room would be at a premium on any spacecraft and reducing the number of people initially required might be desirable. Moore suggests two strategies. The first is to begin with young childless couples, echoing the practice of Polynesian seafaring colonists.

The second is to ask the space crew to postpone reproduction to later in woman's fertile period, perhaps age 35 to 40, creating longer time gaps between the generations. This measure results in a stable population of just 80 but the consequences of the increased medical risks of late childbirth have not yet been considered.

A potential concern is that small populations can suffer a damaging reduction in genetic diversity due to inbreeding, says Dennis O'Rourke from the University of Utah. He considered the same 10-generation, 200-year journey as Moore and looked at both genetic drift and inbreeding.

"The decrease in genetic variation is actually quite small and less than found in some successful small populations on Earth," he says. "It would not be a significant factor as long as the space travellers come home or interact with other humans at the end of the 200 year period."

Gene screening

O'Rourke believes that a more serious concern would be the presence of potentially damaging genotypes in the initial space pioneers. Genetic screening might well be needed, he says: "Any harmful recessive characteristics might lead to increased healthcare loads which would deplete scarce resources."

A final concern raised at the American Association for the Advancement of Science's annual meeting in Boston was the possibility of infighting. Small communities isolated for long periods at research stations in Antarctic and even families travelling on long car journeys, provide examples of how small conflicts can quickly escalate.

But Moore points out: "Some small island communities on Earth have lived in peace and harmony for thousands of years because they have developed ways of solving conflicts. These are not taken to Antarctica."

Via  newscientist.com

Batteries not required, just plug into ear cells

For the first time, an electrical device has been powered by the ear alone.

The team behind the technology used a natural electrochemical gradient in cells within the inner ear of a guinea pig to power a wireless transmitter for up to five hours.

The technique could one day provide an autonomous power source for brain and cochlear implants, says Tina Stankovic, an auditory neuroscientist at Harvard University Medical School in Boston, Massachusetts.

Nerve cells use the movement of positively charged sodium ions and negatively charged potassium ions across a membrane to create an electrochemical gradient that drives neural signals. Some cells in the cochlear have the same kind of gradient, which is used to convert the mechanical force of the vibrating eardrum into electrical signals that the brain can understand.

Tiny voltage

A major challenge in tapping such electrical potential is that the voltage created is tiny – a fraction of that generated by a standard AA battery.

"We have known about DC potential in the human ear for 60 years but no one has attempted to harness it," Stankovic says.

Now, Stankovic and her colleagues have developed an electronic chip containing several tiny, low resistance electrodes that can harness a small amount of this electrical activity without damaging hearing.

The implant was inserted into a guinea pig's inner ear and the electrodes attached to both sides of cochlear cell membranes. Attached to the chip was a low power radio transmitter.

Guinea pig

The device needed kick-starting with a short burst of radio waves, but was then able to use the electrical gradient running across the membrane to sustain the transmitter for up to five hours. Tests showed that the guinea pig's hearing was not affected.

The device works well for short durations but long-term use of the electrodes risks damaging the sensitive tissue inside the ear. The next step will be to make the electrodes even smaller, reducing their invasiveness.

Stankovic says that this is proof of concept that biological sources of energy exist that have not yet been fully considered. "A very futuristic view is that maybe we will be able to extract energy from individual cells using similar designs," she says.

A Super-Earth in the Habitable Zone of a Six-Planet System

A new super-Earth planet that may have an Earth-like climate and be just right to support life has been discovered around a nearby star by an international team of astronomers, led by Mikko Tuomi, University of Hertfordshire, and Guillem Anglada-Escude, University of Goettingen.

The new super-Earth planet exists in the habitable zone of a nearby star and is part of a six-planet system. The system was previously thought to contain three planets in orbits too close to the star to support liquid water. By avoiding fake signals caused by stellar activity, the researchers have identified three new super-Earth planet candidates also in orbit.

Mikko Tuomi said: “We pioneered new data analysis techniques including the use of the wavelength as a filter to reduce the influence of activity on the signal from this star. This significantly increased our sensitivity and enabled us to reveal three new super-Earth planets around the star known as HD 40307, making it into a six-planet system.”


Of the new planets, the one of greatest interest is the one with the outermost orbit from the star -– with a mass at least seven times of the Earth. Its orbit around the host star is at a similar distance to Earth’s orbit around our Sun, so it receives a similar amount of energy from the star as the Earth receives from the Sun - increasing the probability of it being habitable. This is where the presence of liquid water and stable atmospheres to support life is possible and, more importantly, the planet is likely to be rotating on its own axis as it orbits around the star creating a daytime and night-time effect on the planet which would be better at creating an Earth-like environment.

Guillem Angla-Escude said: “The star HD 40307, is a perfectly quiet old dwarf star, so there is no reason why such a planet could not sustain an Earth-like climate.”

Hugh Jones, University of Hertfordshire, added: “The longer orbit of the new planet means that its climate and atmosphere may be just right to support life. Just as Goldilocks liked her porridge to be neither too hot nor too cold but just right, this planet or indeed any moons that is has lie in an orbit comparable to Earth, increasing the probability of it being habitable.”

Earlier this year, the Kepler spacecraft found a planet with a similar orbit. However, Kepler 22d is located 600 light years from Earth, whereas this new super-Earth planet known as HD 40307g is much closer being located at forty-four light years from Earth.

Mikko Tuomi carried out this work as a member of the European science network RoPACS (Rocky Planets Around Cool Stars) - an initiative with a research focus on the search for planets around cool stars. RoPACS has pan-European membership and is led from the University of Hertfordshire by David Pinfield, who commented: "Discoveries like this are really exciting, and such systems will be natural targets for the next generation of large telescopes, both on the ground and in space."

Via astrobio.net

Scientists develop composite material to enhance device response time

Ever feel like your phone is taking an awfully long time to register that swipe to unlock? Well, scientists from Imperial College London and King Abdullah University of Science and Technology are developing a solution that could mean faster response times. By combining polymer semiconductors and small molecules into a composite material to make organic thin-film transistors -- a process known as composite collaboration -- they found a way to increase the speed of the electrical charge moving through a device's components. The end result could someday be a smartphone that reacts to your touch much more quickly than your current handset. If you're so inclined, jump below the break to the presser for a more in-depth explanation.


Via engadget.com

MIT develops self-cleaning, fog and glare free glass

MIT researchers have developed a super clear, self-cleaning glass that is resistant to fog and glare. The new glass could be used in future smartphones, tablets, cars, and buildings, eliminating unwanted reflections and staying smudge-free. Water droplets that fall onto this new glass surface are said to bounce off like “tiny rubber balls.”


The surface of this glass is comprised of nanoscale cones, about 1,000 times to 100,000 times smaller than the diameter of a human hair. The nano-structure is etched into the glass that then goes through a vapor deposition process. It creates air pockets on the surface that minimize the amount of contact between the glass and the water droplets.




The droplets then roll off or bounce off without adhering to the surface. The difference can be seen in the image above, which shows a blue-dyed water droplet sitting on this nano-structured glass (left) versus the droplet on a regular piece of flat glass (right). A Phantom high-speed camera was used to record water dropping onto this new glass surface, showing the droplets form almost perfect beads in the video below.

Via slashgear.com

USC develops printable liquid solar cells for flexible, low-cost panels

Scientists at USC have developed a potential pathway to cheap, stable solar cells made from nanocrystals so small they can exist as a liquid ink and be painted or printed onto clear surfaces.

The solar nanocrystals are about four nanometers in size — meaning you could fit more than 250,000,000,000 on the head of a pin — and float them in a liquid solution, so "like you print a newspaper, you can print solar cells," said Richard L. Brutchey, assistant professor of chemistry at the USC Dornsife College of Letters, Arts and Sciences.

Brutchey and USC postdoctoral researcher David H. Webber developed a new surface coating for the nanocrystals, which are made of the semiconductor cadmium selenide. Their research is featured as a "hot article" this month in the international journal for inorganic chemistry Dalton Transactions.



Liquid nanocrystal solar cells are cheaper to fabricate than available single-crystal silicon wafer solar cells but are not nearly as efficient at converting sunlight to electricity. Brutchey and Webber solved one of the key problems of liquid solar cells: how to create a stable liquid that also conducts electricity.

In the past, organic ligand molecules were attached to the nanocrystals to keep them stable and to prevent them from sticking together. These molecules also insulated the crystals, making the whole thing terrible at conducting electricity.

"That has been a real challenge in this field," Brutchey said.

Brutchey and Webber discovered a synthetic ligand that not only works well at stabilizing nanocrystals, but actually builds tiny bridges connecting the nanocrystals to help transmit current.

With a relatively low-temperature process, the researchers' method also allows for the possibility that solar cells can be printed onto plastic instead of glass without any issues with melting – resulting in a flexible solar panel that can be shaped to fit anywhere.

As they continue their research, Brutchey said he plans to work on nanocrystals built from materials other than cadmium, which is restricted in commercial applications due to toxicity.

"While the commercialization of this technology is still years away, we see a clear path forward toward integrating this into the next generation of solar cell technologies," Brutchey said.

Via usc.edu