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Category: sustainability – Page 696

Membrane spacecraft with 7.7 kW/kg power-to-weight ratio and 4000 ISP

A ‘brane’ is a dynamical object that can propagate through spacetime. Flattening a spacecraft into a membrane, or 2-brane, can produce a low mass vehicle with ultra-high power-to-weight ratio (7.7 kW/kg using thin film solar cells). If most of this power is used by an array of thinned, distributed electrospray thrusters with a specific impulse of 4000 s, a Brane Craft could start in low Earth orbit, land on Phobos, and return to low Earth orbit.

Other possible targets include any near-Earth asteroid and most main belt asteroids. Propellant is stored as a liquid within a 10-micron wide gap between two Kapton sheets that form the main structure of the Brane Craft.

This NASA NIAC project will study how to design an ultra-light dynamic membrane spacecraft, with 3-axis attitude determination and control plus navigation, that can significantly change both its shape and orbit. Conventional sensors like star trackers will have to be replaced by 2-dimensional alternatives. Estimated mass is about 35 grams for a 1 square meter Brane Craft.

Bigelow Aerospace and United Launch Alliance Join Forces to Foster a New Era of Sustainable Commercialization in Low Earth Orbit

Colorado Springs, Colo., (April 11, 2016) – Bigelow Aerospace (BA) and United Launch Alliance (ULA) announced they are partnering to develop and deploy habitable volumes in Low Earth orbit (LEO). The volumes will be based on the Bigelow Aerospace B330 expandable module with the initial launch to orbit in 2020 on ULA’s Atlas V 552 configuration launch vehicle.

The B330 will have 330 cubic meters (12,000 cu ft) of internal space. The craft will support zero-gravity research including scientific missions and manufacturing processes. Beyond its industrial and scientific purposes, however, it has potential as a destination for space tourism and a craft for missions destined for the Moon and Mars.

“We are exploring options for the location of the initial B330 including discussions with NASA on the possibility of attaching it to the International Space Station (ISS),” said Robert Bigelow, founder and president of Bigelow Aerospace. “In that configuration, the B330 will enlarge the station’s volume by 30% and function as a multipurpose testbed in support of NASA’s exploration goals as well as provide significant commercial opportunities. The working name for this module is XBASE or Expandable Bigelow Advanced Station Enhancement.”

Global warming is changing the way the Earth spins on its axis

WASHINGTON (AP) — Global warming is shifting the way the Earth wobbles on its polar axis, a new NASA study finds.

Melting ice sheets — especially in Greenland — are changing the distribution of weight on Earth.

And that has caused both the North Pole and the wobble, which is called polar motion, to change course, according to a study published Friday in the journal Science Advances.

Scientists are developing graphene solar panels that generate energy when it rains

Solar power is making huge strides as a reliable, renewable energy source, but there’s still a lot of untapped potential in terms of the efficiency of photovoltaic cells and what happens at night and during inclement weather. Now a solution has been put forward in the form of producing energy from raindrops.

Key to the new process is graphene: a ‘wonder’ material we’ve heard plenty about before. Because raindrops are not made up of pure water, and contain various salts that split up into positive and negative ions, a team from the Ocean University of China in Qingdao thinks we can harness power via a simple chemical reaction. Specifically, they want to use graphene sheets to separate the positively charged ions in rain (including sodium, calcium, and ammonium) and in turn generate electricity.

Early tests, using slightly salty water to simulate rain, have been promising: the researchers were able to generate hundreds of microvolts and achieve a respectable 6.53 percent solar-to-electric conversion efficiency from their customised solar panel.

Quantum dots enhance light-to-current conversion in layered metal dichalcogenide semiconductors

Improving light-sensing devices with Q-Dots.

Harnessing the power of the sun and creating light-harvesting or light-sensing devices requires a material that both absorbs light efficiently and converts the energy to highly mobile electrical current. Finding the ideal mix of properties in a single material is a challenge, so scientists have been experimenting with ways to combine different materials to create “hybrids” with enhanced features.

In two just-published papers, scientists from the U.S. Department of Energy’s Brookhaven National Laboratory, Stony Brook University, and the University of Nebraska describe one such approach that combines the excellent light-harvesting properties of quantum dots with the tunable electrical conductivity of a layered tin disulfide semiconductor. The hybrid material exhibited enhanced light-harvesting properties through the absorption of light by the quantum dots and their energy transfer to tin disulfide, both in laboratory tests and when incorporated into electronic devices. The research paves the way for using these materials in optoelectronic applications such as energy-harvesting photovoltaics, light sensors, and light emitting diodes (LEDs).

Quantum Dots

Single nanocrystal spectroscopy identifies the interaction between zero-dimensional CdSe/ZnS nano crystals (quantum dots) and two-dimensional layered tin disulfide as a non-radiative energy transfer, whose strength increases with increasing number of tin disulfide layers. Such hybrid materials could be used in optoelectronic devices such as photovoltaic solar cells, light sensors, and LEDs. (click on image to enlarge)

Student-designed ‘FemtoSats’ aim to bring cost of satellite deployment below $1,000

Got a grand burning a hole in your pocket? You could get a new laptop — or you could send this tiny, palm-sized satellite to space. That’s what a team of engineers at Arizona State hope, anyway: their “FemtoSats” are meant to be as cheap a space-bound platform as has ever been devised.

At just 3cm per side and 35 grams (that’s about 1.2 inches and 0.077 pounds, dogs of the Imperial system), the SunCube 1F is the prototype FemtoSat. It’s powered by a salvaged scrap of solar panel (they don’t make them small enough off the shelf), the tiny unit includes propulsion, imaging, communication, and data collection.

“The design standard bootstraps from the Cal Poly CubeSat standard and is extensible, allowing major customization,” wrote Jekan Thanga, the ASU assistant professor who heads up the project, in an email to TechCrunch.

Why fossil fuel power plants will be left stranded — By Martin Wolf | Financial Times


“Virtually all new fossil fuel-burning power-generation capacity will end up “stranded”. This is the argument of a paper by academics at Oxford university. We have grown used to the idea that it will be impossible to burn a large portion of estimated reserves of fossil fuels if the likely rise in global mean temperatures is to be kept below 2C. But fuels are not the only assets that might be stranded. A similar logic can be applied to parts of the capital stock.”

Read more

Elon Musk: Tesla Model 3 orders hit $14 billion in one week

One week after Elon Musk unveiled the Tesla Model 3, the company’s first mass-market car, hundreds of thousands of people have paid $1,000 to reserve the car despite its expected late-2017 launch.

That reservation figure totals to $14 billion (theoretical dollars) in sales, or 325,000 cars, with one big caveat: With only $1,000 down, some — perhaps many — of these orders will inevitably be adjusted or canceled over the next few years. In any event, that’s $325 million paid in preorders to date for a car that basically doesn’t exist yet.

Over 325k cars or ~$14B in preorders in first week. Only 5% ordered max of two, suggesting low levels of speculation.

Solar Cells Will be Made Obsolete

Rectenna Naval Optical 150928122542_1_540x360
A new kind of nanoscale rectenna (half antenna and half rectifier) can convert solar and infrared into electricity, plus be tuned to nearly any other frequency as a detector.

Right now efficiency is only one percent, but professor Baratunde Cola and colleagues at the Georgia Institute of Technology (Georgia Tech, Atlanta) convincingly argue that they can achieve 40 percent broad spectrum efficiency (double that of silicon and more even than multi-junction gallium arsenide) at a one-tenth of the cost of conventional solar cells (and with an upper limit of 90 percent efficiency for single wavelength conversion).

It is well suited for mass production, according to Cola. It works by growing fields of carbon nanotubes vertically, the length of which roughly matches the wavelength of the energy source (one micron for solar), capping the carbon nanotubes with an insulating dielectric (aluminum oxide on the tethered end of the nanotube bundles), then growing a low-work function metal (calcium/aluminum) on the dielectric and voila–a rectenna with a two electron-volt potential that collects sunlight and converts it to direct current (DC).

“Our process uses three simple steps: grow a large array of nanotube bundles vertically; coat one end with dielectric; then deposit another layer of metal,” Cola told EE Times. “In effect we are using one end of the nanotube as a part of a super-fast metal-insulator-metal tunnel diode, making mass production potentially very inexpensive up to 10-times cheaper than crystalline silicon cells.”

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