Manufacturing Bits: Nov. 25

Asteroid mining and metrology; looking at single molecules; China’s graphene center.


Asteroid mining and metrology
The U.S. House of Representatives has approved a new space bill. The bill, entitled H.R. 2262— U.S. Commercial Space Launch Competitiveness, includes a provision that discusses the rights for companies that mine any materials on asteroids. In simple terms, the bill recognizes the right of U.S. companies to own asteroid resources that they mine in space, according to Planetary Resources, an asteroid mining company.

Asteroids are primordial objects in the solar system. Various governments are interested in asteroid mining. First, using the resources from asteroids, companies could build re-fueling stations in space. Asteroids can be broken down into hydrogen- and oxygen-based rocket fuel, according to Planetary Resources.

Second, asteroids are abundant in precious metals, including the platinum group, rare earths, iron, nickel, and cobalt, according to the company, whose investors include the following individuals: Larry Page, chief executive of Google; Eric Schmidt, executive chairman of Google; and Ross Perot, Jr., chairman of Hillwood and The Perot Group.

In July, Planetary Resources said that its first space vehicle, the Arkyd 3 Reflight (A3R), was deployed from the International Space Station’s (ISS) Kibo airlock. At the time, the A3R began a 90-day mission. The demonstration vehicle will validate several core technologies, including the avionics, control systems and software, which the company will incorporate into future spacecraft that will venture into space and prospect for resource-rich near-Earth asteroids.

Meanwhile, to detect whether an asteroid has precious metals or not, Vanderbilt University, Fisk University, NASA’s Jet Propulsion Laboratory and the Planetary Science Institute have developed a gamma-ray spectroscope.

Gamma rays refer to electromagnetic radiation, which have high frequencies. A gamma-ray spectroscope, according to Vanderbilt, records the intensity and wavelengths of the gamma rays coming from a surface. This, in turn, can analyze the concentration of various metals and elements coming from a surface.

Prototype of a CubeSat version of a gamma-ray spectrometer.  (Source: Burger Lab/Fisk University)

Prototype of a CubeSat version of a gamma-ray spectrometer. (Source: Burger Lab/Fisk University)

The spectroscope is based on a new detector technology. It is built around a material called europium-doped strontium iodide (SrI2). “The gold standard for gamma-ray spectroscopy is the high purity germanium (HPGe) detector,” said Fisk Professor of Physics Arnold Burger, on Vanderbilt’s Web site. “However, it requires cryogenic cooling so it is very bulky. It also needs vacuum-tube technology so it consumes too much energy to run on batteries. SrI2 isn’t quite as good HPGe, but it is more than adequate to do the job and it is compact enough and its power requirements low enough so that it can be used in spacecraft and even placed on robotic landers.”

The system has other advantages. “Space missions to the Moon, Mars, Mercury and the asteroid Vesta among others have included low-resolution spectrometers, but it has taken months of observation time and great expense to map their elemental surface compositions from orbit,” said Keivan Stassun, a professor of astronomy at Vanderbilt. “With our proposed system it should be possible to measure sub-surface elemental abundances accurately, and to do it much more cheaply because our sensors weigh less and require less power to operate. That is good news for commercial ventures where cost, power and launch weight are all at a premium.”

Looking at single molecules
Raman spectroscopy is used to determine the chemical structure of a sample. It identifies the compounds present by measuring molecular vibrations.

The problem? The sensitivity of surface-enhanced Raman scattering (SERS) is limited at room temperature. This is because the molecules vibrate too weakly in the process, according to École polytechnique fédérale de Lausanne (EPFL).

To overcome these limitations, EPFL has put a new twist on SERS, which can be used to study single molecules. Researchers enhanced Raman scattering by localizing plasmonic resonances in the near field of metallic nanoparticles of the technology.

EPFL shows how a light-induced force can amplify the sensitivity of a technique used to study single molecules. (Source: EPFL)

EPFL shows how a light-induced force can amplify the sensitivity of a technique used to study single molecules. (Source: EPFL)

To accomplish this feat, EPFL used cavity optomechanics. This, in turn, drove the vibrations of the molecules to large amplitudes. “Our work offers specific guidelines for designing more efficient metallic nanostructures and excitation schemes for SERS,” says Philippe Roelli of EPFL. “It can push the limits of the technique in sensitivity and resolution.”

China’s graphene center
The National Physical Laboratory from the United Kingdom and a group from China have opened a new graphene standards and testing center in Beijing, China.

The so-called Centre in Beijing will lay the foundation for the development of the graphene industry in China. Efforts are being made to implement standards in China. There are also efforts to introduce new methods of measurement by establishing non-contact and contact-type testing facilities for electrical and structural properties of graphene and other 2D materials at the center.