A coating consisting of strands of pure carbon is turning out to be versatile for a variety of applications in the field of spaceflight.
John Hagopian, an optical engineer who works as a contractor at NASA’s Goddard Space Flight Center in Greenbelt, Maryland and Lucy Lim, a scientist at Goddard, are looking into further research into this technology. In a recent instance of carbon-nanotube coating, the scientists have been growing bumps resembling the shape of a button, inside multi-walled nanotubes. These nanotubes have silicon wafer as their substrate.
The bumps/dots, measuring about 50 microns in radius, will serve as a source of ammunition for an electron probe. Such an instrument is capable of analyzing the properties of soil found on bodies devoid of air, like an asteroid or the Moon.
The probe is using funding from PICASSO (Planetary Instrument Concepts for the Advancement of Solar System Observations Program), a subsidiary of NASA. Even though the technology is in its primitive stages of development, it holds promise, according to Lim.
Carbon nanotubes are the primary component of this instrument. It is because of them being good electron emitters. These structures show useful electronic and magnetic properties.
To produce these immensely versatile structures, a substrate such as silicon wafer is kept inside the furnace. Over time the furnace gets heated up, and meanwhile, technicians bathe the silicon wafer with carbon feedstock gas. It will result in the creation of the thin coating of the bumpy/hair-like structures.
In case of the electron emitter, Lim and Hagopian have applied this technique to create these small dots of carbon nanotubes. The dots are developed in a pattern resembling a grid. The lattice structure of dots is placed between the wires made of silicon and a grid, which makes cables and grid generate different voltages. The electric field produced by the voltages will trigger the release of electrons which are within the carbon-nanotube dots.
The novelty about this field emitter is the fact that its size is small, which will result in full addressability. According to Lim, each dot can be activated individually. Thus analyzing different spots and areas on the sample would be possible. However, if the instrument had one electron source, only a single portion of the obtained sample could have been analyzed. Consequentially, finding all the minerals in a sample or their relationship to each other would not be possible.