Carbon nanotubes resemble graphene - a single layer of carbon atoms arranged in a hexagonal pattern - but are rolled into a tube. This super-dark material, made of multiwalled carbon nanotubes, forms a vertical "forest" where light enters and gets trapped, converting into heat instead of reflecting. This property is crucial for NASA's instruments, as stray light can hinder the sensitivity of observations. When applied to telescope structures, carbon nanotubes can eliminate much of this stray light, enabling more precise measurements.

Observing exoplanets is a significant challenge since they orbit stars that are billions of times brighter than the planets themselves. Specialized instruments called coronagraphs are used to block out the star's light, allowing the dim exoplanets to be observed. The carbon nanotube material is critical in these coronagraphs to minimize stray light, enhancing the detection of these distant worlds.

The Habitable Worlds Observatory will utilize a similar approach in its quest to find habitable exoplanets. By analyzing the light spectrum captured by HWO, scientists will identify gases such as water vapor and oxygen, which could indicate the presence of life.

To create a carbon-nanotube-coated apodizer mirror suitable for the HWO, Hagopian's company, Advanced Nanophotonics, LLC, has received Small Business Innovation Research (SBIR) funding. The process involves growing carbon nanotubes on mirrors in precise patterns to eliminate stray light where it is most likely to interfere.

The fabrication of these mirrors involves several steps, including the preparation of a silicon mirror substrate, coating it with layers of dielectric and metal, and patterning the mirror surface using a light-sensitive material and a laser. The mirror is then exposed to high temperatures in a furnace to allow the carbon nanotubes to grow only in designated areas, ensuring the mirror remains reflective where needed and highly absorbent where stray light must be eliminated.

Advanced Nanophotonics has already delivered these mirrors and other components to various researchers, who are testing them to refine designs for future telescopes. Although achieving the desired contrast ratio is currently beyond the capabilities of ground-based telescopes, testing on Earth helps develop the technology and guides the targets that HWO might observe.

The company's work has also led to collaborations on other space missions, including the NASA Ocean Color Instrument aboard the PACE mission, where carbon nanotube coatings are used to prevent stray light from affecting measurements. Additionally, the team is developing carbon nanotubes for use in electron beam emitters and a breathalyzer for detecting Covid-19.

This carbon nanotube technology is proving invaluable not only in space exploration but also in various applications on Earth.

Related Links
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Lands Beyond Beyond - extra solar planets - news and science
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