How do thin films help NASA uncover the secrets to the universe?

The James Webb Space Telescope

In less than two years, mankind will begin a journey that will open new doorways in its understanding of the universe.

The James Webb Space Telescope, launching in March 2021, will study every phase in the history of our cosmos. It is science’s next generation launching telescope, replacing the Hubble Telescope, and will measure many facets of the universe. That includes the first shimmering glows after the Big Bang, and the formation of solar systems capable of supporting life on planets like Earth. It will even examine the evolution of our own Solar System.

The new telescope is named after James E. Webb, the American government official who was the administrator of NASA from 1961 to 1968 and played an integral role in the Apollo program.

At the heart of the telescope is a mirror that reflects light for scientists to garner the mysteries space holds. It’s Manuel Quijada’s job to develop reflective coatings for those mirrors with the highest reflectivity possible, over the broadest spectral range. And then he must create protective coatings to prevent, or at least slow down the destruction of those reflective materials that are subjected to inhospitable environments.

Quijada, a Ph.D., is a supervisory and research physicist at NASA’s Goddard Space Flight Center. The center is in Greenbelt, Maryland, just six-and-a-half miles northeast of Washington, D.C. Quijada works in the Optics branch of the center’s Instruments Systems and Technology Division.

Quijada’s projects incorporate several objectives.

“You want to collect as much light as possible in your telescopes, Quijada said. “There are not that many materials that will achieve the goal we want, to capture as many photons as possible. Sometimes it’s a challenge to find the right material and develop the process to manufacture it. The material might have the desired properties, but if you don’t make it right, it won’t have them.”

Aluminum has the broadest and highest reflectivity among all metals. But the problem with aluminum is that it will degrade with oxidation and the bombardment of infrared light. So Quijada and his team must develop thin film coatings to protect the reflective metal of the mirror.

Thin films are microscopically thin layers of material that are placed onto a metal, ceramic, semiconductor or plastic base. It is usually less than one micron thick. Thin films can be conductive or dielectric (non-conductive) and have many uses. For example, the top metallic layer on a chip and the coating on magnetic disks are thin films. Thin films of photovoltaic material using silicon, cadmium telluride and other elements are used to make solar panels.

“We try to develop a more efficient optical coating to be applied to mirrors,” Quijada said. “We are looking at an aluminum coating applied with a protective layer of thin film coating that will preserve the integrity of the aluminum coating the most, over the longest periods of time. Our missions last for years.”

Among the instruments he uses in his lab for spectral characterizations are a Perkin Elmer Lambda 950 and a HORIBA UVISEL Plus. The latter is a reference ellipsometer for thin film measurements. It allows Quijada to study the various layers one by one. He can extract the optical constants, the properties from the thin film, including the absorption and dielectric characteristics by determining its optical constant.

“The coatings you apply to those mirrors are enabling things that without those, the mission wouldn’t work,” he said. “It’s key to the success of the overall mission.

It never gets boring in Quijada’s line of work.

“The goal is to stay focused,” he said. “There are always missions in the pipeline and the missions and requirements are all different.”

Quijada must develop different thin film coatings for that constant stream of missions. Some employ less reflective metals like silver and gold, which, although aren’t as reflective as aluminum in the ultraviolet part of the spectrum, capture certain wavelengths better in the visible and mid-infrared regions. But silver must be coated with several layers of thin films to protect it from environmental degradation. It’s just one of many problems Quijada must solve.

One of those upcoming missions is Lucy, a space probe that will study Jupiter’s leading and trailing swarms of asteroids. According to NASA, the asteroids serve as time capsules from the birth of our Solar System more than four billion years ago. These primitive bodies hold vital clues to deciphering the history of the Solar System, and perhaps even the origins of life and organic material on Earth.

Lucy got its name from the fossilized human ancestor, discovered in 1974, whose skeleton provided unique insight into humanity's evolution. The mission will launch in October 2021, and complete a 12-year journey to seven different asteroids.

Quijada had an early inkling his interest in astronomy would lead him to study the cosmos. After all, his dad told him so.

Manuel grew up in the Dominican Republic and moved to Puerto Rico as a teenager, where he earned his bachelor’s and master’s degrees in physics. Quijada was awarded his doctorate from the University of Florida in solid state physics. He’s been working for NASA as a contractor and civil servant for 22 years.

After the James Webb Space Telescope launches, another will follow. It’s called the Wide Field Infrared Survey Telescope (WFIRST). It will be used to explore dark matter in space and search for exoplanets in other star systems. WFIRST is expected to launch in the mid-2020s. It’s another project on his plate.

Quijada recognizes his little known role in the development of space exploration is vital in growing our knowledge of the universe.

“Every one of those missions depend on the coatings we provide them,” he said. “We think we play a key role in the overall space exploration program.”