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NASA and the Massachusetts Institute of Technology (MIT) is currently working on the approach, to reduce the size of spectrometers used in space applications, with a view to launch the first such system on board a CubeSat. The size could be reduced drastically, if the development of a prototype instrument based around quantum-dot wavelength “filters” proves successful.

Spectrometers are used in virtually all space missions, and NASA is hoping that adopting quantum dots could transform the way that they are built and integrated, at potentially a very low cost.

Backed by NASA’s Center Innovation Fund, which supports high-risk technology development, Mahmooda Sultana from the Goddard Space Flight Center is collaborating with a research group led by Moungi Bawendi, a chemistry professor at MIT.

Bawendi’s group has pioneered quantum dot technology since the early 1990s, developing photovoltaic, biological and microfluidics applications. Meanwhile, quantum dots are starting to have a major impact on the consumer electronics industry, with a multitude of televisions now featuring the technology to enhance LCD quality.

Sultana says that the approach could miniaturize and potentially revolutionize space-based and other spectrometers, particularly those used on unmanned aerial vehicles (UAV) and small satellites.

Initially, that could be in the form of an absorption spectrometer, where instead of the traditional combination of optical components like gratings, prisms, or interference filters to split light into different wavelengths, quantum dots would effectively do the light filtering themselves.

Because the absorption or emission of light by quantum dots is determined by their diameter - the smaller the dot, the shorter the wavelength - an array of different-sized dots could in principle do the same job as the familiar optics setup.

And even though conventional spectrometers are already being miniaturized thanks to integrated optics and photonics devices, they are still relatively large.

Higher spectral resolution requires long optical paths for instruments that use gratings and prisms. This often results in large instruments. Whereas here, with quantum dots that act like filters that absorb different wavelengths depending on their size and shape, scientists can make an ultra-compact instrument. In other words, they could eliminate optical parts, like gratings, prisms, and interference filters.

In theory, a spectrometer could be based around a virtually unlimited number of dots of different sizes, to provide high-resolution performance. At the moment, Sultana is working to develop and demonstrate a 20 x 20 quantum-dot array sensitive to visible wavelengths needed to image the sun and the aurora.

In principle the approach could be broadened, using quantum dots to cover wavelengths from the ultraviolet to the mid-infrared spectrum - suggesting a wide range of potential applications in Earth observation, heliophysics, and planetary science.

NASA reports that Sultana is developing an instrument concept specifically for a CubeSat application, with MIT doctoral student Jason Yoo looking to synthesize precursor chemicals to create the dots and then print them onto a suitable substrate. Ultimately, researchers want to print the dots directly onto the detector pixels. Although the approach is at a very early stage, the NASA researcher adds that the plan is to raise the technology-readiness level very quickly.