New Fiber-Dispersive Raman Spectrometer Breaks Ground in Spaceborne Biomarker Detection

The Search for signs of extraterrestrial life in space ©Aleksandra - stock.adobe.com

In the ongoing quest to detect signs of life beyond Earth, scientists have faced the formidable challenge of identifying trace amounts of biological material on extraterrestrial surfaces. Traditional Raman spectroscopy, a powerful analytical technique for detecting low-density organic matter, has been hindered by the difficulty of distinguishing weak Raman signals from the overwhelming luminescence noise. However, a team of researchers from Humboldt-Universität zu Berlin and the German Aerospace Center (DLR) has made a significant leap forward with the development of a fiber-dispersive Raman spectrometer (FDRS). This innovative technology promises to revolutionize biomarker detection in space exploration by offering superior sensitivity and reliability (1,2).

Read More: Raman spectroscopy in space

Details of the FDRS Development

The newly developed FDRS employs a novel approach that combines pulsed laser excitation, a single-photon detector (SPD), and a dispersive optical fiber element. Unlike conventional Raman spectrometers, which rely on multi-pixel detector arrays and diffraction gratings, the FDRS uses a long dispersive fiber to delay the arrival of different spectral components onto a single-pixel SPD. This method allows the spectrometer to separate weak Raman signals from stronger luminescence through correlated time-domain measurements. As a result, the FDRS can achieve a much lower detection limit with greater precision, crucial for detecting biomarker-like molecules in difficult space missions (1).

The research, led by Mariia Sidorova, Sergey G. Pavlov, Ute Böttger, Mickael Baqué, Alexei D. Semenov, and Heinz-Wilhelm Hübers, demonstrated the potential of the FDRS in studying key biomolecules. The team focused on the impact of fiber properties and the excitation wavelength of a pulsed laser on the spectral resolution of the FDRS. By carefully selecting and optimizing the FDRS components, they were able to achieve a resolution below 5 cm⁻¹, a significant improvement over existing Raman technologies (1).

Findings and Implications

One of the key findings of the study was the effect of reducing the excitation wavelength and increasing the fiber length on improving spectral resolution. By using shorter wavelengths and longer fibers, the FDRS could achieve higher resolution, which is critical for accurately identifying both inorganic and organic matter in space. The team also highlighted the potential of dispersion-enhanced fibers, such as photonic crystal fibers, to further improve resolution without increasing the instrument's size or weight—a crucial consideration for spaceborne applications.

The researchers also explored the FDRS's ability to suppress unwanted luminescence, a common issue in conventional Raman spectroscopy. The FDRS employs two mechanisms to minimize luminescence interference: first, by using picosecond excitation pulses that prevent luminescence from reaching its steady-state intensity, and second, by time-gating detection, which separates Raman photons from slowly decaying luminescence photons. These mechanisms, combined with the single-pixel detector's inherent noise reduction, make the FDRS particularly well-suited for space missions, where detecting faint biological signals is paramount (1).

Conclusion

The development of the FDRS marks a significant advancement in the field of astrobiology. Its ability to detect low-density biological matter with high sensitivity and precision, while minimizing the risk of sample deterioration, makes it a promising tool for future space exploration missions. The research team's findings suggest that the FDRS could play a crucial role in the search for extraterrestrial life, offering new opportunities to analyze the surfaces and subsurfaces of celestial bodies with unprecedented accuracy (1).

As space agencies around the world prepare for upcoming missions to Mars, the moons of Jupiter and Saturn, and beyond, the FDRS stands out as a powerful instrument that could provide critical insights into the potential for life elsewhere in the universe. This work sets the stage for exciting new discoveries in the quest to understand our place in the cosmos (1).

References

(1) Sidorova, M.; Pavlov, S. G.; Böttger, U.; Baqué, M.; Semenov, A. D.; Hübers, H-W. Feasibility of a Fiber-Dispersive Raman Spectrometer for Biomarker Detection. Appl. Spectrosc. 2024, 0 (0). DOI: 10.1177/00037028241267

(2) Angel, S. M.; Gomer, N. R.; Sharma, S. K.; McKay, C. Remote Raman Spectroscopy for Planetary Exploration: A Review. Appl. Spectrosc. 2012, 66 (2), 137–150. DOI: 10.1366/11-06535