Pushing the boundaries of space exploration with IMS-MS

Author: Joanne Ballantyne

International Space Day is observed annually on the first Friday in May, and is dedicated to the extraordinary achievements, benefits and opportunities within space exploration. In celebration of International Space Day this year, we hope to inspire the next generation of scientists with some of the remarkable contributions mass spectrometry (MS) and ion mobility technology have made to furthering our understanding of outer space. Read on to discover how these unique technologies have helped pioneers to unlock the mysteries hidden in our Solar System.

Past, present, and future of MS in space exploration

MS has long been associated with pushing the boundaries of space exploration. Specially designed MS instruments travelled to the Moon with early Apollo astronauts, where they helped determine the composition of the lunar atmosphere. [1] MS was also used to analyze the upper and lower atmosphere of Venus during the Pioneer missions, revealing a composition of 96% CO2 and 4% N2. [2] The presence of water ice on Mars was confirmed based on MS soil analysis, [3] building on previous gas chromatography (GC)-MS analysis conducted by the Viking 1 & 2 landers. [4] Today, the Mars Curiosity Rover continues to roam across the Martian landscape, collecting valuable information on the Red Planet’s evolution using quadrupole MS. [5,6]

In addition to its use for soil and atmospheric analysis, MS has found a number of further applications in NASA space programs. These include analysing human breath to investigate the impact of microgravity on respiratory function, testing for propellant leaks prior to Space Shuttle launches, and to validate contaminant removal in life support systems aboard the International Space Station (ISS). [2]

So, where does ion mobility technology fit into this picture? It is anticipated that ion mobility spectrometry-mass spectrometry (IMS-MS) will play a key role in helping scientists to uncover the origins of organic matter in extra-terrestrial environments. [7,8]

Combining the power of IMS and MS

Though newer to the field than MS, standalone ion mobility spectrometry (IMS) has already found utility in monitoring air quality on the ISS. As the semi-closed environments on manned spacecraft are particularly vulnerable to contamination, IMS plays the crucial role of ensuring that the air remains safe to breathe. [2,7]

There is an increasing focus on using the combined power of IMS and MS to further our understanding of environments beyond Planet Earth. IMS separates molecules on the basis of their mobility in a carrier gas. As organic materials such as amino acids have been observed to display a strong mass-mobility correlation, this opens up the possibility that IMS-MS can be used to investigate the wealth of organic matter present in outer space. [7,8]

Elucidating the nature of Titan’s haze

The origin and evolution of organic matter in the solar system remains a key question for astrobiologists. Understanding its composition and the processes behind its formation can increase our knowledge of the history of the solar system, inform the search for life (or precursors to life) on other planets, and help clarify the influence of atmospheric processes. [8]

A key approach to solve this riddle is to analyze the elemental composition and chemical structure of the many thousands of organic molecules present in planetary atmospheres – such as that of Titan, Saturn’s largest moon. Titan’s reducing atmosphere of methane and nitrogen gas contains a thick organic haze, whose complex chemical make-up remains largely unknown. [8]

Standalone MS has been investigated for this purpose but was limited in its ability to distinguish between structural isomers of complex organic compounds, which Titan’s haze is rife with. Coupling with chromatographic techniques is one solution to this problem, but this method requires molecules under study to be compared with a reference standard. As relatively little is known about the organic molecules present, this requirement limits its use. A recent study made use of IMS-MS to investigate its effectiveness for this purpose using a laboratory analogue of Titan’s haze. [8]

The results from the study were highly encouraging, allowing isomeric separation of the complex molecules present to produce detailed information on conformational differences. Furthermore, as structural shape is an intrinsic and predictable property, theoretical collision cross section (CCS) calculations were able to provide an overview of the main structural shape of the organic matter present in the sample. [8]

The incredible complexity of the organic material studied, combined with its formation in cold conditions, suggests that this method can also be applied to study the formation of primitive organic material in the outer reduced solar system, including comets and the early Earth. Furthermore, hydrolysis of the organic compounds present in the analogue studied were shown to produce amino acids – considered the building blocks of life as we know it. This highlights the potential of IMS-MS for future experiments in astrobiology. [8]

Demystifying complex organic worlds with IMS-MS

MS has proven itself to be a reliable partner in the quest for a greater understanding of the Universe beyond the confines of our home planet. As we continue to learn more about our solar system, the combined power of IMS-MS will undoubtedly continue to contribute to the elucidation of complex organic worlds such as Titan. Its utility for the analysis of chemically similar components in the atmospheres of other planets has already been demonstrated. In the future, we can only guess at the exciting discoveries IMS-MS will facilitate by aiding pioneers as they probe new horizons.

Further reading

  1. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100039433.pdf
  2. Peter T Palmer, Thomas F Limero, Mass spectrometry in the U.S. space program: past, present, and future, Journal of the American Society for Mass Spectrometry, Volume 12, Issue 6, 2001, Pages 656-675. https://doi.org/10.1016/S1044-0305(01)00249-5.
  3. https://www.newscientist.com/article/dn14442-phoenix-mars-lander-tastes-first-sample-of-water-ice/
  4. Fenselau, C., Caprioli, R., Nier, A.O., Hanson, W.B., Seiff, A., Mcelroy, M.B., Spencer, N.W., Duckett, R.J., Knight, T.C.D., Cook, W.S., Biemann, K., Oro, J., Toulmin, P., III, Orgel, L.E., Nier, A.O., Anderson, D.M., Simmonds, P.G., Flory, D., Diaz, A.V., Rushneck, D.R., Biller, J.A., Owen, T. and Biemann, K. (2003), Mass spectrometry in the exploration of Mars. J. Mass Spectrom., 38: 1-10. doi:10.1002/jms.396
  5. https://www.jpl.nasa.gov/news/news.php?release=2014-307
  6. https://mars.nasa.gov/msl/spacecraft/instruments/sam/
  7. Paul V. Johnson, Luther W. Beegle, Hugh I. Kim, Gary A. Eiceman, Isik Kanik, Ion mobility spectrometry in space exploration, International Journal of Mass Spectrometry, Volume 262, Issues 1–2, 2007, Pages 1-15. https://doi.org/10.1016/j.ijms.2006.11.001.
  8. Julien Maillard, Sébastien Hupin, Nathalie Carrasco, Isabelle Schmitz-Afonso, Thomas Gautier, Carlos Afonso, Structural elucidation of soluble organic matter: Application to Titan’s haze, Icarus, Volume 340, 2020, 113627. https://doi.org/10.1016/j.icarus.2020.113627.