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"Exploring the Chemistry of Mars" Infographic

Infrared spectrometer sheds light on the planet's makeup

An Infrared Light in the Darkness

A mere 50 years ago, we knew almost nothing about the planets of our solar system. We had essentially no informaton on the chemical properties of the planets and their atmospheres until 1969, when NASA launched the Mariner 6 and 7 spacecraft, which both flew within a few thousand miles of Mars.

Each spacecraft carried an infrared (IR) spectrometer designed and built at the College of Chemistry and the Space Sciences Lab at the University of California, Berkeley. The IR instruments on the Mars Mariner spacecraft successfully scanned the atmospheric and surface chemistry of Mars, trasmitting IR spectral data back to Earth.

"The infrared spectrometer was a groundbreaking design of unprecedented sensitivity, mechanical stability, and environmental robustness, which enabled it to make the first chemical measurements of the makeup of the Mars surface and atmosphere."--Richard A. Mathies, chemistry professor, UC Berkeley, 2016

Spectroscopy—What Is It?

Spectroscopy is the study of the interaction between matter and electromagnetic radiation. An IR spectrometer measures the absorption of infrared radiation by a sample. The resulting IR spectrum is characteristic of the chemicals present in the sample.

The spectrometer carried by Mariner 6 and 7 was a 10-inch refelctor telescope that channeled IR light to a beam splitter and then to two different detectors. Channel 1 used a mercury-germanium sensor to detect far-infrared light. Channel 2 used a lead-selenide sensor to detect near-infrared light.

What Did We Learn About Mars?

  • Determination of the composition of the Martian atmosphere
  • Determination of water vapor concentration in the Martian atmosphere
  • First evidence for solid CO2 in the upper atmosphere
  • Observation of solid water hydrates on the Martian surface
  • Detection of goethite, which forms in aqueous weathering processes, the first evidence that there was once liquid water on the Martian surface

A National Historic Chemical Landmark

The American Chemical Society (ACS) designated George Pimentel and Kenneth Herr's design of a revolutionary infrared spectrometer as a National Historic Chemical Landmark in a ceremony at the University of California, Berkeley on May 15, 2017. The Landmarks program (www.acs.org/landmarks) recognizes major achievements in the chemical sciences.

Chemistry Is Out of This World

National Chemisry Week (NCW) is a community-based program of ACS. This annual program unites ACS members with businesses and schools to communicate the importance of chemistry in everyday life. NCW 2018 will be celebrated October 21 to 27 with the theme "Chemistry is Out of This World." Several NCW educational resources are available that focus on space chemsitry. They can be found at acs.org/ncw.