Artist concept of MAVEN spacecraft. (Credit: NASA/Goddard Space Flight Center) Enlarge

July 18, 2013 — When NASA's MAVEN mission begins its journey to the Red Planet later this year, it will be equipped with a special instrument to take the planet back in time.

That instrument is the Neutral Gas and Ion Mass Spectrometer, a network of electrically charged rods that will measure the charged gas particles — or ions — making up Mars' upper atmosphere.

Designed and developed at NASA's Goddard Space Flight Center in Greenbelt, Md., the state-of-the-art instrument will launch aboard MAVEN, short for Mars Atmosphere and Volatile Evolution, in November. Once at Mars, the spectrometer will collect data on the ions above the Red Planet.

"The data could be used to build models showing how Mars has lost the majority of its atmosphere, a phenomenon that continues to be one of the planet's greatest mysteries," said Paul Mahaffy, the spectrometer's principal investigator from Goddard.

Once the MAVEN spacecraft launches, the team would apply radio frequency and electrical voltages to the instrument's four metal cylinders, or quadrupole rods.

Each specific voltage isolates ions based on their specific mass. This allows the instrument to build a profile, known as a mass spectrum, of all the different gas particles present in the Martian atmosphere.

"We're basically sorting ions by mass," Mahaffy said.

Besides measuring the ions already present in the atmosphere, the instrument could also create ions from neutral gas molecules. An electron gun will fire a beam of electrons, breaking the gas molecules into smaller, charged particles. By doing this, the instrument can collect information on all of the gas particles, both neutral and charged, in the upper atmosphere.

"Our part of the overall mission is to measure the neutral and ion composition of the atmosphere," Mahaffy said. "We're measuring ions that are already there and those that are created."

The instrument will measure the composition of the current atmosphere and how variables like time of day change the gas particles over time. This critical information can then be used to build simulations of both the current Martian atmosphere and the atmosphere billions of years ago.

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