Blog | November 8, 2017, 07:13 PST

ACT-America: Settling into the rhythm of the field

By Hannah Halliday / SHREVEPORT, LOUISIANA

A C-130 gets a checkup after a flight. A dedicated flight team keeps the aircraft running and maintained. Credit: NASA/Hannah Halliday.

A C-130 gets a checkup after a flight. A dedicated flight team keeps the aircraft running and maintained. Credit: NASA/Hannah Halliday.

Fieldwork is my favorite part of my job. I have been working as a postdoc at NASA’s Langley Research Center in Hampton, Virginia, for a few days over a year, and I’m still not over the excitement of arriving somewhere new, ready to take measurements and run our instruments.

My background is in chemistry, but I slid into meteorology because I wanted to apply myself to environmental issues that had global impact. That decision put me on a path into the world of air quality research, and ultimately to NASA to work with airborne science. While I’m still new to flying for science, I love working with instruments and taking measurements. Being on an aircraft turns that feeling up to 11.

plane view
The C-130 doesn’t have many windows, but Halliday is lucky to have one beside her seat. Flights often have low-altitude runs, and offer views of the country from unique angles. This is a view of the Mississippi River from the Sunday, Nov. 5, flight. Credit: NASA/Hannah Halliday.

Atmospheric Carbon and Transport-America, or ACT-AMERICA, has been an especially cool project to be involved with because I earned my Ph.D. at Penn State, where principal investigator Ken Davis and other members of the ACT-AMERICA planning team are based. Working with ACT-AMERICA is part serious work and part fun reunion, working with people I know well on a totally new subject and project. I got to fly with the mission last spring, and I’ve come back to join them again for two weeks in Shreveport, Louisiana.

On Saturday, Nov. 4, we took a break from flying to do instrument work and maintenance. For my group, which is tasked with the Atmospheric Vertical Observations of CO2 in the Earth’s Troposphere, or AVOCET, in-situ measurements, that meant calibrating our instruments. When we calibrate, we send our instruments gases that have a known concentration and record what our instruments measure. Doing this regularly allows us to keep track and correct for the instrument drifting over time, and to maintain the accuracy and precision of our measurements.

Our two aircraft, a C-130 and a B-200, are stored in different locations when we’re at our ground sites. The calibration gas tanks are heavy, so for ease of use we’ve built our calibration gas cylinders their own little cart that they live on, which can be towed from one location to another. The cylinders are left on the cart, where we put a regulator on the calibration cylinder we want to use and run a tube into the airplane. It’s a simple solution that lets us easily and quickly use the same calibration gases on two different aircraft.

Hannah Halliday monitors incoming measurements.
Hannah Halliday, right, monitors incoming AVOCET measurements during a Nov. 2 science flight. Next to her are Theresa Klausner and Max Eckle, Ph.D. students with the German Aerospace Center, DLR, which has joined the fall flight campaign to test an instrument that measures methane and ethane. Credit: NASA/David C. Bowman.
Researchers talk during a flight.
Bianca Baier, a postdoctoral researcher with NOAA’s Earth Systems Research Lab in Boulder, Colorado, and Ken Davis, ACT-America principal investigator from Penn State, talk during a flight. Credit: NASA/David C. Bowman.

One of the reasons I love working in science is that our measurements and our work is built on a heap of clever solutions to small problems. While we also stand on the shoulders of scientific giants who had deep insights into the workings of the universe (for instance, Isaac Newton realizing that the gravity affecting an apple also affects the stars), in our day-to-day work we use the cleverness of the people who worked out the universal swage fittings, or the person who figured out how to set up our inlet system to bring air in from outside the plane when we’re at high altitude.

Calibration gas cylinders
Calibration gas cylinders on their transportation cart. During a calibration, scientists use three gases with low, middle and high concentrations, and use this information to understand how the instrument will behave when it “sees” gases in the environment. Credit: NASA/Hannah Halliday.

We’re not all brilliant all the time, but by looking at a problem long enough we can often find a clever solution to a small vexing problem (such as how to quickly transport our calibration cylinders), and that’s where our progress comes from.

On Sunday, Nov. 5, we flew a science mission, measuring the inflow of air from the Gulf of Mexico. It was a busy day for me, because I was both tending my group’s instruments and also taking flask samples for the National Oceanic and Atmospheric Administration (NOAA). NOAA uses glass-lined containers to trap air at specific locations on the flight track. They take these samples back to their lab in Boulder, Colorado, where they measure the greenhouse gases as well as other molecules that help determine whether samples were influenced by other sources, such as traffic or wildfires. My job was to follow their sampling plan, telling their mostly automated system when to collect a sample and coordinating with our in-flight calibrations.

Specialized inlets draw air into the instruments and have different designs based on the needs of the instruments.
Specialized inlets draw air into the instruments and have different designs based on the needs of the instruments. These inlets are located near the front of the aircraft so they don’t sample the exhaust from the engines. Credit: NASA/David C. Bowman.

The flights can be quite busy, and it’s a full day of activity. For the four to five hours that a typical science flight will last, we have an additional three hours of flight prep before we take off, and a debriefing meeting once we land, plus data workup and archiving the preliminary data once we’re back in our hotel rooms.

It’s satisfying work, but it’s important that we have non-flight days like Saturday to catch up on our instrument maintenance as well as personal things—exercise, laundry, even sleep. When we’re in the field there’s no set schedule like when we’re in the office, and it’s important to grab that time when we can, because flight days depend on the weather, and a good measurement day waits for no scientist, not even when they have a plane!

This piece was originally published on the NASA Earth Expeditions blog.


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