The Lab in the Sky Says Goodbye
A NASA DC-8 aircraft used to train many Caltech student-scientists has taken its final flight.
By Andrew Moseman
When the vintage DC-8 airliner made one of its harrowing low passes over California’s Central Valley, things got a little bumpy for the undergraduates packed inside.
It was often hot and stuffy inside the flying atmospheric chemistry laboratory, which NASA had rebuilt in the 1980s and which gave students the chance to perform research, says Emily Schaller (PhD ’08), who ran the NASA internship program from 2011 to 2021. On any given research flight, the jet full of budding chemists and climate scientists, some of whom came from Caltech, might plow through the turbulent air at low altitudes to measure methane emissions from a large cattle ranch or study the health of kelp in the Santa Barbara Channel.
“A fair number of the students would end up losing their lunch,” Schaller says. “But that bonded them in a new way. We used the hashtag #IPukedforScience on social media and, one summer, they made a T-shirt to that effect. But they were all very proud of the data they collected.”
The trusty aircraft gave countless undergraduates a turbulent baptism as airborne scientists. Because it was based at the NASA Armstrong Flight Research Center in the nearby California desert, the DC-8 also helped a generation of Caltech scientists conduct research on Earth’s atmosphere. Now its day is done: The DC-8 made its final science flight in April 2024.
Paul Wennberg, the R. Stanton Avery Professor of Atmospheric Chemistry and Environmental Science and Engineering, tweeted a photo of the DC-8 after it landed at Armstrong, which is near Palmdale, following its swan song. “This was the last science flight of the aircraft,” he wrote. “It is headed to a well-deserved retirement.”
Kat Ball, a graduate student in Wennberg’s lab, was aboard that flight and many others, as the DC-8’s airborne lab powered her graduate research in atmospheric chemistry. Ball uses mass spectrometry to study and quantify pollutants that come not only from vehicle emissions but also from volcanoes, wildfires, agriculture, and manufacturing. While satellites can analyze the atmosphere below them, Ball says they measure the whole column of air and cannot determine the composition of gases at discrete elevations. For that, you still need a plane.
“We could look at different altitudes in a pretty quick time span as the plane went up and down,” Ball says. “The composition can change as you go up and down. That is important for understanding chemistry and how things are transported in the atmosphere.”
History in the Air
The Douglas DC-8 line was among the planes that powered the jet age. It debuted in the 1950s as one of the first narrow-body airliners, allowing for six seats in each row. Douglas (later McDonnell Douglas) made hundreds of DC-8s for clients such as Pan American World Airways up until the early 1970s, when bigger and better jets came on the market. Kirsten Boogaard, deputy project manager for NASA’s DC-8 program, says the specific plane bought by the agency in the 1980s had flown for Alitalia in its previous life. Refitted as a platform for aerial science, the DC-8 would fly for nearly four more decades.
“I was leading a live chat with a classroom back in the United States, and they were asking if we saw Santa.”
NASA’s plane retained some of the first-class seats from its passenger days, and the retro blue carpeting remained too. Apart from that, the DC-8’s redesigned interior bore little resemblance to an airliner. The fuselage was packed full of metal racks where researchers could mount the computers and tools they would monitor during the flight. These machines were connected to instruments mounted on the outside of the plane that sampled the air and were changed to meet the needs of each mission. “We stripped the entire inside to be able to do specific configurations of the scientists and their instruments for each flight,” Boogaard says.
Cushy seats aside, the DC-8 trips were not an exercise in aerial luxury. Flight days, Ball explains, included three hours of prep to work out preflight procedures and instrument calibrations. Then came eight hours in the air, followed by one more after landing to shut down the tools and retrieve data. Some researchers worked these 12-hour shifts for days on end.
John Crounse (PhD ’11), lead staff scientist at Caltech’s Ronald and Maxine Linde Center for Global Environmental Science, flew on the DC-8 for nearly 20 years to map the composition of the atmosphere throughout each year. The proximity of the plane’s home base to Caltech gave Institute researchers a terrific opportunity to study the atmosphere firsthand, he says. “We could take our instrument in a rental truck up to Palmdale in half a day, unload it, put it on the plane, and go back home.”
He also remembers the heat. Much of the plane’s air-conditioning equipment was stripped to make room for laboratory gear. Ducts to blow cool air remained in the front and back of the plane. “By the time you got to the middle, there’s not a lot of airflow that comes out,” he says. “The heat concentrates there, and that’s where we sat for 20 years.”
Around the World
Caltech graduate student Kat Ball fills a cryogenic pump with liquid nitrogen. The pump keeps her instruments clean during the downtime between flights. Image: Kat Ball
The rewards were worth the discomfort, Ball says, and not just because of the unique atmospheric chemistry dataset and scientific opportunities. Flying in the DC-8 allowed her to see the world. Ball’s missions included the Atmospheric Emissions and Reactions Observed from Megacities to Marine Areas campaign in summer 2023, which sampled air above big cities; this meant Ball rode in the plane as it made low passes by the Statue of Liberty. A similar campaign called ASIA-AQ early in 2024 took Ball across the Pacific Ocean to study the atmosphere above East Asian nations such as South Korea, Thailand, and the Philippines. “I’ve been able to see cities all over the world that I would not have gotten to see otherwise,” she says. “And I got to see them from pretty low altitudes.”
Similarly, flights for NASA’s Operation IceBridge mission throughout the 2010s carried Schaller to the far ends of the planet, with close passes over glaciers in Antarctica and Greenland. “One of my fondest memories is flying over the North Pole at about 1,500 feet while the Icebridge team was making measurements of the thickness of the sea,” she says. “I was leading a live chat with a classroom back in the United States, and they were asking if we saw Santa.”
Crounse has flown on nearly a dozen DC-8 research campaigns over the past two decades. One of the most memorable projects, he says, was the Atmospheric Tomography Mission from 2016 to 2018, during which the DC-8 circumnavigated the globe during each of the four seasons of the year. The missions took him to sites including Alaska, Hawaii, the Azores, Chile, and New Zealand. He also traveled over the western United States in 2019 to quantify the atmospheric impacts of major wildfires. “The airplane would go from its maximum altitude, which is somewhere around 12 kilometers, down to about 500 meters above the ocean,” he says. “And it would do that repeatedly throughout the whole flight. That dataset has proven invaluable for understanding the global atmosphere.”
The DC-8’s rugged nature—this was a tough, overbuilt machine, the scientists agree—helped it to withstand its many shaky trips through the atmospheric boundary layer, the lowest portion of the atmosphere affected by Earth’s surface. But even a durable plane does not last forever, especially when decades have passed since the last one was built. “Every time something breaks it’s just a big effort to find that part,” Boogaard says. “You can compare it to an old car.”
But, Wennberg notes, “this old car was an enormous asset for airborne investigations. With its ability to host a large payload and operate from only a few hundred feet above the ground to more than 40,000 feet, the DC-8 was a workhorse for Caltech earth scientists studying global change in atmospheric composition, the glaciers, the oceans, and the terrestrial biosphere.”
NASA recently acquired a Boeing 777 to serve as its next-generation airborne lab, and Boogaard will be moving to the East Coast to oversee its various missions. The DC-8, meanwhile, is not going to the boneyard. NASA has donated the plane to Idaho State University. “They are using it to train the next generation of aircraft technicians,” Boogaard says. “They’re going to get hands-on real-time experience with a beautiful aircraft.”