Two Nasa aviators will climb into a research plane after lunch on Wednesday and take off from Keflavik airport on the western tip of Iceland to chase a total solar eclipse. The plane will head north toward Greenland and then bank south on a gently curving course 40 miles, or 64 kilometers, off the Icelandic coast. At 50,000 feet, the shadow of the moon will race up from behind at more than 2,000 mph, or 3,200 km/h. The spectacle is real. So is the machinery built to catch it.
The pilot will aim to reach the point of greatest eclipse, when the largest fraction of the sun is obscured by the moon, at the moment the shadow catches up with them. For anyone directly beneath the eclipse, the world will go dark for 2 minutes 18 seconds, but by flying at 460 mph along the path of the eclipse, the pilot can extend totality to nearly 3 minutes. The mission turns a natural event into a high-altitude race, with the aircraft and its crew chasing darkness as if it were another target on a flight plan.
The State’s Aircraft, the Sun’s Shadow
Cary Klemm, a sensor equipment operator at Nasa’s Johnson Space Center in Houston who has flown eclipse missions before, described the cockpit at 50,000 feet as a place where the light changes violently. "The big difference is that in the cockpit of an aircraft at 50,000 feet, it’s very bright in the sun. There are no clouds above you, and then all of a sudden, you’re hit with this slam of shadow," he said. "You feel the temperature drop off; you’ll notice that you need more light from your instruments, and it’s kind of a weird, eerie shadow that you’re surrounded by. It wraps around the view in the cockpit."
Hidden in the nose cone of the WB-57 aircraft are four cameras that will take dozens of pictures a second of the occluded sun in different wavelengths of light. The images should capture large, looping ribbons of plasma called prominences and magnetic explosions called nanoflares. Dr Amir Caspi, the principal investigator on the mission at Southwest Research Institute in Boulder, Colorado, said, "I’m super-excited. Solar eclipses give us an opportunity to do science we couldn’t do at any other time." He said nanoflares release thousands of atomic bombs’ worth of energy as they go off around the sun and help explain why the corona, or outer atmosphere, is more than 1,000,000C while the surface is 6,000C.
Cold War Airframe, Modern Data Hunger
Caspi said aircraft are hard to beat for these observations because ground-based cameras have clouds and atmospheric interference to contend with, while space-based cameras can send back only so much data. "As you can imagine, this is terabytes of information," he said. The WB-57 is based on the English Electric Canberra bomber, the RAF’s Cold War tactical nuclear strike aircraft, and flies above the clouds in the stratosphere. That detail sits there without ceremony: a machine designed in the shadow of nuclear war now carries cameras for solar science.
The article also said that in 1923 the U.S. Navy sent a fleet of biplanes to observe an eclipse without much success, and that 50 years later scientists persuaded the French to cut holes in the roof of a Concorde prototype; flying over the Sahara at Mach 2, they kept up with an eclipse shadow for 74 minutes. The history of eclipse chasing is full of state aircraft, military hardware, and institutional ingenuity repurposed for observation. The sky, apparently, is never just the sky.
Caspi said, "Understanding space weather is critical for us as a technological species, and it starts with understanding the processes at the sun." He also said, "What percentage of humanity has ever witnessed a total solar eclipse? It’s a fraction of a fraction of a per cent. If you’re part of that rare group, you’re connected to the Earth and the sun and the solar system. It’s mind-blowing. It makes you feel very special, but also very small because you are this little mote in the universe."
That last line lands harder than the mission’s polished language. A tiny fraction of humanity gets the view. The rest get the spectacle filtered through institutions, aircraft, and expensive instruments, while the state’s old bomber frame keeps doing useful work for the people who can afford to point it at the sun.