Two modern engineering marvels crossed paths this week here in Central America, as the last unflown space shuttle external fuel tank passed through the Panama Canal during a multi-week voyage from New Orleans to Los Angeles.
The tank, ET-94, is a shuttle-era flight artifact sidelined after the Columbia accident in 2003. Now, it is embarking on an outreach mission for the California Science Center, where it will be mated to shuttle Endeavour and a pair of solid rocket boosters, creating a full-scale space shuttle in launch configuration.
Following a signing ceremony and sendoff at NASA's Michoud Assembly Facility on April 12, ET-94 and its barge spent two weeks crossing the Gulf of Mexico and Caribbean Sea. The journey was relatively uneventful, except for a brief stop in the Cayman Islands to dodge 6-meter sea swells. By the start of this week, the tank was poised to enter the Panama Canal, which connects the Atlantic and Pacific oceans.
"This canal is over one hundred years old," said Jeffrey Rudolph, president and CEO of the California Science Center. "And it really is an engineering feat. So it was special to have a part of the space shuttle, which was a modern engineering feat, go through here."
Last unflown space shuttle fuel tank transits Panama Canal Jason Davis / The Planetary Society
On Monday morning at 5:30 a.m., I climbed into a van with a dozen canal workers, science center project managers, and camera operators, who are documenting the tank's trip. We sped from Panama City to Colón, a sea port near the canal's Atlantic entrance. As an outsider, the Panamanian rush hour felt perilous. Stoplights on our route through Colón were far and few between, requiring drivers to play a white-knuckle game of chicken to navigate busy intersections.
At the dock, we boarded a small tugboat and shoved off to meet up with the tank. The local canal veterans stood confidently near the back of our ship, which had no rear railing—inches from tumbling into a choppy wake as the tug bounced along. ET-94 looked like a big orange cigar against the grey, early morning horizon. Its barge, the Gulfmaster I, was moored to a large pink buoy. Nestled next to it was the Shannon Dann, its tugboat from Louisiana. As we approached, some of the canal crew snapped selfies with the one-of-a-kind cargo they were here to escort.
We offloaded some passengers to the Gulfmaster I, and about an hour later, two local crew members leapt from our boat onto the barge's pink buoy to untie the ship. ET-94 was clear and free to navigate toward the Gatun locks, which mark the canal's entrance.
As the crow flies, the Panama Canal measures about 60 kilometers from ocean to ocean. It is not a single waterway connecting the global sea levels of the Atlantic and Pacific. Rather, ships entering either side use a set of locks to reach Gatun Lake, which sits 26 meters above sea level in the middle of Panama. Ships are then lowered back to sea level on the opposite side.
Kenneth Phillips, the curator for aerospace science at the California Science Center, told me he never expected to visit Panama. He said ET-94 was actually not the first shuttle tank to traverse the canal—NASA sent a few to Vandenberg Air Force Base in California when the agency was making preparations to launch shuttles from the West Coast before the Challenger accident in 1986. Those were ultimately shipped through the canal again for launches at Kennedy Space Center.
"Before coming here, I didn't have a clear picture of how the lock system operates," Phillips said. "It's a fascinating civil engineering project. And this is the best combination of civil engineering and aerospace engineering coming together."
The history of the Panama Canal is messy and fraught with international involvement. The U.S. State Department begins the story in 1850, when America and Great Britain signed a treaty to build a canal through Nicaragua. That effort never came to fruition, and in 1880, the French attempted the feat in Panama—then a province of Colombia. The effort was stopped after 20,000 workers died from tropical diseases and construction accidents.
In 1902, the U.S. negotiated a new canal project in Panama, but Colombia disputed the arrangement's financial terms. President Theodore Roosevelt dispatched warships to both the Atlantic and Pacific sides of Panama, and the country declared independence from Colombia in 1903.
Colombian troops were unable to stop the new U.S.-Panamanian alliance, and the U.S. bought the canal land for $10 million plus an annual payment of $250,000. The U.S. also agreed to guarantee Panama's independence. Despite periods of tension throughout the twentieth century, America maintained ownership of the canal until handing it back to Panama on December 31, 1999.
Reaching Gatun Lake from the Atlantic means traversing the Gatun Locks. There are two locks on the Pacific side: Pedro Miguel and Miraflores. Ships entering the canal must cede control of their vessels to the Panama Canal Authority. Small, electric trains called mules attach cables to entering vessels, stabilizing them as they traverse each set of locks.
Although ET-94 measures 49 meters long and sits atop a longer and wider barge, it is dwarfed by the majority of other ships in the canal. From a vantage point at the Gatun Locks, the tank was briefly eclipsed from view by a cargo freighter passing in the opposite direction. The freighter was stacked six-high with tractor trailer-sized cargo containers.
Each chamber is filled and drained with gravity fed water from Gatun Lake, and the water level changes fast enough to be visibly noticeable. Each lock measures 34 by 305 meters, which dictates the maximum size of cargo ships around the world. Massive freighters are within arms' reach as they pass through. After a century of operations, Panama is building new locks sized 55 by 427 meters.
The tank traversed Gatun Locks in less than an hour, and passed into the calm waters of Gatun Lake. There, it spent the night waiting to reverse the process on the Pacific side the next day.
Whereas Monday had been occasionally sunny, thunderstorms blanketed the region on Tuesday, bringing a much-needed downpour to the rainforest, according to locals. On that day, I joined the larger California Science Center contingent, and we set out to spot the tank through chain link fences at Pedro Miguel, the first Pacific lock. Dennis Jenkins, a shuttle program veteran who is overseeing the ET-94 project for the science center, chartered a helicopter to collect footage of the tank from overhead. He succeeded before heavy rain forced the group to reconvene at Miraflores, the final set of Pacific locks.
Miraflores is equipped with a five-story tourist center, complete with balconies and a restaurant overlooking the locks. We were given permission to walk through the rain across the slippery, ancient lock doors to the Miraflores control center, which sits in the middle of the canal's two-lane channel. As ET-94 appeared through the fog, tourists back at the visitor's center crowded balcony railings for a better look. Even a few control center workers came outside, grinning as the tank slid up to the final lock chamber.
As it was back at Gatun, the water drained from the final lock in just a few minutes, leveling the Gulfmaster I barge and Shannon Dann tug level with the Pacific. The massive doors opened, and after years of planning, ET-94 was through. "You're either there or you missed it," Kenneth Phillips told me later.
The tank is now heading northward along the coasts of Central America and Mexico. It will stop in San Diego to chew up any leftover margin allocated for inclement weather before arriving in Los Angeles. The tank will be towed through L.A. streets to the science center on Saturday, May 21.
Early Wednesday morning, I was driven to the airport along a traffic-snarled, backcountry road. Despite the fact that the Panama Canal is a crucial shipping hub for the global economy, much of the country's local infrastructure is in desparate need of upgrades. As we sat in traffic waiting to cross a one-lane bridge near the Pedro Miguel locks, the van's driver lamented the slow pace of politics, and described how happy locals would be to have a simple four-lane road installed.
Then he asked me why I was here. I told him about the space shuttle, the tank, and the canal.
He already knew about ET-94 because his all of friends had been talking about it, and the day before, he was transporting a group of passengers when he spotted the tank in Gatun Lake through a rainforest clearing. He pulled the van to the side of the road, and hopped out with the passengers to snap pictures. As he recalled the scene, I was struck by his enthusiasm, and remarked that living near the canal, he must see lots of interesting things passing through the lake.
"Yes," he said, in his heavy Spanish accent. "But never a rocket."
Expenses for this reporting project were covered by a partnership between The Planetary Society, California Science Center and Toyota.