Starship explosion raises questions about risk to public, environment

The latest disintegration of a SpaceX test flight was a spectacular sight, as broken-up rocket parts streaked like jellyfish tendrils across the Caribbean sky Thursday evening. 

But some experts say focusing on that dazzling light show, as many people and media outlets did, highlights a lack of understanding of the environmental aftermath of these spacecraft failures.  

Moriba Jah, professor of aerospace engineering at the University of Texas Austin, compares it to marvelling at the beauty of a nuclear bomb’s mushroom cloud. 

“Being mesmerized by the magic of the debris [means] not realizing what it implies,” Jah said. “This stuff can harm ecosystems, can affect populations.” 

There is also the more immediate threat, illustrated by this incident, posed by several tonnes of flaming wreckage raining down on the waters and, though the odds are slim, maybe even on some unlucky patch of land.

Airspace risks  

Thursday’s test of Starship — which was made up of two parts, the upper stage Starship (in this case, Ship 33) and the lower stage Super Heavy Booster — lasted about eight and half minutes. In that time, audiences saw the most powerful rocket ever made successfully separate both stages, and an impressive “chopstick” catch of the Super Heavy booster. 

But soon after, SpaceX says it lost its connection to the upper stage. Eventually, confused and awe-struck people in Turks and Caicos saw their evening sky ablaze with the debris of Ship 33. 

Elon Musk, billionaire CEO of SpaceX, suggested the cause was “an oxygen/fuel leak in the cavity above the ship engine firewall.” SpaceX says it’s looking at what went wrong in co-ordination with the Federal Aviation Administration (FAA), which requires a “mishap investigation,” as it did when a 2023 Starship test flight also exploded.

The trajectory for the flight started from Boca Chica, Texas, and headed east over the Caribbean Sea. Spaceflights like this make airspace warnings ahead of time, but the loss of communication spurred another, more urgent one. 

The FAA said in a statement it “briefly slowed and diverted aircraft” where the debris was falling. The result was flights being delayed, circling in place or turning back. 

Some pilots could even see the fireworks from their cockpits.

And for Jah, the risks, even if small, aren’t being fully communicated to air travellers.

“If you and I were going into an airplane and somebody said, ‘Hey, there’s a one in 10,000 chance you won’t make it,’ I’m not going to get on the plane,” Jah told CBC News from Austin, offering some hypothetical odds. 

Boley agrees, saying the risks and costs of the spaceflight industry are being exported to the aviation industry. 

Breaking up is hard to model 

This flight is believed to have broken up over the Atlantic Ocean, and there have been no reports of any injuries or sightings of the debris. 

Aaron Boley, co-director at the Outer Space Institute and an expert in space sustainability, says there isn’t even a sense of how these vessels break apart. 

“The extent of the debris field, how much debris, how much lethal debris — meaning how many chunks come down with a speed that can cause significant damage — that is stuff that is not well understood at this point,” said Boley, who is also an associate professor at the University of British Columbia. 

Jah agrees, calling the simulations “woefully ill at being able to predict anything with any sort of meaningful accuracy” and depending on a “strategy of hope” that a breakup doesn’t result in harm. 

‘Designated hazard area’

Even the most successful end to this Starship launch was going to hit the water anyway — but far away, with a splashdown in the southern Indian Ocean. 

The splashdown zone is a ‘designated hazard area,’ where it’s assumed there’s less risk to human life in such remote areas. However, even planned descents cause airline disruption. Australia’s Qantas airline says SpaceX re-entries have forced delays in recent weeks when flying over the Indian Ocean. 

Splashing down there “is the least worst option,” Boley said, giving people the chance to know roughly where and when things may fall.

But the worst way for debris to come down is in uncontrolled explosions like on Thursday, which is a roll of the dice. 

“You’re just assuming that these pieces are spread out over enough area that it’s just unlikely to actually hit somebody and cause damage,” said Boley. 

Riskier future

Because of all this uncertainty, experts say there isn’t a great sense of how rocket debris affects the marine environment. 

Research in 2016 out of the National Institute of Water and Atmospheric research in New Zealand conducted a review of the potential short- and long-term hazards rocket debris poses to nearby ocean life.  

Its panel of experts found 10 launches, whether successful or not, with each resulting in 40 tonnes of debris “would still have a minor risk.”

But more launches means more risk. 

“At 100 launches the risks could be moderate, and with 1,000 could become high,” they warned. 

Experts say halting spaceflight exploration isn’t the answer — but at the pace the industry is growing, more emphasis needs to be put on calculating the risk to the environment. 

“What are the statistics that we’re going to abide by?” Jah asks. “What are the sort of tests that we’re going to require for people to successfully explore space, but not to the detriment of environmental sustainability?”