European rocket part washes up in the Florida Keys

It’s not uncommon to find spent fireworks around the Fourth of July, but what shark researchers found floating in the shallows of Florida’s isolated Dry Tortugas last week wasn’t just another burnt-out bottle rocket.

It was a chunk of a real rocket the size of a small swimming pool — a remnant of a mission sometime in the past two years by Arianespace, the European consortium that specializes in commercial satellite launches.

The expendable rockets are supposed to break up and sink when they crash in the Atlantic Ocean after launch from a spaceport in French Guiana. But a piece of this one survived intact and drifted hundreds of miles, beaching on low tide along Long Key, one of the small islands ringing Fort Jefferson, the spectacular Civil War era outpost erected on Garden Key some 70 miles west of Key West.

That’s where Wes and Theo Pratt found it on Thursday, July 4th. The Pratts, who spend a month in the Tortugas every year studying the mating habits of nurse sharks, had kayaked the half-mile from Garden Key to watch sharks mingle in Long Key’s unspoiled shallows. Instead, they found a large and curious object stuck in the sand, parts of it bristling with barnacles.

“At first I thought it was a commercial airplane part,’’ said Wes Pratt, an adjunct scientist at the Mote Marine Tropical Research Laboratory on Summerland Key.

They couldn’t budge the thing, even with help from a ranger at Dry Tortugas National Park. Worried it might damage boats in the fort’s harbor or pose a navigation hazard, they tied a light to it and waited for high tide. It floated off late that night and was towed to the fort’s dock.

Glenn Simpson, the park’s manager, who has a background in archaeology, immediately got on the computer to research its origins.

Besides the partial word “nespa” in two-foot-tall letters on its exterior, there were several manufacturing plates, including one with a receiving date of October 2012. Based on that and Arianespace launch dates, Simpson figures it was likely one of four launches since November 2012. Barnacle growth seems to rule out the most recent launch, only a month ago, but some sea life can grow quickly.

The aluminum piece weighs several hundred pounds, but Simpson and Pratt speculate it was kept afloat by insulating foam and a honey-combed metal core between its inner and outer skins that trapped air.

Aaron Lewis, communications director for Arianespace Inc. in Washington, D.C., the consortium’s affiliate in the United States, reviewed photos and said it was “without a doubt” from an Ariane 5 rocket. It’s possibly a piece of fairing, he said, a metal sheathing designed to protect the payload and improve aerodynamics.

Arianespace typically launches satellites for companies like DirecTV. Once the rocket clears the atmosphere, its pieces separate and fall into an isolated area of the Atlantic between South America and Africa — “well away from any population concerns,’’ Lewis said.

The pieces typically sink, he said, but remnants occasionally wash up. A fairing piece from a NASA rocket, for instance, washed up in Hilton Head, S.C., in 2010 several months after a launch.

The find made for an exciting Fourth in the quiet Tortugas, typically home to no more than a few staffers, visiting researchers and campers who ferry over from Key West. Fireworks aren’t allowed in the park but, said Simpson, “We had this. It made our day.’’

Now the question is what to do with the rocket part. Simpson said it will be on temporary display for visitors, but he said he hopes to hear from Arianespace before deciding how to dispose or hopefully recycle the space junk. The park service, perpetually short of funds, would appreciate help defraying the cost of ferrying it back to Key West,

Pratt, the shark researcher, said the company also might want to study the chunk and figure out why it didn’t sink. One plate on it says “property of Arianespace,’’ he said. “It kind of sounds like you want it back if you put a sign like that on it.’’

Arianespace’s Lewis said he wasn’t sure about reclaiming the rocket part.

“I have no idea,’’ he said. “I will check with headquarters.’’