Coke and Pepsi are taking their 87-year-old fizz fight into space, with NASA playing referee.
So far, space agency insiders say, the experience has been less than refreshing.
Because of a compromise reached after weeks of highly sensitive legal negotiations, both beverages are expected to be aboard the shuttle Challenger during its weeklong science mission that begins Friday.
Each soft drink will be in its company's can designed especially for dispensing during weightlessness. The Pepsi can must still pass final tests at Johnson Space Center in Houston but NASA spokesman Brian Welch said no problems are likely.
The shuttle pantry will be supplied with four cans of each soft drink in what is intended as a test of the can technology and a way of giving astronauts more thirst-quenching choices. They now are limited to powdered drinks.
Carbonated beverages have not been carried on the shuttle because no special containers were available to control and dispense the bubbly liquids in zero gravity.
Still, one problem remains. The shuttle has no refrigerator. Never has, never will, as they say in ads for that other soft drink.
"There's really not been a demonstrated need for it," Welch said. Cold and hot water is available, he said.
Coke "was not meant to be consumed warm," said company spokesman Mark Preisinger in Atlanta. However, the cans will be wrapped in insulation to keep down the temperature.
Pepsi tastes better cold, but is refreshing no matter how you drink it, said company spokeswoman Rebecca Madeira in New York.
For its part, NASA is more worried about technology than taste, preferring research over refreshment.
If either or both soft drink cans work well, NASA has retained the legal right to use them in the future, filled with whatever drink the agency chooses.
The flight is a test and "it's not like a matter of astronauts going up there to recline and enjoy the beverage," Welch said.
The Coca-Cola Co. likes to think of the flight in terms of prestige.
"We have had a history of being an innovator in the soft drink industry," and putting Coke in space is another example of that, said Preisinger.
There won't be a big demand for Coke on shuttle flights, but the company is interested in serving the potential market aboard a space station or other space ventures, he said.
The Coke can, which the company said cost $250,000 to develop, looks like a regular 12-ounce can with a special top that includes a drinking spout and valve switch. It dispenses the liquid using a lever that works like a plunger. Pepsi's can is "quite different," but also uses a standard size can with a dispensing valve on top, Madeira said. A pouch inside contains individual pouches of citric acid and sodium bicarbonate.
The acid and sodium mix when the dispensing valve is pressed. That causes the larger pouch to expand with carbon dioxide and fill the void as the liquid is consumed, she said.
Pepsi has been talking to NASA about a space can for at least two years, she said. The technology cost $14 million to develop, but it has other applications for the company.
Like Coke, Pepsi wants to get into space "to be competitive," Madeira said.
For NASA, the soft drink issue first bubbled over in May.
On May 8, Coca-Cola distributed pictures and an announcement that it had developed a space can to be tested on the shuttle as early as July. NASA said then that there had been no final agreement.
Agency sources said the soft drink company had hoped to put the can on a mission in April to coincide with the announcement of the change in Coke's recipe.
Neil Hosenball, NASA's general counsel in Washington, said he was angered when the company went public with the shuttle experiment before reaching a final agreement with NASA. He said he "fired off a letter" to Coca-Cola.
The space agency, which is prohibited from endorsing products, did not want to show a preference for any soft drink.
In late June, NASA announced an agreement with Coke to use the soft drink and its can in July. Five days later, NASA announced that Pepsi had signed up for the same mission.
"It's not impossible," said Welch, that NASA could dispense Coke from Pepsi's can or vice versa.
Meanwhile, NASA says other soft drink companies "are welcome" to devise different containers for shuttle testing.