Chocolate chip cookies have become the first food to be baked in space and took two hours in a special 'zero gravity oven' on the International Space Station.
Astronauts baked five individual biscuits just before Christmas but nobody knows how they taste, as they've been sent back to Earth in a SpaceX capsule for testing.
A specially designed oven was installed on the station as part of an experiment to study cooking options for future long-haul space trips - including to Mars.
The baked treats were prepared by ISS commander Luca Parmitano over several days of experimentation to find the perfect cooking temperature and time.
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In this photo made available by U.S. astronaut Christina Koch via Twitter on Dec. 26, 2019, she and Italian astronaut Luca Parmitano pose for a photo with a cookie baked on the International Space Station
The cookies took 'considerably longer' to bake than they would have on Earth, over two hours for the 'perfect' biscuit, compared to under 20 minutes on the planet.
Three of the cookies are still sealed and frozen in individual baking pouches in a Houston lab after splashing down on Earth two weeks ago.
'There's still a lot to look into to figure out really what's driving that difference, but definitely a cool result,' said Mary Murphy, a manager for Texas-based Nanoracks.
'Overall, I think it's a pretty awesome first experiment.'
The cookies will soon undergo additional testing by food science professionals to determine the final results of the experiment.
The team behind the experiments say this will help experts with future efforts to make long-duration space travel more hospitable.
Located near NASA's Johnson Space Center, Nanoracks designed and built the small electric test oven that was launched to the space station last November.
Italian astronaut Luca Parmitano was the master baker, radioing down a description of each cookie as he baked them one by one in the prototype Zero G Oven.
The first cookie - in the oven for 25 minutes at 300 degrees Fahrenheit ended up seriously under-baked.
He doubled the baking time for the next two, and the results were still so-so.
It wasn't until the fourth cookie, which stayed in the oven for more than two hours that he finally found success.
'So this time, I do see some browning,' Parmitano radioed. 'I can't tell you whether it's cooked all the way or not, but it certainly doesn't look like cookie dough any more.'
The cookies were analysed on board the ISS but the true picture of 'how they taste' and whether they are safe to eat will be assessed on Earth
Parmitano cranked the oven up to its maximum 325 degrees F for the fifth cookie and baked it for 130 minutes. He reported more success than the fourth.
This suggests the ideal temperature for a cookie in space is 325F and should be in for two hours and ten minutes.
The same cookies on Earth bake at 300F for just 16-18 minutes, according to dough suppliers, DoubleTree by Hilton.
In a typical convection oven on Earth, there is a continuous cycle of hot air rising and cool air moving in to replace it, setting up a constant flow of air in the oven that allows for even cooking.
However in the microgravity environment of space, there is no 'up' direction for the hot air to float towards.
Bearing this in mind, NanoRacks designed the space oven with heating elements around the entire interior to distribute heat evenly and develop a pocket of air in the cooking chamber.
The second cookie being removed and the third being installed by astronauts. It took a few days of experimenting one cookie at a time
As for aroma, the astronauts could smell all but the first cookie when they removed them from the oven.
Former NASA astronaut Mike Massimino said the smell would have given the crew a 'sense of home' and a connection to Earth.
He now teaches at Columbia University and is a paid spokesman for DoubleTree.
'The reminder of home, the connection with home, I think, can't be overstated,' Massimino said.
'From my personal experience food is pretty important for not just nutrition but also for morale in keeping people connected to their home and their Earth.'
Eating something other than dehydrated or prepackaged food will be particularly important as astronauts head back to the moon and on to Mars.
A Zero G Kitchen Space Oven and a box of DoubleTree cookie dough. There were already pre-baked DoubleTree cookies on board the station
Nanoracks and Zero G Kitchen, a New York City startup that collaborated with the experiment, are considering more experiments for the orbiting oven and possibly more space appliances. What's in orbit now are essentially food warmers.
There's an added bonus of having freshly baked cookies in space, according to astronaut Koch.
'We made space cookies and milk for Santa this year,' she tweeted alongside a photo of herself and Parmitano posing with the cookie and a pouch of drink.
Nanoracks says additional testing is required to determine whether the three returned cookies are safe to eat.
HOW DO ASTRONAUTS EAT IN SPACE AND HOW IS FOOD STORED?
Astronauts eat three meals a day: breakfast, lunch and dinner.
Calorie requirements differ for astronauts. For instance, a small woman would require only about 1,900 calories a day, while a large man would require about 3,200 calories.
An astronaut can choose from many types of foods such as fruits, nuts, peanut butter, chicken, beef, seafood, candy, brownies, etc.
Available drinks include coffee, tea, orange juice, fruit punches and lemonade.
An astronaut can choose from many types of foods such as fruits, nuts, peanut butter, chicken, beef, seafood, candy, brownies, etc. Available drinks include coffee, tea, orange juice, fruit punches and lemonade
No alcohol is allowed to be consumed on the space station.
Condiments, such as ketchup, mustard and mayonnaise, are provided.
Salt and pepper are available but only in a liquid form because astronauts can't sprinkle salt and pepper on their food in space.
The salt and pepper would simply float away. There is a danger they could clog air vents, contaminate equipment or get stuck in an astronaut's eyes, mouth or nose.
Preparation varies with the food type. Some foods can be eaten in their natural forms, such as brownies and fruit.
Other foods require adding water, such as macaroni and cheese or spaghetti.
An oven is provided in the space station to heat foods to the proper temperature.
There are no refrigerators in space, so space food must be stored and prepared properly to avoid spoilage, especially on longer missions.