Along with other annoyances and dangers of cooking in microgravity
If you missed it, cookies became the first food baked from raw ingredients at the International Space Station (ISS). This was only possible after astronauts received both their first oven and some experimental cookie dough to run trials on. Considering that the conditions at the ISS are very different than back here on earth, some major overhauls had to be made to the baking process.
Each cookie had to be baked one at a time in specialized, silicone pouches, and the bake time was truly unknown. The astronauts only had five chances to explore baking in space.
The first cookie was baked for 25 minutes, which seems a little long for the conditions we have here on earth. Unfortunately, the cookie was actually still raw!
For their second attempt, the astronauts really went for it, and left the cookie in the oven for over 75 minutes! Still no luck! Although they smelled the cookie’s aroma for the first time, the treat still seemed undercooked.
Fast forward to their fifth, and final try at making their first space baked goods. Their last cookie was kept in the oven for 130 minutes at 325°F (the highest temperature the oven can reach)! That’s right, over two hours of bake time and this was deemed their most successful sample.
Even after all their hard work, the astronauts weren’t allowed to enjoy the treats. The cookies were actually packed up for a trip back to earth where they’ll be tested for safety. After all, you can’t risk making astronauts sick up at the ISS.
But, why would it take over two hours to bake one cookie up in space? Especially considering the average bake time for an entire tray of cookies at home is usually less than twenty minutes.
To crack this mystery, we need to take what we know about baking, and apply it to zero gravity conditions.
On earth, most ovens cook food using hot air. The heating element at the bottom of the oven creates hot air that rises up and cooks the food. This makes the top of the oven much hotter than the bottom.
As the air at the top cools down, it falls back to the bottom. This movement of hot air up and cold air down creates a current with air constantly circulating to heat the food. The problem is, without gravity this convection current doesn’t exist, so space ovens must use some other type of heat transfer.
The oven made for the ISS uses coils similar to those in a toaster oven. The oven is cylindrical in shape and built so that the food could be placed directly in the middle. The coils were then positioned to entirely surround the food at the center and direct heat towards it.
Of course, in microgravity you can’t just place your cookies in the oven. They’ll float away. Instead, each cookie was baked in a clear, silicone tray that entirely surrounded the food to help hold it in place. The tray could be slid into the oven framework to be fully secured during baking.
The cookies also needed to be entirely enclosed in the silicone trays to protect against a problem every parent is familiar with — crumbs.
Don’t get me wrong, crumbs are incredibly annoying on earth, but can you imagine what would happen in zero gravity? All those tiny particles floating through the air in random directions.
Sure, that sounds like a real mess, but imagine if the crumbs entered the ventilation system or damaged sensitive equipment? The worst-case scenario involves crumbs entering the electrical panels, which could lead to a fire.
And not just any type of fire, but literal fireballs. Without the pull of gravity downwards, any spark or flame takes the shape of a sphere. Considering everyone is in a contained space, floating fire orbs seems like a really bad idea.
In a similar vein, the astronauts couldn’t bake these cookies from scratch. Can you imagine trying to measure out flour in space? It makes a big enough mess here on earth.
Instead of risking millions of flour particles floating around the space station, the astronauts were sent individual, frozen discs of cookie dough. So, it’s true that cookies were the first food baked on the ISS, but it’s not like the astronauts became avid bakers.
Another huge limitation of baking on the ISS is that the power supply is extremely limited and something like baking cookies is not going to take priority. The oven had to work on about 1/10 the power of a conventional oven on earth.
This also explains why baking the cookies took so long. Just getting the oven to heat up would be much slower at reduced power. So, you should never complain about how long it takes your oven to preheat here on earth.
Another restraint of cooking on the ISS was that the entire process of preheating, baking, and cooling must all take place without opening the oven. The food has to be put in before preheating and only taken out after cooling, because heat doesn’t dissipate the same on earth and under zero gravity.
In space, heat tends to create hot pockets and stay wherever it’s formed, unless a force moves it. This means if the oven door was opened, a giant, heat bubble could enter the space station. Getting chased by a hot ball of air doesn’t sound like a great addition to the relaxing pastime of baking cookies.
Considering the amount of complications like floating fires and hovering heat balls, it’s a wonder an oven was even sent up to the ISS.
Sure, freshly baked cookies have to be a huge morale booster for astronauts who are limited to dehydrated, pre-packaged or freeze-dried meals, but it seems like there’s a long road ahead to understanding how cooking food in space can be done safely.
Ultimately, the goal of testing ovens at the ISS is so that similar appliances could be created for longer missions to Mars or beyond. From this first experiment, on only five cookies, we’ve discovered a lot of new information, but it has also signaled just how much we have to learn about cooking in space.