Eating

Space food – A packet of apricot juice, a can of lamb with vegetables, a silver packet with lasagna, and packages of bread and dried fruit. Photo: NASA

Zvezda Service Module of the International Space Station. Various food items are visible in their bags velcroed to the wall. Photo: NASA

Like the early days, space meals are prepared and eaten under the same basic restrictions ? food and drink has to be somehow confined, or else it will wander off around the station. This is obviously messy and unhygienic; but if free-falling food gets into station equipment, it can also be dangerous. So drinks and soup are served in plastic bags and sipped with straws.

Video: Cosmonauts in the ISS

Much of the American-supplied foods come in sealed pouches. For these, all crews have to do is heat and eat.

Pic: Bags of Space Station food and utensils on tray. Photo: NASA

Sanitation
One of the most asked question about living on the ISS is about the elimination of bodily waste. In other words, how do ISS crews use the toilet?

Using the toilet in the ISS is of course unlike doing it on Earth. There is no gravity, so the use of water and flush system is out of the question. On the ISS, the toilet is operated by air pressure. A fan does the work that gravity does on the ground. Urine is sucked inside the toilet and is collected in a 20-liter container.

When these are full they are discarded in the Progress. For collecting solid waste the toilet has plastic bags you place inside, and air is sucked through tiny holes in the bag. Everything gets collected in the bag and the bags self-close with an elastic string around the opening. You then push the closed bag through a hole into an aluminum container, and put a new bag in place for the next person.

ISS bathroom Photo: NASA

The Hygiene Centre in the bathroom Photo: NASA

ECLSS on the ISS provides the following functions:
? Recycle wastewater (including urine) to produce drinking (potable) water
? Store and distribute potable water
? Use recycled water to produce oxygen for the crew
? Remove carbon dioxide from the cabin air
? Filter the cabin air for particulates and microorganisms
? Remove volatile organic trace gases from the cabin air
? Monitor and control cabin air partial pressures of nitrogen, oxygen, carbon dioxide, methane, hydrogen, and water vapor
? Maintain total cabin pressure
? Detect and suppress fire
? Maintain cabin temperature and humidity levels
? Distribute cabin air between ISS modules (ventilation)

Sleeping pattern
While orbiting the earth, astronauts experience 16 sunsets every 24 hours and a new ‘day’ approximately every 90 minutes. While 16 stunning sunsets is a treat for the astronauts, it poses a challenge to their regular sleeping patterns. Astronauts are allotted 8.5 hours for sleep during each 24-hour period, but many report that they only need 6 to 6.5 hours to feel fully rested. Some believe that this may be the result of the body feeling less fatigued as a result of being in a microgravity environment.

Astronauts use an Earth-based time zone, selected by Mission Control to keep a regular schedule. The majority of space missions are ‘single shift’, meaning that all the astronauts on the mission work and sleep at the same time. During periods when the shuttle is docked at the International Space Station (ISS), the mission may operate on a ‘dual shift’ schedule. Although efforts are made to put both crews on the same schedule, often the shuttle crew or the ISS crew will go to sleep and wake up several hours earlier.

How ISS crews sleep
In space there is no up or down and there is no gravity. As a result, astronauts are weightless and can sleep in any orientation. Due to the microgravity environment, sleeping on the floor is just as comfortable as sleeping on the wall, and astronauts don’t require a mattress. However, they have to attach themselves to a wall, a seat or a bunk bed inside the crew cabin so they don’t float around and bump into something.

Sleep spots need to be carefully chosen – somewhere in line with a ventilator fan is essential. The airflow may make for a draughty night’s sleep but warm air does not rise in space so astronauts in badly-ventilated sections end up surrounded by a bubble of their own exhaled carbon dioxide. The result is oxygen starvation: at best, they will wake up with a splitting headache, gasping for air.