International Space Station: Futuristic Noah's Ark on Steroid

International Space Station is mankind’s greatest achievement in low earth orbit paving the way for a microgravity laboratory about 250 miles (400Km) from earth’s surface. At a speed of 7 Km per second it orbits the earth in 90 minutes. ISS was launched on 2 November 2000. 

Space Station Facts

• The Truss Structure -ISS comprises of hexagonal shaped pressurized modules with 4 big solar arrays all connected via a massive backbone called “Integrated Truss Structure”. It is constructed of stainless steel, aluminum and titanium. These corrosion resistant, light weight, and rigid materials contribute to incredible rigid structures to overcome pull of earth’s gravity. These materials had to compensate for deflections as a result of gravitational pull and vibrations due to extreme speeds which is 5 times the speed of sound.

• Orientation - ISS orientations are determined by controlled moment gyroscopes aboard the ship. In space there’s no right, left, up or down so the orientation is determined via ground based station and satellite based station and gyroscopes. It is the same gyroscopes found in our smartphone.

• Power Generation - The solar arrays are 73m in wide and comprising of 260,000 solar cells generates 84 to 120 kilowatt per day enough to power 40 houses. The photovoltaic Solar cells are made of purified silicon that converts sun’s infrared energy into direct current electricity. 

• Temperature Maintenance - Extreme temperature variations in space which varies from -160 degree celsius at night and 120 degree celsius at day causes onboard electronic controls to malfunction and may even fry and start a fire. ISS has a tendency to capture heat and warm up. Space, being vacuum, one can’t get rid of heat convectively or conductively as there is no atmosphere. One can’t blow fans and radiators to cool them. To prevent critical heating in an extreme event engineers use radiators called Active Thermal Control System. Waste heat is removed in two ways via cold plates and heat exchanges. A series of pipes carrying water cools the ISS. Heat exchange method involves two pipes where one pipe carries hot water and another pipe contains ammonia. Ammonia doesn’t freeze until negative 73 degree celsius. So ammonia flows through pipes and radiates heat and continues to circulate within the pipe network before freezing. Drawback of the system being water circulation.

• Drinking Water - ISS for its first decade of operation was supplied with water from earth at an exorbitant ferrying price. Source of water in ISS comes from humidified air of breathing, reclaimed water from space toilet called waste containment system. All of it is circulated through a special waste purification system filtering out particles and decontaminating bacteria producing pure water at end. In 2010 ferrying of water into ISS was solved when Sabatier System was installed which uses nickel Catalyst to catalyse carbon dioxide with hydrogen to produce water and methane. Since ISS already has hydrogen and Carbon Dioxide it helps to repurpose them into producing water. Water is also being used to produce oxygen by breaking down H2O via electrolysis method.

• Threats of Micro Meteorites and Debris and Superhero Fabric - To protect ISS from 100,00 debris ranging in size from 1cm to 10cm speeding at 25 times speed of sound  NASA devised Whipple Shield. This is a multi layer system designed to mitigate impact energy by capturing fragmented pieces of debris at different layers and reduce impact energy. The layers consists of aluminum, ceramic fibres such as- kevlar and nextel. With an inhuman ability to withstand heat of 2000 degree farenheit, stronger than aluminium and able to withstand meteroids Nextel is termed as superhero fabric. Kevlar maintains its strength and resilience especially at cryogenic temperatures (-196 degree celsius). Kevlar is best known for its usage in Ballistic Vests.

  
  

• Waste Management - Waste generated onboard can’t be just thrown out the window, one because of danger of depressurization and instant freezing and two it may become part of space debris floating at a speed of 28,000 km per hour. So what ISS does is when crews return from ISS waste are being thrown out at a low enough altitude the atmosphere vaporizes the waste into ash and smaller enough nascent pieces where it can no longer pose any threat.

• A spacecraft can arrive at the space station as soon as four hours after launching from Earth.

International Space Station Size & Mass

Pressurized Module Length: 218 feet along the major axis (67 meters)

Truss Length: 310 feet (94 meters)

Solar Array Length: 239 feet across both longitudinally aligned arrays (73 meters)

Mass: 925,335 pounds (419,725 kilograms)

Habitable Volume: 13,696 cubic feet (388 cubic meters) not including visiting vehicles

Pressurized Volume: 35,491 cubic feet (1,005 cubic meters)

Power Generation: 8 solar arrays provide 75 to 90 kilowatts of power

Lines of Computer Code: approximately 1.5 million

Onboard Sensors: On-orbit software monitors approximately 350,000 sensors, ensuring station and crew health and safety.