A house in the sky


* Una casa en el cielo

The International Space Station (ISS), the largest engineering project in the history of Humankind, is flying at 400 kilometers above the Earth, already inhabited uninterruptedly since the year 2000, after a multi-decade long effort.

The rocket genius Wernher von Braun proposed the idea of ​​an orbiting station back in the '50s. But in the following decade the challenge was simply to find out if humans could manage to survive a space flight: the Mercury capsules were designed for missions lasting just 1 day.

With the proposed trips to the Moon, began the experimentation of longer-duration human spaceflights, of up to 2 weeks.

Only in the '70s, for military reasons, the Soviets started to build reconnaissance space stations: the Almaz / Salyut series of disposable cylinders, crewed for up to 1 month.

The first multi-mission station was the U.S.'s Skylab, which received three scientific crews, with a maximum stay of 3 months, as it was not capable of receiving resupply ships. The first that showed this capability were the Salyut 6 and Salyut 7, around 1980. In this manner cosmonauts could be kept in space for up to 1 year, and at the same time the arrival of another crew for relay was also possible.

And in 1986, the assembly of the first permanently inhabited space station, the Soviet/Russian 6-module Mir, began.


In the United States of America, in response to these Soviet achievements, the construction of a much larger permanent station was proposed, with the participation of its allies in the Cold War: Japan, Canada and Western Europe. The project officially started in 1984 and it was called Freedom. It gave meaning to the Space Shuttle program as it required extensive construction in orbit, unlike all previous stations that were modular in design and were assembled in space via remote control in a few steps.

Despite the strong lobby of the Aerospace Industry, the project was delayed many times and was threatened with cancellation by the U.S. Congress, which saw no justification to the costs. It was enormously complicated and the number of flights needed to build it were unprecedented.


But the collapse of the Soviet Union brought a 180-degree political change and the International Space Station found a new meaning for its existence. As the Clinton-administration diplomat Madeleine Albright explained, now the project would serve as a strategic alliance with Russia to take advantage of the capabilities of the Russian aerospace industry and prevent its transfer to enemies of the United States of America.

A new agreement was signed in 1993, and it is based on a symbiosis between a projected Russian station (the Mir-2) and Freedom. It was re-named simply International Space Station or ISS, for its acronym in English, and will be four times bigger than Mir. It is the most expensive engineering project in History: US$ 100 000 million.


The stated aim is to build a unique, world-class laboratory which will provide an international platform for advances in Science and Technology in areas such as Biology, Medicine, Materials Science, Earth observation, space observation and technological developments, using basically 3 things that are absent down here on Earth: nearly-perfect vacuum, abundant cosmic radiations and weightlessness. The cost is justified by the alleged achievements in space exploration, scientific research, business and educational opportunities. In addition, to the senior partner, the USA, there is the appeal of maintaining global leadership.


To grasp the experience of Mir, between 1995 and 1997 U.S. Space Shuttles docked with that pioneer station and U.S. astronauts spent several months there. The ISS came in 1998, thus Mir was abandoned a few years later.

The assembly of the new station will require more than 100 components that must be taken into space in about 40 flights. The Russian modules, launched by rockets (usually Proton), are prefabricated and self-propelled, and once in orbit fit together automatically. The parts of the USA, Canada, Japan and European countries rode in the cargo compartment of the Space Shuttle and were installed using robotic arms and by astronauts in extravehicular activities, about 160 of these in total.

Up to once per month, the ISS will be visited by various freight vehicles, including the Russian Progress, the European Space Agency's ATV and Japan's HTV, all uncrewed and disposable, and also by container modules manufactured by Italy and at their time transported by the U.S. Space Shuttle. These ships are also used to adjust the station's orbit, and when departing they take the trash with them.


Living in a space station, as astronaut Shannon Lucid said, is living in the bowels of a machine. All six walls are covered with wires, tubes and devices; going from one room to another room is done through hatches. It is full of hums and buzzes and it can even rotate.

The ISS is inhabited since 2000, and many experiments such as crystal growth, growing plants, blood tests, studies of auroras, astronomical observations, weather observations and diverse cartography are already routinely performed. But still after the inauguration, maintenance will take most of the crew time. Astronauts work closely with technicians of the ground control centers, and in fact most of the tasks are performed by remote control from Moscow or Houston, so that the people who are in space remain available for operations that require direct human intervention.

The crews are relieved every 6 months, which is the most the human body endures in good condition in space. From time to time, they receive visits, bringing supplies and even space tourists. The crew follows a 24-hour day (with 8 hours per day, 6 days a week) but due to the ISS orbital velocity dawn, dusk and dawn again happen onboard in just 90 minutes.

The crew sleep in small private lockers, and must exercise two hours a day to keep muscles and skeleton in good condition. They have a kitchen with microwave oven and freezer, so they eat normal foods; The only thing that is not allowed is fried cooking. Hygiene is done with the help of vacuum hoses and the shower is once a week: water is scarce, but anyway there is not much dirt up there.

As sending 1 kg of supplies costs US$ 20,000, there is no other solution: everything must be recycled. The sophisticated system converts sewage water in commercial-quality drinking water; oxygen is retrieved from the water vapor released by respiration and perspiration, while CO2 is removed from the air.

During free time, weightlessness helps in relaxation, and isolation is combated by using amateur radio equipment. A limited amount of personal items could be carried onboard, such as books or musical instruments. Space holidays are Cosmonautics Day (12 April), 1 May, Thanksgiving Day (fourth Thursday in November) and Christmas.


The utilization of the ISS by each partner will be proportional to the capital invested. Particularly striking is the absence of China and India, which are also space powers, but these nations follow their own policies. But a Chinese space ally, Brazil, was attracted and participated as indirect partner: some U.S. equipment were outsourced in exchange for rights to carry experiments, though the agreement was later canceled. Meanwhile, the Brazilian government bought a commercial space ticket from Russia to carry an astronaut to visit the ISS in 2006. He was the first astronaut from a South American country. It is expected that hundreds of people will go to the International Space Station before the end of its useful life.

Though the ISS has suffered due to budget cuts and technical problems, like the Columbia fatal accident in 2003, its official opening is expected during the year 2013.


Despite sharing a single commander on a periodical basis, each country maintains sovereignty over their respective parts at all times.

UNITED STATES: Zarya cargo module, Unity, Harmony and Tranquility connecting modules, Destiny laboratory, Quest airlock chamber and Cupola of observation.

RUSSIA: Zvezda service module, Pirs and Poisk docking modules, Rassvet cargo module. Not yet installed: Nauka laboratory.

JAPAN: Kibo laboratory, Exposed Platform for experiments, with its robotic arm, Logistics Module.

EUROPEAN COUNTRIES: Columbus Laboratory.

CANADA: Cargo Crane, sliding on the main beam, highly maneuverable and equipped with a "hand", with capacity of over 100 ton.


Final length: 108 meters

Final width: 73 meters

Final mass: Approximately 400 tons

Crew: 6

Speed: 28 000 km/h

Altitude: 400 km

Life expectancy: 15 years after completion in 2011.

Aldo Loup.

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Based on a lecture given at USP, originally on 28 August 1999. Originally published in ABC Color, on 2 April 2006. Photograph: The International Space Station (ISS) performing its silent trajectory in the vacuum far above the clouds, on 23 May 2011. The docked space shuttle is the "Endeavour", during its final flight. Credit: photo taken by the flight engineer Paolo Nespoli from aboard the Soyuz TMA-20, while leaving the ISS at the end of his stay of 159 days as a member of Expedition 27. Courtesy NASA.