The idea of living in space was the very first step towards a space station. The first person to write about living and traveling in space was the noted renaissance astronomer Johannes Kepler in the early 1600s. He was the first to realize that planets were worlds, that there was space between the planets and he wrote that one day people would travel through space.
In the 1860s, Edward Everett Hale wrote the “Brick Moon” which was published in the Atlantic Weekly magazine. The Brick Moon had many of the characteristics of a space station; it was a man-made structure that orbited Earth and provided housing and life support for its crew while serving as a navigation aid for people on Earth.
Others, like the Russian theoretician Konstantin Tsiolkovsky were thinking about designs for space stations that could use sunlight for power and that would serve as miniature Earths, with growth of vegetation in the interior.
The first details of the engineering, design and construction of a space station were described by Herman Noordung, in 1928. He described a “wohnrad” or “living wheel“; a wheel shaped rotating space station. He reasoned that the rotation would be required to create artificial gravity for the crewmembers. He described how it would be assembled first on the ground for testing and then its individual parts launched by rocket for reassembly in orbit.
Willy Ley wrote about life in a space station in 1952. “When man first takes up residence in space, it will be within the spinning hull of a wheel-shaped space station [revolving] around the earth much as the moon does. Life will be cramped and complicated for space dwellers; they will exist under conditions comparable to those in a modem submarine…it will be a self-contained community in which all man’s needs, from air-conditioning to artificial gravity, have been supplied.” [Willy Ley and Chesley Bonestell in The Conquest of Space, Viking Press.] Their ideas went nationwide in Collier’s Magazine and on the Walt Disney television program.
The US government began to develop space station concepts in the 1950s. One of the early concepts was the US Army Project Horizon modular orbital station which would serve to house crews and refuel spacecraft on their way to a moon base. In the early 1960s, NASA’s Manned Spacecraft Center (now Johnson Space Center in Houston) elaborated on the requirements for a station and they patented the concept. Concepts for the first US space station, which would later become known as Skylab, started about this time.
Almost simultaneously, the Soviet Union planned a super rocket launcher that would orbit a large space station. The rocket, designated the N-1, would also be pressed into service for the Soviet manned Moon landing program. But test launches beginning in 1969 proved unsuccessful and so the Soviets turned their attention to smaller stations which could be launched by their most powerful functioning rocket, the Proton.
Assembly
The ISS components were built in various countries around the world, with each piece performing once connected in space, a testament to the teamwork and cultural coordination.
Like a Lego set, each piece of the ISS was launched and assembled in space, using complex robotics systems and humans in spacesuits connecting fluid lines and electrical wires.
The ISS is the largest humanmade object ever to orbit Earth. ISS has a pressurized volume of approximately 900 m3 (31,000 ft3) and a mass over 400,000 kg (900,000 lbs). Actual numbers vary as logistics resupply vehicles come and go on a frequent and regular basis.
The ISS solar arrays cover an area of 2,247 m2 (24,187 ft2) and can generate 735,000 kW-hours of electrical power per year.
The ISS structure measures 109 m (358 ft) (across arrays) by 51 m (168 ft) (module length from the forward end of PMA2 to the aft end of the SM).
ISS orbits at an altitude of between 370–460 km (200–250 nmi). Its falls towards Earth continually due to atmospheric friction and requires periodic rocket firings to boost the orbit. The ISS orbital inclination is 51.6°, permitting ISS to fly over 90% of the inhabited Earth.
ISS carries a crew of between 3 and 13 depending on then number of people and passenger vehicles during handover periods, It continually hosts a crew of seven.
Building the ISS required 36 Space Shuttle assembly flights and 6 Russian Proton and Soyuz rocket launches. More launches are continuing as new modules are completed and ready to become part of the orbiting complex.
Logistics, resupply and crew exchange have been provided by a number of vehicles including the
Space Shuttle, Russian Progress and Soyuz, Japanese H-II Transfer Vehicle (HTV), European Automated Transfer Vehicle (ATV) and commercial Dragon, Cygnus and Starliner vehicles.
For more information about the International Space Station assembly elements visit https://www.nasa.gov/international-space-station/international-space-station-assembly-elements/.
The complex assembly of space station would have been impossible without the skilled labors of spacewalking astronauts and cosmonauts. Spacewalks, or Extravehicular activity (EVA) were conducted in Earth orbit, on the Moon’s surface, and in deep space between the Earth and Moon in prior programs.
The cumulative experience of the EVAs conducted prior to the start of ISS assembly formed a solid basis on which to build the necessary spacewalking skills but during the ISS Program more spacewalks have been conducted than in all prior programs, combined. At one time ‘the wall of spacewalks‘ was seen as a formidable obstacle to assembling the ISS but spacewalks and assembly missions have proceeded almost with no hindrances.
In the two+ decades since station assembly began, more than 260 spacewalks for assembly, maintenance, and reconfiguration have been required. Spacewalks were essential to preparing the ISS to accommodate its first occupants.
Astronauts Jerry L. Ross and James H. Newman conducted the first ISS EVA on December 7, 1988, during the STS-88 mission, to connect electrical and data cables between the station’s first two modules,FGB ZaryaandNode 1 Unity. Over the course of the first five shuttle assembly missions, 12 crew members conducted 10 spacewalks prior to the Expedition 1 crew taking up residence on the station. During STS-96, the second assembly mission in May 1999, Tamara E. “Tammy” Jernigan became the first woman to perform an EVA at ISS. Astronaut Edward T. “Ed” Lu and cosmonaut Yuri I. Malenchenko conducted the first U.S.-Russian EVA at station during the June 2000 STS-101 mission. The two connected electrical and data cables betweenFGB Zaryaand the newly arrivedService Module Zvezda. In preparation for that spacewalk Russian engineers modified the Hydrolab facility at the Gagarin Cosmonaut Training Center to accommodate the U.S. EMU spacesuits. American engineers adapted the Neutral Buoyancy Laboratory at NASA’s Johnson Space Center to accommodate the Expedition 1 crew train using either the US EMU or Russian Orlan spacesuits.
Following the arrival of Expedition 1 crew members William M. Shepherd, Yuri P. Gidzenko and Sergei K. Krikalev aboard the space station on Nov. 2, 2000, the pace of assembly and the number of spacewalks increased significantly. Between December 2000 and April 2003, 38 astronauts and cosmonauts completed 41 EVAs, including the first staged from station itself, using an ISS airlock, rather than from the visiting Space Shuttle. On March 10, 2001, Expedition 2 astronauts James S. Voss and Susan J. Helms conducted a spacewalk during STS-102 that, at eight hours and 56 minutes, still stands as the longest EVA in history. In April 2001, Canadian Space Agency astronaut Chris A. Hadfield became the first Canadian to conduct a spacewalk at the orbiting laboratory during STS-100, the flight that brought theCanadarm2robotics system to the space station. On June 8, Voss joined Expedition 2 cosmonaut Yuri V. Usachev for the first Russian segment EVA, an ‘internal’ spacewalk insideZvezda’sTransfer Compartment to prepare it for the arrival of a new module.
The STS-104 mission in July 2001 brought theUS-built Quest‘Joint’ Airlock to the station, providing station a standalone EVA capability with accommodations for either the U.S. Extravehicular Mobility Unity (EMU) or Russian Orlan suits. Michael L. Gernhardt and James F. Reilly performed the first EVA fromQueston July 20. The Russian Pirs (Pier)module arrived at station on Sept. 17, 2001, providing the Russian segment with its own airlock capability. On Oct. 8, Expedition 3 cosmonauts Vladimir N. Dezhurov and Mikhail V. Tyurin staged the first EVA fromPirs.
Along with American and Russian crewmates, international partners continued to play a role in spacewalking, with Philippe Perrin becoming the first astronaut from France to perform a spacewalk at station during the STS-111 mission in June 2002.
Following the Space ShuttleColumbiaaccident, station spacewalks continued, but only from the Russian segment with the added complication that with the resident crew size was reduced to two, the pair of spacewalking crew members left no one inside to monitor its systems. Although this posed a slightly increased risk should something go wrong, these “two-person” spacewalks proved essential during the shuttle hiatus. Expedition 8 crew members Aleksandr Y. Kaleri and Mike Foale conducted the first of these EVAs on Feb. 26, 2004. Foale had prior experience with the Orlan suit, as he had completed an EVA during his long-duration stay aboard Mir in 1997. The crew had to cut the spacewalk short due to Kaleri’s suit overheating and water droplets forming inside his helmet. The crew later identified the problem as a kink in the water line in his liquid cooling garment. The incident provided a preview of a more serious problem, which would occur in an EMU during an EVA more than nine years later.
On the STS-114 shuttle Return to Flight mission, Soichi Noguchi became the first astronaut from the Japan Aerospace Exploration Agency (JAXA) to conduct an EVA at station on July 30, 2005. The first ESA (European Space Agency) astronaut to perform a station spacewalk was Expedition 13 crew member Thomas A. Reiter from Germany on Aug. 3, 2006.
Although all spacewalks carry a certain amount of risk, two examples illustrate how some are riskier than others. The objectives of the STS-120 mission in October 2007 included not only the delivery of theHarmonymodule to station, but also the relocation of the P6 truss segment from its location atop the Z1 truss, where it had been since December 2000, to the outboard port-side truss. During the overall reconfiguration of the station’s power systems earlier in 2007, the P6’s solar arrays were rolled up.After the crew members relocated P6 to the outboard truss, they began to unfurl the two arrays. The first array opened without incident, but with the second array nearly unfurled, the astronauts noticed a tear in a small portion of the panel and immediately halted the deployment to prevent further damage.Working with the crew aboard, mission managers devised a plan to have one of the astronauts essentially suture the tear in the panel. Appropriately enough, one of the two STS-120 spacewalkers, Scott E. Parazynski, was also a physician, and he put his suturing skills to good use. Attached to a portable foot restraint, Parazynski was hoisted atop not only the station’s robotic arm, but also the shuttle’s boom normally used to inspect the shuttle orbiter’s tiles — the impromptu arrangement providing just enough reach for Parazynski to successfully repair the torn array using improvised “cufflinks.” After he secured five cufflinks to the damaged panel, crew members inside the station fully extended the array as Parazynski monitored the event.
For more information about spacewalks visit https://www.nasa.gov/international-space-station/space-station-spacewalks/.
