So far, the emphasis in this Introductory Section has been on satellites that orbit the Earth (and in Sections 19 and 20, satellites that orbit or fly by other planets/moons or remain around the Earth as platform-mounted telescopes that peer beyond the Solar System). Yet experience has shown time and again that humans are often superior in performing certain remote sensing tasks (such as photography [Section 12]) at Earth from a variety of space platforms. Overall, humans have large and vital roles in conducting space experiments and other operations.
In the Overview we alluded to small space capsules or larger Space Transportation System (STS) vehicles (Shuttles) that are built to allow humans to spend short periods in orbit or in transit (as to the Moon) for days to a few weeks. Yet there is a distinct and valuable role for putting astronauts/cosmonauts into earth-orbiting space systems that are designed to stay in space for durations of months to years. These systems can be conveniently dubbed Space Stations - characterized by being larger, more versatile, and more fully equipped to harbor the human occupants safely for long periods, so that they can perform a variety of special tasks that take time. These include time-extended scientific experiments, manufacturing items in near-zero gravity, and repeated observations of Earth or astronomical phenomena. A Space Station can also be designed to serve as an intermediate stop and jumping-off point for space vehicles (manned or unmanned) that go to higher earth-orbits, the Moon, and the planets.
This page summary will be constructed primarily from information from two Internet sites dealing with space stations: (1), (2). These numbers will be used below with individual images to tie them to their source site. You can log on to each site for more details. And for the curious, there is a Web site that lists all the flights of every kind of humans into space, visited at List of Human Space Flights.
The notion of a manned orbiting platform around Earth actuallly occurs in a book published just two years after the Civil War. The famed writer, Edward Everett Hale (author of "The Man without a Country") conceived of a space station as a sphere made of bricks, shown below:
Even more imaginative is "From the Earth to the Moon" by Jules Verne (it appeared in French in 1865 and in English in 1873). The spaceship in the Verne book looked like this:
The engrossing story had three Frenchmen, one the builder of this bullet-shaped vehicle, fired from a 274 meter deep vertical circular shaft dug into a Florida site. The craft was launched by exploding guncotton. This propelled it to escape velocity (> 17,500 mph) to the Moon, which it orbited, and then returned (total trip time 243.5 hours) for a landing on Earth. A number of aspects of the trip were remarkably prescient (after all, Verne ranks as one of the top science fiction writers of all time), not least of which was the name Columbiad that he gave to the spacecraft. Compare his craft with the Apollo Columbia Lunar Service Vehicle that actually went to the Moon less than 110 years later:
In 1928, the German Hermann Noordung first published his ideas on the feasibility of a manned platform in space. His colleague, the Romanian Hermann Oberth actually coined the term "space station" to descibe this concept
The famed rocketer, Wernher von Braun, may have been the first (in late 1945) to envision a believable configuration for a large space platform in space. It consisted of circular modules in a wheellike design and rotated to simulate gravity.
But the Space Age, which opened with Sputnik in 1958, had to get started before serious efforts were made to investigate the potentialities of establishing a station that would remain for long periods and be periodically to continually inhabited with humans performing useful tasks. In the 1960s, ideas were "floated" in both the Soviet and American space programs.
The Soviet space program focused early on establishing Space Stations. It began with the Salyut series. The first Station - Salyut 1 - was inserted into orbit on April 19, 1971. Here is a photo of this facility:
The first 3-man crew arrived a few days later after being launched by the workhorse Soyuz booster (shown below). But, something stuck and they couldn't get into it, requiring them to return to Earth. The second crew, with tools to open the Salyut, did enter and stayed for 16 days. But, tragically, upon return, a leak in their spacecraft sucked out all oxygen, so that they died enroute.
The Russians were developing another spacecraft to be used for military observations. This Almaz vehicle was a response to the U.S. Air Force's plans for manned observatories. The first Almaz was "disguised" as Salyut-2 to prevent other nations from awareness of the "spy" effort. This Salyut-2 was launched unmanned on April 3, 1973 but was never visited because a fire broke out onboard, so damaging the ship that it was uninhabitable and was decelerated into the atmosphere on May 28, 1973. The Almaz space station as it was being build appears below. Beneath it is a cutaway that shows its sophistication, and its deployment in space with its transfer vehicle, Soyuz, is at the bottom:
Another aborted military Space Station, Cosmos 557, launched on May 11, 1973, was never visited.
Although the Soviet space program had an early lead in operating Space Stations, the U.S. program made a "giant leap" with its Skylab station by putting up a facility that had a number of scientific instruments and experiments. Launched on May 14, 1973 on a Saturn 14-B rocket (page Intro-7), Skylab successfully achieved orbit but suffered two serious setbacks: 1) it lost one of its solar panels as that was deployed; and 2) part of its outer hull was ripped off. Nevertheless, the first crew (which arrived in a separate vehicle) of three astronauts was able to improvise a protective covering made of gold-surfaced sheeting. This Skylab-2 mission was followed by Skylab-3 and Skylab-4, leading to a combined occupancy time of 73 days by the three crews, each able to conduct most experiments. Several EVAs (Extra-Vehicular-Activity) or spacewalks occurred from Skylab. (The very first EVA was made by Aleksei Leonov on March 18, 1965 from a Voshkod-2 spacecraft; the first astronaut to EVA was Edward White who exited Gemini-4 on June 3, 1965.) Skylab was functional until February of 1977 after which it was decelerated to burn up over the Pacific Ocean. Here are views of Skylab in orbit and a cutaway which shows some of the crew cabin:
Still in the competition, the Soviet program launched another military station, Salyut-4, on December 26, 1974. Six visits, totaling 93 days, continued until February, 1977.
A Space Station of sorts was created for a short time when an American Apollo Command Module spacecraft (once destined to be the Apollo 18 mission vehicle before the Moon landing program was terminated) docked with a Russian Soyuz craft on July 17, 1975. Ostensibly, a show of "comradeship" in space, a practical purpose was to determine the ability (and possible problems) of a spacecraft from either of these countries to come to the aid of the other in case of emergency and need for rescue. Here is an artist's sketch of the two ships joined and beneath it are the five spacemen who shared their spacecraft for a brief time:
Salyut-5 (Almaz-3) was the last Soviet strictly military Space Station venture. It lasted from June 26, 1976 to August 8, 1977 and was visited by six crew missions.
With Salyut-6, the Station remained viable for 4 years, 306 days (Sept.'77-July'82) During that interval there were 35 trips (cumulative 1 year, 170 days) by 2-cosmonaut crews. The Station was capable of docking two spacecraft.
The last and longest (8 years, 268 days; April 19, 1982 to February 7, 1991) of the Salyut series was Salyut-7. It hosted 29 visits (although 2 crews failed to dock and enter) including one that reached it from the new MIR station (see next page).
The reader may be wondering by now just how the astronauts and cosmonauts traveled and and from the various Space Stations. Two space vehicles provided the vast majority of transportation systems (although two new ones are being used for the International Space Station ISS)(next page).
The longest transfer spacecraft still active is the Soviet's Soyuz vehicle, now operating in more advancing versions after its first launch in 1969. The Soyuz was first developed to compete with the Apollo system when in the '60s the Soviet space program still considered itself competively in the race to the Moon. Soyuz has proved itself so reliable and versatile that it has served many times as the transfer ship for visits to the Salyuts, MIR, and the ISS. "Soyuz" can refer both to the launch vehicle and the transfer module. Here is this pairing during a launch.
The first Soyuz, developed starting 1966 with launch in 1969, is shown below. This basic configuration has remained essentially as shown to the present. But there have been four variants, each improved over its predecessor and given new modifications. The sequence: Soyuz, Soyuz-T, Soyuz-TM, and Soyuz-TMA. A cutaway shows the general interior of the three component modules of the latest, the TMA.
The last pair of photos show the Soyuz transfer vehicle approaching the ISS and docked with the ISS. The Soyuz, originally designed for two passengers, now holds 3 comfortably and four cramped inside if the Soyuz serves as an escape vehicle in an emergency. The Soyuz Landing Module returns to Earth as a capsule (separated from the other components) supported by parachutes that touches down on land at one of the space port facilities the Russians manage or "rent" (Baikinur, in Kazakhstan; its replacement, Svobodny; the Northern Cosmodrome; Yepatorlyas in the Ukraine).
For its first 20+ years, the U.S. space program depended on returning its astronauts to safe landings in the Pacific Ocean (or other marine waters if needed) by splashdown. By the 1970s, the need for a capability of touching down on land and being able to reuse the spacecraft led to design of a "space plane" known popularly as the Space Shuttle (technically, they are called Space Transport Systems [STS]). The first flight of the Shuttle was a launch on April 12, 1981 from Kennedy Space Center and a landing at Edwards Air Force Base in California.
The Space Shuttle is a complicated vehicle, and we will not treat it in detail here. Make note in the above photo of the large (orange-brown) liquid fuel tank and the two solid rocket boosters that are external to the Shuttle (which does have its own engines for use at the end of launch and for maneuvering in space and during the landing cycle. Here is a cutaway diagram that indicates the cabin area, the cargo bay, and tail assembly. Many Shuttles had a large crane for removing cargo from the bay.
While launch and insertion into orbit are usually the most precarious, but thrilling, phase of a Shuttle mission, landings have been almost routine. The prime site of choice is back at Kennedy Space Center. Here is a Shuttle about to land at KSC; a drove parachute helps to slow its landing speed which still exceeds 100 mph.
The next photo shows the Shuttle as it landed at Edwards Air Force Base (the first 9 missions used the natural playa surface in the Mojave Desert of California as a landing strip; most later Shuttles landed at Kennedy Space Center, but as of now 50 have used Edwards AFB, usually because of bad weather at Cape Canaveral; there is a third site - not used sofar - in New Mexico.
Since launch at Vandenberg AFB on the California coast was less practical than at Kennedy, those Shuttles that had to use Edwards AFB have to get back to Florida. This is accomplished by lifting the Shuttle onto fittings atop a 747 airliner. This photo gives a good impression of the size of the Shuttle:
There have been 119 flights of 5 Shuttles: Atlantis, Challenger, Columbia, Discovery, and Endeavor. (Enterprise was flown once as a test mission.) Over the years, two were destroyed while in flight - Challenger during launch in Florida; Columbia over Texas during final approach to landing. Information on individual flights appears as a List of Space Shuttle Missions on the Web.
The Shuttle has performed a variety of missions during its usual 6 to 14 day stay in space. One is to launch spacecraft into final orbit; the best known cargo was the Hubble Space Telescope. Also conducted are scientific experiments and medical investigations into the human response to weightlessness and other body hazards. EVAs have allowed servicing of satellites in reachable orbits. For much of the last 7 years the Shuttle has carried some of the structural components of the International Space Station (that effort has been suspended following the Columbia accident in 2003 but after major improvements in safety features the flights Discovery completed a resumption mission in August 2005 but again problems with debris have grounded the fleet until Spring of 2006.
The Soviet/Russian space program has its own Shuttle, Buran, which is essentially a copy of the American vehicle. It has flown only once (unmanned) in 1988 but was dropped from their space program because of signs of unreliability. Here is Buran in its landing mode.
Both the Shuttle and Soyuz have been key transport vehicles that make round trips to MIR and ISS - the two Space Stations discussed on the next page.Source: http://rst.gsfc.nasa.gov