Modern orbital space exploration
author Paul Boșcu, July 2017

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At the end of the Space Race of the 1960s’ and early 1970s’ both the Soviet and American space programs lost funding for manned exploration to other celestial bodies. Instead the Americans and Russians started to focus on orbital manned missions. Both countries started building space stations, which became more and more complex. Because they needed a cheaper and reliable way of hurling their astronauts into space NASA started the Space Shuttle program. After the end of the Cold War new possibilities of cooperation resulted in the International Space Station being built.

The Mir (which stands for “peace” in Russian) space station was a grand success that enhanced the reputation of the Soviet space program. Its existence also played a fundamental role in creating a new era of cooperation between the U.S. and the Soviet Union — cooperation that culminated with missions in which the Space Shuttle docked at Mir.

Living and working in the ISS comes with a particular set of challenges, and the astronauts are making valuable scientific contributions with the experiments they conduct onboard. Although the station is decidedly unglamorous and can’t accommodate untrained astronauts, it provides a basis upon which civilian forays into space might, in the future, be built.

In the early 1960s NASA planners envisioned a space station program as the next step after Apollo. It was assumed that the United States would establish large space stations in orbit around Earth and possibly outposts on the Moon. In fact, NASA hoped to put at least one twelve-person space station in Earth orbit by 1975. This would require a new type of reusable space plane to carry cargo and personnel to and from the station. However, these grand plans did not mesh with the political, cultural, and technological realities of the times.

Salyut and Skylab, the first Soviet and american space stations were built during the last stages of the Space Race. The Soviets had lost the race to the moon so they saw a last chance at glory in building the first space station. NASA didn’t want to be left behind so they build Skylab as e response.

Building a space habitat is a tremendous challenge, starting with the need for very powerful rockets that could lift much more than just a manned space capsule or an unmanned robot probe. A large space habitat would have to be assembled from many modules that would be launched separately and would never land on Earth again. Astronauts would have to travel to and from the space station in other vehicles.

Beginning in 1952, Wernher von Braun and Chesley Knight Bonestell, Jr., sketched an early dream of living in giant structures in space in magazine articles. In the 1970s, Gerard Kitchen O’Neill calculated how many resources would be required to build a city in space, in the shape of cylinder, a mile (1,600 m) long. There would be room inside for a million people. Work on smaller space platforms began in the 1960s. Scientists working for the United States Air Force were first to suggest an actual plan to build a habitat in space. It was called the Manned Orbital Laboratory (MOL) and would have been built inside the shell of a Titan rocket.

Von Braun and Bonestell drew a space station shaped like a huge bicycle wheel, bigger than a sports stadium, with just a few spokes and a large central hub where spaceships could dock. By slowly spinning, these habitats could create a realistic illusion of gravity for folks living inside.

The idea of the permanently orbiting space station had been around almost as long as the idea of space travel. One of the earliest studies was published in 1928 by an Austro-Hungarian soldier named Herman Potocnik, writing under the name of Hermann Noordung. Potocnik’s writings were so detailed that he even included an orbiting space telescope.

O’Neill suggested that the space citizens could sell energy back to Earth by collecting sunlight with enormous solar cells and beaming microwaves back to antennas on the ground. They could get the raw materials to build these solar cells by mining the surface of the Moon.

The USAF’s plan was to launch astronauts to the MOL in a Gemini-type capsule. The astronauts would have lived on board MOL for a month at a time, using telescopes to look down on Earth and watch the military operations of other countries. Soon, however, robotic telescopes were designed for these missions, and the Air Force cancelled the program after just one unmanned test launch.

Soviet space engineers developed the first space habitat. It was called Salyut, and it had about as much room as a small motor home. At least 10 were eventually built, and the first, called Salyut 1, was launched April 19, 1971. Cosmonaut Viktor Ivanovich Patsayev was the first human to climb aboard a space station when he and two other cosmonauts rocketed to Salyut 1 in a Soyuz capsule. Some of the Salyuts were used for military missions, the rest for scientific research.

When the Soviets realized that they could not beat the Americans to the Moon during the 1960s, they turned their attention to other space goals. In 1971 they put the first of many Soviet space stations into orbit around Earth. Soviet and Russian cosmonauts spent the next three decades gaining valuable experience in long-duration space flight.

The Soviet space station Salyut 1 was launched from the Baikonur Cosmodrome in what is now Kazakhstan. The station was placed into orbit approximately 200 kilometers (124 miles) above Earth. The station was built so that Soviet scientists could study the long-term effects on humans living in space. A crew of three cosmonauts flew aboard Soyuz 10 to the station a few days after the station was placed in orbit. However, they were unable to dock with it, so they were forced to end their mission early and return to Earth.

The Soviet spacecraft Soyuz 11 successfully docked with Salyut 1, and three cosmonauts inhabited it for twenty-four days. They were killed as they returned to Earth, when a valve opened on their spacecraft and allowed it to depressurize. At that time, cosmonauts did not wear pressurized space suits during launch or reentry. The Soviet space agency canceled future flights to the station and began an extensive redesign of the Soyuz spacecraft.

In October 1971 Salyut 1 fell into Earth’s atmosphere and was destroyed. In total, the Soviets put seven Salyuts into orbit. These stations were visited by cosmonauts and scientists from a number of countries, including France, India, and Cuba. In 1984 three Soviet cosmonauts spent 237 days aboard Salyut 7. This was a new record for human duration in space. Salyut 7 was deorbited in February 1991.

NASA eventually built a space station in the 1970s, using an empty rocket booster as a space station. It was originally called the Orbital Workshop, but it became known as Skylab. Originally the plan was to use a working rocket booster and rebuild it from the inside after the fuel was consumed in the launch. However, the Saturn V rocket was so powerful that it could boost Skylab directly into orbit, even without the extra fuel. So, it was possible to send Skylab already fitted out for astronauts to live in it.

Long before an Apollo spacecraft landed on the Moon, NASA planners were looking ahead to their next great project. The Apollo Applications Program (AAP) began in 1963 with a plan to use leftover Apollo hardware in some kind of orbiting station including a laboratory, workshop, and space telescope. When the Apollo 20 mission was canceled in 1970, the AAP inherited a Saturn V rocket. It used the rocket as the launch vehicle for a newly developed station called Skylab.

The Skylab program had two primary goals: prove that humans could live and work in space for extended periods of time and expand knowledge of solar astronomy using a space based telescope. The program was composed of four flights.

The unmanned Skylab station was launched into orbit. It was damaged during liftoff when a protective shield came loose and smashed against the solar panels, ripping one of them off and damaging the other. A team of three Skylab astronauts was scheduled to launch the next day. However, their flight was delayed for ten days as engineers assessed the damage to the station.

The astronauts, called the Skylab 2 crew, finally launched on May 25, 1973. They successfully docked with the station and began repairing its damaged components. Crewmembers deployed a temporary sail-like shield to replace the torn-off solar panel. Their mission lasted just over twenty-eight days, a new record for Americans in space. This record was bested by the astronauts of Skylab 3 and Skylab 4.

The Skylab 3 mission included two spiders named Anita and Arabella. The spiders were part of an experiment suggested by Judith Miles, a high school student from Lexington, Massachusetts. She wondered if spiders would be able to spin their webs in microgravity. NASA scientists seized on the idea and sent the spiders into space in cages equipped with still cameras and television cameras. The public became enthralled in hearing about the two spiders. Neither spider adjusted well to the new environment. Arabella’s initial webs were sloppy and lopsided. However, after a few days the spider began spinning web patterns like it would on Earth. Both spiders died during the mission, apparently of dehydration.

The Skylab was not designed for long-term use. It had no method of independent reboost to keep it from falling out of orbit. As a result, on July 11, 1979, the station reentered Earth’s atmosphere and broke apart over the Pacific Ocean.

Despite its early mechanical problems, Skylab was considered a great success. The total number of hours spent in space by Skylab astronauts was greater than the combined totals of all space flights made up to that time. NASA gained valuable knowledge about human performance under microgravity conditions.

There are some important medical problems involved in living in space for longer than a few days. Because persons in space don’t feel the force of gravity, they gradually lose strength in their bones and muscles. After a few months in space, there is a risk that astronauts won’t be able to recover their strength when they return to Earth.

Medical experts learned that vigorous exercise helps keep the human body healthy in space, so any modern space station include exercise equipment similar to what is used in a gym.

After Skylab, NASA wanted to stop using space capsules that could only go into space and return to Earth once. The idea of a reusable plane that could be launched into space on a rocket but land on a regular runway turned into the space shuttle. Its first flight was in 1981. The Space Shuttle program finished it’s last flight in 2011. The last mission was flown by the shuttle Atlantis.

The space shuttle has a cargo bay about the size of a bus. Its purpose was to carry different kinds of hardware into orbit around Earth, such as the Hubble Space Telescope, and even rockets that can fire after they are released from the cargo bay and travel farther into the solar system. However, the most important payload that the space shuttle was built to carry is the modules for the space station that NASA wanted to build.

The first flights of the Space Shuttle program (which is technically called the Space Transportation System, or STS) began well after the end of Project Apollo in 1975. However, the design and engineering work that went into the Space Shuttle commenced long before that. As early as 1968, scientists were developing plans and specs for a fleet of vehicles that could deliver and retrieve payloads in space.

The Space Shuttle program became a reality in 1972 when President Richard Nixon confirmed that the federal government would support the development of a reusable spacecraft that launched like a traditional rocket but landed on a runway like a glider. By 1976, contractors had developed and started testing the Enterprise, the first Space Shuttle orbiter. It lacked engines and heat shields but provided enough of the core design to be suitable for glide-landing tests.

After the concept of glide landing a spacecraft was proven, NASA was able to refine the orbiter’s design and build Columbia, the first production Space Shuttle.

The first Space Shuttle orbiter was originally supposed to be called Constitution, but fans of the television show Star Trek staged a massive write-in campaign and convinced NASA officials to rename the orbiter Enterprise.

Much of the cast of the original Star Trek series was on hand when Enterprise was dedicated. Today, Enterprise can be seen at the Intrepid Sea, Air & Space Museum in New York.

Launching something that’s as much of an investment of time and resources as the Space Shuttle calls for some pretty intense safety precautions to protect both the orbiter and its crew. Weather is one of those issues that can cause some serious trouble for a Shuttle launch. Aside from positive weather conditions, in order for a Space Shuttle to be cleared for launch, it must successfully complete a range of preflight preparations and checks. All the onboard systems must be tested, and any critical problem that results halts the launch countdown.

NASA staff members carefully monitored the weather near Florida’s Kennedy Space Center (the official Space Shuttle launch site) on launch days. In particular, they kept an eye out for storms with lightning. Weather also had to be favorable at one of the abort landing sites located around the world, in case something went wrong during launch.

Safely launching a Space Shuttle also required being prepared for emergencies, particularly because history has shown that launch and landing are the two most dangerous parts of a spaceflight. Consequently, each Space Shuttle has five “abort modes” that allow it to safely terminate rather than complete its mission.

After reaching orbit, the Space Shuttle began its mission. Although their most-common purpose was to bring supplies and payloads (cargo) to and from the ISS, Space Shuttles were also capable of retrieving satellites from orbit, launching robotic spacecraft, and carrying advanced scientific instruments such as telescopes and instruments to map the Earth. The crew compartment was the main place where the astronauts lived and worked.

The crew compartment was separated into a flight deck, complete with navigational systems; a middeck with a galley, bunks, and exercise equipment; and a lower deck with a life-support system. The life-support system turns the Space Shuttle into an environment suitable for humans. It provides breathable air, drinkable water, food, electrical power, waste removal, temperature control, and a host of other essential functions. The Shuttle is also equipped with a communication system that allows the astronauts to talk with flight controllers back home.

If a particular Shuttle mission involves retrieving or deploying a satellite, or even deploying payloads into orbit, the astronauts used a tool called the Remote Manipulator System (RMS). This robotic arm is equipped with a camera and can be controlled from the flight deck; it can pick up and release payloads from the Shuttle’s payload bay. Most current uses for the RMS involve the installation of modules and components on the International Space Station. The RMS also serves as an important safety device for inspecting the Shuttle’s thermal tiles for damage after liftoff.

One major technological innovation of the Space Shuttle is its ability to return to Earth via the ground rather than the ocean. Unlike earlier American spacecraft that could land only by splashing down in the water, the Shuttle can leave Earth orbit and reenter the atmosphere on a carefully calculated trajectory that brings it to its landing site.

Computer programs controlled most aspects of the Space Shuttle’s landing, though the pilot could land the spacecraft manually if necessary (for example, if a computer problem arises during reentry). However, the final approach and runway landing was usually done under manual control because the well-trained Space Shuttle pilots could land the Shuttle better than the computer can.

The U.S. Space Shuttle program consisted of a fleet of five vehicles. The first two (Columbia and Challenger) are no longer operational due to devastating explosions. The remaining three are the Space Shuttles Discovery, Atlantis, and Endeavour. Another vehicle, the Enterprise, was created for ground-landing test purposes and turned out to be too expensive to retrofit for spaceflight.

The first Space Shuttle to take flight was Columbia during the 1981 STS-1 mission. STS-1 was essentially a test flight designed to ensure that all instruments, components, and life-support systems aboard the Space Shuttle were fully functional and ready for duty. During this flight, Commander John Young and Pilot Robert Crippen proved that the Space Shuttle could be successfully orbited and returned to Earth.

Launched in 1983, with a crew of four, STS-6 was the first flight of Space Shuttle Challenger. Two astronauts performed the first spacewalk of the Shuttle program, testing out new spacesuits.

Lessons learned from the design of the first two orbiters allowed Discovery to be almost 7,000 pounds (3,175 kilograms) lighter than Columbia. On its maiden voyage in 1984, Discovery deployed a series of three communications satellites. Sixteen years later, Discovery was responsible for two rather notable missions: deploying the Hubble Space Telescope and launching the solar explorer Ulysses.

Atlantis took flight after Discovery and featured a number of improvements over its predecessors. For example, it was much quicker to build than Discovery because the thermal tiles were redesigned and their application became much faster as a result. Atlantis’s big claim to fame is that it was the first Space Shuttle to successfully dock with Mir, the Russian space station.

Intended as a replacement for Challenger, Endeavour was the last Space Shuttle to join the fleet of orbiters. It pioneered a number of new features, including a drag chute to aid the Shuttle’s glide landing, changes to the steering system, and an increased payload capacity.

The Space Shuttle wasn’t just a tool for ferrying around astronauts, satellites, space probes, and supplies. It was also a unique opportunity for doing science in space. Toward that end, NASA and the European Space Agency (ESA), in the 1980s, committed to developing a mobile laboratory, Spacelab, that could function inside the Space Shuttle. Spacelab provided a platform for collaboration between the United States and Europe, considering the first entire laboratory module was provided by ESA, as were later components. Astronauts from several different countries eventually conducted research and experiments within Spacelab.

Spacelab modules and pallets could be customized to accommodate the research planned for a particular mission. Each overall module consisted of a core module, an experiments module, and between one and three pallets, depending on the mission and its configuration. Access tunnels and adapters were also included for astronauts to enter and leave Spacelab from the crew cabin on the Space Shuttle’s flight deck.

The first Spacelab, Spacelab 1, was launched aboard Space Shuttle Columbia’s STS-9 mission in November 1983. All in all, 25 Space Shuttle missions launched with Spacelab components. The final flight with a Spacelab element was STS-99, aboard Space Shuttle Endeavour in February 2000.

Spacelab was a proving ground, in a sense, for the Space Shuttle’s scientific capabilities. Numerous experiments were conducted within Spacelab in areas of biology, crystallography, and, of course, astronomy.

Among the Space Shuttle program’s notable “firsts” was bringing America’s first female astronaut into space. Sally Ride joined NASA’s astronaut program in 1977 and spent years undergoing the various types of flight, survival, and navigation training required for astronauts. In 1983, she made history with her first spaceflight aboard the Space Shuttle Challenger.

During their six days in space aboard Challenger, Ride and four other astronauts (Robert Crippen, Frederick Hauck, John Fabian, and Norman Thagard) became, at the time, the largest crew to travel in space. The astronauts deployed communications satellites while in orbit and performed a range of experiments in microgravity.

Rick Hauck was the mission’s pilot. He recalled: ‘We’d have press conferences, and Sally would be the focus of 99 percent of the questions, but that was fine. I remember one press conference just before we flew. Someone from Time magazine or something said: “Sally, do you think you’ll cry when you’re in orbit?” And of course, she kind of gave him this “You gotta be kiddin’ me” kind of look and said: “Why doesn’t anyone ever ask Rick those questions?”

Dr. Ride went on to fly on other Space Shuttle missions for a total of more than 340 hours in space. She was also one of the astronauts assigned to research the Challenger disaster of 1986.

The Space Shuttle had a healthy track record when the January 28, 1986, flight of the Challenger was scheduled for launch. Challenger was the second vehicle of the Space Shuttle fleet to be launched into orbit, and it had already completed nine successful missions. Exactly 73 seconds after liftoff, the orbiter broke into fragments, killing all seven crew members onboard. Because of the popularity of the Teacher in Space Program, the launch was televised live around the world, so millions of people watched helplessly as the Challenger crew perished.

This tenth voyage was extra-special because Christa McAuliffe, a New Hampshire–based teacher and the first astronaut to take flight as part of NASA’s Teacher in Space Program, was aboard. The Teacher in Space Program was designed to interest more of the general public in the space program.

After Challenger’s demise, the Space Shuttle program was stopped for 32 months. A governmental commission called the Rogers Commission was appointed by President Ronald Reagan to figure out what had happened. The conclusions of the commission brought to light flaws in how NASA addressed known problems, as well as the agency’s unwillingness to heed engineering and other warnings. These problems were rectified before the Space Shuttle program resumed in 1988. The Teacher in Space Program, however, couldn’t be resurrected.

The Teacher in Space Program, along with other attempts to send private, non astronaut citizens into space, was abandoned after the Challenger disaster. Only in recent years has the idea of sending educators into space received serious, renewed interest, such as the private Teachers in Space program started by the Space Frontier Foundation in 2006.

NASA’s Teacher in Space Program was launched in 1984 as a means to create greater general interest in math, space, and science among America’s youth. The program was quite popular: It had 11,000 applicants in its first year. Christa McAuliffe was the chosen one, slated to be the first teacher to launch into orbit aboard the Space Shuttle Challenger. Barbara Morgan, a teacher from Idaho, was McAuliffe’s backup and went on to become a full-fledged NASA astronaut.

All was not completely lost when the program closed down as a result of the Challenger disaster. NASA instituted a replacement program in the 1990s called the Educator Astronaut Program. Instead of training teachers as temporary astronauts, the program recruited them to become permanent astronauts. After their space journeys, participants gain employment through NASA (usually as mission specialist-educators) instead of returning to their teaching careers.

Although the liftoff of Space Shuttle Columbia on mission STS-107 appeared to go well on January 16, 2003, engineers studying the details of the launch noticed a problem. During the launch, a piece of the Space Shuttle’s foam insulation broke loose from the external propellant tank and hit the left wing. As Columbia reentered the Earth’s atmosphere at the end of its mission, the compromised wing was destroyed by the heat caused by atmospheric drag. The entire spacecraft soon broke apart as it hurtled toward the Earth. People on the ground reported hearing a loud boom as the sky filled with smoke and flying debris.

Even if the astronauts onboard had realized the problem, there was little they could’ve done in the way of repairs. The Space Shuttle started losing its thermal tiles, and ground observers witnessed a number of bright flashes.

Following are the names of the final crew members of Space Shuttle Columbia: Pilot William McCool, Payload Specialist Ilan Ramon (from Israel), Payload Commander Michael Anderson, Mission Specialist Kalpana Chawla, Mission Specialist Laurel Clark, Mission Specialist David Brown.

As with the Challenger accident in 1986, Columbia’s demise caused the Space Shuttle program to cease operations for more than two years. During this time, organizational and decision-making procedures at NASA were overhauled, and technical design changes were made that would help limit foam detachment in later missions. Special cameras were also added to later Space Shuttle missions for purposes of surveying the orbiters’ thermal tiles for damage.

This delay in Space Shuttle operations led to a halt of progress on the International Space Station, because the Space Shuttle was its primary means of receiving supplies and new components. Basic equipment and new crew members were supplied by the Russian Federal Space Agency during that interim.

Immediately after the Columbia disaster, President Bush appointed a panel to investigate what happened. The panel was called the Columbia Accident Investigation Board (CAIB). In August 2003 the CAIB released its report, CAIB Report: Volume 1, which concluded that the most likely cause of the accident was a damaged thermal protection tile on the orbiter’s left wing. Video clips of the launch showed a large piece of foam falling off the external tank and striking the left wing eighty-two seconds after liftoff.

NASA decided that the first two shuttle flights after the Columbia disaster would be ‘‘test’’ flights to assess the effectiveness of new safety changes. Discovery was selected for the first RTF mission. More than one hundred cameras were installed on exterior spacecraft surfaces and at ground locations to provide an array of observation angles during ascent. Technical and time limitations also prevented NASA from successfully hardening orbiter surfaces to prevent damage from debris impacts.

Discovery launched from the KSC for a fourteen-day mission. The orbiter, with a seven member crew onboard, docked with the ISS and unloaded equipment there. The shuttle landed safely at the Edwards AFB NASA proclaimed the first RTF a success. However, camera footage showed that foam debris had shed from the external tank during shuttle ascent. Luckily, the debris did not hit the orbiter. NASA and the public realized that the hazard that had doomed Columbia had not been eliminated, but merely avoided by chance this time.

The task force noted that ‘‘it has proven impossible to completely eliminate debris shedding from the External Tank. The hard fact of the matter is that the External Tank will always shed debris, perhaps even pieces large enough to do critical damage to the Orbiter.’’

As of December 2007, the space shuttle had undertaken five successful missions since the second RTF flight. All the missions were dedicated to ISS assembly. Extensive imaging and visual inspections were conducted during each shuttle flight to identify any damage to the thermal protection system due to foam debris impacts during launch. In all cases the orbiters were deemed structurally sound for reentry.

A freak hail storm in February 2007 damaged Atlantis as it sat on the launch pad for an expected launch of STS-117 in March 2007. That mission had to be delayed for nearly three months, seriously affecting the shuttle’s future launch schedule.

With all their space station expertise, did the Soviets ever develop their own version of the Space Shuttle? The answer is yes, although it never brought cosmonauts into space. The Buran program was the Soviet Union’s answer to the American Space Shuttle. Five Burans were commissioned, but only one was ever deemed space worthy. The sole launch of the Buran program took place in 1988. Due to political circumstances the project was initially put on hold before being canceled by the Russian government in 1993. No other Buran flights ever occurred.

The Buran spacecraft, with its life-support system and computer displays only partially completed, successfully launched into orbit, circled the Earth twice in just over three hours, and then made a completely automated landing on a runway at the Baikonur Cosmodrome. All seemed well until the Soviets realized the spacecraft had suffered damage to its thermal protection tiles during the flight —damage that would’ve been costly to fix.

The next logical step was to assemble a space habitat out of separate modules that could be launched like Salyut or Skylab. Seven separate modules were launched by the Soviet Union, beginning in 1986, to build Mir. In total, Mir was about as big as a school classroom, divided into smaller sections by the individual modules. Dozens of cosmonauts—and seven astronauts from the United States—spent many months living on Mir. When the political situation changed, and Russia took over the space projects of the former Soviet Union, plans for a second Mir space platform were dropped.

Following the achievements of the Salyut space station program, Soviet space research turned toward the creation of a more modular space station design that could accommodate more research labs, house more cosmonauts, and boast more-sophisticated capabilities. The space stations of the Salyut program were meant as one-shots, single modules to be visited by crews over the course of a few years, but not as permanent outposts in orbit. The many lessons learned and experiences gained from this series of stations made the Soviet Union the clear leader in long-term orbital missions.

Still smarting from the failure of their lunar exploration program, and faced with the futuristic Space Shuttle program from NASA, the Soviets saw the development of a long-term, modular space station as a clear way to meet both political and technical goals while boosting the space exploration profile of their country. The Mir program was developed, starting in 1976, to meet these goals. Ten years later, the station was launched into orbit.

The basic design of the Mir space station focused on modules that were launched into orbit and attached together in space. The Core Module, which went up first in 1986, held the station’s control center as well as living space for the cosmonauts. As more Mir modules were prepared and ready to go on the ground, other teams of cosmonauts launched and prepared the space station to accept its new arrivals.

Because existing rockets had limits in terms of how big and how heavy their payloads could be, the modular approach to space station construction allowed for Mir to be much bigger than previous stations. Additionally, it was much cheaper to launch individual completed modules one at a time. Some of these modules could automatically dock with each other, whereas others were attached together by cosmonauts during spacewalks.

Because the launch of the station itself was something of a rush job due to political deadlines, a lot of work was left to be done in orbit to get Mir up and running. The first cosmonauts to reach Mir, Leonid Kizim and Vladimir Solovyov, got a ride on the Soyuz T-15 mission in March 1986, which remained with Mir for about 50 days before taking a trip to the older Salyut 7 space station, which was still in orbit. While inside Mir, Kizim and Solovyov helped set up the new space station and performed a number of experiments.

Russian cosmonauts repeatedly set and broke space duration records aboard the Mir station. Vladimir Titov and Musa Manarov reached the one-year milestone when they completed 366 days in space in 1988. By 1995 the record was 437.7 days, set by Valeri Polyakov. As of 2017, this was still the record. The Mir is also famous for its nongovernmental inhabitants. Beginning in the 1980s the Soviet space program suffered financial difficulties. To raise funds, the space agency sold seats on Mir to a variety of foreign astronauts and adventurers.

Russian cosmonaut Valeri Polyakov is the holder of the record of the longest single stay in space in human history. He stayed aboard the Mir station for more than 14 months. His total space experience is more than 22 months.

In 1990 the japanese journalist Toyohiro Akiyama became the first citizen of Japan to fly in space and the first private citizen to pay for a space flight. Akiyama’s television network paid $28 million to send him on a seven-day mission to Mir.

In 1991 the British chemist Helen Sharman spent eight days in space after winning a contest sponsored by a London bank.

With the fall of the former Soviet Union in 1991, a new era of cooperation was suddenly possible between Americans and Russians. Joint space missions once again became a way to meet the two superpowers’ political and scientific goals. As a way of discovering more about the business of constructing modular space stations, the U.S. became involved with the Mir project, sending both supplies and astronauts to the now-Russian space station. As part of the Shuttle-Mir program, a series of 11 Shuttle missions docked with Mir between 1994 and 1998.

In order for the Americans to contribute resources and astronauts to the Mir program, the Space Shuttle had to get involved. This exchange was conducted through the Shuttle-Mir program, which was also seen as the predecessor to the International Space Station. One of these missions launched an American astronaut into space in a Soyuz spacecraft and a Russian cosmonaut into space on the Space Shuttle.

The new era of cooperation in space began in 1994 with the STS-60 mission of Space Shuttle Discovery, which brought Russian cosmonaut Sergei Krikalev into space and included audio and video conversations with the Mir crew. In 1995, Discovery performed a rendezvous with Mir that included a close approach and a flight around the station as a dress rehearsal for an actual docking.

In June 1992 U.S. president George H.W. Bush and Russian president Boris Yeltsin signed the Agreement between the United States of America and the Russian Federation Concerning Cooperation in the Exploration and Use of Outer Space for Peaceful Purposes. NASA and the Russian Space Agency (which had been recently created) worked out a plan for joint shuttle-Mir missions. Both agencies considered this a prelude to a joint U.S.- Russian space station.

Daily life on Mir involved a combination of work, play, and exercise. Cosmonauts wore lightweight flight suits while they moved between the different modules, which connected together via nodes. As with any space station, the cosmonauts floated rather than walked to work; they also had to keep a close grip on portable equipment as they moved about during the day.

Adjusting to weightlessness is one of the challenges faced by anyone who spends time in space. Mir residents were still able to brush their teeth, use the bathroom, shave, and perform most of the other basic functions that they did on Earth, but they had to do so rather differently.

Astronauts and cosmonauts conducted significant experiments aboard Mir. Many were geared toward helping scientists understand more about how people and plants can live and function in the microgravity environment of space. Mir cosmonauts also performed astronomical observations and studied the Earth from orbit.

As the Mir space station aged, cosmonauts had to spend more and more time repairing it. In fact, on a typical mission with a mixed crew of three people, the two Russian cosmonauts devoted most of their time to space station maintenance while the American astronaut performed scientific experiments.

When the first Americans arrived at Mir in 1995, the station had already been in orbit for nine years. The cosmonauts spent the vast majority of their time doing repair and maintenance tasks. The ageing station was plagued with computer crashes. In 1997 a fire broke out in a compartment. The men fought the flames with towels and a few working fire extinguishers. Russian mission control downplayed the fire to the public and American officials, telling them it was a minor and isolated event. In truth, there had been a similar occurrence several years before in which a candle had burst into flames.

On February 23, 1997, a fire broke out aboard Mir when a cosmonaut lit a lithium perchlorate candle. Flames one-foot long shot out of the unit and ignited the canister. At the time, there were six men aboard the station: four Russians, a German, and an American. The fire quickly filled the spacecraft with smoke. The Russians ordered everyone to evacuate the station. However, the fire blocked access to one of the two Soyuz capsules that served as their lifeboat. Only three men would be able to escape if the hull was breached.

Many of the ship’s fire extinguishers malfunctioned or were bolted down and could not be released. After fifteen minutes the fire died, apparently snuffed out by lack of oxygen in its immediate area. The crew had donned respirators and floated quietly, barely moving for hours as they waited for the ship’s ventilation system to remove the smoke.

The fire in February 1997 was followed by even more problems aboard Mir. Only a week later, a camera failed during a docking exercise and the station was nearly rammed by a supply ship. In late March the cooling system failed. The temperature rose to 95 degrees Fahrenheit on the station, and it was permeated by an odor of antifreeze. High carbon dioxide levels forced the crew to limit their physical activity.

After almost ten years of continual habitation, the last crews left Mir in mid-1999. A brief, privately funded mission returned to the Russian space station in 2000 to try to salvage it as a commercial enterprise of some sort, but to no avail. With the Russian Federal Space Agency turning its support to developing the new International Space Station, Mir’s long lifetime was officially over. Robotic supply ships used their engines to bring it into an orbit that would intersect with Earth’s atmosphere in a controlled way to ensure that most of the station burned up and the remnants fell harmlessly into the ocean.

The return of the 135-ton space station to Earth in March 2001 was visible with the naked eye. Observers reported seeing a bluish flare, followed closely by a sonic boom as the space station reentered the atmosphere. Mir completely broke apart upon re entry, as expected, and dropped into the Pacific Ocean off the coast of Australia.

The 39th, and final, manned mission to Mir was Soyuz TM-30, launched in April 2000. Given sufficient resources Mir could perhaps have been patched up and helped to continue, but Russia’s commitment to the International Space Station and its limited resources meant that it had to be canceled.

After the collapse of the Soviet Union, NASA had the opportunity to form a partnership with Russia. NASA’s plan for a space habitat was merged with the proposals for a second Mir, and a more ambitious project began. It was called the International Space Station (ISS). When the space shuttle Endeavour brought the Unity module to space and connected it to the Russian-built Zarya module in December 1998, the ISS was born. Dozens of astronauts have lived there already. Other countries, such as Brazil, Canada, Italy, and Japan, have also joined the global effort.

Skylab, the Salyuts and Mir have all re-entered and burned up in the atmosphere, so the ISS is now the world’s only space station. It is the largest object humans have yet put in outer space. Even though it may be many years before there are cities in space, we can say that the permanent occupation of space by human beings has already begun.

The International Space Station (ISS), however, was conceived as a first step toward a continuous human presence in space and a step toward the future of humans as a space-faring race. It was established early on that a permanent orbital base would greatly facilitate exploration of the rest of the solar system (largely by serving as a “way station” for other destinations).

The ISS must be counted a success, having suffered only minor problems of the sort that are likely to occur when living and working in space. There has been the odd smoke incident, torn solar panels, faulty bearings and a crashed computer, but nothing so far on the scale of previous missions and previous space stations. For the most part, the station operates relatively quietly and efficiently.

Since 1998, a mix of Soyuz rockets, Proton rockets, and the Space Shuttle has launched various components of the ISS into orbit. Space Shuttle flights have been largely devoted to ISS construction since 2000, and the end of the Shuttle program in 2010 was arranged to coincide with the completion of the ISS in 2011. Afterward, the ISS was serviced by Russian Soyuz capsules and automated supply ships. The International Space Station (ISS) has been home to at least one crew (or expedition, as ISS crews are officially known) since 2000. The first crew consisted of Commander Bill Shepherd, Soyuz Commander Yuri Gidzenko, and Flight Engineer Sergei Krikalev. Due to the station’s current size, ISS crews consist of six people. The ISS is able to support more astronauts, but only for a short period of time.

Various countries have supplied astronauts, equipment, and modules to the ISS to help further scientific research and exploration in space. The Japanese Kibo module is the biggest component of the ISS.

The Expedition 1 crew traveled to the ISS in a Russian Soyuz rocket and remained in orbit for 135 days. Subsequent teams have journeyed to the ISS via the Space Shuttle or a Soyuz rocket and spent increasing amounts of time in space.

The ISS is the most health conscious place in all of space. After all, the men and women aboard it must constantly check on and maintain the operational health of the station (as well as their own health). The ISS astronauts spend considerable time doing maintenance on their habitat.

When they’re not performing upkeep on the station (or conducting experiments), astronauts aboard the ISS spend time caring for themselves. They aim to sleep a reasonable amount each evening and fit in exercise sessions throughout the day to try and mitigate the loss of muscle tone and bone mass that comes in space.

Although astronauts can conceivably become ill aboard the ISS, they’re carefully screened for infections before making the journey. And sure, bacteria and fungi are bound to grow wherever humans are involved, but the ISS astronauts use advanced tests to locate the areas that require extra cleaning. In addition to cleaning the station, personal hygiene also occupies more time in orbit than it does on the ground.

One of the more interesting aspects of living in orbit has to do with microgravity, the very low-gravity environment found in orbit around the Earth. Thanks to this lovely phenomenon, even ordinary tasks, such as writing with a pen or walking across the room, take on an entirely different meaning (like when the pen floats away and walking is really more like flying). It takes time for astronauts to get used to the fact that they’re no longer weighed down by gravity.

Biology experiments take a high priority on the ISS, because how the human body performs long-term in space is of the utmost interest for future missions to the Moon, Mars, or beyond. Astronauts study bone density, muscle tone, and other aspects of the human anatomy as they change in microgravity. Other experiments on the physics side of things help solve the mysteries of how fluids behave in space, as well as in examining the effect of low gravity on fluids and fluid combinations.

Crystal growth in microgravity is studied for its ability to teach scientists about the physical properties of particular chemical solutions. The value of growing these tiny crystals in space is that gravity doesn’t disturb or impact their growth, meaning their structure can be observed in a purer fashion. The crystals are then brought back to Earth for study in laboratories. Growing pure crystals allows their physical properties to be studied in detail in Earthbound laboratories, which may lead to the development of new materials and better medicines.

The Hubble Space Telescope, the world’s biggest telescope in space, has not only made amazing discoveries about the nature of the universe but it has also greatly helped popularize astronomy.

Hubble images have revealed aspects of the universe that were largely unknown in previous years. For instance, Hubble data has suggested that black holes are likely to exist in the centers of all galaxies, and it has even helped scientists estimate their masses. More recently, observations from Hubble have provided direct images of extrasolar planets for the first time and revealed young stars with planet-forming disks of dust and debris around them.

The scientific discoveries made by Hubble are magnificently varied. For example, Hubble has recorded optical phenomena related to gamma-ray bursts that give crucial information about how stars are formed. Additionally, in 2001, research teams were able to use Hubble data to make a measurement of the rate of expansion of the universe, which can be used to determine both the age and the ultimate fate of the universe.

First suggested in the 1940s by Lyman Spitzer, the Hubble Space Telescope took many years to reach fruition as the world’s biggest telescope in space. A deal with the European Space Agency (ESA) in the late 1970s resulted in the ESA supplying solar panels and one instrument for the telescope in return for a percentage of observing time. Work began on the telescope in 1978 with an initial planned launch date in 1983, but the launch was postponed due to construction delays. The telescope was launched in 1990.

Hubble was finally completed in the mid-1980s and was scheduled for launch in late 1986. However, the Challenger disaster of early 1986 grounded all Space Shuttle flights until 1988. As a result, the telescope didn’t launch until April 1990 when Space Shuttle Discovery carried it into orbit.

The Hubble Space Telescope was named after Edwin Hubble, a pioneering American astronomer. After a brief career in law, Hubble studied astronomy and created a system for listing and classifying the galaxies that he observed. He was one of the first modern-era scientists to map the cosmos. He also came up with a method, known as Hubble’s Law, for discerning the nature of the ever-expanding universe.

Gamma rays are a very high-energy, short-wavelength form of electromagnetic radiation given off by some of the most energetic, and rarest, celestial phenomena such as supernovas (star explosions), black holes that are in the process of pulling in mass, solar flares, and pulsars (rapidly spinning stars). They’re also difficult to study from the ground, which is why NASA’s second Great Observatory, the Compton Gamma Ray Observatory (CGRO), was launched into orbit by Space Shuttle Atlantis in 1991.

CGRO didn’t look like a telescope in the traditional sense of the word. Instead of having a small primary mirror and light-gathering arrangements, CGRO’s instruments had to be large to detect rare gamma-ray photons. In fact, at the time of its launch, CGRO was the heaviest satellite devoted to astrophysics ever flown.

CGRO takes its name from Dr. Arthur H. Compton, a Nobel Prize–winning scientist who made great strides in the field of high-energy physics.

At the end of its planned lifetime, one of the gyroscopes that helped control the spacecraft’s orientation in space failed. Unlike the Hubble Space Telescope, CGRO wasn’t designed to be serviced by astronauts, so the failed device couldn’t be replaced. Instead of waiting for a second gyroscope to fizzle out and leave the spacecraft unmaneuverable, NASA decided to bring CGRO out of orbit in a controlled crash. Most of the spacecraft burned up in the atmosphere on June 4, 2000, with the rest falling safely into the Pacific Ocean.

The third of the four Great Observatories is the Chandra X-Ray Observatory, launched in 1999 by Space Shuttle Columbia. X-ray observations are particularly well-suited to space telescopes because they’re absorbed by the Earth’s atmosphere almost completely. Chandra was designed to be able to detect X-ray emissions that were 100 times fainter than anything seen before by previous satellites.

Because X-rays are given off by energetic sources in the Milky Way Galaxy and in other galaxies, Chandra has been able to observe remnants from supernovas and the centers of galaxies. It has also observed neutron stars and black holes and helped astronomers understand dark matter. Chandra has also detected cool gas spiraling into the center of a nearby galaxy and caught X-rays being given off as material in a planet-forming disk fell back onto its central star, helping astronomers understand the role of gas and dust in planet formation.

The observatory was named after Indian astrophysicist Subrahmanyan Chandrasekhar. Frequently called by the less-formal moniker Chandra, he was widely regarded as a preeminent physicist who was one of the first to apply the principles of physics to astronomy. His studies of the stars earned him a Nobel Prize in Physics.

Chandra was officially designed as a five-year mission, but it’s still going strong 17 years after launch. The next major X-ray observatory, the Advanced Telescope for High Energy Astrophysics is a project proposed by the ESA. It is scheduled for launch in 2028.

Infrared telescopes, such as the Spitzer Space Telescope, are a great addition to the study of space because they detect and measure the heat (infrared energy) given off by objects within certain wavelengths. Spitzer was launched aboard a Delta II rocket in 2003 and was expected to function through mid-2009. It is still operating, although at a reduced capacity.

The view of telescopes that operate at visible wavelengths (such as the Hubble Space Telescope) is frequently blocked by gas, dust, and other obstructions; infrared telescopes like Spitzer, on the other hand, can see through the haze and yield brand-new information from deep galaxies, new stars, and other objects that can’t be seen through conventional means.

The Spitzer Space Telescope was named after Lyman Spitzer, who first proposed the idea of a space telescope in the 1940s. Spitzer has taken a variety of stunningly beautiful images of the cosmos, which are also scientifically indispensable. As a complement to Hubble, Spitzer has revealed the details of star-forming regions and extrasolar planets. It has also provided proof of supermassive black holes, found evidence of stars that could have formed shortly after the Big Bang, and provided new details about the structure of the center of the Milky Way Galaxy.

Infrared radiation, or radiation that falls along the electromagnetic spectrum between visible light and microwave radiation, may be best known for its use in night-vision goggles. With that in mind, thinking of Spitzer as the world’s biggest and most-expensive set of night-vision goggles isn’t entirely off-base!

Because an infrared telescope detects heat, the telescope itself must remain as cold as possible to perform its observations, and even in the cold, dark vacuum of space, extra cooling is required. Spitzer keeps itself cool with the aid of a cryostat, a device that uses a helium tank to lower the telescope detector’s temperature. Solar shields on the spacecraft also help.

Scientists sent Spitzer into an Earth-trailing heliocentric orbit, which means that the telescope follows Earth in its orbit around the Sun instead of orbiting around the Earth itself. A natural cooling effect is one benefit of this orbit, because the spacecraft is relatively far away from the heat-emanating Earth; as a result, the mission was able to reduce the amount of coolant it had to carry.

An infrared project that’s planned but not yet launched is the James Webb Space Telescope (JWST). Scheduled for liftoff in 2018, the mission goals of JWST are to use infrared technology to help locate the oldest galaxies in the universe. Such information would help scientists connect the dots between the beginning of the universe, the Big Bang theory, and the Milky Way Galaxy. JWST will be capable of studying early to recent solar systems, and ultimately, it’ll be able to help demonstrate how solar systems like ours were formed.

The design for the telescope is quite grand: The main mirror measures 21 feet (6.5 meters) in diameter. The sheer size of the mirror means JWST must be launched in a folded state and opened up after the telescope makes it into orbit. Several other new technologies will help JWST gather significant data, and like the Spitzer infrared telescope described in the previous section, JWST will require cooling mechanisms in order to maintain its effectiveness.

The JWST mission is officially being planned by NASA, the Canadian Space Agency, and the European Space Agency, but its data will be valuable to scientists worldwide.

The telescope is named after NASA’s second administrator, James E. Webb. Webb played an important role during NASA’s Apollo missions of the late ‘60s and early ‘70s.