The Final Frontier: Space Stations
Yo, ET, Phone Home
Lavinia Ponniah
The International Space Station consists of 3 parts: the ZARYA Control Module,
the UNITY Connecting Module, and the wholly Russian-made Service Module. Mission
Commander Robert Cabana and Russian Cosmonaut/Mission Specialist Sergei Krikalev
successfully launched the first component of the space station, the ZARYA Control
Module, on 20 November 1998. The next component, the UNITY Connecting Module, was
launched on the Endeavor Space Shuttle on 10 December 1998 at 1:15pm CST.
The Discovery Space Shuttle and two Russian rockets will conduct
approximately 45 missions to launch and assemble the 200 elements that will
comprise the completed Space Station. Control for the space station is
currently done from both Mission Control in Houston and the Russian Mission Control
Center in Korolev (Outside Moscow). In 2004 an estimated 460 tons of
structures, modules, equipment and supplies will have been placed in orbit.
Figure 1. The International Space Station
Space stations are designed to contain astronauts who will be in charge of managing and manipulating all the equipment aboard. These manned space installations are launched into the Earth’s orbit at an altitude of approximately 400 kilometers from the Earth’s surface. A space station serves a variety of purposes. Once in orbit, the astronauts aboard can carry out a series of tests, experiments and activities. Permanent laboratories are set up where gravity, temperature and pressure can be manipulated to achieve numerous scientific and engineering pursuits that are impossible in ground based laboratories. A space station is a test bed for future technologies and a lab for research on new advanced industrial material, communication technology and medical research. Most importantly, a station can provide a starting base for new voyages to explore deeper into space.
At one time, the U.S. space program was shrouded with skepticism and tragedy. After the Apollo disaster and the economic recession in the wake of the Vietnam War, there were severe cutbacks to the U.S. space program. But NASA fought for a new plan to create a space station that was larger and generally more efficient and technologically advanced than the Russian Salyut. This NASA project would use launch vehicles and spacecraft already developed and available from the Apollo project. Hence, the birth of NASA'a SKYLAB 1.
SKYLAB 1 was in operation from 14 May 1973 to 8 February 1974. It’s main body was made from the cavernous fuel tank of the 3rd stage of the Saturn V rocket. This massive structure had a much larger living space than the Soviet Salyut. The launch thrust for SKYLAB 1 was provided by the 1st and 2nd stages of the Saturn V rocket. The craft carrying the astronauts was comprised of the original Apollo command module, service module and the lunar landing module. The plan called for the crew to be launched aboard the Saturn V and dock with the SKYLAB, and then for the crew to transfer over to the space station. The return trip to earth was via the re-entry command module. Unfortunately, during the ascent of the SKYLAB main body, the external solar meteoroid shield was ripped off, tearing away one of the solar panel wings. Without this shield, the temperature inside the station shot up to 52 C (125 F). This accident mandated that repairs be done prior to any long-term manned operations of the space station. After three subsequent manned repair missions to the station, the program was closed down at the end of 1974. When the Space Shuttle Program started up again, there were plans to rendezvous with the SKYLAB. Unfortunately, intense solar activity in the late 1970’s caused the Earth’s upper atmosphere to expand outwards, producing unexpected drag forces on the SKYLAB. This atmospheric drag, slight as it was, ultimately resulted in the premature re-entry into the Earth’s atmosphere and finally the disintegration of SKYLAB over the Australian continent.
Undaunted and with a new and improved vision in hand, the idea for the First International Space Station was first set forth during the State of the Union Speech by U.S. President Ronald Reagan in January 1984. In his speech, Reagan called for a new effort, the Space Station Freedom, as being the next developmental strategy for the space shuttle program. The International Space Station was envisioned as a permanent, multi-purpose manned facility that would circle the earth at an approximate altitude of 400 km (248 miles) and an orbital angle of 51.6 degrees. The space station would accommodate 6 astronauts in 2 living modules with an additional 7 experimental and 2 supply modules.
The new station’s purpose was to fulfill experimental, observational, human habitation, supply and power supply functions. With a 10-year target of establishing this geo-orbital space station, the new space station project began with the participation of the U.S. National Aeronautics and Space Administration (NASA), the Science and Technology Agency (STA) of Japan, the European Space Agency (ESA) and the Canadian Space Agency (CSA). Subsequent budget cuts in the United States space program caused the project to be modified. As a cost cutting consequence, the construction of Space Station Alpha would now be done with Russian participation. The new station was then appropriately renamed the International Space Station.
The International Space Station hit it’s first milestone on 29 January 1998 when senior government officials from 16 countries met in Washington D.C. The various representatives signed agreements establishing the project and the framework for cooperation among the partners for the design, development, operation and utilization of the space station. The signing venue was the Dean Acheson Auditorium, where Acting Secretary of State Strobe Talbott signed the 1998 Intergovernmental Agreement on Space Station Cooperation, along with representatives from Russia, Japan, Canada and participating countries of the European Space Agency (Belgium, Denmark, France, Germany, Italy, Netherlands, Norway, Spain, Sweden, Switzerland and United Kingdom).
With a series of space shuttle launches to the Russian Space Station MIR, Phase 1 of the International Space Station was set in motion. These rendezvous and docking missions to MIR also involved long term occupation for seven astronauts aboard the space station. Previously, U.S. astronauts were only able to stay up to two weeks aboard a space station in orbit. This time, astronauts spent a total of 978 days aboard the MIR Space Station. During this period, the astronauts carried out approximately 140 scientific experiments in microgravity involving life sciences and environmental research.
Figure 2. Russian Space Station MIR
The life sciences experiments involved various tests and analyses of the human metabolic, neurosensory, cardiovascular and pulmonary systems in microgravity. For example, it was found that purer protein crystals could be grown in space than on Earth. By analyzing these crystals grown in space, earth-bound scientists are developing medicines that target particular disease-causing proteins. Through similar space-based research, the development of cures as well as more effective treatments for cancer, diabetes, emphysema and immune disorders also show great promise. New space-influenced drugs that fight influenza and post surgery inflammation are already in clinical trials. Future research on extended exposure to weightlessness will also prove to be beneficial. Various changes in the human body that result from these prolonged space flights mimic those seen on Earth as a result of aging. Conditions and diseases like bone and muscle loss, sleep disorder and hypertension are being tackled vigorously by the research scientists aboard the space station. Understanding the causes for these changes may lead to the development of counter measures against bone loss, muscle atrophy, loss of balance and other disorders.
Another series of experiments also carried out in the MIR space station were specifically targeted to analyze the properties of microgravity. Research and experiments that analyzed fluid dynamics, material and combustion science in space will help the development of new materials more suited for microgravity. Studies on the relationship between organic life and gravity were also carried out aboard the MIR space station.
Support technology research and physical and psychological studies were also carried out on board Mir that were aimed towards the construction and implementation of a safer and more comfortable habitation in space. Through these research programs, scientists were able to learn various risk reduction methods associated with assembling and operating the new International Space Station. After the near disastrous fire aboard the MIR Space Station, additional research and experiments were carried out to help improve the design of the International Space Station. These efforts in turn led to significant improvements in software, hardware and procedural modifications to the new space station, like a single command shutdown of the ventilation systems to prevent any fire in the station from spreading. New protective coatings will also be installed on the new space station cooling lines to prevent corrosion. Additional tracking lights will also be put in the new space station to aid navigation systems during docking and rendezvous operations. A few other vital changes were also made to the new space station design, like more simplified locations for medical kits and fire extinguishers. Quick disconnect capabilities for the many cables in the new space station were also designed in the event of depressurization within a module. As a consequence of the long term research and engineering work done on Mir, a much safer, more efficient and advanced space environment has been created for the new space station. Eventually, research in the areas of fluid dynamics, severe space engineering on space transportation, robotics, telescience, communication, energy and structures will significantly elevate the technologies used aboard all future space stations. Finally, ZARYA was launched in November 1998 and UNITY soon followed her in December 1998. The Service Module will be launched in 1999, providing the initial living quarters and life support systems for the crew who will be occupying the station. If all goes as planned, the International Space Station will be permanently inhabited after the year 2000.
The new station will be fully equipped with laboratory modules, robot arms, and will be occupied by a crew of seven living and working on board. Various assembly and maintenance operations aboard the space station will involve space walking missions by the astronauts who will be working with new state of the art space robotics. The mechanical arms aboard both the Space Shuttles and the International Space Station will operate as space cranes, and will be used to maneuver large modules and components to the astronauts' work areas.
Figure 3. Shuttle Arm in Action
The International Space Station is an incredible combination of engineering design and technological brilliance. The station consists of a central truss with large solar panels on each end. The Japanese Experimental Module (JEM), US Laboratory and Habitation Modules, European Experiment Module, Russian Research and Service Modules will be attached to this central truss.
Canada has been developing the robotic arm systems, which will play a vital role in the assembly and maintenance of the space station. The Japanese Experimental Module (JEM) is divided into 4 parts: the pressurized module, experimental logistics module, exposed facility, and the remote manipulator. The pressurized module will enable the crew aboard to carry out experiments under "shirt sleeve" conditions and normal atmospheric conditions.
The exposed facility is a platform designed for various material and scientific experiments and observational activities that require a zero gravity or near vacuum testing environment. All the materials and consumables transported from Earth to sustain activities aboard the JEM will be stored and monitored in the experimental logistics module.
The most important part of the International Space Station is the ZARYA Control Module. This is the first pressurized module and has an operational lifetime of 15 years. It is 43-foot long, and weighs approximately 20 tons. ZARYA provides the propulsion, command and controls systems power, communications and remote control docking abilities with the Russian Service Module. ZARYA was lifted into orbit by a Russian Proton Rocket from the Baikonur Cosmodrome in Kazakhstan, Russia in November 1998. ZARYA was built by Russian scientists but the effort was subsequently taken over by the United States and is now wholly owned by NASA. The Khrunichev State Research and Production Space Center in Moscow built ZARYA, under a subcontract of The Boeing Company for NASA.
ZARYA will become the station’s passageway, docking port and fuel tank and will later be used as a cargo and storage hold. The 35 feet long, 11 feet wide solar arrays and the 6 nickel cadmium batteries will provide the 3 kilowatts of electrical power needed aboard the space station. ZARYA's side docking ports were designed to accommodate Russian Soyuz piloted spacecraft and the unpiloted Progress resupply spacecraft. ZARYA is a functional cargo block and it provides the orientation control for the 3 man crew living aboard the Service Module. Its 16 fuel tanks hold approximately 6 tons of propellant and its 24 large and 12 small steering jets are new generation technology for space altitude control systems. The spacecraft is also equipped with 2 large and powerful engines available for reboosting the spacecraft as well as making major orbital changed and alterations.
Figure 4. ZARYA
ZARYA was taken into space on a three-stage proton rocket. During the launch, the module’s systems are kept idle to conserve battery power. Once it was in its 137 by 211 statue mile orbit, the module separated from the proton rocket’s third stage and progressed into an initial elliptical orbit. A set of preprogrammed commands automatically activated the module’s systems and deployed the solar arrays and communications antennas. After operational tests to ensure that "all systems are go", the module fired its engines to circularize its orbit at an altitude of approximately 240 statute miles. The Space Shuttle Endeavor would then later rendezvous and capture the spacecraft to attach the second element of the International Space Station, the UNITY Connecting Module.
Thirteen days after ZARYA rocketed into orbit, the UNITY Connecting Module was launched aboard the Space Shuttle Endeavor, in December 1998. The 6-sided Connecting Module was constructed at the Marshall Space Flight Center in Huntsville, Alabama and shipped to the Kennedy Space Center launch site for final assembly and launch preparations. UNITY has 6 berthing or attachment ports, one on each side, to which future modules will be attached. With its two mating adapters attached, it weighs 23,350 pounds and is approximately 33 feet long and 15 feet in diameter. The UNITY was designed to capture ZARYA and attach itself to it while the astronauts from the space shuttle Endeavor carried out EVA (External Vehicle Adjustments) projects 1, 2 & 3.
Figure 5. The mated Russian-built Zarya (left) and U.S.-built Unity modules in space
The umbilical connections to activate the power were done in the EVA 1 space walk mission. The completion of EVA 1 meant power and a fully activated space station. During EVA 2, translation aids and tools such as handrails and foot restraint sockets, as well as early communication system antennas (ECOMM) were installed. Finally, in EVA 3, a large tool-bag for storing EVA tools on the outside of the station and other communication system equipment were installed. The foot restraints were then repositioned as needed, which finally completed UNITY’s mission.
Between now and the launch of the Service Module in July 1999, which will ultimately provide life support, navigation, propulsion, communication and other functions to the crew aboard, the STS-96 shuttle missions will provide the space station will all its requirements. A U.S. space shuttle will carry internal logistics and resupply cargo for the stations outfitting. The shuttle will also transport the external Russian cargo crane that is to be mounted on the exterior of the Russian Station segment. The crane will also be used to perform spacewalking maintenance activities. The remaining shuttle missions will deliver cargo, gyroscopes and solar power panels to the International Space Station. The first crew to live aboard the International Space Station will be comprised of U.S. Astronaut Bill Sheperd, Space Shuttle Soyuz Commander Yuri Gidzenko. and Flight Engineer Sergei Krikalev. These pioneers will be living and working aboard the space station for approximately 5 months.
Figure 6. Shuttle With Space Station Habitat Module On Board
As the International Space Station orbits the Earth, it will pass over most of America, Australia, New Zealand, South Africa and numerous other countries and will be visible in the night sky. Much has already been achieved from this International Space Station project, and with continued financial and governmental support we are bound to achieve far more.
Fittingly, let's close this article with some lines from one of the most famous space adventures of all, STAR TREK: " Space — This is the new frontier. To boldly go where no man has gone before."
Copyright 1999, Lavinia Ponniah, All Rights Reserved
This article appeared in the February 1999 issue of 21st
21st, The VXM Network, https://vxm.com