By Vladimir LOBACHEV, Dr. Sc. (Tech.), Director of Mission Control Center

Managing the mission of a modern spacecraft is a task of major technical complexity which covers the activities of the crew, the functioning of the on-board systems and dealing with a range of research and economic tasks and objectives embraced by the mission program.

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The key role in dealing with this host of problems belongs to the Main Mission Control Center (TsUP)-the main R&D center of the Central Research Institute of Mechanical Engineering-the brain trust of Russia's Aerospace Agency. Its experts not only conduct on- the-spot assessment of the feedback from various spacecraft, but also control them on their missions, maintain coordination with ground services on the cosmodrome, and the command-and-measuring and search-and-rescue complexes, the Cosmonauts Training Center, the academic and specialized R&D organizations, designers of the appropriate equipment and also with the mass media.

The Center is in charge of the MIR mission launched on February 20, 1986, of the International Space Station whose construction was started in orbit on November 20, 1998, the flight of the OKEAN-0 space probe which is conducting remote sounding of the earth surface and of the World Ocean, and the booster stage of the Zenith-3 SL carrier rocket ("Marine Start" international project). The Center has on its record the Buran mission, and the unmanned missions to the Moon, Venus, Halley's Comet, Mars and its Fobos satellite.

The Center counts the beginning of its operation from the historic launch in the Soviet Union on October 4, 1957 of the world's first Sputnik artificial satellite. Codenamed by its designers by an abbreviation PS-1 (meaning "first one") it was equipped with only two automatically activated radio transmitters, a power source, ventilator and pressure and temperature sensors. But even at that initial stage it became quite clear that we had to have a specialized data collection and processing center keeping check on such and even more complex space missions. With this aim in view Soviet experts started setting up special ground stations for mission tracking and control. Established at the State R&D Institute No. 88 (now the Central R&D Institute of Mechanical Engineering of the Russian Aerospace Agency(*)) was a specialized computer center (its founder and first director was M. Kazansky). It was commissioned in October 1960 and assumed the functions, first, of a "duplicate" or stand-by, and later the main ballistics center which was headed by I. Bazhinov (1917-1991). The first space probes controlled by this agency were the unmanned Luna-4 and manned Vostok-5 and Vostok-6 spaceships.

In 1965 the Computer Center was transformed into a Coordinating-Computer Center which was to supply relevant information to the respective state commissions, to process and present information on the tests of manned and unmanned spaceships and satellites launched for research and economic applications. And its was renamed into the Main Ballistics Center while controlling the flights of the manned Soyuz spaceships and unmanned interplanetary stations.

Much of the credit for the establishment of the Coordinating-Computer Center belongs to Yuri Mozzhorin (1920-1998) who was the director of the aforesaid R&D Institute No. 88 (TsNIIMASh). Under his guidance the world's first command-and-measuring complex was set up in 1956-1961 which embraced a complex array of ground flight-control instrumentation for orbital and interplanetary missions. The direct administrative management of the Center was exercised by A. Militsyn, Cand. Sc. (Tech.).

In the early 1970s in preparation for the Soviet-American Soyuz-Apollo mission our Center was established on the basis of the aforesaid predecessor of ours with a new set of technical equipment and facilities. The first spacecraft controlled by the Center were the unmanned Soyuz spaceships which were updated for their new tasks. The satellites underwent flight tests codenamed Kosmos-638 and Kosmos-672.

From 1973 the Center was put in control of all space missions in this country and also of manned orbital stations including Salute-Soyuz-Progress long-term complexes. Since 1986 the Center has been working with the Mir orbital station. In 1988 it ensured the functioning of the Buran space shuttle. Center experts managed all 9 manned spacecraft under the Intercosmos program and also the international crews missions with the participation of representatives of France, India, Syria, Bulgaria, Afghanistan, Japan, Great Britain, Australia, Germany, the European Space Agency, the United States and Slovakia.

Working there on a permanent basis is the Main Operational Control Group on the Mir program which includes scientists, ballistics experts, doctors, specialists in onboard systems and technical service experts.

Control of the Mir orbital station is exercised from 4 rooms: the Central one-of the station as a whole, and the other three (called minor or operational) rooms of the manned Soyuz-TM

* See: A. Morozenko, V. Shutov, "Korolyov, Capital of Russian Cosmonautics", Science in Russia, No. 1, 2000.-Ed.

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spacecraft, unmanned space freighters Progress-M (in the year 2000 the modernized Progress-MG craft was added to their "family") and Kvant, Kvant-2, Kristal, Spektr and Priroda space modules which belong to the space-station project.

One more Central Room was set up for control of the Buran mission. It has now been reequipped for the program of the International space station and will administer its Russian segment. One of the smaller control rooms is already engaged on this program, managing the flight of the functional-cargo module Zarya-the first module of the new space station which is being built with the participation of the United States, Russia, West European countries, Japan and Canada.

The minor rooms of the TsUP control the operation of unmanned interplanetary stations and circum-terrestrial spacecraft used for scientific and economic studies.

Attached to the Center are consultative teams from countries participating in international space projects. Earlier these teams came and went as need be and now their presence has become practically permanent. Thus NASA experts from the United States have been permanently present at the Center since 1995 when joint flights of Russian and American cosmonauts began on board the Mir station and the US space shuttles. At the present time we have set up a control section for US modules which will be incorporated into the International Space Station. The task of the NASA specialists working here is to manage the flight of the segment developed in the United States in case their own Mission Control in Houston, Texas, goes out of order. A similar Russian section has been set up by our specialists in the US Center and both are interconnected by all the necessary lines of communication and maintain round-the-clock information exchange.

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Our Center assumes control of a space mission right after the separation of a spacecraft from the last stage of the carrier rocket and bears the responsibility for the whole mission until the spaceship switches off its engines and begins the descent from orbit. At the stages of preparations for launch and putting a spacecraft into orbit we control the functioning of the board systems by telemetering data, watch the crew on television and monitor their radio traffic with the launch team. Traced on the main screen in the Central Room is the flight of the carrier rocket all through the launch stage. After separation of the craft, the land-based tracking stations take over the reception and passage to us of telemetering data, trajectory information and TV pictures from board the craft. All these data are immediately processed by the TsUP computer complex and visualized on displays in the control rooms. The telemetering data is subjected then to detailed analysis in support teams which present to an expert who is responsible for a comprehensive analysis of the situation their conclusion on the conditions and the functioning of each of the onboard systems.

The Mission Controller on duty sums up the information from different services and takes a decision on the subsequent flight program with the appropriate commands relayed to the spacecraft where they are carried out by the command-and-program support systems.

For data input the Center has a powerful communications room which can cover the needs of an average city. Together with the telecommunications center it takes care of the entire volume of information

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exchange not only with tracking stations and national organizations participating in mission control, but also with all the main space centers of our foreign partners-the United States, European Space Agency, Germany, and so on.

As has already been mentioned the input data we get is fed to the Computer Complex which is subdivided into 4 functional sections: ballistic, telemetering, command and display technologies.

The ballistic-navigational support covers the range of tasks on the flight trajectory of spacecraft, its maintenance and obtaining the whole volume of navigational data. Our experts determine the craft position and what maneuvers should be carried out for its trajectory correction both on near-Earth orbits and interplanetary missions. Each individual flight chart of a spacecraft calls for some specific ballistic calculations. For example, in dealing with a craft's descent from orbit it is necessary to model the operation of the automatic onboard system, the craft's aerodynamic and dynamic characteristics, incidental upsets in the density of the earth's atmosphere, conditions of the spacecraft entry into it, maximal overloads, heat losses and overheating.

The complexity of tasks of the ballistic-navigational support depends on the spacecraft designation, program and the specifics of each individual stage. For manned circum- terrestrial spacecraft, for example, one can single out 3 points calling for different ballistic- navigational support: formation of the operational orbit, orbital flight and return to earth. At the first stage specialists determine the actual flight trajectory and calculate maneuvers which are necessary for going into the required orbit.

During the orbital flight itself they conduct periodic checks of the craft parameters, the accumulating disturbances and carry out

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necessary corrections. The implementation of a program of scientific experiments necessitates a large volume of special ballistic calculations including the prognostication of lighting levels of the areas under observation, determination of the angle of the turn of a satellite or a space station for targeting its instruments on the objects under study, etc. And the most crucial part of a mission is the craft's descent and landing. Here one has to choose the landing site, calculate the maneuver of leaving the orbit and the trajectory of descent, the time and coordinates of the landing spot. For all of these calculations mathematical support has been provided in the form of automatic program systems which can allow to accept and process navigational data transmitted from the tracking stations and to supply information to the users in a visual form.

And just as complicated is the task of monitoring the onboard equipment and its control in order to ensure the implementation of the mission program and the required flight conditions. Consequently it is necessary to keep check on the current conditions of the equipment which is done with the help of an array of onboard sensors measuring all sorts of things, such as the temperature of various structural elements, gas pressure, current supply to the instrumentation, pressure drops in hydraulic pumps, and so on and so forth.

The obtained parameter values, translated into electric signals are transmitted to the onboard telemetering system which blends the signals into several information streams with the help of transmitters emitted to the ether. They are collected by the TsUP through the land-based tracking stations, where they are processed and analyzed. From the torrent of such data only the authentic values are

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picked up, decoded and put on a time scale. Their number reaches 1,000 for the Soyuz-TM and Progress-M spaceships, and it is 5,000 for the Mir station and 2,000 for each of its modules.

From the results of their analysis specialists draw conclusions on the working conditions of various onboard systems, the reserves and rates of utilization of various resources (working medium, electricity, etc.), the accurate observance of the preset control regimes, tightness of compartments, temperature and humidity regimes and spatial orientation. On the basis thereof recommendations are issued for the staff on the necessary procedures.

The processing, analysis and recording of data are done on a real timescale. That means that during communication sessions with the spacecraft the values of the parameters under control become available to Center experts practically without delays. This was made possible by the Center's being equipped with one of the most advanced high-rate (up to 100 Mbite/s) local computer network based upon fiber optics channels of communication.

One of the major tasks of the Center consists in the scientific-methodological support for specific tasks and objectives included into a particular mission program. These are: studies of the earth surface, planets of the solar system, stars, galaxies, outer space; studies of the impact of space flight factors on the human organism, plants and different animals; development of new materials in zero-gravity, etc. If, for example, it is planned to obtain pictures of the earth surface, experts have to anticipate in advance the likely cloud cover over that area. In the registration of solar flares, ground facilities are used to detect the time of increased solar activity in order to choose the best period for observations.

Certain space studies require some simultaneous activities and observations on the ground. For example, comprehensive experiments on remote sounding of the earth surface from space are often accompanied by simultaneous aerial photography of the same areas from planes and helicopters and also by ground measurements. A comparison of the results makes it possible to pinpoint distortions caused by the atmosphere.

Effective control of space probes depends to a large extent on timely reports by experts on the progress of a mission. All such data are supplied to specialists directly at their work stations with the help of electronic and optical displays and also alphabetic-digital displays showing the position of a probe in orbit, the time till the next communications session, the program of the upcoming studies, a general assessment of the already obtained results and many other things. And there are also video monitors set up directly at work stations of specialists which help them pick up just the data of interest for each one of them.

Flawless coordination in the functioning of the control systems and the ability to find the right solutions in any situation are achieved through careful and painstaking preparations for every particular mission. And the Center begins preparations for any coming mission when work on a particular space probe is still in progress.

At the training stage usually all of the Center's instruments and systems are brought into play and also a mockup of a new space probe. The staff members carry out the training with reference to specific tasks and at their work stations. This takes up about half of the total training time after which training sessions for all sorts of emergencies are conducted.

And parallel to all that specialists are busy seeking new solutions for mission control, work out programs, build up new databanks related to the forthcoming missions. All such command-and-programming data are passed to a simulator stand-an analog of the spacecraft, including such details as mockups of crew bays. Environmental objects (the Earth, the Sun, stars, other space devices, etc.) observed by the cosmonauts during flights either directly or through special devices are reproduced by imitators of the environment.

The central part of the modelling stand is a computer complex operating on programs which describe in a digital form the angular and progressive movements of the spacecraft, the impact .of orbital environment upon it and the response of the onboard systems. Sometimes the stand includes some real instruments which makes it possible to check on their performance in an interplay with other systems in the conditions which simulate reality to a maximum extent.

Multifunctional control panels control the operation of the stand and modelling results. They input to the computer complex the initial ballistic flight data, helping to select the optimal operating regimes for the onboard systems, imitate all sorts of "emergencies" and work out the appropriate response from the land-based tracking stations.

The technical facilities of the Center are functionally intertied with the modelling stand using the same lines of communication as in real flights.

Summing it up, one could say that the "key word" of our Center is dependability which stands for highly reliable data and safety in orbital flight.

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