ABSTRACT. Russian Space Agency (RSA) actively develops international cooperation with national space agencies from other foreign countries in area of joint space projects implementation. Examples of such activities are operations of numerous astronaut expeditions from Western Europe and United States of America on-board orbital station "MIR", conducting join experiments on science equipment on "MIR" station, preparing MARS-96 expedition. So for last years astronauts from Germany (program MIR-92), Austria (AstroMIR), United Kingdom, France (ALTAIR, Cassiopee), European Space Agency (EUROMIR 94,95), USA (MIR - Shuttle, MIR - NASA) and others worked on board Russian orbital space station "MIR". Preparing German astronaut mission by project MIR 96/97 now takes place.

On board station MIR conducts Russian - German experiments by project "Nature".

Significant role in realization those and future projects belongs to Russian Mission Control Center - Moscow as a central link of whole control contour.

This document presents MCC-M telecommunication systems that provide international space program realization.

The importance of exploring Outer Space and substantial expenditures required for space-oriented programs justify a wide-spread geography and multinational pattern of efforts. Each draft project evolves to its maturity via coordination, concurrence, approval, simulation and operational phases. A noticeable cost reduction can be reached by extensive usage of wide-band telecommunication (TC) loops that allow discussions of pending issues and early preparation for the upcoming meeting or mission.

Each participant covers its geographical area of responsibility: Russia - Russian Mission Control Center (MCC-M), Germany - GSOC, USA - Marshall Space Flight Center, France - CADMOS TOULOUSE.

Russian Mission Control Center (MCC-M) has advanced systems for telecommunication with each of it Western partners from Space Centers.

Overviews of these systems are presented below.

TC system was established in 1994 by link segment NASA in MCC-M for providing joint space flights programs MIR-Shuttle and MIR-NASA (figure 1,2). System links MCC-M - MSFC (Marshall Space Flight Center), GSFC (Goddard Space Flight Center) and through the NASA network to JSC (Johnson Space Center). The System consists of :

• 12 voice channels for interaction experts to control Shuttle, MIR, MCC-M, MCC-Houston and astronauts (Flight Directors, Ground Controllers, Surgeons, Consultants, Air-Ground etc.).
  Data throughput of this channel from 16 to 32 Kb/sec.

• 16 telephone line by 16 Kb/sec links with American Automatic Telephone Stations.
• Video conference for organization of communications of American astronauts on orbital station MIR with their families for the long time flight.
• The data exchange channel that has 64Kb/sec throughput.
  

On basis of this channel in MMC-M remote segment LAN MCC-H connected to LAN MCC-M for data exchange during program MIR_SHUTTLE and MIR-NASA is organized.

Figure 2 shows possibility of TC system to transfer TV from MCC-M to MCC-H.

The system is used by MCC-M clients and provided flights during program STS-63, 71 . . . , including the longest flight of American astronaut Shannon Lucid on board of orbital station MIR.

For communication with partners in Western Europe for maintenance program EUROMIR - 94,95 in MCC-M terminal of DICE system (Direct Inter-establishment Communication Experiment) was established.

This system allows the transmission of a high quality Audio/Video/Data signal using small earth stations (V-sat stations EUTELSAT standard) and videoconferencing easily implementable equipment.

For the project Euromir an EUTELSAT satellite has been rented in order to use this equipment as often and as efficiently as possible.

Such a capability will also allow EAC to be more flexibility during the mission preparation phase with regard to its intense communications with Star City and the crew/training team at EAC.

However, even though the DICE system will constitute the core part of the communications system due to its flexibility, extensive use of the existing facilities implemented by ESA through the years to improve the communications between Europe and Russia will be necessary. Indeed these already existing facilities will be of a great help where reliable telephone/fax/computer services are required (see Figure 3).

As the main Interface during the mission, all types of data provided by ZUP will be processed/stored by SCOPE. The following services will be supported by SCOPE during the Mission phase with high reliability:

• Audio
• A highly reliable link is required between ZUP and SCOPE. This link which will allow a continuous mission coverage will be supported via the DICE system with throughput of 64 Kbps.
• Video link
• Daily Video data transmission (real-time and play-back) from ZUP towards SCOPE (and other remote-USOC's) using the DICE system (throughput up to 2 Mbps).
• Daily Video conferences (i.e. mission activity debriefings) between all parties (throughput: 384 kbps).
• Fax
• A reliable link is available during the mission between Russia and Europe.
• Fax support is based on dedicated machines which are connected to ESAPAC, ESA X.25 network, by means of packet assemblers/dissemblers (PAD).
• Data Transfer (MIR Housekeeping data)
• MIR flight data and TM data (i.e. orbit parameters) is transmitted to SCOPE (and USOC's) using the DICE system via a 64 kbps channel.
• E-mail
• The E-mail capabilities (PROFS system) were available during the mission for a quick exchange of information between the centers and also to allow team members to be in contact with their home bast. Because only basic functionality is required (no special format or high resolution printing), the terminal connections will share the PAD used for Fax connections.
  

It was the USOC's in continuous listen-in mode during the mission during nominal activity. The following services will be supported by the DICE system, via an EUTELSAT satellite during the mission with high reliability:

• Audio
• This link is supported via the DICE system with a throughput of 64 Kbps dedicated to the audio signal.
• Video link
• Daily Video data transmission (real-time and play-back) from ZUP towards the remote-USOC's using the DICE system ( throughput: up to 2 Mbps).
• Daily Video conferences (i.e. mission activity debriefings) between all parties ( throughput: 384 Kbps).
• Fax
• Fax support is based on dedicated machines which are connected to ESAPAC, ESA X.25 network.
• Data Transfer (MIR Housekeeping data)
• MIR flight data and TM data (i.e. orbit parameters) transmitted to USOC's using the DICE system via a 64 kbps channel.
• E-mail
• The E-mail capabilities (PROFS system) are available at USOC's site and will be used for a quick exchange of information between the centers.

This system was created for providing interaction between MCC-M and CADMOS in project "Cassiopee". (see Figure 4).

This system has following capabilities:

• 4 leased line for voice communication between operators in MCC-M and CADMOS
• - voice communication of operators CADMOS through MCC-M with orbital station MIR.

• - Data Transfer (MIR Housekeeping data and experiments data) via 64 Kbps channel
• - Fax and telephone
• - Video data transmission (real-time and play-back) from MCC-M towards CADMOS using Russian relay satellite.

Especially in detail consider on telecommunication system MCC-M GSOC.

Communication system between Russian and German sites is developed in 3 stage:

• on the first stage 1994 the system interaction between Russian and German Control Centers (MCC-M-GSOC) has been developed and tested

• on the second stage 1995 the system created on first stage was upgraded for better reliability and improvement maintenance characteristic; In that period TC system MCC-M/GSOC was commissioned as a prime system to support EUROMIR-95 project activities. And, for example, MCC-M/GSOC loop elements backed up critical operations of MIR/Shuttle Program by patching MCC-M to MCC-H, USA via Germany, this increasing reliability of TC.

• on the third stage 1996 list of organization - operation participants was extended (was added MCC-M, STAR CITY, Rocket Space Corporation "Energy" (RSC), Space Research Institute, Science Research Center), also ground communication infrastructure was extended, network interaction for digital data exchange organized, and very essentially telephone and fax communications expanded.

The last two stages have been performed according to General agreement between DARA and Russian Space Agency dated April 5, 1995.

The structural scheme of this communication system is shown on figure 5. In the process of creation this system the following was made:

• the satellite channel between MCC-M and GSOC which uses geostationary communication satellite EUTELSAT. This communication channel has following characteristic: with the help of this channels of information exchange is organized transfer different Data with throughput in 83,2Kb/sec (DATA), fax messages - 64Kb/sec (FAX), television (TV), telephone talks (TLF) with more than 50 subscribers on the Russian site, direct voice connection (VOICE) and network interaction MCC-M - GSOC with throughput 9,6 Kb/sec;

• the radio relay communication channel MCC-M - Space Research Institute with throughput 64Kb/sec, destines for data transfer (DATA), telephone talks (up to 11 subscribers), fax messages exchange and network interaction between Space Research Institute and GSOC; This line will be used for "MARS-96" project to connect Russian Institute of Space Research (with NPO "Lavochkin" as a co-partner) MCC-M and GSOC.

• the direct radio communication channel Science Research Center(SRC) - MCC-M with 512 Kb/sec throughput , destines for organization network interaction SRC - GSOC with rate 24Kb/sec, and also for data transfer through SRC - MCC-M line with rate 38,4 Kb/sec and telephone talks for four subscribers between MCC-M and RSC.; This line will be used for "Nature" ("Priroda") project, launched by Russian Space Agency and DARA.

• the fiber optic communication channel between RSC "Energy" and MCC-M with throughput 2048 Kb/sec, destines for organization network communications RSC "Energy" and MCC-M with rate 512 Kb/sec, data exchange with rate 9,6 Kb/sec, telephone talks (up to 12 subscribers) and fax communications with rate up to 16 Kb/sec between RSC "Energy" and GSOC;

• two communications channels MCC-M - STAR CITY: the first is analog and uses coaxial cable, destines for transfer television signals from STAR CITY to MCC-M and GSOC; the second is digital and uses radio channel with throughput 64 Kb/sec and destines for data transfer from(to) STAR CITY to(from) GSOC with rate 9,6 Kb/sec, from(to) STAR CITY to(from) MCC-M with rate 38,4 Kb/sec, for organization telephone talks 12 subscribers and fax messages exchange between STAR CITY and GSOC with rate up to 32 Kb/sec. This line will be used to support simulations of German astronauts in "MIR-96/97" project time frame.

The communication system is developed from universal transfer information point of view, invariant to different it kinds in different program, with possibility easily expanded system throughput ( increasing rate of data transfer up to rate provided channels throughput and number of telephone and fax communications subscribers defined numbers capacity on the office telephone stations.

However this system has several defects:

• Its "weak point" is multiplexor TDM which works with satellite communication channel set up in MCC-M on the beginning stage of communication system creation. TDM doesn't provide full utilization of rate of communication lines MCC-M - SRC, MCC-M - Space Research Institute, MCC-M - STAR CITY, MCC-M - RSC "Energy";
• Inasmuch as system was designed and created in 2 stages and during it creation is used technical facilities establish or designed earlier in MCC-M and GSOC, then in common scheme of technical facilities was used equipment identical by assignment but produced different brand-name firms. As a result we had no problem during data transfer according to international standards (RS-232, V.35, RS-422 etc.) but when we tried to organize telephone talks and fax communication we had problem because we used recommendations E@M, which uses five classes of official alarm. As a result of utilization of equipment of different vendors which applies different classes official alarm we had problems in conjunction this equipment. We succeed to resolve this problems at the expense of additional instruments developed in MCC-M and removed all contradictions.

Thus we can draw a conclusion that for developing such system in current or future program mutual cooperation is necessary to provide full preliminary job examination allowing to estimate level of readiness, choose optimal structure of usable equipment and firm that it produce

In conclusion it's necessary to note that creation of this system was financed by DARA as well as Russian Space Agency and earlier existed technical potential was successfully used.