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RadioAstron Mission Element Overview

Mission Elements

The main mission elements (ME) are:

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Nomenclature

Before proceeding further, the nomenclature used within the handbook will be briefly described.

An observation is a single continuous event, usually lasting for several hours, when SRT antenna is pointed to the chosen radio sources and all scientific and service on-board equipmet operate in accordance with the program stored in the SC on-board memory.

An experiment is one or more observations of a single source at a single frequency within a single proposal. Experiment codes of five characters are used in naming GRT related files. For experiments with multiple epochs (i.e. multiple observations) the six character observation code is sometimes used.

A tracking pass is a single continuous occasion in which the two-way link is established between a single GTS and the space radio telescope (SRT). An observation consists of one or more tracking passes.

A control session is a telemetry (TM)communication with the SpaceCraft (SC) in order to transmit defenite sequence of commands which will be memorised in the on-board memory, to receive TM-information from the SC, and to conduct orbit measurements in P and C bands. The duration of control session is from 2 to 4 hours.

Ku-band science data telemetry is the real-time link between the GTS and the SRT. The nominal downlink frequency is 15.062 GHz.

X-band phase transfer is the real-time up-down link between the GTS and SRT. The up-link nominal frequency is 7.125 GHz, and downlink is at 8.47 GHz.

C-band telemetry is conducted between the Control Station (CS) and the SRT. Commanding is done at the uplink frequency of 5.008 GHz, and housekeeping telemetry (and range and range-rate monitoring) at the down-link frequency of 5.884 GHz.

P-band telemetry is conducted between the Control Station (CS) and the SRT. Commanding is done at the uplink frequency of 0.770 GHz, and housekeeping telemetry (and range and range-rate monitoring) at the down-link frequency of 0.930 GHz.

A self-hold mode is such a state of the SC, when only necessary equipment is switched on to provide correct functioning of the system with minimum power consumption. In this mode the SC is always ready to receive commands from CS.

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Overview of this document

An overview of the data products and interfaces is given in the table on the following page. The 'X' in the file extension column refers to the designated code for the relevant tracking station or ground radio telescope. These are described in more detail later in the document.

Origin / Data Product File Ext. User
RSOG    
    Long-Term Experiment Schedule gst ME
    Observation Summary File osf Corr (GTS?)
    GRT Schedules crd, skd, drg' GRT
    Merged Correlator Input Log vs Corr
    Calibration and Flag files tsm Corr, PI
        (Flag Table) - -
        (Amplitude Calibration) - -
        (Phase Calibration Data) - -
    RSOG Status Reports svg ME
GOCG    
    Space Radio Telescope Schedule srs GTS
    Constraints to SC Operations cns RSOG
    Control Session Files spr CS
    Executed Sequence of Events xse NAV
    Telemetry Prognosis Files tpf GOCG
    SRT Status Report svg RSOG
Navigation    
    Long-Term Predicted Orbit opr RSOG
    Orbit for Scheduling opr RSOG
    Orbit for Tracking opr GTS
    MBC OD Results onp CS
    State Vectors icv Nav
    Tracking Data odf Nav
        (X-Band Data) odf Nav
        (C-Band Data) odf MMNAV,MBC
    Reconstructed Orbit - -
        (JPL MMNAV Orbit) bsp Corr
        (ASC Orbit) scf PC
    Navigation Status Reports ? RSOG
GTS Products    
    VLBI Tapes -- Corr
    Telemetry Header File (THF) ktX RSOG
    Time Corrections File (TCF) kcX Corr (RSOG?)
    Time Components File tcX Corr (RSOG?)
    Data Processing Log (to VLBA) klX Corr
    Data Processing Log (to S2) ksX Corr
    Station Performance Log (SPL) kpX RSOG
    JPL/DOTS Monitor Data File (MDF) kmX RSOG
    GTS Status Reports stX RSOG
GRT Products    
    VLBI Tapes - Corr
    GRT Log File X Corr
    GRT Calibration Data X PI, Corr
    GRT Clock Offset Data X Corr
    GRT Gain Curves -- PI, Corr
    GRT Status -- ME
Correlator Products    
    Correlator Output -- PI
    VLBI Tape Management - ME
    VLBI Tapes - GRT, GTS
    NRT Fringe Detector Results - RSOG (Corr?)
    Correlator Status Reports sco RSOG


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