IMAGE Detailed Mission Requirements (DMR)

Final - July 1998

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IMAGE 1405 -- Frequency Utilization Summary - Operating Description

The DSN is used for all IMAGE flight operations.

The IMAGE spacecraft provides an uplink and downlink communication capability which is compatible with the DSN 34 m and 26 m stations.

The IMAGE uplink rate is 2000 bps. The IMAGE downlink rates are 2,285,700 bps, and 44,000 bps.

All communication formats and frequencies are specified in Section 2000.

IMAGE 1420 -- Spacecraft/Payload Telemetry Systems Description

Data Storage: The IMAGE Control and Data Handling (C&DH) subsystem provides storage for instrument science data, spacecraft and instrument housekeeping data, spacecraft event messages, and absolute and relative time-tagged commands. Concurrent data acquisition, storage, and playback operations are supported.

Downlink: Normally, IMAGE will make one (1) telemetry transmission per orbit. The telemetry rates are selectable depending on the phase of the mission. In all downlink formats/rates, Reed-Solomon error correction coding is added. The telemetry data is phase modulated directly onto the S-band downlink carrier.

Upon receipt by DSN, the telemetry is demodulated, recorded, and transmitted to the SMOC.

IMAGE 1421 -- Spacecraft/Payload Telecommunication System Parameters - Telemetry

The IMAGE transponder transmitter and telemetry link characteristics are listed below:

Table 1000-2: IMAGE Transponder Transmitter and Telemetry Link Characteristics

a. RF Output Power 5.0 Watts
b. Transmit Frequency (S-Band) 2272.500 MHz
c. Coherent Turnaround Ratio 240/221
d. Frequency Stability 30 ppm (non-coherent)
e. Direct Carrier Modulation Rate 2.5 Mbps BPSK
f. Linear Phase Modulation 1.3 radians
g. Ranging SRA with 0.33 m.i.
h. Coding PN & R/S
i. Sub-carrier Frequency Selected *1.7 MHz
j. Sub-carrier Type *Filtered Sq. Wave
k. Sub-carrier Stability *+/-0.005%
l. Sub-carrier Modulation *BPSK
m. Sub-carrier Mod Index *1.3 radians
n. Sub-carrier Data Rate * 64 kbps
o. Telemetered Monitors Temp.; RF Pwr. Out;
DC Converter Voltage
p. Commands Accepted Transmitter Power ON/OFF; SCO ON/OFF;
Coherent Mode ON/Off; Ranging ON/OFF
* Note: This subcarrier mode and the direct carrier modulation mode are mutually exclusive
Simultaneous ranging and 2.5 Mbps data direct carrier modulation is acceptable.

IMAGE 1430 -- Spacecraft/Payload Command Systems Description

The IMAGE spacecraft accepts commands at uplink rates of 2000 bps. The command data structure complies with the CCSDS telecommand recommendations. The onboard command processing function supports both Command Operations Protocol (COP) -1 and Bypass command modes.

Command operations will include both real-time commanding and stored command loads uplinked to the spacecraft via DSN (real time) throughput commanding service. Real-time commanding is the uplink of commands or data intended for immediate implementation/use by onboard systems. Real-time commanding enables the immediate verification of command reception through the COP-1 protocol, as well as the verification of command implementation through telemetry of affected system parameters. Stored command loads consist of absolute and relative time based command data files. These commands and data are stored in the onboard memory and are intended for future use by onboard systems. Stored command loads direct and provide necessary data for the onboard processors to perform autonomous operations between ground contacts. The reception of stored command load data by the spacecraft is provided through the COP-1 protocol.

For all mission phases, real-time commanding is required during DSN contact periods. During nominal operations the frequency of stored command loads will normally be one load per week. All stored command loads performed will occur within the normal pass time frame; stored command loads do not affect the duration of the daily pass period.

Stored command loads will primarily consist of commands associated with the pass operations schedule. These commands affect onboard configurations and operations required in support of the daily pass operations.

The IMAGE SMOC will format all commands (real-time and stored command load) and transmit them to the DSN for uplink to the spacecraft. Real-time commands will be generated by the SMOC and transmitted to the DSN at generation time for immediate uplink. The SMOC may format a command load and transmit the command load data as it is generated to the DSN for immediate uplink to the spacecraft.

Normally, a command uplink will occur once per week to load a schedule. The IMAGE SMOC will format the commands and transmit them to DSN for uplink to the spacecraft. Command data structure is based upon the CCSDS COP-1 recommendations.

IMAGE 1431 -- Spacecraft/Payload Telecommunications System Parameters - Command

The IMAGE transponder receiver and command link characteristics are listed below:

Table 1000-3: IMAGE Transponder Receiver and Command Link Characteristics

Table 1000-4 contains the IMAGE communications commands.

Table 1000-4: Communications Subsystem Commands

1 Transmitter Power ON 2 Transmitter Power OFF
3 Subcarrier Oscillator ON 4 Subcarrier Oscillator OFF
5 Coherent Mode ON 6 Coherent Mode OFF
7 Ranging ON 8 Ranging OFF
9 Convolutional Encoder ON 10 Convolutional Encoder OFF
11 Transmit Ant. Select LGA 12 Transmit Ant. Select MGA
13 Receive Ant. Select LGA - 1&2 14 Receive Ant. Select LGA - 1 Only

1431.3 The following is the Initial Acquisition Configuration:

1,3,5,7,10,11,13, and Receiver On (hard-wired)

IMAGE 1711 -- Launch Vehicle Flight Sequence - Mark Events

The launch profile for a typical Delta 7320 family is shown in Figure 1000-5.

Figure 1000-5 shows spacecraft Launch to separation details.

Delta 7325 IMAGE Mission Preliminary Boost Phase Profile

Figure 1000-5: Delta 7325 IMAGE Mission Preliminary Boost Phase Profile

Event MET (seconds)
Liftoff 0.0
Mach 1 36.1
Maximum dynamic pressure 50.6
Solid motor burnout(3) 64.0
Solid motor separation(3) 110.0
Main engine cutoff 261.3
Vernier engine cutoff 267.3
Stage 1/2 separation 269.3
Stage 2 ignition 274.8
Fairing separation 300.0
First stage 2 cutoff 696.0
Start stage 3 ignition time delay relay, Fire spin rockets 3020.7
Stage 2/3 separation 3023.7
Stage 3 ignition 3060.7
Stage 3 burnout 3125.4
Deploy Yo-Yo weights (despin stack) 3270.7
Spacecraft Separation 3275.7

Delta 7325 IMAGE Mission Preliminary Orbit Injection Profile

Figure 1000-6: Delta 7325 IMAGE Mission Preliminary Orbit Injection Profile

IMAGE 1715 -- Spacecraft/Payload Major Mission Events

Table 1000-5 summarizes IMAGE operations.

Table 1000-5: IMAGE Operations Summary

  • Launch to 3rd Stage Sep.
    (0 - 20 min)
    (Ready for Initial Acquisition)
  • Purge Continues until Lift-off
  • No Instrument Activities Baselined
  • No Active Thermal Control
  • No Power to P/L Baseplate
  • 3rd-Stage Sep. To Reorient.
    (20 min - Day 7) (0.75 rpm)
  • S/C Outgassing
  • P/L Survival Heaters On
  • CIDP & Instrument Electronics Turn-on,
    Communications Check, Turn Off
  • RPI Spin-up #1
    (Day 8 - Day 14) (-> 13 rpm)
  • Sun-safe Condition at All Times
  • RPI Antenna Deploy to 120 m
    (Day 15) (->0.97 rpm)
  • CIDP On
  • RPI Deployers Activated
  • Other Instruments Off
  • RPI Spin-up #2
    (Day 16 - Day 18) (->1.4 rpm)
  • Instruments Turn-on (No High Voltage)
  • Instruments Open Doors
  • Instrument Outgassing
  • RPI Deploy #2 to 160 m
    (Day 19) (-> 0.73 rpm)
  • RPI Spin-up #3
    (Day 20 - Day 22) (-> 0.96 rpm)
  • Instrument High Voltage Power Supplies On
  • HVPS Ramp to Sun-safe Level
  • RPI Deploy #3 to 210 m
    (Day 23) (-> 0.5 rpm)
    (pause at 0.5 rpm)
  • Sun Warning Pulse Tests
  • HVPS Ramp to Science Levels (0.5 rpm only)
  • Preliminary Images (0.5 rpm only)
  • First Images (Day 24)
  • RPI Spin-up #4
    (Day 25 - 35) (-> 0.77 rpm)
  • Instruments in Sun-safe Condition
  • Checkout Period
    (Day 36 - Day 39) (0.5 rpm)
  • Spin Rate Trim to Exactly 0.5 rpm
  • Instruments to Full Operational Condition
  • First Science Images
  • Compatibility Tests (Cycle Active/Inactive)
  • RPI Test
  • Calibration - All Instruments
  • Configure for Normal Operations
  • LENA Resurfacing and HV-Checkout
    (Day 40)
  • Normal Science Ops
    (41 days - 2 years)
  • Instruments in Science Mode 1715-1

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Author and Curator:

Dr. D.R. Williams,, +1-301-286-1258
NSSDC, Mail Code 633, NASA/Goddard Space Flight Center, Greenbelt, MD 20771

NASA Approval: J. L. Green,
Last Revised: 04 November 1998