IMAGE Detailed Mission Requirements (DMR)

IMAGE 1405 -- Frequency Utilization Summary - Operating Description

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

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

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

PARAMETER	VALUE
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

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

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

a. Receive Frequency: S-Band (2092.59375 MHz)

b. Carrier Tracking Range: +- 140 kHz v c. Carrier Acquisition Threshold (sweep mode): -125 dBm

d. Carrier Tracking Threshold (sweep mode): -125 dBm

e. Maximum Carrier Loop Tracking Range: +-140 kHz at threshold (Tol. +10 kHz)

f. Acquisition Sweep Rate: 32 kHz/sec max (at threshold)

g. Acquisition Times: Uplink sweep: 15 sec max

h. Noise Figure: 5 dB max

i. Loop Noise Bandwidth (2 bL): 800 Hz fixed (non-expanding)

j. Dynamic Range: -40 dBm to threshold

k. Maximum input signal (carrier threshold): +3 dBm (Tracking Loop SNR = 0 dB)

l. AGC curve maximum input power limit: -50 dBm

m. Pre-selector Filter: 2 pole, 150 MHz

n. Pre-detection Bandwidth: 1.0 MHz

o. Spurious Response: >60 dB below desired response

p. Ranging Channel: PN Code with 0.5 Mod Index

q. Command Channel Bandwidth: 1.5 kHz to 1.2 MHz

r. Command Sub-carrier Frequency: 16 kHz

s. Command Data Rate: 2,000 bps

t. Command Threshold @10^-6 BER: -118 dBm @ 2 kbps & 1 radian mod index

u. Telemetry Output: Signal Strength; Loop Stress; Converter Voltage; Carrier Lock/Demod Lock

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

Figure 1000-5 shows spacecraft Launch to separation details.

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

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) DSN CONTINUOUS SUPPORT (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) DSN CONTINUOUS SUPPORT	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) ONE DSN CONTACT/ORBIT	Sun-safe Condition at All Times
RPI Antenna Deploy to 120 m (Day 15) (->0.97 rpm) DSN CONTINUOUS SUPPORT	CIDP On RPI Deployers Activated Other Instruments Off
RPI Spin-up #2 (Day 16 - Day 18) (->1.4 rpm) ONE DSN CONTACT/ORBIT	Instruments Turn-on (No High Voltage) Instruments Open Doors Instrument Outgassing
RPI Deploy #2 to 160 m (Day 19) (-> 0.73 rpm) DSN CONTINUOUS SUPPORT
RPI Spin-up #3 (Day 20 - Day 22) (-> 0.96 rpm) ONE DSN CONTACT/ORBIT	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) DSN CONTINUOUS SUPPORT	Sun Warning Pulse Tests HVPS Ramp to Science Levels (0.5 rpm only) Preliminary Images (0.5 rpm only)
First Images (Day 24) ONE DSN CONTACT
RPI Spin-up #4 (Day 25 - 35) (-> 0.77 rpm) ONE DSN CONTACT/ORBIT	Instruments in Sun-safe Condition
Checkout Period (Day 36 - Day 39) (0.5 rpm) ONE DSN CONTACT/ORBIT	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) DSN CONTINUOUS SUPPORT
Normal Science Ops (41 days - 2 years) ONE DSN CONTACT/ORBIT	Instruments in Science Mode 1715-1

Author and Curator:

NASA Approval: J. L. Green, james.l.green@gsfc.nasa.gov
Last Revised: 04 November 1998