CASSINI In Space

 

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GALILEO

The Galileo Energetic Particles Detector

 

Galileo EPD Handbook

 

Chapter 2. EPD Software

 

EPD SBAND Mission Software Requirements (continued)

Source: S. Jaskulek, various dates

 

CDS-Produced EPD Telemetry Record

 

 

Table 12. EPD Science Record Format vs. Format Number

 

Format
Number
Telem. 
Alloc.,
 
bps
Accum. 
Period, cycles
Rate 
Channels
Chan. 
Map
CMS PHA Events Hskpg/
Status, bits

Telem. Out, 
bps
1,2,3,4,5 5 6 356 1 12 40 5.08
6,8 10 3 356 1 12 40 10.16
7 15 2 451 1 12 40 15.24
9,10 20 2 451 2 24 40 20.03
11 30 1 356 1 12 40 30.48
12 40 1 451 2 24 40 40.07

 

 

Packet Type Data Size Description
Packet 1   Rate Bin Data
    Map1 401 bytes  
    Map2 508 "  
Packet 2   CMS PHA and Housekeeping/Status Data
    Map1 35 bytes  
    Map2 65 "  

 

RECORD/PLAYBACK SCIENCE PACKET HEADER

 

Figure 1. EPD2 Record Mode Packet Header

 

Field Name Data Offset Field Size Content/Description
Time Include Flag 0 1 =1, 1st packet and every 16th thereafter
APID 1 7 =0A hex
Packet Size 8 9 =76, 152, or 228
Packet Sequence # 17 7 0=127
Packet Time 24 32/0 * R-R-R-mf
EPD Minor Frame Data 56/24 * 608 76-byte EPD Record Packet
EPD Minor Frame Data 664/632 * 608 76-byte EPD Record Packet
EPD Minor Frame Data 1272/1240 * 608 76-byte EPD Record Packet

 

* The first number is for time included, the second is for time not included.

Time Included - This bit indicates if the time filed contains information. For the Record Mode data, time is included in the first packet of a new rate and every 16th packet thereafter. For those packets without the time, the packet is shortened by 32 bits.

 

Application ID - This 7-bit field generated by the CDS for all packets, and is used to identify the source of the data.

 

Size - This 9-bit field indicates the number of data bytes included in the packet.

 

Sequential Number - This 7-bit counter is incremented for each new EPD packet created.

 

Time - This 32-bit value will contain time reference data whenever the "Time Incl." flag is set. The format is "R-R-R-mf." This is the 24 least significant bits of the S/C RIM counter + spacecraft minor frame clock.

 

EPD2 REAL-TIME SCIENCE PACKET

 

Figure 2. EPD1 RT Mode Packet Header

  

Field Name Data Offset Field Size Content/Description
Time Include Flag 0 1 =1, Always
APID 1 7 =31 hex
Packet Size 8 9 =401 Map 1, Rate Packet
=508 Map 2, Rate Packet
=35 Map 1, PHA/Hskg Packet 
=65 Map 2, PHA/Hskg Packet
Packet Sequence # 17 7 0-127
Format ID 24 4 1:5 bps
2:10 pbs
3:15 bps
4:20 bps
5:30 bps
6:40 bps
Packet Time 28 28 1/2 R-R-R-mf
EPD RT Data 56   Rate or PHA/Housekeeping Data

 

Time Included - This bit indicates if the time filed contains information. For the RT Mode data, time is included in every packet.

 

Application ID - This 7-bit field generated by the CDS for all packets, and is used to identify the source of the data.

 

Size - This 9-bit field indicates the number of data bytes included in the packet.

 

Sequential Number - This 7-bit counter is incremented for each new EPD packet created.

 

Telemetry Format - This 4-bit field indicates which CDS-EPD data collection mode was used to generate the record.

 

1: 5 bps 2: 10 bps
3: 15 bps 4: 20 bps
5: 30 bps 6: 40 bps

 

Time - This 28-bit value will contain time reference data whenever the "Time Incl." flag is set. The format is "1/2 R-R-R-mf." This is a translation of the 28 LSBs of the spacecraft minor frame clock.

 

 

Continue 

 

Return to Galileo EPD Handbook Table of Contents Page.

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Updated 1/2/19, Cameron Crane

QUICK FACTS

Manufacturer: The Galileo Spacecraft was manufactured by the Jet Propulsion Laboratory, Messerschmitt-Bölkow-Blohm, General Electric, and the Hughes Aircraft Company.

Mission Duration: Galileo was planned to have a mission duration of around 8 years, but was kept in operation for 13 years, 11 months, and 3 days, until it was destroyed in a controlled impact with Jupiter on September 21, 2003.

Destination: Galileo's destination was Jupiter and its moons, which it orbitted for 7 years, 9 months, and 13 days.