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GALILEO

The Galileo Energetic Particles Detector

 

Galileo EPD Handbook

 

Appendices

 

Appendix E. EPD File Structure (continued)

 

3. Rate Block

Source: T. P. Armstrong, July 24, 1985

 

The rate block is a spin-synchronous reformatted collection of the count rates in all EPD channels. The fundamental unit of this block is the spacecraft spin, nominally 20 seconds, but with anticipated small variations about this value. The rate block is constructed in a payload fixed coordinate system. The angular sectors are nominally 5.625, 11.25, or 22.5 degrees, are obtained from 1/3, 2/3, or 4/3 second samples which are taken in a time synchronous mode. DECREEP algorithm is described in EPD Proc section 4.3.2. Each rate block will contain the data from one spin (in the case of the highest resolution--20 seconds) at a specified motor step position. A full, unit sphere scan, therefore, requires 7 such records and might be regarded as a "logical record". However, in many operational circumstances, the EPD instrument will not be in full scan. If it is "parked" the logical record would be one spin in duration--appearing as a single physical record.

 

The rate average is performed in spacecraft payload coordinates. Sector 1 is defined to begin at the time when the zero degree detector axes pass through the Jovian equatorial plane. The 180 degree detector data will be stored in sector 1 one half of a spin later and thus will correspond to the same look direction as the zero degree data. The relationship of the 64, 32, and 16 sector data is

 

 R16(1) = <R32(1)+R32(2)> = <R64(1)+R64(2)+R64(3)+R64(4)>

 

where R16, R32, and R64(I) stand for the 16, 32, and 64 sector data, respectively, at the I th sector and < > stands for an average.

 

Item Name Length
1 Spin Block
Variables: T64(64), T32(32), T16(16)
Contents:

Durations (seconds) of each of the sectors.  This may vary from sector to sector if the spin  rate changes.

Variables: PHIDOT (2)
Contents: Spin rate at beginning and end of spin
Variable: TSPIN
Contents: Duration of this spin
Variable: FNSPIN
Contents: Number of spins in this record
128 4-byte reals


2 4-byte reals
 

1 4-byte real
 
1 4-byte real
2 Motor Block
Variable ISTEP(12)
Type: 4 byte integer
Contents:
  1. Step position of this record
  2. Motor mode; 0=parked, 1=scanning
  3. Number of positions in this scan
  4. Direction of scan; +1=increasing, -1=decreasing, 0=turn position
  5. Maximum position in this scan (1-7)
  6. Minimum position in this scan (0-6)
  7. Next expected position (0-7)
  8. Former position (0-7)
  9. Index of this position (1-NPOS, see 3 above)
12 4-byte integers
3 Magnetic Field Block
Variable: BDATA(64,4):
Contents: Magnetic field measurements in despun payload
coordinates at the times of the 64 sectors
of this spin.
   BDATA(I,1) = Bx, nanotessla, for Ith sector
BDATA(I,2) = By, nanotessla, for Ith sector
BDATA(I,3) = Bz, nanotessla, for Ith sector
BDATA(I,4) = No. of samples, for Ith sector
 
4 R64(4,64) Count Rates for 4 Channels
Units: Counts/second
Type: 4 byte real numbers (DEC)
  1. EO
  2. EI
  3. A0
  4. A1
 
5 R32(16,32) Count Rates for 16 Channels at 32 Sector Positions.
Units: Counts/second
Type: 4 byte real numbers (DEC)
1. A0 Summed
2. A1 Summed
3. A2  
4. A3  
5. A4  
6. A5  
7. A6  
8. A7  
9. E0 Summed
10. E1 Summed
11. E2  
12. E3  
13. F0  
14. F1  
15. F2  
16. F3  
  
6 R16(100,16) Count Rates for 100 Channels at 15 Sector Positions
Units: Counts/second
Type: 4 byte real numbers (DEC)
1. A0 Summed
2. A1 Summed
3. A2 Summed
4. A3 Summed
5. A4 Summed
6. A5 Summed
7. A6 Summed
8. A7 Summed
9. A8  
10. DC0   
11. DC1  
12. DC2  
13. DC3  
14. E0 Summed
15. E1 Summed
16. E2 Summed
17. E3 Summed
18. F0 Summed
19. F1 Summed
20. F2 Summed
21. F3 Summed
22. B0  
23. B1  
24. B2  
25. CP1  
26. CP2  
27. CP3  
28. CA0  
29. CA1  
30. CA2  
31. CA3  
32. CA4  
33. CM0  
34. CM1  
35. CM2  
36. CM3  
37. CM4  
38. CM5  
39. CN0  
40. CN1  
41. CH0  
42. CH1  
43. CH2  
44. CH3   
45. CH4  
46. CH5  
47. CE1  
48. CE2  
49. CE3  
50. CP1P  
51. CP2P  
52. CP3P  
53. CA0P  
54. CA1P  
55. CA2P  
56. CA3P  
57. CA4P  
58. CM0P  
59. CM1P  
60. CM2P  
61. CM3P  
62. CM4P  
63. CM5P  
64. CN0P  
65. CN1P  
66. CH0P  
67. CH1P  
68. CH2P  
69. CH3P  
70. CH4P  
71. CH5P  
72. CE1P  
73. CE2P  
74. CH3P  
75. AS  
76. BS  
77. CS  
78. DS  
79. EB1  
80. EB2  
81. FB1  
82. FB2  
83. JA  
84. JB  
85. JC  
86. KS  
87. LS  
88. JAP  
89. JCP  
90. KP  
91. Spare  
92. Spare  
93. Spare  
94. Spare  
95. Spare  
96. Spare  
97. Spare  
98. Spare  
99. Spare  
100. Spare  
    
7 Data presence/quality flags
Units: None
Type: 2 byte integer
Contents:
  Byte 2: 0000 Data missing (not on EDR)
  0010 Data missing (wrong subcom pos.)
  0100 Data invalid (motor movement)
  0110 Data invalid (exceed max. rate)
  1000 Data invalid (discontinuity)
  1010 Data invalid (spare)
  1100 Data invalid (spare)
  1110 Data invalid (spare)
  0001 Data valid (nominal)
  0011 Data valid (high threshold)
  0101 Data valid (autocal. fault)
  0111 Data valid (spare)
  1001 Data valid (spare)
  1011 Data valid (spare)
  1101 Data valid (spare)
  1111 Data valid (spare)
  Byte 1: Unsigned integer no. of samples in this average.
  N64(4,64) Array of flags for R64(4,64)
  N32(16,32) Array of flags for R32(16,32)
  N16(100,16) Array of flags for R16(100,16)
  

 

 

Next: 4. CMS PHA Block 

 

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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.