HAYABUSA2 HAYABUSA KAGUYA AKATSUKI Curation SAKIGAKE Viking Apollo

ALSEP Word Allocation

The allocations of ALSEP words (10-bit of data) are different among the Apollo stations. The allocations and down-link information are given on this page. The information on EASEP (Apollo 11) word allocation is from "MSC Internal Technical Note, Data Processing Plan for ALSEP and EASAP (MSC-00119, Rev.1, 1969)", and the ALSEP word allocationis from "Apollo Lunar Surface Experiment Package Archive Tape Description Document"(JSC-09652, 1975).

Down-link information

Normal Data RateSlow Data Rate
1060 bits/sec530 bits/sec
10bits/word10bits/word
64words/frame64words/frame
640bits/frame640bits/frame
0.943 ms/bit1.887 ms/bit
9.43 ms/word18.87ms/word
603.77 ms/frame18.87 ms/frame
Data are transmitted MSB first (Bit 1)

(1) Apollo 11

Frame Constitution

1. Data System (CONT)                             5 words  
  A. Control
  B. Command Verification (CV)
  C. House Keeping (HK)
2. Passive Seismic Experiment (PSE)              43 words
  A. Long-period Sensor X-component (LPX)
  B. Long-period Sensor Y-component (LPY)
  C. Long-period Sensor Z-component (LPZ)
  D. Short-period Sensor Z-component (SPZ)
  E. Tidal X-component (TidX)
  F. Tidal Y-component (TidY)
  G. Tidal Z-component (TidZ)
  H. Instrument Temperature (InstT)
3. Unassigned (NA)                                 15 words

1
CONT		2
CONT		3
CONT		 4
SPZ		5
NA		6
SPZ		 7
NA		8
SPZ
9
LPX		10
SPZ		11
LPY		12
SPZ		13
LPZ		 14
SPZ		15
NA		16
SPZ
17
NA		18
SPZ		19
NA		20
SPZ		21
NA		 22
SPZ		23
NA		24
SPZ
25
LPX		26
SPZ		27
LPY		28
SPZ		29
LPZ		 30
SPZ		31
NA		32
SPZ
33
HK		34
SPZ		35
TidX or TidZ		36
SPZ		 37
TidY or InstT		38
SPZ		39
NA		40
SPZ
41
LPX		42
SPZ		43
LPY		44
SPZ		45
LPZ		 46
CV		47
NA		48
SPZ
49
NA		50
SPZ		51
NA		52
SPZ		53
NA		 54
SPZ		55
NA		56
NA
57
LPX		58
SPZ		59
LPY		60
SPZ		61
LPZ		 62
SPZ		63
NA		64
SPZ

TidX and TidY are allocated in Words 35 and 37, respectively, when the frame counter is an even number, and TidZ and InstT are allocated in Words 35 and 37, respectively, when the frame counter is an odd number.

ALSEP Words 1-3

The first 22 -bits of words 1, 2 and 3 contain the main-frame sync code (Barker code). Bits 3 through 9 of ALSEP Word 3 contain the frame count used to identify the parameters output by the 90-channel subcommutator. The frame count counts from 1 to 89 and then resets to 0 upon reaching the 90th channel. Bit -10 of Word 3 is the mode bit, which identifies Bit Rate or ALSEP ID on designated frames according to the frame count.

ALSEP Word1ALSEP Word2 ALSEP Word3
Bit No1234567 8910123456 7891012345 678910
Bit allocation111000 100100001 110110126 25242322 2120
ContentsBarker code Barker code complement Frame Count (1-89, 0)Mode bit

Frame countMode bit Content
11Normal Data Rate
21Slow Data Rate
30 or 1ALSEP ID
011(A11)
010(A12)
110(A14)
011(A15)
001(A16)
100(A17)
40 or 1
5 0 or 1
all other frame 0

Command Verification

Command verification is provided in ALSEP Word 46. Bits 3 through 9 reflect the 7-bit command as received by the ALSEP, and bit 10 is a message acceptance pulse (MAP). The MAP reads out a "1" when an error check has been successful and a command has been acted upon. The Command Verification Word reads zeros except during the one ALSEP main frame following receipt of a command.

Bit No1234567 8910
Content00Command ReceivedMAP:1=GOOD

House Keeping

ALSEP Word 33 is the output of the 90-channel subcommutator. Some of the channels are used by the experiments. The contents of the House Keeping data are different depending on the frame count, and they are listed in reference "Apollo Lunar Surface Experiment Package Archive Tape Description Document"(JSC-09652, 1975)

Bit No1234567 8910
Content00Digital Analog Housekeeping Data

(2)Apollo 12

Frame Constitution

1. Data System (CONT)                             5 words  
  A. Control
  B. Command Verification (CV)
  C. House Keeping (HK)
2. Passive Seismic Experiment (PSE)              43 words
  A. Long-period Sensor X-component (LPX)
  B. Long-period Sensor Y-component (LPY)
  C. Long-period Sensor Z-component (LPZ)
  D. Short-period Sensor Z-component (SPZ)
  E. Tidal X-component (TidX)
  F. Tidal Y-component (TidY)
  G. Tidal Z-component (TidZ)
  H. Instrument Temperature (InstT)
3. Lunar Surface Magnetometer (LSM)              7 words
4. Solar Wind Spectrometer Experiment (SWS)      4 words
5. Suprathermal Ion Detector Experiment (SIDE)   5 words
*LSM data will not appear on any ARCSAV tapes after June 14, 1974.

1
CONT		2
CONT		3
CONT		 4
SPZ		5
LSM		6
SPZ		 7
SWS		8
SPZ
9
LPX		10
SPZ		11
LPY		12
SPZ		13
LPZ		 14
SPZ		15
SIDE		16
SPZ
17
LSM		18
SPZ		19
LSM		20
SPZ		21
LSM		 22
SPZ		23
SWS		24
SPZ
25
LPX		26
SPZ		27
LPY		28
SPZ		29
LPZ		 30
SPZ		31
SIDE		32
SPZ
33
HK		34
SPZ		35
TidX or TidZ		36
SPZ		 37
TidY or InstT		38
SPZ		39
SWS		40
SPZ
41
LPX		42
SPZ		43
LPY		44
SPZ		45
LPZ		 46
CV		47
SIDE		48
SPZ
49
LSM		50
SPZ		51
LSM		52
SPZ		53
LSM		 54
SPZ		55
SWS		56
SIDE
57
LPX		58
SPZ		59
LPY		60
SPZ		61
LPZ		 62
SPZ		63
SIDE		64
SPZ

TidX and TidY are allocated in Words 35 and 37, respectively, when the frame count is an even number, and TidZ and InstT are allocated in Words 35 and 37, respectively when the frame count is an odd number.

The allocation and contents of ALSEP Words 1-3, Command Verification and House Keeping are the same as those of Apollo 11.

(3)Apollo 14

Frame Constitution

1. Data System (CONT)                                       5 words  
  A. Control
  B. Command Verification (CV)
  C. House Keeping (HK)
2. Passive Seismic Experiment (PSE)                       44 words
  A. Long-period Sensor X-component (LPX)
  B. Long-period Sensor Y-component (LPY)
  C. Long-period Sensor Z-component (LPZ)
  D. Short-period Sensor Z-component (SPZ)
  E. Tidal X-component (TidX)
  F. Tidal Y-component (TidY)
  G. Tidal Z-component (TidZ)
  H. Instrument Temperature (InstT)
3. Charged Particle Lunar Environment Experiment (CPLEE)    6 words
4. Suprathermal Ion Detector Experiment (SIDE)              5 words
5. Unassigned                                               4 words
1
CONT		2
CONT		3
CONT		 4
SPZ		5
CV		6
SPZ		 7
CPLEE		8
SPZ
9
LPX		10
SPZ		11
LPY		12
SPZ		13
LPZ		 14
SPZ		15
SIDE		16
SPZ
17
CPLEE		18
SPZ		19
CPLEE		20
SPZ		21
Not Assigned		 22
SPZ		23
CPLEE		24
SPZ
25
LPX		26
SPZ		27
LPY		28
SPZ		29
LPZ		 30
SPZ		31
SIDE		32
SPZ
33
HK		34
SPZ		35
TidX or TidZ		36
SPZ		 37
TidY or InstT		38
SPZ		39
CPLEE		40
SPZ
41
LPX		42
SPZ		43
LPY		44
SPZ		45
LPZ		 46
SPZ		47
SIDE		48
SPZ
49
Not Assigned		50
SPZ		51
Not Assigned		52
SPZ		 53
Not Assigned		54
SPZ		55
CPLEE		56
SIDE
57
LPX		58
SPZ		59
LPY		60
SPZ		61
LPZ		 62
SPZ		63
SIDE		64
SPZ

TidX and TidY are allocated in Words 35 and 37, respectively, when the frame count is an even number, and TidZ and InstT are allocated in Words 35 and 37, respectively, when the frame count is an odd number.

The allocations and contents of ALSEP Words 1-3, and House Keeping are the same as those of Apollo 11. However, Command Verfication is provided in ALSEP Word 5.

(4)Apollo 15

Frame Constitution

1. Data System (CONT)                                       5 words  
  A. Control
  B. Command Verification (CV)
  C. House Keeping (HK)
2. Passive Seismic Experiment (PSE)                       42 words
  A. Long-period Sensor X-component (LPX)
  B. Long-period Sensor Y-component (LPY)
  C. Long-period Sensor Z-component (LPZ)
  D. Short-period Sensor Z-component (SPZ)
  E. Tidal X-component (TidX)
  F. Tidal Y-component (TidY)
  G. Tidal Z-component (TidZ)
  H. Instrument Temperature (InstT)
3. Lunar Surface Magnetometer (LSM)                         7 words
4. Solar Wind Spectrometer Experiment (SWS)                 4 words
5. Suprathermal Ion Detector Experiment (SIDE)              5 words
6. Heat Flow Experiment (HFE)                               1 words
*SWS and LSM data will not appear on any ARCSAV tapes after June 14, 1974.

1
CONT		2
CONT		3
CONT		 4
SPZ		5
LSM		6
SPZ		 7
SWS		8
SPZ
9
LPX		10
SPZ		11
LPY		12
SPZ		13
LPZ		 14
SPZ		15
SIDE		16
SPZ
17
LSM		18
SPZ		19
LSM		20
SPZ		21
LSM		 22
SPZ		23
SWS		24
HFE
25
LPX		26
SPZ		27
LPY		28
SPZ		29
LPZ		 30
SPZ		31
SIDE		32
SPZ
33
HK		34
SPZ		35
TidX or TidZ		36
SPZ		 37
TidY or InstT		38
SPZ		39
SWS		40
SPZ
41
LPX		42
SPZ		43
LPY		44
SPZ		45
LPZ		 46
CV		47
SIDE		48
SPZ
49
LSM		50
SPZ		51
LSM		52
SPZ		 53
LSM		54
SPZ		55
SWS		56
SIDE
57
LPX		58
SPZ		59
LPY		60
SPZ		61
LPZ		 62
SPZ		63
SIDE		64
SPZ

TidX and TidY are allocated in Words 35 and 37, respectively, when the frame count is an even number, and TidZ and InstT are allocated in Words 35 and 37, respectively, when the frame count is an odd number.

The allocation and contents of ALSEP Words 1-3, Command Verification and House Keeping are the same as those of Apollo 11.

(5)Apollo 16

Frame Constitution

1. Data System (CONT)                                       5 words  
  A. Control
  B. Command Verification (CV)
  C. House Keeping (HK)
2. Passive Seismic Experiment (PSE)                        43 words
  A. Long-period Sensor X-component (LPX)
  B. Long-period Sensor Y-component (LPY)
  C. Long-period Sensor Z-component (LPZ)
  D. Short-period Sensor Z-component (SPZ)
  E. Tidal X-component (TidX)
  F. Tidal Y-component (TidY)
  G. Tidal Z-component (TidZ)
  H. Instrument Temperature (InstT)
3. Lunar Surface Magnetometer (LSM)                         7 words
4. Heat Flow Experiment (HFE)                               1 words
5. Unassigned                                               8 words
*HFE data will not appear on any ARCSAV tapes.

1
CONT		2
CONT		3
CONT		 4
SPZ		5
LSM		6
SPZ		 7
Not Assigned		8
SPZ
9
LPX		10
SPZ		11
LPY		12
SPZ		13
LPZ		 14
SPZ		15
Not Assigned		16
SPZ
17
LSM		18
SPZ		19
LSM		20
SPZ		21
LSM		 22
SPZ		23
HFE		24
SPZ
25
LPX		26
SPZ		27
LPY		28
SPZ		29
LPZ		 30
SPZ		31
Not Assigned		32
SPZ
33
HK		34
SPZ		35
TidX or TidZ		36
SPZ		 37
TidY or InstT		38
SPZ		39
Not Assigned		40
SPZ
41
LPX		42
SPZ		43
LPY		44
SPZ		45
LPZ		 46
CV		47
Not Assigned		48
SPZ
49
LSM		50
SPZ		51
LSM		52
SPZ		 53
LSM		54
SPZ		55
Not Assigned		56
Not Assigned
57
LPX		58
SPZ		59
LPY		60
SPZ		61
LPZ		 62
SPZ		63
Not Assigned		64
SPZ

TidX and TidY are allocateds in Words 35 and 37, respectively, when the frame count is an even number, and TidZ and InstT are allocated in Words 35 and 37, respectively, when the frame count is an odd number.

The alloctaion and contents of ALSEP Words 1-3, Command Verification and House Keeping are the same as those of Apollo 11.

(6)Apollo 17

Frame Constitution

1. Data System (CONT)                                       5 words  
  A. Control
  B. Command Verification (CV)
  C. House Keeping (HK)
2. Lunar Ejecta and Meteorite Experiment (LEAM)             2 words
3. Lunar Mass Spectrometer Experiment (LMS)                 4 words
3. Heat Flow Experiment (HFE)                               1 words
4. Lunar Surface Gravimeter Experiment (LSG)                
  A. Seismic data (LSG-Seis)                               31 words
  B. Tidal data (LSG-Tide)                                  1 word
  C. Free Mode data (LSG-Free)                              1 word
  D. Sensor Temperature (LSG-Temp)                          1 word
  E. House Keeing Data (LSG-HK)                             2 words 
5. Unassigned                                             15 words
6. Reserve Power                                            1 word

1
CONT		2
CONT		3
CONT		 4
LSG-Seis		5
LMS		6
LSG-Seis		 7
CV		8
LSG-Seis
9
Not Assigned		10
LSG-Seis		11
Not Assigned		12
LSG-Seis		 13
Not Assigned		14
LSG-Seis		15
Not Assigned		16
LSG-Seis
17
LMS		18
LSG-Seis		19
LMS		20
LSG-Seis		 21
LMS		22
LSG-Seis		23
HFE		24
LSG-Seis
25
LSG-Tide		26
LSG-Seis		27
LSG-Free		28
LSG-Seis		 29
LSG-Temp		30
LSG-Seis		31
LEAM		32
LSG-Seis
33
HK		34
LSG-Seis		35
LSG-HK		36
LSG-Seis		 37
LSG-HK		38
LSG-Seis		39
LEAM		40
LSG-Seis
41
Not Assigned		42
LSG-Seis		43
Not Assigned		44
LSG-Seis		 45
Not Assigned		46
LSG-Seis		47
Not Assigned		48
LSG-Seis
49
Not Assigned		50
LSG-Seis		51
Not Assigned		52
LSG-Seis		 53
Not Assigned		54
LSG-Seis		55
Not Assigned		56
LSG-Seis
57
Not Assigned		58
LSG-Seis		59
Not Assigned		60
LSG-Seis		 61
Not Assigned		62
LSG-Seis		63
Reserve Power		64
LSG-Seis

The allocation and contents of ALSEP Words 1-3, and House Keeping are the same as those of Apollo 11. However, Command Verfication is provided in ALSEP Word 7.

Last Modified: 26 March 2019