The Galileo Energetic Particles Detector
Galileo EPD Handbook
Chapter 1. Instrument Summary
Mechanical System Overview (continued)
With the exception of the LM124, the EPD Radiation Analysis in Table 2 has been submitted to JPL. JPL will run a computer simulation to determine what the estimated radiation dose will be for the parts and points of interest (POIs) shown in Table 2.
TABLE 2. EPD RADIATION ANALYSIS
| Subsystem | Part Type |
| Data System | 1802, μP |
| Data System | TCC244, RAM |
| Data System | TCC244, RAM |
| Data System | 1834, ROM |
| Motor Control | 1802, μP |
| Motor Control | TCC244, RAM |
| PHA | AD571, A-D Converter |
| PHA | 1834, ROM |
| CMS Electronics | Log Amplifier |
| CMS Electronics | Discrim |
| LEMMS I | Discrim (2N3251) |
| LEMMS I | Discrim (2N3251) |
| LEMMS II | Discrim (2N3251) |
| LEMMS II | Discrim (2N3251) |
| LEMMS II | Discrim (2N3251) |
| LEMMS III | Discrim (2N3251) |
| LEMMS III | Discrim (2N3251) |
| CMS Rate Logic | Accumulator |
| CMS Rate Logic | Accumulator |
| LEMMS Rate Logic | Accumulator |
| LEMMS Rate Logic | Accumulator |
| Bus Adapter | Accumulator |
| ATC 1 | 2N2219 |
| ATC 2 | 2N2219 |
| ATC 3 | 2N2219 |
| ATC 4 | 2N2219 |
| LEMMS Telescope | POI |
| LEMMS Telescope | POI |
| CMS Electronics (TOF) | POI |
| CMS Electronics (Filter) | POI |
| Axis of Rotation | POI |
| ATC 1-4 | LM124 |
The preliminary radiation analysis for the experiment is shown in Table 3. This analysis was completed ten months ago. The dosages shown were calculated by a computer simulation. Some of the device locations have since changed.
TABLE 3. PRELIMINARY RADIATION ANALYSIS
| Detector Point | Part, Location | DOSE (k Rad) |
| 1 | 1802, Data System | 77.2 |
| 2 | RAM and ROM, Data System | 75.8 |
| 3 | Misc., Data System | 106 |
| 4 | Misc., Data System | 81.6 |
| 5 | 1802, Motor Control | 73.5 |
| 6 | TCC244, Motor Control | 94.2 |
| 7 | AD571, PHA | 54.9 |
| 8 | 1834, PHA | 38.1 |
| 9 | Log Amp, CMS Analog | 85.3 |
| 10 | Discrim., CMS Analog | 87.6 |
| 11 | Misc., Rotating Section | 114 |
| 12 | Misc., Rotating Section | 72.1 |
Table 4 shows a summary of the radiation dosages that some of the parts in the instrument are capable of withstanding. If the dosage levels for the parts are exceeded in the JPL simulation, spot shielding will be installed.
TABLE 4. PARTS CAPABILITY SUMMARY
| CD4000 Series | 400 K rad |
| CDP1802 | 200 K rad |
| CDP1834 | 200 K rad |
| CDP1852 | 200 K rad |
| TCC244K | 200 K rad |
| APL Discriminator | TBD |
| MPAe Discriminator | TBD |
| Accumulator | 300 K rad |
| Log Amplifier | TBD |
| 2N2219 | TBD |
| AD571 | 75 K rad |
| LM124 | TBD |
Dr. Studemann commented that the hybrids and the transistors in the voltage switching portion of the electronics are being tested. At least five of each type of part are being tested. Ted Mueller commented that only the discriminators for the LEMMS electronics have been investigated by JPL.
Our estimate of the EPD masses is shown in Table 5. The estimate shows the change in mass between the present estimate and the previous estimate. This is a summary of previously published numbers, rather than a comprehensive review of the instrument itself. The latest estimate shows an increase of 94 grams. The latest calculations for the protective cover show that it is heavier than expected, and the pottings and coatings increased in weight because of a different coating technique.
TABLE 5. EPD MASS ESTIMATE
| Subsystem | Present Estimate |
Previous Estimate |
Delta |
| LEMMS Telescope Assembly Telescope with MMP Preamps and Housing Thermal Control |
894a,150c 25e |
754a,157c,30c 44a,100e 25e |
-41 |
| CMS Telescope Assembly Telescope with MMP Thermal Control |
310a,14c 20e |
290a,29e 20e |
+5 |
| CMS Electronics Assembly TOF Analog Filters Shield Housing |
370c 177c 20c 233c |
370c 177c 20c 233c |
|
| Telescope Support | 50c | 50c | |
| Motor Assembly Motor Polytwist Encoder |
757a 250c 12a,55c |
757a 250c 70c |
-3 |
| Motherboard Assembly | 267c | 267c | |
| CMS Analog Electronics | 65a,152c | 65a,143c | +9 |
| CMS Rate Logic | 116a,61c | 116a,61c | |
| LEMMS I | 147c | 167e | -20 |
| LEMMS II | 158a | 173e | -15 |
| LEMMS III | 149e | 172e | -23 |
| LEMMS Rate Logic | 103a,61c | 103a,61c | |
| Motor Driver | 550a | 550a | |
| Motor Control | 133c,18c | 113a,18c | |
| Pulse Height Analyzer | 148c | 148c | |
| Data System | 360c | 360c | |
| Bus Adapter | 133c | 133c | |
| Calibrator/Housekeeping | 125c | 125c | |
| Power Supply | 348a | 348a | |
| Protective Cover and Actuators | 270c | 150e | +120 |
| Thermal Blanket | 232c | 230c | +2 |
| Potting and Coatings | 152c,48e | 130e | +70 |
| Frame | 691c | 691c | |
| Cover | 612c | 600c | +12 |
| Passive Shield | 60c | 60c | |
| P.C. Mounting Bolts | 68c | 65c | +3 |
| Hardware | 30e | 30e | |
| TOTAL | 8594 | 8475 | +119 |
| Liens | Counterbalance 65c AD571 rad shield 33c |
||
| TOTAL Including Liens: | 8687 grams | ||
| MASS | PERCENT | GRAMS |
| Actual | 43.1 | 3742 |
| Calculated | 55.6 | 4827 |
| Estimated | 1.3 | 123 |
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Updated 8/23/19, Cameron Crane
QUICK FACTS
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.