The Space Environment In-Situ Suite is comprised of four sensors that monitor proton, electron, and heavy ion fluxes in the magnetosphere. The information provided by SEISS is critical for assessing the electrostatic discharge (ESD) risk and radiation hazard to astronauts and satellites. In addition to hazard assessment, the information from SEISS can be used to warn of high flux events, mitigating any damage to radio communication.
The first data plot from SEISS. Credit: NOAA
The SEISS instrument suite consists of: the Energetic Heavy Ion Sensor (EHIS), the Magnetospheric Particle Sensors - High and Low (MPS-HI and MPS-LO), and the Solar and Galactic Proton Sensor (SGPS). The instrument suite also includes the Data Processing Unit (DPU). Data from SEISS drive solar radiation storm portion of NOAA space weather scales and other alerts and warnings and improve energetic particle forecasts.
SEISS Sensors
EHIS Sensor
The EHIS measures heavy ion fluxes in the magnetosphere to provide a complete picture of the energetic particles surrounding Earth. This includes particles trapped within Earth’s magnetosphere and particles arriving directly from the sun and cosmic rays which have been accelerated by electromagnetic fields in space. This information is used to help scientists protect astronauts and high altitude aircraft from high levels of harmful ionizing radiation.
| Parameter | Reference | Requirement | EHIS Design Concept |
|---|---|---|---|
| Particle energy range | PORD156 | 10 MeV/nucleon to 200 MeV/nucleon | 10 MeV/nucleon to 200 MeV/nucleon |
| Particle energy bands | PORD158 | 5 logarithmically spaced | 5 logarithmically spaced |
| Particle mass bands | PORD157; Appendix I | H through Ni, individually | H through Ni, individually |
| Particle flux range (cm2 s sr MeV/nuc)-1 | PORD167 | Maximum: 5.0 x 104(E/nuc)-2.3 Minimum: 5.5 x 10-2 (E/nuc)-1.0 | Maximum: 5.0 x 104(E/nuc)-2.3 Minimum: 5.5 x 10-2 (E/nuc)-1.0 |
| Maximum flux sensitivity | PORD169 | No rollover through x3 max | No rollover through x3 max |
| Minimum flux sensitivity | PORD168 | 10 counts above background in each band (mass and energy) in a 5-minute period | 10 counts above background in each band (mass and energy) in a 5-minute period |
| Flux measurement accuracy | PORD160 | 25% via ground calibration | 25% via ground calibration |
| Out-of-band response | PORD97 | <10% after ground processing | <10% after ground processing |
| Viewing Direction | PORD162 | -Z (anti-Earthward) | -Z (anti-Earthward) |
| Sensor FOV | PORD162 | <=30 deg cone half angle | 28 deg cone half angle |
| Data refresh rate | PORD164 | 5 minutes | 5 minutes |
| Data latency | PORD165 | <5 sec | <5 sec EHIS + DPU |
| Noise | PORD86 | <10% thresholds >100 kEV | <10% thresholds >100 kEV |
| Energy band stability | PORD88 | < +/- 3% | < +/- 3% |
| Size | UIID47 | 15,080 cm3 EHIS CBE | |
| Maximum Dimension | UIID48 | <=40 cm | 35.4 cm (chassis) |
| Power | UIID36 | 6.3 W EHIS CBE | |
| Mass | UIID44 | 4.5 kg EHIS CBE | |
| Data rate | UIID27 | 512 bps EHIS CBE | |
| EHIS Modes | PORD52 PORD59 PORD61 PORD90 | Safe Mode Normal Mode Diagnostic Mode In Flight Calibration | Safe Mode Normal Mode Diagnostic Mode In Flight Calibration |
MPS-LO Sensor
The MPS-LO sensor measures electron and proton flux over an energy range of 30ev to 30kev. MPS-LO is able to tell scientists the amount of charging by low energy electrons that a GOES-R Series spacecraft is undergoing. Spacecraft charging can cause ESD and arcing between two differently charged parts of the spacecraft. This discharge arc can cause serious and permanent damage to the hardware on board a spacecraft, which affects operation, navigation and interferes with measurements being taken.
| Parameter | PORD Requirement | Heritage | Requirement | MPS-LO Concept Design |
|---|---|---|---|---|
| Particle Energy Range | 551,562 | 30 eV to 30 keV | 30 eV to 30 keV | 30 eV to 30 keV |
| Electron Flux Range (cm2-s-ster-keV)-1 | 115 | 1x104 E-1.3 to 0.75x109 E-1.3 | 9x104 E-1.3 to 8x108 E -0.8 | 0.1 x (9x104 E-1.3) to 1 x (8x108 E-0.8) |
| Ion Flux Range (cm2-s-ster-keV)-1 | 116 | 60 x (40 E-0.8) to >1.1x107 E-0.8 | 4.0 x 103 E-0.8 to 1.1x107 E-0.8 | 1 x (4x103 E-0.8) to 25 x (1.1x107 E-0.8) |
| Energy Bands | 559 | 19 | 15 | 15 |
| Flux Accuracy | 104 | 20% | 25% | 25% |
| YZ Viewing Angles | 565 | 0° to 90° | 0° to 170° | 0° to 180° |
| YZ Angular Channels | 564 | 6 | 5 | 12 (+2 Overlap) |
| XZ FOV (FWHM) | 564, UIID51 | 4° Symmetric | < 30° | 5° Symmetric |
| Data Refresh Rate | 110 | 1 sec | 30 sec | 1 sec |
| Data Latency | 111 | N/A | < 5 sec | < 5 sec |
| Energy Band Width | 84 | 4% of band's central energy | < 10% | 7% |
| Energy Band Stability | 586 | <+3% | <+3% | <+3% |
| Parameter | Reference | Requirement | MPS-LO Concept Design |
|---|---|---|---|
| Size | UIID47 | 12,384 cm3 MPS-LO CBE | |
| Maximum Dimension | UIID48 | <=40 cm | 31 cm (chassis) 31.6 cm (envelope w/MLI-CBE) |
| Power | UIID36 | 5.5 W MPS-LO CBE | |
| Mass | UIID44 | 7.7 kg MPS-LO CBE | |
| Data rate | UIID27 | 11 kbps MPS-LO CBE | |
| MPS-LO Modes | PORD52 PORD59 PORD61 PORD90 | Safe Mode Normal Mod Diagnostic Mode In Flight Calibration | Safe Mode Normal Mod Diagnostic Mode In Flight Calibration Standby Mode |
MPS-HI Sensor
The MPS-HI sensor monitors medium and high energy protons and electrons which can shorten the life of a satellite. High energy electrons are extremely damaging to spacecraft because they can penetrate and pass through objects which can cause dielectric breakdowns and result in discharge damage inside of equipment.
| Parameter | Reference | Requirement | MPS-HI Design Concept |
|---|---|---|---|
| Electron energy range | PORD558 | 50 keV to 4 MeV 10 log bins; >2MeV integral | 50 keV to 4 MeV 10 log bins; >2MeV integral |
| Proton energy range | PORD558 AppendixI-4 | 80 keV to 10 MeV 7 log bins | 80 keV to 12 MeV 11 log bins |
| Electron flux (cm2 s sr keV)-1 | PORD115 | Minimum: 1.9x106 E-2.2 Maximum: 7.2x1011 E-2.8 | Minimum: 1.9x106 E-2.2 Maximum: 7.2x1011 E-2.8 |
| Proton flux (cm2 s sr keV)-1 | PORD116 | Minimum: 6.6x105 E-2.3 Maximum: 1.7x108 E-1.6 | Minimum: 6.6x105 E-2.3 Maximum: 1.7x108 E-1.6 |
| Flux measurement accuracy | PORD104 | 25% | 25% |
| YZ viewing angles | PORD564 PORD565 | 170 deg in YZ plane Centered on +Z or -Z | 170 deg in YZ Centered on +Z or -Z |
| Angular bins | PORD565 | 5 bins; <=45 deg apart | 5 bins; 35 deg apart |
| XZ sensor FOV | PORD564 | <=15 deg cone half angle | 5 deg cone half angle |
| Data refresh rate | PORD110 | 30 sec | <30 sec; 1 sec goal |
| Data latency | PORD111 | <5 sec | <5 sec MPS-HI + DPU |
| Noise | PORD85,86 | <10keV 30 keV to 100 keV <10% thresholds >100 kEV | <10keV 50 keV to 100 keV <10% thresholds >100 kEV |
| Energy band stability | PORD88 | < +/- 3% | < +/- 3% |
| Size | UIID47 | 22,500 cm3 MPS-HI CBE | |
| Maximum Dimension | UIID48 | <=40 cm | 34 cm (chassis) 34.6 cm (envelope w/ MLI-CBE) |
| Power | UIID36 | 12.6W MPS-HI CBE | |
| Mass | UIID44 | 13.0 kg MPS-HI CBE | |
| Data rate | UIID27 | 12 kbps MPS-HI CBE | |
| Dosimeters | Appendix I | 2 to 4 dosimeters | 2 dosimeters behind 100 mil and 200 mil shields |
| MPS-HI Modes | PORD52 PORD59 PORD61 PORD90 | Safe Mode Normal Mode Diagnostic Mode In Flight Calibration | Safe Mode Normal Mode Diagnostic Mode In Flight Calibration |
SGPS Sensor
The SGPS measures the solar and galactic protons found in the Earth's magnetosphere. The data provided by SGPS assists the Space Weather Prediction Center's Solar Radiation Storm Warnings. These particular measurements are crucial to the health of astronauts on space missions, though passengers on certain airline routes may experience increased radiation exposure as well. In addition, these protons can cause blackouts of radio communication near the Earth's poles and can disrupt commercial air transportation flying polar routes. The warning system allows airlines to reroute planes that would normally fly over Earth’s poles.
| Parameter | Current SGPS Specification | PORD Requirement |
|---|---|---|
| Proton Energy Range | 1 MeV to 500 MeV in 10 log bins plus >500 MeV Integral | 151, 139 |
| Flux Range (cm2-s-ster-keV)-1 (Min) | 8x102 E-1.8 / >500 MeV = 4x102 | 151 |
| Flux Range (cm2-s-ster-keV)-1 (Max) | 5.4x109 E-2.1 / >500 MeV = 2x103 | 151 |
| Differential Direct Energy Flux Accuracy | 25% | 144 |
| Sensor Heads | 2 Identical viewing in +X and -X | 146 |
| XY Sensor FOV | <=90° Symmetric | 146 |
| XZ Sensor FOV | <=90° Symmetric | 146 |
| Data Refresh Rate | 1 minute (goal 1 second) | 148 |
| Noise | < 10 keV for bands with threshold energy between 30 keV and 100 keV, <10% of band’s threshold energy at >100 keV | 85, 86 |
| Energy Band Stability | <+3% | 88 |
| Size | 26.6 cm, 26.6 cm, 12.6 cm CBE | |
| Mass | 4.9 kg CBE | |
| Power | 5.1 W CBE |
