| Frequency Range: | 1-30 MHz |
|---|---|
| Antenna: | Crossed dipoles (transmitter) Four short dipoles |
| Transmit Power: | 10 to 200 W |
| Pulse Width: | 30-100 µs (coded) |
| Sweep Speed: | Variable (typical 1 MHz/s) |
| Frame Time: | Variable (typical 30 s) |
| Receiver: | Software-Controlled |
| Receiver Dynamic Range: | 100-120 dB |
| Orbit: | 1500-2000 km |
| Inclination: | 65 degrees (to include HAARP) 45 degrees (for mid-latitude) |
| Data Storage: | On-orbit processing |
Space Weather Systems
Topside Sounder
Monitor of ionospheric data through single point of entry
- Science missions: regional, global monitoring
- Propagation: HF/VHF, anomalous radio, transionospheric
- Scintillation
- Transionospheric communication
- Ionospheric effects and surveillance: seismic activity, explosions, lightning
Flexible, a flying HF/VHF bus
- Receive-only mode: monitor emissions, noise
- Transmit-only mode: jam, communicate
- Communication mode: bent pipe
- Space Radar (SAR imaging) mode: ocean waves, ground conductivity, underground imaging, foliage penetration, ocean surface wind
Ionospheric electron density distributions with height, latitude, longitude, and time under different conditions are essential for scientific, technical, and operational purposes. A satellite-based swept-frequency HF sounder can obtain electron density profiles on a global scale. We have developed an improved HF sounder, using recent developments in technology, electronics, and processing capabilities. This will provide electron density distributions, contours of fixed densities, maps of foF2, and hmax on a global scale. It will let users map irregularities, estimate anomalous propagation, find conditions for ducting, and determine angle of arrivals. It can perform various plasma diagnostics. Users can program the flexible system from the ground up to perform a variety of experiments in the space. Needs for such a system exist throughout the DoD and through several civilian agencies.
Specifications
Benefits
The topside sounder will provide primary measurements of the electron density distributions through most of the ionosphere, throughout the world, and for various solar and geophysical conditions. SAR mode will make possible precise mapping of ionospheric irregularities. This will:
- Provide electron densities and temperatures to validate theoretical models, and contribute to empirical models of the ionosphere.
- Validate the density distributions derived from indirect techniques such as model inversion of satellite EUV measurements, tomographic inversion of total electron content (TEC), or integrated column densities from ground-based observations of satellite beacons.
- Provide inputs for assimilative ionospheric forecast models.
- Improve GPS performance with measured plasmaspheric TEC.
- Map global ionospheric parameters, including electron densities and electron temperatures, hence plasma scale heights, for scientific research, and operational systems.
- Allow monitoring of seismo-ionospheric events such as earthquakes and nuclear explosions.
- Map precise irregularities, tilts and ionospheric anomalies, facilitating the understanding, and prediction of scintillations and of other satellite communication issues.
- Provide superior understanding of anomalous radio propagation through ducting, z-mode, around-the-world propagation, sporadic-E, and scatter propagation.
- Measure various plasma resonances near the spacecraft, measure precise magnetic fields, and diagnose the topside ionosphere’s response to HF modification experiments.
- Provide a HF test-bed in the ionosphere for various sophisticated experiments.
- Test technology for diverse areas of communications, radar, space exploration, and related areas.
System Integration Plan and Engineering Design
Satellite System: Other sensors, payload mass, power requirements, thermal requirements, pointing control and knowledge, on-board data reduction and compression, data storage, telemetry, command handling, interaction among sensors, redundancy, and environmental issues. Much of this will depend on the selection of the appropriate satellite bus, e.g., buses made by Spectrum Astro, OSC, and Ball Aerospace.
Launch System: Launch vehicle, launch site, and certification. This will reflect the payload, satellite bus, and desired orbit. Possibilities include Pegasus and Taurus, but consideration will include others.
Ground Segments: S-band versus X-band telemetry; one versus multiple ground stations; command structure, and control; cross-links; data reduction, visualization, and archiving; and data distribution to end users.
Operational Plan: Agencies, experimental priorities, and experimental plans.
Commercial Applications
Direct observations of ionospheric features are crucial for various operations in communications, navigation, early warning, and radar. These will be invaluable for agencies like the Navy, Air Force, Army, NSA, CIA, DISA, and NOAA. The data will be of immense help to ionospheric scientists, radio and communications engineers, ionospheric modelers, radio amateurs, and the space-weather community. Ionospheric predictions and information will also help GPS users, radio users, satellite users, and electric utilities. Alternatively, the ionospheric data from one such topside sounder and from other sources could assimilate into a new generation of physical models providing global ionospheric predictions. Insurance providers could sell such systems’ data to satellite systems, electric utility providers, space weather analysts, radio communication, and radio users. A network of such topside sounders (six) would provide complete coverage for operational systems.
