1. Radio Technology in Space Explorations
Ionosphere
Vertical
Echo
Disturbance
Disturbance
Paul Song
University of Massachusetts Lowell

2. Radio Technologies in Space
Space passive radio receptions
Plasma conditions
Source of signals (ionospheric coupling)
Space interferometry (location finding)
Radio sounding (remote sensing)
Ground based: ionosonder
Space borne: radio plasma imager, ionospheric
Ground penetration
Jupiter icy moon
Space high power transmission
Sounding technology
Transceivers, digital processing, antennas

3. VLF to Satellite Propagation Mode
Earth – Ionosphere waveguide
Leakage out of waveguide through the ionosphere
Whistler mode to the IMAGE satellite

4. IMAGE ORBIT
September – October, 2003
VLF

5. Dynamic Spectra Measured from IMAGE/RPI
Passive mode
NLK-Washington
24.8 kHz

6. Observations of NML station, 2001/2002
La Moure, ND, L=3.26, 500 kW

7. Signal amplitude vs. station-footprint
distance
Signal amplitude, dB
10dB/1000km
DHO
Distance, km

8. from ground-based transmitters
VLF power in space
from ground-based transmitters
Peak electric field amplitude:  100 V/m
Assuming whistler wave phase velocity: ~ 0.1 c
Magnetic field amplitude at foot: 2×10-11 T (20 pT)
Poynting Flux: 510-9 W/m2
Total flux: ~ 50 kW out of 500 kW
Ionospheric coupling factor < 10%

9. Structured E contours, Digi field of view, ISR pencil beam

10. Principles of Radio Sounding
Radio waves are reflected at wave cutoffs (n = 0)
In a cold, magnetized plasma
Ionic or ordinary (O-mode): Wave frequency = fp
Extraordinary (X-mode): Wave frequency =
Echo from reflections perpendicular to density contours (at reflection point)
Echo
Refracted rays
n=0
n>0
n<0
Use crossed-dipole antennas
to identify O and X waves

11. Sounding Tools ionospheric ground-based sounding
RCV ARRAY
XMT ANTENNA
DPS 4
RCV ANTENNA

12. Automatic Ionogram Scaling
Electron density profile

13. Ne(h,t) at the Magnetic Equator
Cachimbo 16 October 2002
midnight
noon

14. Interferometric Doppler Imaging
The digisonde, operating in the skymap/drift mode, is designed to measure the drift velocity components on a routine basis. In this mode the ionosonde sounds at one or more fixed frequencies and receives and records the reflected signal from each antenna separately.
This technique depends on the presence of ionospheric structures that are embedded in the background plasma.

15. Digisonde Skymaps

16. Real Time Digisonde F Region Drift

18. IMAGE Spacecraft 20-m dipole along z Launched 25 Mar 2000
500-m dipoles in spin plane
20-m dipole along z
RPI:
<10 W radiated power
3 kHz – 3 MHz
300 Hz bandwidth
Launched 25 Mar 2000

19. RPI
IMAGE Instrument Deck

20. Electronics Unit
RPI on IMAGE

21. Sounding in Magnetosphere

22. Field-Aligned Propagation RPI Plasmagram Fig 2 of GRL paper
(Reinisch et al., GRL, 2002)

23. Plasma Density Along Field line

24. One Pass of IMAGE on June 8, 2001
IMAGE trajectory

25. Two dimensional density distribution for MLT=8.0 on June 8, 2001

26. Plasmasphere Depleting and Refilling
full
depleted
Lppstorm
DST
Storm

27. Before Storm Partial Recovery Storm Peak
Identified plasmasphere, plasma trough, density depletion, aurora/cusp, and polar cap
The densities and the locations of these regions vary in accordance with the different solar wind/IMF conditions, not correlated with the Dst variations

28. Acceleration regions

29. Comparison of the Jupiter moons (Icy surface of Europa)

30. Prometheus: Project Overview
Salient Features
Nuclear fission-powered electric propulsion systems will enable a new era of exploration across the solar system
There will be unprecedented science data return through high power science instruments and advanced communications technology
Science
The Europa mission is the highest priority for a flagship mission in this decade (ref: Academy decadal report)
Search for evidence of global subsurface oceans on Jupiter’s three icy Galilean moons that may harbor organic material

31. Planetary Advanced Radio Sounder (PARS)
Heritage from IMAGE Radio Plasma Imager (RPI)

32. Echogram collected by the University of Kansas coherent chirp-radar operating at peak transmit power of about 100 W from aircraft at 500 m above the Greenland ice surface. Provided by S. P. Gogineni, Univ. of Kansas.

33. TOPAS TOPside Automated Sounder
Ionospheric Topside Sounding
TOPAS TOPside Automated Sounder
TOPAS
Vertical
Echo
Ionosphere
Disturbance
Disturbance Tx

34. TOPAS Topside Automated Sounder
A frequency-versatile space-based Doppler radar system operating in MF – HF - VHF bands
MHz (and higher frequencies for interferometry)
Global measurement of peak ionospheric electron density and peak height.
In-situ density and entire profiles from ~1000 km down to F-layer peak in real time
Real time data analysis using TOPIST software
Direction finding techniques
to locate disturbances in the ionosphere
position detection of radio transmitters
Inter-satellite HF measurements
Accurate distance measurements
Inter-satellite columnar electron content

35. TOPAS : Topside Plasma Radar

36. Topside Sounding
~200 km

37. Dual-Frequency Precision Ranging
Swarm spacecraft configuration
for precision interferometry
W transmissions from each s/c
- Each s/c transmits its own frequency
- Each s/c receives all frequencies
Swarm performs as a multi-antenna
interferometer for precision angle-of-arrival
measurements --High resolution interferometry for detection of radio transmitters

38. Magnetospheric Tomography
A 7-satellite constellation
Each satellite transmits and receives signals
Tomography methods are used to infer the plasma density distribution within the constellation

39. Objective and Approach
Abel and Thorne, 1998
Precipitation lifetime (days)
L-shell
Objective: Mitigate threats to low-earth orbit satellites (LEO) from energetic electrons.
Energy range: 0.5~2.5 MeV
L-range: 1.7~3.5
Approach: pitch-angle scattering by whistler mode waves

40. LORERS Mission

41. DSX Spacecraft

42. Advanced Technology at the Center for Atmospheric Research
RF Technologies
Analog: Front-end design (receivers/transmitters), Low/high power amplifiers, filters, Antenna design
Digital: Up/down-converters, Synthesizers, Pulse code modulation (CCK & PSK), Spectral analysis using FPGA’s and DSP’s, FFTs, Filters, FPGA (Altera Stratix and Actel Radiation hardened)
Mixed: AtoD, DtoA
General: Circuit Board design and layout, Power Supply development, Radiation hardened circuit technology
Computer Hardware Technologies
Computer Systems: Embedded Computers (SPARC and Intel), Embedded microcontrollers (PIC)
Enclosures and Backplanes: VME chassis, CompactPCI chassis, Ruggedized and space flight chassis
Computer Software Technologies
Operating Systems: Windows XP, Linux, Embedded Real time OS (RTEMS and VxWorks)
Languages: C++, Java, Assembler (Intel X86, PIC embedded and DSP)
Development Tools
ModelSim Verilog
Altera development suite (Quartus II)
Gnu software development tools