Results from the Mars Express Active Ionospheric Sounder

1. Results from the Mars Express Active Ionospheric Sounder D. D. Morgan1, D. A. Gurnett1, D. L. Kirchner1, F. Duru1, R. L. Huff1, D. A. Brain2, W. V. Boynton3, M. H. Acuña4, E. Nielsen5, A. Safaeinili6, J. J. Plaut6, G. Picardi7 1Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 2Space Physics Research Group, Space Sciences Laboratory, University of California, Berkeley, California 3Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 4NASA Goddard Space Flight Center, Greenbelt, Maryland 5Max-Planck-Inst. For Solar System Research, Katlenburg-Lindau, Germany 6Jet Propulsion Laboratory, Pasadena, California 7Infocom Department, “La Sapienza,” University of Rome, Rome, Italy

2. Mars Express Dec. 25, 2003 P-03-14 Dipole Antenna: 2 x 20 m

3. Mars Express Orbit

4. Nominal Mars Express Orbital Parameters at Insertion • Orbital Inclination: 86.3° • Apocenter: 11,560 km (altitude) • Pericenter: 258 km (altitude) • Orbital period: 7.5 h • Observing time about periapsis: ~1h

5. Mars Express Radar Transmitter

6. Mars Express Spacecraft

7. Summary of Active Ionospheric Sounder sequence • 160 frequencies sampled between 0.1 and 5.4 MHz (receive frequencies can be varied). • 1 pulse every 7.857 ms, bandwidth = 10 kHz • 80 receive times per frequency , 91.4 μs/sample • Complete cycle every 7.543 s (data rate limited).

8. Timing of AIS data

9. Radar Reflections from the Ionosphere

10. Ionogram inversion • Time delay equation:

11. Example Ionogram

12. Topics of Interest • Maximum electron density and total electron content • Detection of magnetic fields • Double and complex traces and oblique echoes • Surface reflection and ionospheric absorption • Ionogram inversion • Spacecraft local electron density • Total electron content

13. Maximum electron density and total electron content

14. Maximum Electron Density Versus Solar Zenith Angle From Gurnett et al.,2005

15. Safaeinili et al. LPSC, 2006

16. Spacecraft-local electron density

17. Inbound Electron Density Orbit 2018

18. Inbound Electron Density Orbit 2032

19. Inbound Electron Density Orbit 1994

20. Log10 ne

21. Ionogram inversion • Time delay equation:

22. Radar Reflections from the Ionosphere

24. Corrected altitude Apparent altitude

34. Detection of magnetic fields

36. Electron Cyclotron Echoes

37. Comparison of the Measured and Model Magnetic Field Strength

38. Electron Cyclotron Echoes, Video/Audio

39. Double and Complex Ionospheric Traces

40. Oblique Echoes

42. Comparison of Oblique Echoes to Crustal Magnetic Fields

43. Oblique Echoes and Crustal Magnetic Fields

44. Best Fit Range to a Fixed Target

46. Surface reflection and ionospheric absorption

47. Surface reflection visibility statistic • V = 0 for “not visible” or 1 for “visible”, tabulated for each ionogram. • We select ionograms at 850 km ± 10 km altitude (10 ionograms) and average v.

48. Comparison with other data sets • Averaged surface reflection visibility. • Background of Mars Global Surveyor Electron Reflectometer (>10 MeV) with two hour smoothing to remove orbit signature. • Background of Mars Odyssey Gamma Ray Spectrometer (> 10 MeV). • GOES-12 Solar Environment Monitor soft x-ray flux (Earth). • NOAA daily X and M class flare counts.

49. Overview of data

50. Table 1: Absorption Events Event # Start End ΔT, days 1 20050710-09:31 20050725-08:33 15.0 2 20050801-06:33 20050808-14:06 7.3 3 20050823-03:10 20050827-07:51 4.2 4 20050901-02:23 20050904-11:12 3.4 5 20050905-13:53 20050923-18:16 18.2 ?