Spacecraft Plasma Interactions Network in Europe (SPINE)

Click here to go directly to the database of spacecraft charging events of the Freja satellite.



This database contains information on spacecraft charging events identified during the operation of the Freja satellite. A total of 291 surface charging events have been detected. The Freja spacecraft was a polar orbiting spacecraft with a perigee near 600 km (above south pole area) and an apogee of about 1800 km (above the north polar area).

The data are sorted according to all the parameters displayed. Just select the physical conditions and a list of events will be displayed, select one of the events and which page of data you desire and the corresponding data will be displayed.


For each event the following data is included:


Plots Type 1:

  • Spectrogram of HF emissions (30 kHz - 2 MHz)
  • Langmuir probe current
  • Ion (O+) data
  • High energy (MATE) electron data (available before orbit 1600)
  • Medium energy (TESP) electron data (available after orbit 730)

Plots Type 2:

  • Enlarged ion (O+) data
  • Eclipse/Sunlight conditions 
  • Freja spin axis angle vs geomagnetic field direction 
Sizes of PDF files are about 100-500 Kb. A description of how the charging events have been identified can be found in the work package documentation for WP110 and WP130. They are readable by the free Adobe Acrobat Reader.

Note: After orbit 1600 the MATE data is only available as an integrated flux. Read the work package reports carefully and take contact with the Swedish Institute of Space Physics, Uppsala, before using any of the data presented here. The data interpretation may be heavily dependent on instrumental capabilities and measurement mode types. The reduced statistical database can be downloaded as an ascii file. The data is listed event for event with the following content:

  • orbit no
  • year
  • month
  • day
  • UT [hour, minutes, seconds] (at the peak of charging)
  • Altitude [km]
  • CGLAT [degrees]
  • Longitude [degrees]
  • MLT
  • Peak charging level [V]
  • Event duration [s]
  • Sunlight conditions (Eclipse = 1, Sunlight = 0, Both = 2)
  • Electron density [m^-3]
  • Electron spectral type (TESP = 1, MATE = 2)
  • 16 values of electron spectra [cm^-2 s^-2 str^-1 eV^-1]
  • Freja spin axis angle vs. magnetic field direction [degrees]