| definition |
- [Text from the NASA THEMIS home page, http://www.nasa.gov/mission_pages/themis/spacecraft/ESA.html ]
The Electrostatic Analyzers (ESAs) (on THEMIS) measure how many electrons and ions they detect with a specified energy from a certain direction at a given time (the particle distribution function) over the energy range from ~3 eV to 30 keV. These thermal electrons and ions are the particles responsible for creating the aurora. The ESA measurements allow scientists to derive the density, velocity, and temperature of the ambient electrons and ions (plasma). Knowing these quantities at the five THEMIS probes will allow scientists for the first time to determine the time of substorm onset.
More Information:
http://www.nasa.gov/mission_pages/themis/spacecraft/ESA.html
Group: Instrument_Details
Entry_ID: THEMIS-ESA
Group: Instrument_Identification
Instrument_Category: Solar/Space Observing Instruments
Instrument_Class: Magnetic Field/Electric Field Instruments
Short_Name: ESA-THEMIS
End_Group
Group: Associated_Platforms
Short_Name: THEMIS
End_Group
Online_Resource: http://www.nasa.gov/mission_pages/themis/spacecraft/ESA.html
Online_Resource: http://themis.ssl.berkeley.edu/instrument_esa.shtml
Sample_Image: http://www.nasa.gov/images/content/164126main_idpu_med2.jpg
Creation_Date: 2008-08-12
Group: Instrument_Logistics
Instrument_Owner: NASA
End_Group
End_Group
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