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Energetic Neutral Atom Imager

NSSDCA ID: 2006-027A-01

Mission Name: USA 184
Principal Investigator:Dr. David J. McComas


The TWINS neutral atom imager is based on the MENA imager developed for the IMAGE mission.

TWINS combines two sensor heads to provide a field of view of +/-60 degrees, about the rotation direction (10 degrees off-nadir pointing). The instrument uses alternating biased and grounded collimator plates to reject charged particles and set the instantaneous azimuthal field of view. A carbon foil is used to produce secondary electrons for time-of-flight (TOF) measurement, and a position sensitive anode provides angular determination. Gold transmission gratings are used to block ambient ultraviolet light, to which the detectors are sensitive. Velocity analysis (from TOF measurements) combined with pulse-height analysis provides statistical mass determination.

Since the spacecraft is three-axis stabilized, the instrument is located on a rotating actuator platform to provide 360 degrees azimuthal coverage. Expected specifications are: energy range, 1-100 keV; mass identification, H, O; time resolution, 60 s image.

Alternate Names

  • TWINS1/EnergeticNeutralAtomImager

Funding Agency

  • NASA-Science Mission Directorate (United States)


  • Space Physics: Ionospheric Studies
  • Space Physics: Magnetospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Dr. Natalia E. Papitashvili



NameRoleOriginal AffiliationE-mail
Dr. Ruth SkougCo-InvestigatorLos Alamos National Laboratory
Dr. Jerry GoldsteinGeneral ContactSouthwest Research
Dr. David J. McComasPrincipal InvestigatorSouthwest Research
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