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FAST (SMEX 2, Explorer 70)


The FAST (Fast Auroral Snapshot Explorer) was successfully launched on 1996-08-21 into its intended orbit. FAST investigates the plasma physics of auroral phenomena at extremely high time and spatial resolution using the full complement of particle and fields instruments. FAST is the second spacecraft in the Small Explorer (SMEX) program at NASA-GSFC.

In order to capture the auroral phenomena over small time (microseconds) and spatial scales, FAST utilizes high speed data sampling, a large, fast-loading ("burst") memory, and a smart, on-board software to trigger on the appearance of various key phenomena. Using a 1 Gb solid-state memory and a data acquisition rate of 8 Mbs (almost two orders of magnitude faster than previous satellites), FAST produces high-resolution "snapshots" of auroral arcs and other interesting auroral events.

FAST flies in a highly eccentric, near-polar orbit. The orbit processes nominally one degree per day throughout the planned mission duration of one year. Scientific investigations will operate in a campaign mode (about 60 days long) as apogee transitions through the northern auroral zone and in less intense survey mode during the rest of the orbit.

The FAST mission uses a unique, lightweight, orbit-normal spinner spacecraft developed by the SMEX project. The spacecraft has body-mounted solar arrays, and is spin-stabilized, rotating at 12 rpm with the spin axis normal to the orbit plane ("cartwheel").

FAST (Fast Auroral Snapshot Explorer) features four experiments to analyze the changing electric and magnetic fields, and the flow of electrons and ions above the aurora:

  • Electric Field Experiment (Langmuir probes),
  • Magnetic Field Experiment (searchcoil and fluxgate magnetometers),
  • Time-of-Flight Energy Angle Mass Spectrograph (TEAMS),
  • 16 Electrostatic Analyzers [ESA].
Nation: USA
Type / Application: Research
Operator: NASA
Contractors: NASA Goddard Space Flight Center
Equipment: Electric Field Experiment, Magnetic Field Experiment, TEAMS, 16 ESAs
Propulsion: ?
Power: Solar cells, batteries
Lifetime: 1 year
Mass: 191 kg
Orbit: 350 × 4200 km, 83
Satellite COSPAR Date LS Launch Vehicle Remarks
FAST (SMEX 2, Explorer 70) 1996-049A 21.08.1996 Va, L-1011, RW30/12 Pegasus-XL


  • NSSDC Master Catalog: FAST

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