C/NOFS (P00-3)

C/NOFS [AFRL]

The C/NOFS (Communications / Navigation Outage Forecasting System) mission is to forecast and specify ionospheric scintillations in the Earth's equatorial region.

Scintillations are random fluctuations in signal phase and amplitude that develop when radio waves pass through ionospheric electron density irregularities. Irregularities randomly scatter the incident signals, causing interference patterns to form as the waves propagate away from the ionosphere and thereby generate scintillations. Scintillations degrade the performance of communication, navigation, and surveillance systems that rely on trans-ionospheric radio wave propagation. With scintillation forecasts, the warfighter can modify mission plans and prevent potential mission failures by optimizing and tailoring communications routes, paths, and/or priorities and effectively use satellite communication, navigation, and surveillance assets.

The primary objective of C/NOFS is to develop the capability to forecast the onset of equatorial ionospheric irregularities causing scintillations. The C/NOFS payload will investigate the onset of equatorial spread F (ESF) through various in situ and remote sensing techniques from a satellite platform and from the ground.

The six instruments that comprise the C/NOFS payload (described below) are classified into four groups, depending on the measurements that they perform: 

• Ions and Electric Fields
  • Planar Langmuir Probe (PLP) - in situ measurements of plasma density and density fluctuations.
  • Vector Electric Field Instrument (VEFI) - in situ measurements of a) vector AC and DC electric fields related to plasma drift and irregularity development and b) vector magnetic fields related to plasma irregularities.
  • Ion Velocity Meter (IVM) - in situ measurements of plasma drift velocities, DC electric fields and ion temperature. Optimized for operations at high ion densities.
• Neutral Winds
  • Neutral Wind Meter (NWM) - in situ measurements of large spatial scale (15-30 km), low altitude (<600 km), background neutral winds in zonal, meridional and vertical directions and neutral wind composition. Also in situ measurement of small spatial scale (1 km), low altitude neutral wind vector in meridional and vertical directions.
• Electron Density Profile
  • C/NOFS Occultation Receiver for Ionospheric Sensing and Specification (CORISS) - this instrument was formerly known as the Ionospheric Occultation Experiment (IOX) - remote sensing of the electron density vertical profile at various bearings relative to track (where rising and setting GPS satellites are visible).
• Ionospheric Scintillations
  • Coherent Electromagnetic Radio Tomography (CERTO) - radio beacons that permit direct measurement of ionospheric scintillation parameters at several frequencies by ground receivers. Used for scintillation measurements in the region between the C/NOFS satellite and the Earth.

Both the Neutral Wind Meter (NWM) and the Ion Velocity Meter (IVM) are provided by NASA as the CINDI (Coupled Ion-Neutral Dynamics Investigation) payload, which was selected as an Explorer Mission of Opportunity.

Mission duration is one year design life with a three year goal. Reentry occured on 28 November 2015.