The SWING (Space Weather Ionosphere Nanosat Generation) mission is a nanosatellite-based demonstration mission developed within ESA's Distributed Space Weather Sensors System (D3S) programme and currently planned for launch in the late 2027 – early 2028 timeframe (TBC).

SWING is ESA's first dedicated Space Weather mission, providing measurement data for space weather services.

The spacecraft will operate in a near Sun-synchronous low Earth orbit at altitudes of approximately 500-600 km, enabling continuous observations of the ionosphere and the near-Earth radiation environment.

The mission combines measurements of energetic particles, ionospheric plasma, solar X-ray flux and GNSS radio-occultation observations to monitor the effects of space weather on the ionosphere which can affect navigation, timing and communication services.

Payloads Suite an Data Products

The mission is carrying the following four complementary instruments:

• DREAM (CNES-STEEL): Radiation monitor for energetic electron and proton measurements.
• mNLP (Eidel): Langmuir probes providing measurements of local electron density, electron temperature and spacecraft potential.
• XFM-NS (Isaware): X-ray sensor for solar X-ray flux measurements.
• Aquila (Syntony): GNSS radio-occultation receiver providing ionospheric sounding and scintillation observations.

DREAM

DREAM (Détecteur Radiation Energétique Adaptable et Miniaturisé) is a compact radiation monitor based on silicon diode detectors and designed to measure energetic charged particles in low Earth orbit. The instrument measures protons from 13 MeV to >190 MeV and electrons from 350 keV to 3 MeV.

DREAM consists of two detector heads. Sensor A is optimised for proton measurements and incorporates two silicon diodes behind aluminium shielding, while Sensor B is optimised for electron measurements and uses a silicon diode protected by tungsten and aluminium shielding.

The instrument records particle counts and energy spectra in 256 channels. Ground processing converts these measurements into calibrated proton and electron flux products suitable for radiation environment monitoring and analysis.

The nominal measurement cadence is 8 seconds, with configurable acquisition periods between 8 and 256 seconds.

Expected data products include:

• Proton fluxes (per energy channel)
• Electron fluxes (per energy channel)

m-NLP

The m-NLP (multi-Needle Langmuir Probe) is an in-situ plasma diagnostic instrument designed to measure ionospheric electron density, electron temperature and spacecraft potential at high temporal resolution.

The instrument consists of a compact electronics unit connected to two deployable boom assemblies carrying four cylindrical Langmuir probes. During nominal operations, three probes operate at fixed bias voltages to provide continuous electron density measurements, while the fourth probe performs voltage sweeps to derive electron temperature and spacecraft potential. The four-probe configuration provides redundancy and improves measurement availability under varying spacecraft orientations.

The instrument provides measurements of ionospheric electron density over the range relevant to the SWING mission, approximately 10⁹ to 10¹² m⁻³, together with spacecraft potential measurements in the range from -7.5 V to +7.5 V.

In nominal operating mode, electron density measurements are provided at a cadence of approximately 47 Hz, while electron temperature is derived from sweep measurements acquired every 10 second.

In addition to the primary plasma measurements, m-NLP data can be processed to derive the local power spectrum of electron-density fluctuations and an estimate of the S4 scintillation index. These products provide information on ionospheric irregularities that may affect GNSS navigation signals and radio-wave propagation.

Expected data products include:

• Electron density
• Electron temperature
• Spacecraft potential
• Ionosphere scintillation S4 parameter

XFM-NS

The XFM-NS (X-ray Flux Monitor for Nanosatellites) is a solar X-ray spectrometer designed to monitor solar X-ray emission associated with solar activity and solar flares. The instrument measures solar X-ray photons over the nominal energy range from 0 to 30 keV.

The instrument is based on a silicon drift detector (SDD) coupled with front-end processing electronics and a thermally stabilised detector assembly. Incoming X-ray photons are detected through photoelectric absorption in the silicon detector and analysed to determine their energy. The detector is actively temperature controlled to maintain stable spectral performance throughout the mission.

For SWING, the wide field of view of ±18.25° ensures the solar observations can be performed for a good part of the orbit while maintaining negligible contamination from near-Earth X-ray background sources.

Science data are provided in two complementary formats. Spectral products consist of full X-ray spectra distributed over 512 energy channels, with the highest channel recording all events above 30 keV.

In addition, XFM-NS produces solar X-ray flux products in six configurable energy bands derived from the measured spectra. These products support operational monitoring of solar activity and solar flare evolution.

The nominal cadence of the spectral products is 60 seconds, while flux products are generated with a baseline cadence of 1 second. Both cadences can be adjusted during mission operations.

Expected data products include:

• Solar X-ray spectra
• Solar X-ray fluxes in six energy channels

Aquila GNSS Radio-Occultation Receiver

Aquila is a dual-frequency GNSS radio-occultation (GNSS-RO) receiver designed to monitor the ionosphere using signals transmitted by the Galileo and GPS navigation satellite constellations. The instrument tracks both setting and rising occultation events, allowing observations of GNSS signals as they propagate through ionospheric plasma layers and undergo refraction. The receiver supports GPS L1/L5 and Galileo E1/E5 signals and operates using dedicated radio-occultation tracking channels.

The instrument is equipped with two antennas and supports simultaneous tracking of multiple occultation events. Aquila provides eight dedicated radio-occultation channels, enabling the simultaneous tracking of up to four occulted GNSS satellites. Occultation events are predicted and detected autonomously on board, allowing automated acquisition and tracking of suitable observations.

The acquired observations enable the derivation of Slant Total Electron Content (STEC), Doppler excess, carrier-phase measurements and ionospheric scintillation parameters derived from variations in GNSS signal amplitude and phase. Ground processing of these measurements provides information on electron-content variations and ionospheric disturbances along the signal propagation path.

For each occultation event, the instrument records raw GNSS observables at a rate of 50 Hz including carrier-to-noise ratio (C/N₀), pseudo-range, carrier-phase and Doppler measurements. In addition, correlation-function samples from the tracked occultation signal are generated together with equivalent measurements from reference non-occulted GNSS satellites. These observations constitute the primary data products used for radio-occultation processing.

Expected data products include:

• Slant Total Electron Content (STEC) profiles
• Doppler-excess and excess-phase measurements
• S4 and Sigma-phi (Sφ) scintillation parameters
• Fading depth
• Fade duration
• Time between fades

Data Access and Formats

SWING measurements and derived data products will be made available through the ESA Space Weather Portal HAPI service. Time-series datasets can be retrieved in csv or JSON format together with associated metadata files. For XFM-NS, calibrated spectral products are provided in FITS format.