Unintended electromagnetic radiation from Starlink satellites detected with LOFAR between 110 and 188 MHz

Abstract

We report on observations of 68 satellites belonging to the SpaceX Starlink constellation with the LOFAR radio telescope. Radiation associated with Starlink satellites was detected at observing frequencies between 110 and 188 MHz. A combination of broad-band features, covering the entire observed bandwidth, as well as narrow-band (bandwidth < 12.2 kHz) emission at frequencies of 125, 135, 143.05, 150, and 175 MHz, was observed. The presence and properties of both the narrow- and broad-band features vary between satellites at different orbital altitudes. While the narrow-band detections at 143.05 MHz can be attributed to reflections of radar signals from the French GRAVES Space Surveillance Radar, the signal properties of the broad- and narrow-band features at the other frequencies suggest that this radiation is intrinsic to the Starlink satellites and it is seen for 47 out of the 68 Starlink satellites that were observed. We observed spectral power flux densities vary from 0.1 to 10 Jy for broad-band radiation, to 10 to 500 Jy for some of the narrow-band radiation, equivalent to electric field strengths of up to 49 dB[uV/m] (as measured at a 10 m distance from the satellites, with a measurement bandwidth of 120 kHz). In addition, we present equivalent power flux density simulations of the full Starlink phase 1 constellation, as well as other satellite constellations, for one frequency band allocated to radio astronomy by the International Telecommunication Union (ITU). With these, we calculate the maximum radiation level that each satellite constellation would need to have to comply with regulatory limits for intended emissions in that band. However, these limits do not apply if the radiation is unintended, that is to say if it does not originate from intentionally radiated signals for radio communication or other purposes. (shortened)

20 pages, 14 figures, in press

References in corpus (7)

• The NumPy array: a structure for efficient numerical computation
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• The Low Earth Orbit Satellite Population and Impacts of the SpaceX Starlink Constellation
• Science With The Australian Square Kilometre Array Pathfinder
• The LOFAR radio environment
• Visibility Predictions for Near-Future Satellite Megaconstellations: Latitudes near 50 Degrees will Experience the Worst Light Pollution
• Aggregate Effects of Proliferating LEO Objects and Implications for Astronomical Data Lost in the Noise

Cited by in corpus (17)

• Detection of intended and unintended emissions from Starlink satellites in the SKA-Low frequency range, at the SKA-Low site, with an SKA-Low station analog
• Transient RFI environment of LOFAR-LBA at 72-75 MHz: Impact on ultra-widefield AARTFAAC Cosmic Explorer observations of the redshifted 21-cm signal
• The Growing Impact of Unintended Starlink Broadband Emission on Radio Astronomy in the SKA-Low Frequency Range
• A Simultaneous Dual-site Technosignature Search Using International LOFAR Stations
• Near-field imaging of local interference in radio interferometric data: Impact on the redshifted 21 cm power spectrum
• Broadband Polarized Radio Emission Detected from Starlink Satellites Below 100 MHz with NenuFAR
• Altitude Estimation of Radio Frequency Interference Sources via Interferometric Near Field Corrections
• Enhanced detection and identification of satellites using an all-sky multi-frequency survey with prototype SKA-Low stations
• Temporal variability in low-frequency radio interference: Insight from high-cadence monitoring at a candidate radio notification zone in Malaysia
• TABASCAL: Removing multi-satellite interference from radio interferometry observations
• Satellite Impact on Astronomical Observations Based on Elliptical Orbit Model
• The impact of lunar topography on the 21-cm power spectrum for grid-based arrays : Insights for the Dark-ages EXplorer (DEX)
• SNIFFLES I: Intended Emission, Unwanted Emission, and Unintended Radiation from Low-Earth Orbiting Satellites Impacting Radio Astronomy from 1-26 GHz
• A Multi-Site Study of Radio Environment for Cosmology Experiments
• Operational Non-identifiability of Single-epoch Low-rank RFI Mitigation: Controlled Failure-mode Analysis and HERA Evidence
• An SBC-based controller and processor for the laboratory model of PRATUSH Digital Receiver
• Mitigating incoherent excess variance in high-redshift 21 cm observations with multi-output cross-Gaussian process regression