StarUnLink: identifying and mitigating signals from communication satellites in stellar spectral surveys

Abstract

A relatively new concern for the forthcoming massive spectroscopic sky surveys is the impact of contamination from low earth orbit satellites. Several hundred thousand of these satellites are licensed for launch in the next few years and it has been estimated that, in some cases, up to a few per cent of spectra could be contaminated when using wide field, multifibre spectrographs. In this paper, a multistaged approach is used to assess the practicality and limitations of identifying and minimizing the impact of satellite contamination in a WEAVE-like stellar spectral survey. We develop a series of convolutional-network-based architectures to attempt identification, stellar parameter and chemical abundances recovery, and source separation of stellar spectra that we artificially contaminate with satellite (i.e. solar-like) spectra. Our results show that we are able to flag 67 per cent of all contaminated sources at a precision level of 80 per cent for low-resolution spectra and 96 per cent for high-resolution spectra. Additionally, we are able to remove the contamination from the spectra and recover the clean spectra with a <1 per cent reconstruction error. The errors in stellar parameter predictions reduce by up to a factor of 2-3 when either including contamination as an augmentation to a training set or by removing the contamination from the spectra, with overall better performance in the former case. The presented methods illustrate several machine learning mitigation strategies that can be implemented to improve stellar parameters for contaminated spectra in the WEAVE stellar spectroscopic survey and others like it.