Keith’s note: A preprint was posted on Wednesday 3 Dec 2025 titled “Voyager 1 Data Reveals Signatures of the Local Gas and Cosmic-Ray Source Distributions“ which refers to “recent Voyager 1 data taken in the local ISM” and that “this work is partially funded via NASA grants 80NSSC22K0477, 80NSSC22K0718, and 80NSSC23K0169.” A NASA (American) mission is sending back data that from interstellar space. No other nation has a growing fleet of interstellar missions. Talk about taking the lead in space exploration. Yes, this is nerdy stuff – but it is still baffling to me that the agency simply cannot back up the whole “Make America Great In Space (again)” mantra with actual, no kidding, examples of pre-eminence in space. Data summary below.
Voyager 1 Data Reveals Signatures of the Local Gas and Cosmic-Ray Source Distributions
“We investigate the effects of the nearby interstellar medium (ISM) on the locally measured cosmic-ray (CR) spectra. Using the GALPROP code we explore how variations in the local gas and source distributions affect spectral features at low energies. Comparing with recent Voyager 1 data taken in the local ISM, we show that for a realistic interstellar gas distribution, the nearest source of the low energy CR particles observed nearby the Solar system is constrained to be within the range ~150-200 pc distant. We find that the modelling supports the conclusion of Cummings et al. (2025) that there is a significant fraction of primary Boron in its observed spectrum at low energies. Our study shows that detailed modelling of the immediate Galactic environment is required to robustly infer Galactic CR propagation parameters from local measurements, and that accounting for nearby ISM structure can alleviate tensions between direct CR data and global propagation models.”
Caption: Elemental ratios for He, O, and Fe compared with V1 data. For each ratio, the corresponding V1 ratio has been derived from the spectra using power-law interpolation at the geometric mean energy for the elemental denominator species. Uncertainties are obtained by combining in quadrature the 1-sigma uncertainties for each elemental species interpolated using the same method. Left panel: ratios for combinations with 3D/GP2D and S25 gas models with source density hole sizes 0, 100, and 200 pc. Right panel: ratios for S25 gas model with source density hole sizes 0, 100, 150, 200, and 400 pc. Line styles are same as for Fig. 2, with the addition of double-dot dashed and triple-dotted dashed lines for 150 pc and 400 pc source density holes, respectively.
