The unprecedented quality of the data collected by the AMS-02 experiment onboard the International Space Station allowed us to address subtle questions concerning the origin and propagation of cosmic ...rays. Here we discuss the implications of these data for the injection spectrum of elements with different masses and for the diffusion coefficient probed by cosmic rays through their journey from the sources to the Earth. We find that the best fit to the spectra of primary and secondary nuclei requires (1) a break in the energy dependence of the diffusion coefficient at energies ∼300 GV; (2) an injection spectrum that is the same for all nuclei heavier than helium, and different injections for both protons and helium. Moreover, if to force the injection spectrum of helium to be the same as for heavier nuclei, the fit to oxygen substantially worsens. Accounting for a small, Xs∼0.4 g cm−2, grammage accumulated inside the sources leads to a somewhat better fit to the B/C ratio but makes the difference between He and other elements even more evident. The statistic and systematic error bars claimed by the AMS collaboration exceed the error that is expected from calculations once the uncertainties in the cross sections of production of secondary nuclei are taken into account. In order to make this point more quantitative, we present a novel parametrization of a large set of cross sections, relevant for cosmic ray physics, and we introduce the uncertainty in the branching ratios in a way that its effect can be easily grasped.
The Modular Multispectral Imaging Array (MMIA) is a suite of optical sensors mounted on an external platform of the European Space Agency’s Columbus Module on the International Space Station. The ...MMIA, together with the Modular X- and Gamma- ray Sensor (MXGS), are the two main instruments forming the Atmosphere-Space Interactions Monitor (ASIM). The primary scientific objectives of the ASIM mission are to study thunderstorm electrical activity such as lightning, Transient Luminous Emissions (TLEs) and Terrestrial Gamma-ray Flashes (TGFs) by observing the associated emissions in the UV, near-infrared, x- and gamma-ray spectral bands. The MMIA includes two cameras imaging in 337 nm and 777.4 nm, at up to 12 frames per second, and three high-speed photometers at 180–230 nm, 337 nm and 777.4 nm, sampling at rates up to 100 kHz. The paper describes the MMIA and the aspects that make it an essential tool for the study of thunderstorms. The mission architecture is described in Neubert et al. (Space Sci. Rev. 215:26,
2019
, this issue) and the MXGS instruments in Østgaard et al. (Space Sci. Rev. 215:23,
2019
, this issue).
We report the observation of new properties of primary cosmic rays, neon (Ne), magnesium (Mg), and silicon (Si), measured in the rigidity range 2.15 GV to 3.0 TV with 1.8 × 106 Ne , 2.2 × 106 Mg , ...and 1.6 × 106 Si nuclei collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. The Ne and Mg spectra have identical rigidity dependence above 3.65 GV. The three spectra have identical rigidity dependence above 86.5 GV, deviate from a single power law above 200 GV, and harden in an identical way. Unexpectedly, above 86.5 GV the rigidity dependence of primary cosmic rays Ne, Mg, and Si spectra is different from the rigidity dependence of primary cosmic rays He, C, and O. This shows that the Ne, Mg, and Si and He, C, and O are two different classes of primary cosmic rays.
Substantial leaps in the understanding of quantum systems have been driven by exploring geometry, topology, dimensionality and interactions in ultracold atomic ensembles
. A system where atoms evolve ...while confined on an ellipsoidal surface represents a heretofore unexplored geometry and topology. Realizing an ultracold bubble-potentially Bose-Einstein condensed-relates to areas of interest including quantized-vortex flow constrained to a closed surface topology, collective modes and self-interference via bubble expansion
. Large ultracold bubbles, created by inflating smaller condensates, directly tie into Hubble-analogue expansion physics
. Here we report observations from the NASA Cold Atom Lab
facility onboard the International Space Station of bubbles of ultracold atoms created using a radiofrequency-dressing protocol. We observe bubble configurations of varying size and initial temperature, and explore bubble thermodynamics, demonstrating substantial cooling associated with inflation. We achieve partial coverings of bubble traps greater than one millimetre in size with ultracold films of inferred few-micrometre thickness, and we observe the dynamics of shell structures projected into free-evolving harmonic confinement. The observations are among the first measurements made with ultracold atoms in space, using perpetual freefall to explore quantum systems that are prohibitively difficult to create on Earth. This work heralds future studies (in orbital microgravity) of the Bose-Einstein condensed bubble, the character of its excitations and the role of topology in its evolution.
We report the observation of new properties of primary iron (Fe) cosmic rays in the rigidity range 2.65 GV to 3.0 TV with 0.62×10^{6} iron nuclei collected by the Alpha Magnetic Spectrometer ...experiment on the International Space Station. Above 80.5 GV the rigidity dependence of the cosmic ray Fe flux is identical to the rigidity dependence of the primary cosmic ray He, C, and O fluxes, with the Fe/O flux ratio being constant at 0.155±0.006. This shows that unexpectedly Fe and He, C, and O belong to the same class of primary cosmic rays which is different from the primary cosmic rays Ne, Mg, and Si class.
This study analyzes the performance of a tape-like bare electrodynamic tether as a promising propellant-free technology for the International Space Station (ISS) station-keeping, supporting the ...concept that the technology can provide significant mission benefits by reducing the ISS reliance on costly refueling operations for orbit maintenance. Convenient control laws for managing the electrical power supplied to the tether are proposed, exploring two distinct scenarios. The first involves using the electrodynamic tether continuously to counteract aerodynamic drag. The second adopts a cyclic approach, alternating between boosting the station with the tether and allowing for periods of natural decay. Optimal tether geometry, aimed at maximizing system efficiency, is also detailed. The study specifies an electrodynamic tether configuration featuring a 6-kilometer-long aluminum ribbon, 5 cm wide and 50 μm thick, capable of overcoming aerodynamic drag ranging from 0.40 N to 0.80 N. Additionally, numerical simulations assess the tether performance under real environmental conditions. Furthermore, the study briefly introduces the potential of a photovoltaic tether as a fully autonomous system capable of supplying the necessary input power.
•Electrodynamic tethers are proposed as a promising technology for ISS station-keeping•Air drag compensation and zig-zag are novel control strategies for orbit maintenance•Optimization codes are implemented for the identification of tether characteristics•The performances of the tether are investigated through numerical simulations•Bare Photovoltaic Tethers are proposed as autonomous systems for power harvesting
We present a measurement of the cosmic ray (e^{+}+e^{-}) flux in the range 0.5 GeV to 1 TeV based on the analysis of 10.6 million (e^{+}+e^{-}) events collected by AMS. The statistics and the ...resolution of AMS provide a precision measurement of the flux. The flux is smooth and reveals new and distinct information. Above 30.2 GeV, the flux can be described by a single power law with a spectral index γ=-3.170±0.008(stat+syst)±0.008(energy scale).
Precise knowledge of the charge and rigidity dependence of the secondary cosmic ray fluxes and the secondary-to-primary flux ratios is essential in the understanding of cosmic ray propagation. We ...report the properties of heavy secondary cosmic ray fluorine F in the rigidity R range 2.15 GV to 2.9 TV based on 0.29 million events collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. The fluorine spectrum deviates from a single power law above 200 GV. The heavier secondary-to-primary F/Si flux ratio rigidity dependence is distinctly different from the lighter B/O (or B/C) rigidity dependence. In particular, above 10 GV, the F/Si/B/O ratio can be described by a power law R^{δ} with δ=0.052±0.007. This shows that the propagation properties of heavy cosmic rays, from F to Si, are different from those of light cosmic rays, from He to O, and that the secondary cosmic rays have two classes.
Abstract This study reports some results obtained on nucleate flow boiling on an isolated nucleation site in microgravity. The experiments have been carried out aboard the International Space Station ...thanks to the Reference Multiscale Boiling Investigation (RUBI) device. Results reveal the pronounced influence of heat flux, subcooling temperature, flow rates on the bubble behavior, and more specifically on its growth rate. Deviations from the classical square-root time law of diffusive growth are observed at high subcoolings and high flow rates.
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