Swarm of lightsail nanosatellites for Solar System exploration.

This paper presents a study for the realization of a space mission which employs nanosatellites driven by an external laser source impinging on an optimized lightsail, as a valuable technology to launch swarms of spacecrafts into the Solar System. Nanosatellites propelled by laser can be useful for heliosphere exploration and for planetary observation, if suitably equipped with sensors, or be adopted for the establishment of network systems when placed into specific orbits. By varying the area-to-mass ratio (i.e. the ratio between the sail area and the payload weight) and the laser power, it is possible to insert nanosatellites into different hyperbolic orbits with respect to Earth, thus reaching the target by means of controlled trajectories in a relatively short amount of time. A mission involving nanosatellites of the order of 1 kg of mass is envisioned, by describing all the on-board subsystems and satisfying all the requirements in terms of power and mass budget. Particular attention is paid to the telecommunication subsystem, which must offer all the necessary functionalities. To fabricate the lightsail, the thin films technology has been considered, by verifying the sail's thermal stability during the thrust phase. Moreover, the problem of mechanical stability of the lightsail has been tackled, showing that the distance between the ligthsail structure and the payload plays a pivotal role. Some potential applications of the proposed technology are discussed, such as the mapping of the heliospheric environment.

Solar ultraviolet light collector for germicidal irradiation on the moon.

Prolonged human-crewed missions on the Moon are foreseen as a gateway for Mars and asteroid colonisation in the next decades. Health risks related to long-time permanence in space have been partially investigated. Hazards due to airborne biological contaminants represent a relevant problem in space missions. A possible way to perform pathogens' inactivation is by employing the shortest wavelength range of Solar ultraviolet radiation, the so-called germicidal range. On Earth, it is totally absorbed by the atmosphere and does not reach the surface. In space, such Ultraviolet solar component is present and effective germicidal irradiation for airborne pathogens' inactivation can be achieved inside habitable outposts through a combination of highly reflective internal coating and optimised geometry of the air ducts. The Solar Ultraviolet Light Collector for Germicidal Irradiation on the Moon is a project whose aim is to collect Ultraviolet solar radiation and use it as a source to disinfect the re-circulating air of the human outposts. The most favourable positions where to place these collectors are over the peaks at the Moon's poles, which have the peculiarity of being exposed to solar radiation most of the time. On August 2022, NASA communicated to have identified 13 candidate landing regions near the lunar South Pole for Artemis missions. Another advantage of the Moon is its low inclination to the ecliptic, which maintains the Sun's apparent altitude inside a reduced angular range. For this reason, Ultraviolet solar radiation can be collected through a simplified Sun's tracking collector or even a static collector and used to disinfect the recycled air. Fluid-dynamic and optical simulations have been performed to support the proposed idea. The expected inactivation rates for some airborne pathogens, either common or found on the International Space Station, are reported and compared with the proposed device efficiency. The results show that it is possible to use Ultraviolet solar radiation directly for air disinfection inside the lunar outposts and deliver a healthy living environment to the astronauts.

Dependence of the damage in optical metal/dielectric coatings on the energy of ions in irradiation experiments for space qualification.

Terrestrial accelerator facilities can generate ion beams which enable the testing of the resistance of materials and thin film coatings to be used in the space environment. In this work, a [Formula: see text]/Al bi-layer coating has been irradiated with a [Formula: see text] beam at three different energies. The same flux and dose have been used in order to investigate the damage dependence on the energy. The energies were selected to be in the range 4-100 keV, in order to consider those associated to the quiet solar wind and to the particles present in the near-Earth space environment. The optical, morphological and structural modifications have been investigated by using various techniques. Surprisingly, the most damaged sample is the one irradiated at the intermediate energy, which, on the other hand, corresponds to the case in which the interface between the two layers is more stressed. Results demonstrate that ion energies for irradiation tests must be carefully selected to properly qualify space components.

A hybrid metal-dielectric zero mode waveguide for enhanced single molecule detection.

We fabricated hybrid metal-dielectric nanoslots and measured their optical response at three different wavelengths. The nanostructure is fabricated on a bilayer film formed by the sequential deposition of silicon and gold on a transparent substrate. The optical characterization is done via fluorescence spectroscopy measurements. We characterized the fluorescence enhancement, as well as the lifetime and the detection volume reduction for each wavelength. We observe that the hybrid metal-dielectric nanoslots behave as enhanced zero mode waveguides in the near-infrared spectral region. Their detection volume is such that they can perform enhanced single-molecule detection at tens of µM. We compared their behavior with that of a golden ZMW, and we demonstrated that the dielectric silicon layer improves both the optical performance and the stability of the device.

Extreme Ultraviolet Multilayer Nanostructures and Their Application to Solar Plasma Observations: A Review.

The advent of nanoscale multilayer (ML) technology has led to great breakthroughs in many scientific and technological fields such as nano-manufacturing, bio-imaging, atto-physics, matter physics and solar physics. ML nanostructures are an enabling technology for the development of mirrors and reflective gratings having high efficiency at normal incidence in the extreme ultraviolet (EUV) range, a spectral region where conventional coatings show a negligible reflectance. In solar physics, ML mirrors have proved to be key elements for both imaging and spectroscopy space instruments, as they allow to make observations of EUV solar plasma emissions with spatial and spectral resolutions never reached before. ML-based instruments have been used in many of the major solar satellites and have flown in numerous sounding rocket experiments; moreover, in the last two decades many studies were performed in order to develop ML structures with increasingly better performance for future solar missions. In this paper, a review of the most promising ML nanostructures developed so far and applied to the observation of solar plasma emission lines is presented. After a brief recall of ML theory, a detailed discussion of the most promising material pairs and layer stack structures proposed and applied to past and current space missions will be presented; in particular, the review will focus on the ML structures having high efficiency in the 6 nm-35 nm wavelength range. Finally, the ML stability to low energy ion bombardment will be discussed.

Osmium atomic-oxygen protection by an iridium overcoat for increased extreme-ultraviolet grating efficiency.

The deposition of a 30-A-thick layer of iridium upon a 250-A-thick osmium reflective layer for use as a diffraction grating in the Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) satellite observatory has provided sufficient protection from an expected maximum orbital atomic-oxygen fluence of 1 x 10(16) atoms/cm2. The grating parameters of groove constant and depth, efficiencies of zeroth-order, first and second inside orders, and first inside-order efficiency positional uniformity as well as stray light near the first inside order of the Ir-Os-coated grating were measured within a CHIPS spectral bandpass of 90-260 A. Stray-light measurements were also made near the first inside spectral order at 304, 584, and 1216 A. The results make the Ir-Os coat an acceptable grating reflectivity layer for CHIPS and other spaceborne extreme-ultraviolet spectrometers that employ grazing-incidence reflection optics.

Extreme-ultraviolet calibration of thin-film Zr filters for the cosmic hot interstellar plasma spectrometer.

The design and calibration of thin-film Zr transmission filters for the Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) spaceborne astronomical telescope is presented. The transmission of a 1,000-A-thick Zr filter is measured for wavelengths from 45 to 1,304 A as well as its variability with respect to expected space-flight enviromental extremes of temperature, vibration, and atomic O bombardment. For the CHIPS spectral band of 90-260 A, the transmission of the Zr fiter is deemed useful between 90 and 200 A and is stable with respect to expected temperature and vibrational changes. The maximum atomic O bombardment decreases the filter transmission between 90 and 130 A by approximately 20% and does not appreciably affect the rest of the CHIPS bandpass. These results make Zr an acceptable filter candidate for CHIPS.