Development of University-Friendly CubeSat Bus and Ground Station Architecture Using Software-Defined Radios

The goal of the research and development presented in this paper is to introduce a CubeSat bus and ground station architecture that is made to be much more approachable to schools and universities. The three main pillars of the effort are low-cost, maintaining flexibility, and lowering the bar of entry. The presented CubeSat bus includes PyCubed board which houses most of the core satellite bus components on a single board. The board can handle main processing, data storage, UHF radio communication, telemetry sensors, and power management. This UHF radio is paired with a software-defined radio (SDR) that serves as the ground station radio. For a faster data rate downlink of payload data, a low-cost SDR (Ettus B205mini) is paired with a RaspberryPi processor. By leveraging the flexibility of SDRs, one SDR at the ground station is agile enough to provide UHF up/downlink for the CubeSat bus comm, as well as receiving S- or X-band payload data downlink. This proposed architecture will enable project teams to rapidly achieve a baseline capability with the satellite bus such that the development schedule and cost can be drastically reduced while providing the students with the full-cycle experience of satellite engineering

An Exploration of the Small Satellite Value Chain and the Future of Space Access

“Space is hard” is a saying that has been made popular in the last few years. It is not just the engineering that is challenging, but also applies to the business of space as well. From supply chain to regulation, the space industry’s infrastructure is not prepared to handle the influx of demand forecasted through the next decade, especially in the small satellite segment. Accordingly, space businesses are looking to cost effectively and quickly build and deploy space payloads while being able to refresh their technologies as advancements are made on Earth. In this paper, we will explore a small satellite customer’s journey from ideation to launch and operations including a survey of the commercial and government entities involved. We will discuss the costs associated with the current processes from both a financial and schedule perspective. An important aspect to this study is to understand that there are many trade-offs to be made, from a whole turn-key solution from ideation to operations, to an entire a la carte solution with space customers “DIY-ing” it. We will provide a broad overview of the providers in each of the value chain segments from payload development, manufacturers, testing, regulatory, launch, and operations. Finally, we will discuss opportunities to make space access easier and the outlook of the value chain as space commercialization becomes a reality over the next decade, including new impactful technologies such as on-orbit servicing and repair. Reusable infrastructure is the key to solving these customers’ pain points as satellites are disposable assets today

Water Vapor Independent Satellite Propulsion System (WISP) for Nanosatellite Orbit Maintenance

While nanosatellites have been widely implemented for scientific applications, power constraints, large free-space path losses, and system complexity prevent many researchers from fielding novel sensing hardware. Additionally, dead-on-arrival missions contribute to the growing volume of orbital debris. Access to lower orbits would decrease downlink losses, improve optical sensor performance, and ensure natural de-orbit for inoperable payloads. Conventional satellite propulsion technologies are capable of providing thrust required to maintain a low orbit, but increase system complexity and draw power away from the sensors. The United States Naval Academy has developed the Water Vapor Independent Satellite Propulsion system (WISP) to maintain orbits as low as 250km without drawing electrical power during steady state operation. This system utilizes an aqueous methyl alcohol propellant that passively evaporates across a phase separation boundary prior to exiting through a nozzle. Since this process occurs passively based on propellant evaporation properties and expansion chamber conditions, no electrical power is required during steady state operation. Theoretical calculations show that this system of 1U volume (10 x 10 x 10cm) is capable of providing sufficient thrust to maintain orbit for approximately 30 days

Heating temperature prediction of concrete structure damaged by fire using a Bayesian approach

A fire that occurs in a reinforced concrete (RC) structure accompanies a heating temperature, and this negatively affects the concrete material properties, such as the compressive strength, the bond between cement paste and aggregate, and the cracking and spalling of concrete. To appropriately measure the reduced structural performance and durability of fire-damaged RC structures, it is important to accurately estimate the heating temperature of the structure. However, studies in the literature on RC structures damaged by fire have focused mostly on structural member tests at elevated temperatures to ensure the fire resistance or fire protection material development; studies on estimating the heating temperature are very limited except for the very few existing models. Therefore, in this study, a heating temperature estimation model for a reinforced concrete (RC) structure damaged by fire was developed using a statistical Bayesian parameter estimation approach. For the model development, a total of 77 concrete test specimens were utilized; based on them, a statistically highly accurate model has been developed. The usage of the proposed method in the framework of the 500 ◦C isotherm method in Eurocode 2 has been illustrated through an RC column resistance estimation application

Methods for Making an Electroactive Device Fabricated with a Nanotube Film Electrode

Disclosed is a single wall carbon nanotube (SWCNT) film electrode (FE), all-organic electroactive device systems fabricated with the SWNT-FE, and methods for making same. The SWCNT can be replaced by other types of nanotubes. The SWCNT film can be obtained by filtering SWCNT solution onto the surface of an anodized alumina membrane. A freestanding flexible SWCNT film can be collected by breaking up this brittle membrane. The conductivity of this SWCNT film can advantageously be higher than 280 S/cm. An electroactive polymer (EAP) actuator layered with the SWNT-FE shows a higher electric field-induced strain than an EAP layered with metal electrodes because the flexible SWNT-FE relieves the restraint of the displacement of the polymeric active layer as compared to the metal electrode. In addition, if thin enough, the SWNT-FE is transparent in the visible light range, thus making it suitable for use in actuators used in optical devices

On Sub-ENSO Variability

Multichannel singular spectrum analysis (MSSA) of surface zonal wind, sea surface temperature (SST), 20° isotherm depth, and surface zonal current observations (between 1990 and 2004) identifies three coupled ocean–atmosphere modes of variability in the tropical Pacific: the El Niño–Southern Oscillation (ENSO), the annual cycle, and a mode with a 14–18-month period, which is referred to as sub-ENSO in this study. The sub-ENSO mode accounts for the near 18-month (near annual) variability prior to (following) the 1997/98 El Niño event. It was strongest during this El Niño event, with SST anomalies exceeding 1°C. Sub-ENSO peak SST anomalies are ENSO-like in structure and are associated with eastward propagating heat content variations. However, the SST anomalies are preceded by and in near quadrature with relatively strong remotely forced westward propagating zonal current variations, suggesting the sub-ENSO mode arises from the zonal-advective feedback. The sub-ENSO mode is found to exist also in an intermediate complexity model (ICM) of the tropical Pacific. A heat budget analysis of the model’s sub-ENSO mode shows it indeed arises from the zonal-advective feedback. In the model, both ENSO and sub-ENSO modes coexist, but there is a weak nonlinear interaction between them. Experiments also show that the observed changes in sub-ENSO’s characteristics may be explained by changes in the relative importance of zonal and vertical advection SST tendencies

Plasmonic colloidal nanoparticles with open eccentric cavities via acid-induced chemical transformation

Surface-enhanced Raman spectroscopy (SERS) has been considered a promising technique for the detection of trace molecules in biomedicine and environmental monitoring. The ideal metal nanoparticles for SERS must not only fulfill important requirements such as high near-field enhancement and a tunable far-field response but also overcome the diffusion limitation at extremely lower concentrations of a target material. Here, we introduce a novel method to produce gold nanoparticles with open eccentric cavities by selectively adapting the structure of non-plasmonic nanoparticles via acid-mediated surface replacement. Copper oxide nanoparticles with open eccentric cavities are first prepared using a microwave-irradiation-assisted surfactant-free hydrothermal reaction and are then transformed into gold nanoparticles by an acidic gold precursor while maintaining their original structure. Because of the strong near-field enhancement occurring at the mouth of the open cavities and the very rough surfaces resulting from the uniformly covered hyperbranched sharp multi-tips and the free access of SERS molecules inside of the nanoparticles without diffusion limitation, adenine, one of the four bases in DNA, in an extremely diluted aqueous solution (1.0 pM) was successfully detected with excellent reproducibility upon laser excitation with a 785-nm wavelength. The gold nanoparticles with open eccentric cavities provide a powerful platform for the detection of ultra-trace analytes in an aqueous solution within near-infrared wavelengths, which is essential for highly sensitive, reliable and direct in vivo analysis.None1132sciescopu