Álvaro Romero-Calvo

Álvaro Romero-Calvo
Georgia Institute of Technology | GT · School of Aerospace Engineering

PhD
Low-Gravity Science and Technology Laboratory

About

63
Publications
17,173
Reads
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296
Citations
Introduction
Assistant Professor (tenure-track), Daniel Guggenheim School of Aerospace Engineering, Georgia Institute of Technology
Additional affiliations
January 2020 - July 2022
University of Colorado Boulder
Position
  • Research Assistant
Description
  • Working under an Air Force Office for Scientific Research contract in the study of touchless spacecraft potential measurement techniques.
November 2016 - November 2017
Universidad de Sevilla
Position
  • Student
June 2016 - January 2019
Lynzos SL
Position
  • Researcher
Description
  • Characterization and classification of periodic dissipative systems and development of advanced analysis tools, with a special focus on biometric signals and Heart Rate Variability analysis.
Education
July 2019 - July 2022
University of Colorado Boulder
Field of study
  • Aerospace Engineering Sciences
September 2017 - July 2019
Politecnico di Milano
Field of study
  • Space Engineering
September 2016 - November 2017
Universidad de Sevilla
Field of study
  • Aeronautical Engineering

Publications

Publications (63)
Conference Paper
Full-text available
High-power SmallSats are faced with a limited number of thermal control technologies, many of which are not well suited to a compact form factor or large heat load. This work proposes a new SmallSat heat transfer system composed of a liquid metal cooling loop driven by a magnetohydrodynamic (MHD) pump. The MHD pump leverages the Lorentz force to dr...
Conference Paper
Full-text available
The operation of spacecraft life support systems is challenged by the microgravity environment. The near-absence of buoyancy impacts the electrolytic production of oxygen and hydrogen by demanding complex multiphase flow management technologies. Although successful in short-term missions, existing solutions lack the reliability and mass efficiency...
Conference Paper
Full-text available
In-situ resource utilization (ISRU) of liquid-gas/solid mixtures in partial and microgravity conditions poses a significant challenge due to reduced buoyancy forces. Capillary or mechanical phase separation technologies have traditionally been employed to overcome these issues, but they lack the stability and efficiency desired for many space appli...
Conference Paper
Full-text available
Novel applications of magnetism are the focus of multiple research efforts, in a diverse set of disciplines, including aerospace technologies. Due to the inherent material variations in hysteresis-producing coils and other factors, manufacturing errors in permanent magnets are expected. Thus, investigations involving magnetic materials often requir...
Conference Paper
Full-text available
The importance of propellant sloshing for the operation of space vehicles has been known since the early days of space exploration. Sloshing can induce undesired fluid-structure interactions and impact system dynamics, potentially leading to mission failure. Model-ing and mitigating this effect is, therefore, an essential component of launch vehicl...
Conference Paper
Full-text available
CubeSat propulsion imposes unique propellant management issues. The requisite form factor often necessitates conformal tank geometries and high-density two-phase propellants. Fluid management in these saturated propellant systems cannot be accomplished using conventional capillary devices, and current state-of-the-art alternatives are volumetricall...
Presentation
The realization of long-term space travels and the establishment of a lunar research platform are challenged by the lack of technological device architectures for efficient, stable and continuous oxygen production. One obstacle is that the near-absence of buoyancy in microgravity results in hindered gas bubble desorption at the electrode-electrolyt...
Presentation
Water electrolysis is the fundamental chemical process for oxygen and hydrogen production in space. It is widely employed in modern environmental control and life support systems, propulsion technologies, and high-density energy storage devices. Furthermore, future interplanetary missions are likely to employ water as a commodity acquired and proce...
Presentation
One of the major challenges human space exploration faces is the absence of buoyancy forces in orbit. Consequently, phase separation is severely hindered which impacts a large variety of space technologies including propellant management devices, heat transfer and life support systems e.g., during the production of oxygen and the recycling of carbo...
Presentation
Photoelectrochemical (PEC) monolithic devices for oxygen and chemical production are attractive for space applications due to predominant weight and volume constraints as well as a high system tunability. Here, advanced semiconductor-electrocatalyst systems integrate the processes of light absorption, charge separation and catalysis in one device -...
Article
Full-text available
Ultraviolet lasers are proposed as a replacement for low-energy electron beams in touchless spacecraft potential sensing. Theoretical considerations support their use as photoelectron sources due to their insensitivity to the electrostatic environment, which leads to more robust and controllable systems. The feasibility of this approach is verified...
Conference Paper
An analytical model is developed to estimate the performance of a novel low-gravity magnetohydrodynamic (MHD) electrolytic cell architecture. This technology is currently under development with the ultimate goal of separating hydrogen and oxygen from water in microgravity. The model employs the balance of moments between the Lorentz force and the s...
Conference Paper
Full-text available
Water electrolysis is a key technology for oxygen and hydrogen production in space, finding application in environmental control and life support systems, propulsion technologies, and high-density energy storage devices. However, the management of multiphase flows in microgravity is complicated due to the absence of buoyancy. Diamagnetic buoyancy c...
Conference Paper
Full-text available
Low gravity fluid management is key to a variety of spaceflight applications from life support systems aboard the international space station to propellant management in satellite tanks. Various methodologies have been developed to drive fluids to their desired positions in a microgravity environment, but these traditional strategies are not partic...
Conference Paper
Full-text available
Novel active sensing technologies have been recently proposed to touchlessly measure the electrostatic potential of non-cooperative objects in Geosynchronous Equatorial Orbit and cislunar space. This technology involves a servicing spacecraft that makes us of an electron beam or UV laser to excite secondary electron and photoelectron emissions. The...
Article
Full-text available
A method has been proposed to estimate the electric potential of co-orbiting spacecraft remotely using x-rays that are excited by an electron beam. Prior work focused on the theoretical foundation and experimental validation of this approach using flat target plates. Although useful for concept validation, flat plates do not adequately represent th...
Article
Full-text available
A coupled ferrohydrodynamic interface-tracking model is introduced for the analysis of the equilibrium, linear stability, and modal response of magnetic liquid interfaces in surface tension-dominated axisymmetric multiphase flows. The incompressible viscous mass and momentum balances are solved together with the steady-state Maxwell equations by fo...
Article
Full-text available
The active deorbiting and passivation of launch vehicles has become key for the implementation of modern space debris mitigation guidelines. Appropriate engine restart conditions must be provided as part of this process. Ullage motors have been traditionally employed to induce active settling and ensure a gas-free propellant supply to the engines....
Article
Full-text available
The absence of strong buoyancy forces severely complicates the management of multiphase flows in microgravity. Different types of space systems, ranging from in-space propulsion to life support, are negatively impacted by this effect. Multiple approaches have been developed to achieve phase separation in microgravity, whereas they usually lack the...
Thesis
Full-text available
The commercialization of the sub-orbital environment, the ambition to make humans a multi-planetary species, and the urgent need for sustainable space operations are driving the development of a new generation of space systems. The use of electromagnetic forces (and electromagnetism, in general) is proposed in this dissertation to enable mid-distan...
Article
Full-text available
The secondary electron method has been recently proposed to touchlessly sense the electrostatic potential of non-cooperative objects in geosynchronous equatorial orbits and deep space. This process relies on the detection of secondaries generated at the target surface, that is actively irradiated by an electron beam. Although the concept has alread...
Conference Paper
Full-text available
Ultraviolet lasers are proposed as a replacement for low-energy electron beams to induce the emission of secondary electrons in touchless spacecraft potential sensing technologies. Theoretical considerations show that the measurement process becomes significantly less sensitive to the electrostatic environment and leads to more robust, controllable...
Conference Paper
Full-text available
A method has been proposed to estimate the electric potential of co-orbiting spacecraft remotely using x-rays that are excited by an electron beam. Recent work experimentally investigated the remote electric potential estimation of objects with complex shapes and differentially-charged components, and a new analysis method was proposed that enables...
Article
Full-text available
Electrostatic perturbations can have significant effects during terminal proximity operations in high earth orbits, with torque levels exceeding 5 mN-m during severe charging events. These torques can impart 1°/s rotational rates to uncontrolled bodies, such as debris or servicing clients, during rendezvous and proximity operations. A sub optimal,...
Conference Paper
Full-text available
The active deorbiting and passivation of launch vehicles has become key for the implementation of modern space debris mitigation guidelines. Appropriate engine restart conditions must be provided as part of this process. Ullage motors have been traditionally employed to induce active settling and ensure a gas-free propellant supply to the engines....
Article
Full-text available
The management of fluids in space is complicated by the absence of relevant buoyancy forces. This raises significant technical issues for two-phase flow applications. Different approaches have been proposed and tested to induce phase separation in low-gravity; however, further efforts are still required to develop efficient, reliable, and safe devi...
Article
Full-text available
The Electrostatic Charging Laboratory for Interactions between Plasma and Spacecraft (ECLIPS) research vacuum chamber has recently been developed as part of the Autonomous Vehicle Systems Laboratory at the University of Colorado Boulder. The experimental spacecraft charging research facility allows conducting experiments relevant to charged astrody...
Conference Paper
Full-text available
A method has been recently proposed to estimate the electric potential of co-orbiting spacecraft remotely using x-rays that are excited by an electron beam. Prior work focused on the theoretical foundation and experimental validation of this method using flat target plates. Although useful for the validation of this concept, flat plates do not adeq...
Article
Full-text available
Novel active sensing methods have been recently proposed to measure the electrostatic potential of non-cooperative objects in geosynchronous equatorial orbit and deep space. Such approaches make use of electron beams to excite the emission of secondary electrons and X-Rays and infer properties of the emitting surface. However, the detectability of...
Conference Paper
[The final version of this work can be found at http://doi.org/10.2514/1.A35355] The secondary electron method has been recently proposed to touchlessly sense the electrostatic potential of non-cooperative objects in geosynchronous equatorial orbits and deep space. This process relies on the detection of secondaries generated at the target surface,...
Article
Full-text available
This paper describes an inexpensive, non-invasive, and highly adaptable surface reconstruction device for opaque liquids. The instrument was developed to study the lateral sloshing of ferrofluids in microgravity as part of the UNOOSA DropTES 2019 StELIUM project. Its design is driven by the geometrical and mechanical constraints imposed by ZARM’s d...
Article
Full-text available
The sloshing of liquids in low-gravity entails several technical challenges for spacecraft designers due to its effects on the dynamics and operation of space vehicles. Magnetic settling forces may be employed to position a susceptible liquid and address these issues. Although proposed in the early 1960s, this approach remains largely unexplored. I...
Article
Full-text available
The sloshing of liquids in low-gravity entails several technical challenges for spacecraft designers and operators. Those include the generation of significant attitude disturbances, the uncontrolled displacement of the center of mass of the vehicle or the production of gas bubbles, among others. Magnetic fields can be used to induce the reorientat...
Article
Full-text available
This paper addresses the operation in microgravity of the surface reconstruction device whose design is detailed in the first part of the manuscript. The system, employed during the drop tower campaign of the UNOOSA DropTES 2019 StELIUM experiment, studies the axisymmetric and lateral oscillations of a ferrofluid solution in microgravity. The free...
Conference Paper
[The final version of this work can be found at http://doi.org/10.2514/1.A35190] Novel active sensing technologies have been recently proposed to measure the electrostatic potential and characterize non-cooperative objects in Geosynchronous Equatorial Orbit (GEO) and deep space. Such technologies make use of electron beams to excite the emission of...
Conference Paper
[The final version of this work can be found at https://doi.org/10.1016/j.actaastro.2021.12.037] The Electrostatic Charging Laboratory for Interactions between Plasma and Spacecraft (ECLIPS) research vacuum chamber facility has recently been developed as part of the Autonomous Vehicle Systems Laboratory at the University of Colorado Boulder. This e...
Conference Paper
[The final version of this paper can be found in http://arc.aiaa.org/doi/abs/10.2514/1.A35021] The management of fluids in space is complicated by the absence of strong buoyancy forces. This raises significant technical issues for two-phase flows applications, such as water electrolysis or boiling. Different approaches have been proposed and test...
Conference Paper
Full-text available
The term sloshing refers to the movement of liquids in partially filled containers. Low-gravity sloshing plays an important role in the configuration of space vehicles, as it affects their dynamics and complicates the propellant management system design. Magnetic forces can be used to position a susceptible fluid, tune its natural frequencies, and...
Article
Full-text available
Liquid sloshing represents a major challenge for the design and operation of space vehicles. In low-gravity environments, a highly non-linear movement can be produced due to the lack of stabilizing forces. This gives rise to significant disturbances that impact on the propulsion and attitude control systems of the spacecraft. The employment of magn...
Article
Full-text available
The formulation of the total force exerted by magnetic fields on ferrofluids has historically been a subject of intense debate and controversy. Although the theoretical foundations of this problem can now be considered to be well established, significant confusion still remains regarding the implementation of the associated expressions. However, th...
Conference Paper
[The final version of this paper can be found in https://doi.org/10.1016/j.actaastro.2021.06.045] The sloshing of liquids in low-gravity entails several technical challenges for spacecraft designers and operators. Those include the generation of significant attitude disturbances, the uncontrolled displacement of the center of mass of the vehicle o...
Article
Full-text available
The sloshing of liquids in microgravity is a relevant problem of applied mechanics with important implications for spacecraft design. A magnetic settling force may be used to avoid the highly non-linear dynamics that characterize these systems. However, this approach is still largely unexplored. This paper presents a quasi-analytical low-gravity sl...
Conference Paper
[The final version of this work can be found at https://doi.org/10.1016/j.actaastro.2021.08.029 and https://doi.org/10.1016/j.actaastro.2021.07.020] Liquid level measurement devices are required in experimental sloshing research. Several techniques with different capabilities and degrees of complexity have been historically proposed to cover this n...
Conference Paper
Full-text available
The Lunar Meteoroid Impact Observer (LUMIO) is a 12U CubeSat designed to observe, quantify, and characterize the impact of meteoroids on the lunar surface. The combination of a highly demanding Concept of Operations (ConOps) and the characteristics of the deep-space environment determine the configuration of the spacecraft. This paper presents the...
Conference Paper
Liquid sloshing represents a major challenge for spacecraft design and operation. In low-gravity environments, a highly non-linear movement is produced due to the lack of stabilizing forces. This gives rise to significant disturbances that impact on the attitude control system of the vehicle. The employment of magnetically susceptible fluids may op...
Conference Paper
Full-text available
The increasing density of space debris in the Low Earth Orbit and the need to face long-term manned missions have raised the interest on vehicle health monitoring systems. Active monitoring techniques involving a network of sensors may assist in the impact detection and evaluation process, reducing the cost and risk of such activities. However, any...
Conference Paper
Full-text available
Abstract presented to the 26th European Low Gravity Research Association Biennial Symposium and General Assembly.
Poster
Full-text available
The sloshing of magnetic liquids has distinctive characteristics that may become useful for the control of propellants in space. Magnetic fields can be used to shift the natural frequencies and damping ratios of an oscillating fluid. In the framework of the UNOOSA DropTES Programme, StELIUM (Sloshing of magnetic LIqUids in Microgravity) will study...
Thesis
The term sloshing refers to the forced movement of liquids in partially filled containers. In a low-gravity environment, the liquid mixes with pressurizing gas bubbles and adopts a random position inside the tank, resulting in unwanted perturbations and a complicated design. Liquid sloshing has consequently been a major concern for space engineers...
Presentation
Full-text available
The term sloshing refers to the forced movement of liquids in partially filled containers. In a low-gravity environment, the liquid mixes with pressurizing gas bubbles and adopts a random position inside the tank, resulting in unwanted perturbations and a complicated design. Liquid sloshing has consequently been a major concern for space engineers...
Technical Report
Full-text available
Technical Experiment Report of the European Space Agency Drop Your Thesis! 2017 team "The Ferros". Site: http://eea.spaceflight.esa.int/portal/exp/?id=9692
Article
Full-text available
The effective discrimination between patients at risk of Arrhythmic Mortality (AM) and Non-Arrhythmic Mortality (NAM) constitutes one of the important unmet clinical needs. Successful risk assessment based on Electrocardiography (ECG) records is greatly improved by the combination of different indices reflecting not only the pathological substrate...
Poster
Full-text available
Ferrofluids are colloidal suspensions of magnetic nanoparticles in a carrier liquid. It is beneficial, for both fundamental research and future applications of ferrofluids in space, to obtain reliable measurements of the dynamics of ferrofluids in microgravity. This field remains unexplored since experiments in microgravity are expensive and the ac...
Conference Paper
Full-text available
Ferrofluids are colloidal suspensions of magnetic nanoparticles in a carrier liquid. It is beneficial, for both fundamental research and future applications of ferrofluids in space, to obtain reliable measurements of the dynamics of ferrofluids in microgravity. This field remains unexplored since experiments in microgravity are expensive and the ac...
Thesis
Full-text available
The purpose of this project is the development and testing of a new geographical surface heat exchange measurement technique. The proposed approach is based on the indirect evaluation of advective moist air heat fluxes and employs the most simple instrumentation available at the moment, consisting on a network of automatic meteorological stations....

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