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F. Francisco

Publications and source records attributed to F. Francisco.

12 recordsLinked to original sources
arXiv2022

Towards a Classification Scheme for the Rocky Planets based on Equilibrium Thermodynamic Considerations

A classification scheme for rocky planets is proposed, based on a description of the Earth System in terms of the Landau-Ginzburg Theory of phase transitions. Three major equilibrium states can be identified and the associated planetary states or phases are: Earth-like Holocene state; hot Venus-like state; cold Mars-like state. The scheme is based on an approach proposed to understand the Earth transition from the Holocene to the Anthropocene, driven by the impact of the human action on the Earth System. In the present work we identity the natural conditions that cause transformations on the planets forcing them into one of the states identified above. We discuss how the parameters that describe these transformations can be related with exoplanets observables. In analysing the relevant physical parameters, we were stroke by the similarities between Earth and Venus, and how likely is that the Anthropocene transition may lead to hot-house Earth scenario.

astro-ph.EP↗
arXiv2019

A Physical Framework for the Earth System in the Anthropocene: Towards an Accountancy System

At a time when humanity has achieved global dominance at a scale that was previously thought impossible, it might also face an existential threat due to the consequences of that overwhelming influence on our common home, the Earth System (ES). In this work we explore how Physics may help us to understand the transitions that the ES is going through and lead us to a physically motivated accounting system that allows for setting boundaries to our negative influence on the ecosystems.

physics.soc-ph↗
arXiv2019

Towards a Physically Motivated Planetary Accounting Framework

In this work we present a physically motivated planetary Accounting Framework for the Earth System. We show that the impact of the human activity in terms of the Planetary Boundary variables can be accounted for in our Landau-Ginzburg phase transition physical formulation. We then use the interaction between climate change and ocean acidification mechanisms to exemplify the relation of the concentration and flux of substances of the Planetary Boundaries variables, as proposed by the accounting framework of Kate and Newman, with the underlying thermodynamical transformation, quantifiable by the Landau-Ginzburg inspired model. In this work we present a physically motivated planetary Accounting Framework for the Earth System. We show that the impact of the human activity in terms of the Planetary Boundary variables can be accounted for in our Landau-Ginzburg phase transition physical formulation. We then use the interaction between climate change and ocean acidification mechanisms to exemplify the relation of the concentration and flux of substances of the Planetary Boundaries variables, as proposed by the accounting framework of Kate and Newman, with the underlying thermodynamical transformation, quantifiable by the Landau-Ginzburg inspired model.

physics.ao-ph↗
arXiv2019

Ensuring Uninterrupted Power Supply to Lunar Installations Through an Organic Rankine Cycle

We propose using the temperature gradients between the Moon's surface and the soil at a certain depth to power an Organic Rankine Cycle that could supply a permanent installation, particularly at night, when solar power is not available. Our theoretical and engineering considerations show that, with existing working fluids and quite feasible technical requirements, it is possible to continuously yield $25\,{\rm kW}$ to sustain a 3 member crew.

astro-ph.IM↗
arXiv2018

A phase-space description of the Earth System in the Anthropocene

Based on a dynamic systems approach to the Landau-Ginzburg model, a phase space description of the Earth System (ES) in the transition to the Anthropocene is presented. It is shown that, for a finite amount of human-driven change, there is a stable equilibrium state that is an attractor of trajectories in the system's phase space and corresponds to a Hothouse Earth scenario. Using the interaction between the components of the ES, it is argued that, through the action of the Technosphere, mitigation strategies might arise for which the deviation of the ES temperature from the Holocene average temperature is smaller.

physics.ao-ph↗
arXiv2018

A physical framework for the Earth System, the Anthropocene Equation and the Great Acceleration

It is proposed, based on the Landau-Ginzburg Theory of phase transitions, that the transition of the Earth System from the stable conditions of the Holocene to the human driven condition of the Anthropocene is, actually, a phase transition, a qualitative change away from its Holocene equilibrium state. Based on this physical framework, one obtains the Anthropocene equation, the so-called Great Acceleration and shows that (i) the Earth System temperature on the new equilibrium state diverges from the average temperature of the Holocene as the cubic root of the human intervention, described by a parameter, $H$; (ii) the human induced departure from the Holocene can be as drastic as the ones due to natural, astronomical and geophysical causes; (iii) the susceptibility of the Earth System to human effects is much more relevant near the phase transition. The procedure to obtain numerical predictions from data is also exemplified through one of the existing proposals to account for human impact on the Earth's Holocene equilibrium.

physics.gen-ph↗
arXiv2016

Hyperbolic orbits of Earth flybys and effects of ungravity-inspired conservative potentials

In this work we take a critical look at the available data on the flyby anomaly and on the current limitations of attempts to develop an explanation. We aim to verify how conservative corrections to gravity could affect the hyperbolic trajectories of Earth flybys. We use ungravity-inspired potentials as illustrative examples and show how the resulting orbital simulations differ from the observed anomaly. We also get constraints on the model parameters from the observed flyby velocity shifts. The conclusion is that no kind of conservative potential can be the cause of the flyby anomaly.

gr-qc↗
arXiv2014

Modelling the nongravitational acceleration during Cassini's gravitation experiments

In this paper we present a computation of the thermally generated acceleration of the Cassini probe during its solar conjunction experiment, obtained from a model of the spacecraft. We build a thermal model of the vehicle and perform a Monte Carlo simulation to find a thermal acceleration with a main component of $(3.01 \pm 0.33) \times 10^{-9} {\rm m/s^2}$. This result is in close agreement with the estimates of this effect performed through Doppler data analysis.

gr-qc↗
arXiv2012

Modelling the reflective thermal contribution to the acceleration of the Pioneer spacecraft

We present an improved method to compute the radiative momentum transfer in the Pioneer 10 & 11 spacecraft that takes into account both diffusive and specular reflection. The method allows for more reliable results regarding the thermal acceleration of the deep-space probes, confirming previous findings. A parametric analysis is performed in order to set an upper and lower-bound for the thermal acceleration and its evolution with time.

physics.space-ph↗
arXiv2011

Testing the Flyby Anomaly with the GNSS Constellation

We propose the concept of a space mission to probe the so called flyby anomaly, an unexpected velocity change experienced by some deep-space probes using earth gravity assists. The key feature of this proposal is the use of GNSS systems to obtain an increased accuracy in the tracking of the approaching spacecraft, mainly near the perigee. Two low-cost options are also discussed to further test this anomaly: an add-on to an existing spacecraft and a dedicated mission.

physics.space-ph↗
arXiv2011

Probing the Flyby Anomaly with the Galileo Constellation

In the last few years, the so-called flyby anomaly has been widely discussed, but remains still an illusive topic. This is due to the harsh conditions experienced during an Earth flyby as well as due to the limited data available. In this work, we assess the possibility of confirming and characterizing this anomaly by resorting to the scientific capabilities of the future Galileo constellation.

gr-qc↗