Frederico Francisco

Thermal Analysis of the Pioneer Anomaly: A Method to estimate radiative momentum transfer

We present a methodology based on pointlike Lambertian sources that enables one to perform a reliable and comprehensive estimate of the overall thermally induced acceleration of the Pioneer 10 and 11 spacecraft. We show, by developing a sensitivity analysis of the several parameters of the model, that one may achieve a valuable insight into the possible thermal origin of the so-called Pioneer anomaly.

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.

Modeling 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

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

(3.01 \pm 0.33) \times 10^{-9} {\rm m/s^2}

A physical framework for the earth system, Anthropocene equation and the great acceleration

. This result is in close agreement with the estimates of this effect performed through Doppler data analysis.

Estimating the thermally induced acceleration of the New Horizons spacecraft

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.

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

Abstract 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 at the future 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 Earths Holocene equilibrium.

Estimating Radiative Momentum Transfer Through a Thermal Analysis of the Pioneer Anomaly

Residual accelerations due to thermal effects are estimated through a model of the New Horizons spacecraft and a Monte Carlo simulation. We also discuss and estimate the thermal effects on the attitude of the spacecraft. The work is based on a method previously used for the Pioneer and Cassini probes, which solve the Pioneer anomaly problem. The results indicate that after the encounter with Pluto there is a residual acceleration of the order of

OSS (Outer Solar System): A fundamental and planetary physics mission to Neptune, Triton and the Kuiper Belt

10^{-9}~\mathrm{m/s^2}

On small satellites for oceanography: A survey

, and that rotational effects should be difficult, although not impossible, to detect.