71 research outputs found
Constraining the Nordtvedt parameter with the BepiColombo Radioscience experiment
BepiColombo is a joint ESA/JAXA mission to Mercury with challenging
objectives regarding geophysics, geodesy and fundamental physics. The Mercury
Orbiter Radioscience Experiment (MORE) is one of the on-board experiments,
including three different but linked experiments: gravimetry, rotation and
relativity. The aim of the relativity experiment is the measurement of the
post-Newtonian parameters. Thanks to accurate tracking between Earth and
spacecraft, the results are expected to be very precise. However, the outcomes
of the experiment strictly depends on our "knowledge" about solar system:
ephemerides, number of bodies (planets, satellites and asteroids) and their
masses. In this paper we describe a semi-analytic model used to perform a
covariance analysis to quantify the effects, on the relativity experiment, due
to the uncertainties of solar system bodies parameters. In particular, our
attention is focused on the Nordtvedt parameter used to parametrize the
strong equivalence principle violation. After our analysis we estimated
which is about 1~order of magnitude
larger than the "ideal" case where masses of planets and asteroids have no
errors. The current value, obtained from ground based experiments and lunar
laser ranging measurements, is .
Therefore, we conclude that, even in presence of uncertainties on solar system
parameters, the measurement of by MORE can improve the current precision
of about 1~order of magnitude
Addressing some critical aspects of the BepiColombo MORE relativity experiment
The Mercury Orbiter radio Science Experiment (MORE) is one of the experiments
on-board the ESA/JAXA BepiColombo mission to Mercury, to be launched in October
2018. Thanks to full on-board and on-ground instrumentation performing very
precise tracking from the Earth, MORE will have the chance to determine with
very high accuracy the Mercury-centric orbit of the spacecraft and the
heliocentric orbit of Mercury. This will allow to undertake an accurate test of
relativistic theories of gravitation (relativity experiment), which consists in
improving the knowledge of some post-Newtonian and related parameters, whose
value is predicted by General Relativity. This paper focuses on two critical
aspects of the BepiColombo relativity experiment. First of all, we address the
delicate issue of determining the orbits of Mercury and the Earth-Moon
barycenter at the level of accuracy required by the purposes of the experiment
and we discuss a strategy to cure the rank deficiencies that appear in the
problem. Secondly, we introduce and discuss the role of the solar
Lense-Thirring effect in the Mercury orbit determination problem and in the
relativistic parameters estimation.Comment: 29 pages, 5 figures. Presented at the Seventh International Meeting
on Celestial Mechanics, San Martino al Cimino (Viterbo, Italy), 3-9 September
201
Nested modalities in astrophysical modeling
In the context of astrophysical modeling at the solar system scale, we investigate the modalities implied by taking into account different levels of detail at which phenomena can be considered. In particular, by framing the analysis in terms of the how-possibly/how-actually distinction, we address the debated question as to whether the degree of plausibility is tightly linked to the degree of detail. On the grounds of concrete examples, we argue that, also in the astrophysical context examined, this is not necessarily the case
The relativity experiment of MORE: global full-cycle simulation and results
BepiColombo is a joint ESA/JAXA mission to Mercury with challenging objectives regarding geophysics, geodesy and fundamental physics. In particular, the Mercury Orbiter Radioscience Experiment (MORE) intends, as one of its goals, to perform a test of General Relativity. This can be done by measuring and constraing the post-Newtonian (PN) parameters to an accuracy significantly better than current one. In this work we perform a global full-cycle simulation of the BepiColombo Radio Science Experiments (RSE) in a realistic scenario, focussing on the relativity experiment but solving simultaneously for all the parameters of interest for RSE in a global least squares fit within a constrained multiarc strategy. The results on the achievable accuracy for each PN parameter will be presented and discussed
Carbonic Anhydrase and Heavy Metals
Carbonic anhydrase (CA; EC 4.2.1.1) is a zinc metalloenzyme catalysing the reversible hydration of CO2 to produce H+ and HCO3−. Its activity is virtually ubiquitous in nature.
The review focuses on one interesting but less investigated aspect of the biochemistry of this metalloenzyme, encompassing several areas of interest from human health to environmental science: the relationships between carbonic anhydrase and heavy metals
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