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0712.3934[abs pdf]
- Title:
A critical analysis of the GP-B mission. I: on the impossibility of a
reliable measurement of the gravitomagnetic precession of the GP-B gyroscopes
Authors:
G. Forst
In this paper we discuss the impossibility for the Gravity Probe B (GP-B)
experiment to provide a clean and undisputable test of the gravitomagnetic
precession of its four gyroscopes and of the Lense-Thirring effect.
Lense-Thirring effect and geodetic precession have already been measured by
Lunar Laser Ranging (LLR), laser ranged satellites, binary pulsars and
accretion disks of black holes and neutron stars. In this paper we show that in
the GP-B experiment there are critical problems for measuring Lense-Thirring
effect and geodetic precession by the GP-B data analysis. The GP-B data
analysis is extremely model dependent and relies on the assumptions about the
unknown quadrupole moment induced by the gyroscopes rotation, both: (I) its
size and (II) its direction with respect to the quadrupole moment due to
fabrication and (III) its unknown rate of change due to variations of the
gyroscopes rotation rate. The huge systematic biases in the GP-B data amount to
about 1000 milliarcsec/year, but the GP-B team has claimed to be able to model
90 % of this signal, thus leaving the systematic biases at the level of about
100 milliarcsec per year, that is $\sim 300 %$ of the Lense-Thirring effect
effect of the GP-B gyroscopes; any further modelling will result in a rough
test of Lense-Thirring effect that will be highly model dependent and extremely
affected by other huge unknown systematic biases. In this paper we show that
such claims are necessarily highly model dependent and then are very much
affected by huge unknown systematic biases. We give an important example of
these systematic biases of which there is no mention in the discussions of the
GP-B team.
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| WuBo [2009-07-30 08:54:50] |
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