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pioneer 10 acceleration
In message , alistair
writes Dark energy could be causing the anomalous acceleration of pioneer 10. The solar system is surrounded by the spherical Oort cloud.If dark energy consists of particles that flow into the galaxy, the Oort cloud would shield the solar system from those particles.However a gap in the Oort cloud would allow some dark energy particles to flow into the solar system. Dark energy accounts for up to 70 per cent of the mass of the universe and the universe has an approximate average mass density of 10 ^ -27 kg/ m^3.So, as an approximation, dark energy has a mass density of about 10 ^ -27 kg/ m^ 3 too.If dark energy particles move at close to the speed of light then 10 ^ -27 kg of them will move through one metre in 10 ^ -8 seconds. The particles will have a total momentum of 10 ^ -27 x 10 ^ 8 = 10 ^ -19. The maximum force the particles can exert in 10 ^ -8 seconds on one square metre of pioneer 10 is given by Force = rate of change of momentum / time Force = (10 ^ -19 minus 0 ) / 10 ^ - 8 = 10 ^ -11 Newtons. Now assuming pioneer 10 has an area facing the direction of travel of the dark energy particles through the Oort cloud and that area is at most 100 square metres (perhaps someone on sci.physics.research knows the exact area!) then the total force on pioneer 10 due to dark energy is 10 ^ -11 x 100 Newtons = 10 ^ - 9 Newtons.Since acceleration = force / mass and assuming pioneer 10 has a mass of about 1000 kg ( again, perhaps someone on sci.physics.research can put an exact figure to this), then the acceleration of pioneer 10 towards the sun caused by dark energy particles would be about 10 ^ - 9 / 1000 = 10 ^ -12 m / s ^2.The figure Nasa gives is 10 ^ -10 m / s ^2. If the exact mass and area of pioneer 10 are used, the answer given for the acceleration of pioneer 10 due to dark energy flowing through a gap in the Oort cloud could well be a lot closer to the value Nasa gives. There are a few problems with this idea :-) The paper by Anderson et al. which everyone cites is available online at http://xxx.lanl.gov/abs/gr-qc/0104064. It has figures for the mass of the Pioneers (223 kg dry mass) and their surface area (or at least that of the dish antenna, which accounts for nearly all of it. It's a 2.74 meter dish giving an area of 5.9 square meters. Also, the two Pioneers are going in nearly opposite directions. If you want to try your idea on Galileo, the launch mass (which includes 925 kg of propellant) was 2223 kg and the area was 19.5 square meters - mostly sunshade and RTGs as the main antenna notoriously failed to deploy :-( -- What have they got to hide? Release the full Beagle 2 report. Mail to jsilverlight AT merseia.fsnet.co.uk is welcomed. |
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