= KuiperBelt =

|| [[ attachment:fig2a.png | {{ attachment:fig2a.png | | height=300  }} ]] || [[ http://iopscience.iop.org/1538-3881/122/2/1051/pdf/200414.web.pdf | The Structure of the Kuiper Belt: Size Distribution and Radial Extent, Brett Gladman et. al. ]] <<BR>><<BR>> I may be misinterpreting this graph - the legend for this curve is 1 billion years after solar system formation, it is now 4.6 billion years, and the trend for the multiple curves in the original is for low mass objects to merge, pushing the top of the curve downwards.  Many objects will get perturbed into comet trajectories or solar escape.  The "small" (mountain to asteroid sized) objects with small areas will be very difficult to observe, but the [[LSST]] will help find such objects in vast quantities. <<BR>><<BR>> When I get time, I will track down the D. Davis paper. ||

Bottom of page 1065: The disk mass in the observed region out to  ≈60 AU is ≈0.1 M,,earth,, (6e23 kg), only weakly
dependent on the roll-over size and radial distribution.

The Kuiper belt starts at approximately 30 AU;  most is too difficult to observe.

The characteristic light pressure mass density M,,λ,, ( kg/m² ) is  L,,⊙,, / 4π c μ,,⊙,, = 3.846e26 / 4 π 2.99792e8 * 1.32712e20 = 7.45e-4 g/m².  A perfect [[IRfilter | front-side IR filtering ]] back-side emissive thinsat masses 1/3 of that, 2.48e-4 g/m².  Assume some imperfections, 3e-4 kg/m².

A 3e-4 kg/m², 50 AU Dyson shell ( 7.46e12 m, 7e26 m², g,,⊙,, = 2.38e-6 m/s² ) uses 2.1e23 kg of ice and other materials.  Presume we use 10% of that as reaction mass, 2.1e22 kg, total 2.3e22 kg and use the other 3.7e22 as a reserve.   As the sun heats up over the next few billion years, the shell must move further out to stay cool, and the light pressure will increase, so more ice must be mined from the Oort cloud and other ice bodies passing the solar system to continuously add to the mass of the shell.

||                       ||   Pluto  ||     Eris || !MakeMake||
|| Aphelion   AU         ||     49.3 ||     97.7 ||     52.8 ||
|| Perihelion AU         ||     29.7 ||     38.6 ||     37.9 ||
|| Semimajor Axis AU     ||     39.5 ||     68.1 ||     45.3 ||
|| Angular vel. ω  rad/s || 8.05e-10 || 3.56e-10 || 6.56e-10 ||
|| Eccentricity e        ||    0.245 ||    0.434 ||    0.164 ||
|| Velocity v,,o,,   m/s ||     4895 ||     4010 ||     4490 ||
|| Aphelion Velocity m/s ||     3932 ||     2796 ||     3857 ||
|| Perihelion V      m/s ||     6843 ||     7085 ||     5370 ||
|| Orbital period   Gsec ||     7.82 ||     17.6 ||     9.75 ||
|| Inclination degrees   ||     17.4 ||    44.04 ||       29 ||
|| Radius             km ||     1190 ||     1163 ||      715 ||
|| Mass               kg ||   1.3e22 ||  1.66e22 ||          ||
|| Mass           Earths ||   0.0022 ||   0.0028 ||          ||
|| Density         g/cm³ ||     1.84 ||     2.52 ||          ||
|| Escape velocity   m/s ||     1210 ||     1380 ||          ||
|| Gravity          m/s² ||     0.62 ||     0.82 ||          ||
|| Core pressure     GPa ||      0.7 ||      1.2 ||          || WAG ||
|| Rotation period   sec ||   5.52e5 ||          ||          ||
|| Rotation speed    m/s ||       13 ||          ||          ||
|| Axial tilt    degrees ||      120 ||          ||          ||

 . Challenger Deep 110 MPa,  Earth core 350 GPa, Jupiter 4 TPa, Sun 30 PPa
 . Carbon Fiber 1 GPa compression at 300K, 60% better at LN2 temperature