BSTAR

Article summary

BSTAR is a way of modeling aerodynamic drag on a satellite in the simplified general perturbation model 4 satellite orbit propagation model. Traditionally, aerodynamic resistance ("drag") is given by : F_\text{D} = \frac{1}{2} \rho C_\text{d} A v^2 where \rho is the air density, C_\text{d} is the drag coefficient, A is the frontal area, and v is the velocity. The acceleration due to drag is then : a_\text{D} = \frac{F_\text{D}}{m} = \frac{\rho C_\text{d} A v^2}{2m} In aerodynamic theory, the factor : B = \frac{C_\text{d} A}{m} is the inverse of the ballistic coefficient, and its unit is area per mass. Further incorporating a reference air density and the factor of two in the denominator, we get the starred ballistic coefficient: : B^* = \frac{\rho_0 B}{2} = \frac{\rho_0 C_\text{d} A}{2m} thus reducing the expression for the acceleration due to drag to : a_\text{D} = \frac{\rho}{\rho_0} B^* v^2 As it can be seen, B^* has a unit of inverse length. For orbit propagation purposes, there is a field for BSTAR drag in two-line element set (TLE) files, where it is to be given in units of inverse Earth radii. The corresponding reference air density is given as 0.15696615\text{ kg}/(\mathrm{m}^2 \cdot R_\text{Earth}) .…

Key claims

1. area: 2m — source: Wikipedia · confidence 0.95

Discussion questions

1. Summarise the article in your own words. Which single claim would you verify first, and why?
2. The record states that the area is "2m". What evidence would count against this claim?
3. Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
4. If two sources disagreed about one of these facts, what would you need in order to trust one over the other?

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