Tangential YORP, or TYORP, has recently been demonstrated to be an important factor in the evolution of an asteroids rotation state. It is complementary to normal YORP, or NYORP, which used to be considered previously. While NYORP is produced by non-
symmetry in the large-scale geometry of an asteroid, TYORP is due to heat conductivity in stones on the surface of the asteroid. Yet to date TYORP has been studied only in a simplified 1-dimensional model, substituting stones by high long walls. This article for the first time considers TYORP in a realistic 3-dimensional model, also including shadowing and self-illumination effects via ray tracing. TYORP is simulated for spherical stones lying on regolith. The model includes only 5 free parameters, and the dependence of the TYORP on each of them is studied. The TYORP torque appears to be smaller than previous estimates from 1-dimensional model, but still comparable to the NYORP torques. These results can be used to estimate TYORP of different asteroids, and also as a basis for more sophisticated models of TYORP.
Given the impressive investment by the nation in observational Astronomy and Astrophysics facilities coming on line now and in the near future, we advocate for an increased investment in applied and fundamental research on Astrophysical and Celestial
Dynamics (ACD). Specifically we call for a) continued and expanded support for applied research in ACD, b) creation of support for fundamental research in ACD and its subfields, and c) the creation of a unified program to help scientists coordinate and collaborate in their research in these fields. The benefits of this proposal are threefold. First, it will enable researchers to interpret and understand the implications of newly observed phenomena that will invariably arise from new facilities and surveys. Second, research on fundamentals will foster connections between specialists, leveraging advances found in one sub-field and making them available to others. Third, a coordinated approach for applied and fundamental research in ACD will help academic institutions in the United States to produce future researchers trained and knowledgeable in essential subfields such as Mathematical Celestial Mechanics and able to continue its advancement in conjunction with the increase in observations.
