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We propose a new multi-moment numerical solver for hyperbolic conservation laws by using the alternating polynomial reconstruction approach. Unlike existing multi-moment schemes, our approach updates model variables by implementing two polynomial reconstructions alternately. First, Hermite interpolation reconstructs the solution within the cell by matching the point-based variables containing both physical values and their spatial derivatives. Then the reconstructed solution is updated by the Euler method. Second, we solve a constrained least-squares problem to correct the updated solution to preserve the conservation laws. Our method enjoys the advantages of a compact numerical stencil and high-order accuracy. Fourier analysis also indicates that our method allows a larger CFL number compared with many other high-order schemes. By adding a proper amount of artificial viscosity, shock waves and other discontinuities can also be computed accurately and sharply without solving an approximated Riemann problem.

Star sensors play an important role in spacecraft attitude determination. It is common for the roll accuracy of a traditional star sensor with single field of view to be significantly worse than the cross-axis accuracy. Many satellites utilize two/three onboard star cameras for their attitude determination in x, y, z 3-axis. The dual-field-of-view star sensor has been proposed, which can image stars from two orthogonal directions on the same CCD simultaneously. This paper focuses on the critical issue of tagging the star spots from one of the fields of view so that these stars can be recognized. Star light from one direction is modulated by an optical grating in order to tag star images from this viewing field and distinguish them from the star images from another direction. Diffraction splits by phase gratings and amplitude gratings are compared in feasibility and complexity by numerical simulations.