Stability Analysis for Equivalent Circular Cylindrical Shell

Ring truss antenna is an ideal structure for large satellite antenna, which can be equivalent to circular cylindrical shell model. Based on the high-dimensional nonlinear dynamic vibration and bifurcation theory, we focus on the nonlinear dynamic behavior for breathing vibration system of ring truss antenna with internal resonance. The nonlinear transformation and Routh-Hurwitz criterion are used to analyze the stability of equilibrium point after disturbance, and the theoretical analysis is verified by numerical simulation. It provides a reference to ensure the stability and control parameters of satellite antenna in complex space environment.

Emerging Trends of Space-Based Wireless Sensor Network and Its Applications

There is a great demand in space and earth observations applications. Traditional satellite missions have complex design architecture involving high cost in design, operation, launch and maintenance. Thus single large satellite is replaced by multiple, small satellites with distributed network, collaboratively performing the same functionality of large satellite. This has been motivated researchers to explore the application of terrestrial Wireless Sensor Network (WSN) to space. The main objective of using space based WSN is to have full power of remote sensing capabilities at all the relevant time horizons and geographical scales with high performance and low cost. It also strives for an optimal solution that gratifies the standards, sizes, air interfaces, network architecture, access schemes, fault tolerance, operating system, hardware components of on-board diagnostics etc. This chapter discusses the characteristics and challenges of Space-Based Wireless Sensor Network (SWSN).

The fast rotation of Orcus obtained from TESS measurements

<p>(90482) Orcus is one of the largest Kuiper belt objects, with one known, relatively large satellite, Vanth. There have been several ~10-20h rotation periods reported in the literature for Orcus, with considerable uncertainty. Here we report on recent measurements of Orcus with the TESS Space Telescope providing a light curve period of 7 h, the fastest rotation among those large trans-Neptunian objects for which the rotation is not expected to cause a distorted, triaxial ellipsoid shape, like in the case of Haumea. While moons of large Kuiper belt objects are usually assumed to be formed from an original large body via collisions, the fast rotation may point to a scenario in which Vanth was captured from a nearby heliocentric orbit early in the history of the Solar system, and subsequent tidal evolution led to the present, nearly circular orbit. In this sense the Orcus-Vanth system is peculiar, as the present rotational characteristics and satellite orbits of all other large Kuiper belt objects are consistent with a collisional origin. </p>

Equilibrium models of the Milky Way mass are biased high by the LMC

ABSTRACT Recent measurements suggest that the Large Magellanic Cloud (LMC) may weigh as much as 25 per cent of the Milky Way (MW). In this work, we explore how such a large satellite affects mass estimates of the MW based on equilibrium modelling of the stellar halo or other tracers. In particular, we show that if the LMC is ignored, the MW mass within 200 kpc is overestimated by as much as 50 per cent. This bias is due to the bulk motion in the outskirts of the Galaxy’s halo and can be, at least in part, accounted for with a simple modification to the equilibrium modelling. Finally, we show that the LMC has a substantial effect on the orbit Leo I which acts to increase its present-day speed relative to the MW. We estimate that accounting for a $1.5\times 10^{11} \, \mathrm{M}_\odot$ LMC would lower the inferred MW mass to $\sim 10^{12} \, \mathrm{M}_\odot$.