Many applications use the NORAD SGP4 orbital model for predicting satellite ephemerides and often these applications require knowledge of the errors associated with those predictions. Unfortunately, the SGP4 orbital data, in the form of two-line element (TLE) sets, does not provide any kind of accuracy information. Some approaches have been published which purport to estimate these errors by pe...

The Kolmogorov Arnold and Moser (KAM) theorem states that a lightly perturbed Hamiltonian system will have solutions which lie on a torus. Earlier work by the second author has shown that most Earth satellite orbits perturbed by the geopotential lie on KAM tori. The problem then arises as to how to convert the current satellite tracking orbits to KAM tori. A KAM torus is characterized by three ...

As a service to the satellite operator community, the Center for Space Standards & Innovation (CSSI) offers SOCRATES—Satellite Orbital Conjunction Reports Assessing Threatening Encounters in Space. CSSI runs a list of all satellite payloads on orbit against a list of all objects on orbit using the catalog of all unclassified NORAD two-line element sets (TLEs) to look for satellite conjunctions ...

The endogenous retroviral envelope glycoprotein, gp70, implicated in murine systemic lupus erythematosus (SLE), has been considered to be a product of xenotropic, polytropic (PT) and modified PT (mPT) endogenous retroviruses. It is secreted by hepatocytes like an acute phase protein, but its response is under a genetic control. Given critical roles of TLR7 and TLR9 in the pathogenesis of SLE, w...

Based on the archive of TLE data spacecraft, placements Low Earth Orbit spacecraft (Аl-Farabi-2), Medium (BEIDOU-3 M20), and High (IPM 2 & BREEZE-M R/B) were predicted in coordinate form using first set SGP4/SDP4 model Python. The also by STK software. actual above obtained directly parsing their data, errors two prediction methods calculated. Subsequently, compared, similarity error accura...