Reentry Satellite

RE-ENTRY

Author: Sindhuraa Natarajan

Abstract: The trajectory modeling of uncontrolled satellites close to reentry in the atmosphere is still a challenging activity. After a brief overview of the relevance of the risk related to satellite reentries and debris survival down to the ground, the paper describes some of the methods and techniques developed in support of the reentry predictions carried out for civil protection purposes. An appropriate management of the intrinsic uncertainties of the problem is in fact critical for the dissemination of the information, avoiding, as much as possible, misunderstandings and unjustified alarm. Tracking data may be sparse and not particularly accurate, the objects’ complicate shape and unknown attitude evolution may render difficult the aerodynamic computations and, last but not the least, the models used to predict the air density at the altitudes of interest, as a function of solar and geomagnetic activity, are affected by significant uncertainties. Satellites don't have to stay up in Earth's orbit forever. Old satellites sometimes fall back to Earth. Because of the harsh conditions of re-entry, they can severely burn up on their way down. However, some of them can survive the fall and hit the Earth's surface. In controlled falls, engineers manipulate the propulsion systems on a satellite to make it fall in a safe place, like the ocean. Special attention is paid to the evaluation of the risk, the Thermal protection systems, the Reentry vehicle design consideration, and the definition of reentry and risk windows. When possible, the discussion is supported by real data, results and examples, often based on the authors’ direct experience and researches.

SATELLITE

nuclear weapon could be practical they lacked an essential ingredient: an atmospheric reentry technology.

Fig. 1 Reentry of Satellite

In theory, the nation first developing reentry technology had a decisive military advantage, yet it was unclear whether the...