R-axis — Points outward from the spacecraft origin along its position vectors (with respect to the center of Earth). Measurements along this axis are referred to as radial. S-axis — Completes the right hand coordinate system. This axis points in the direction of the velocity vector, but is only parallel to it for circular orbits.

The nadir [a] [b] is the direction pointing directly below a particular location; that is, it is one of two vertical directions at a specified location, orthogonal to a horizontal flat surface. The direction opposite of the nadir is the zenith .

2015年9月15日 · Considering the case of a nadir-pointing satellite (which naturally applies for GNSS satellites with only few exceptions), the pitch and roll angles vanish and the spacecraft attitude can be fully described by the yaw-angle alone.

2009年1月1日 · In this paper, we study the three-axis attitude stabilization problem for a nadir-pointing spacecraft using only magnetic torquers as actuators. Magnetic attitude control is of great use to small satellites due to its lightweight and low power requirements.

2020年1月3日 · The gravity gradient stabilization scheme can be beneficial for coarse pointing (~5 deg) around the nadir axis, while the other two axes still will need to be stabilized. The oscillations of the nadir-pointing axis are called librations and can be …

CubeSat vehicle pointing mode, specified as Earth (Nadir) Pointing, Sun Tracking, or Custom Pointing. The CubeSat vehicle uses the pointing mode for precise attitude control. For no attitude control, select Standby (Off). Programmatic Use

2020年8月1日 · Based on the derived model, the nadir-pointing control problem is formulated and an adaptive attitude control law with parameter identification is developed. In the proposed control law, periodic angular reference signal is exerted firstly to tune the adaptive parameters, and the misalignments of the rotational component are identified ...

forces can always keep a specific spacecraft axis nadir pointing. This is achieved by using a boom extending a small distinct mass (usually a magnetometer in order to

2022年10月1日 · This paper proposes a novel nadir-pointing guidance method for satellites constrained by the deviation of sun-pointing, to ensure the attitude of the satellite steering smoothly. The main idea of establishing the expected attitude contains two steps.

2016年6月30日 · Abstract: A low-cost attitude determination and control system (ADCS) is proposed for nadir-pointing control. This system comprises three-axis magnetorquers and magnetometers. The aim for developing this system is to establish a nadir-pointing control method using only low-cost spacecraft components for active control.