# Orbit-Relative Reference Frames

Creation date: 2019-09-09 18:03:03 Update date: 2019-09-16 20:43:34

Policy: Expert Review

Authority: CCSDS.MOIMS.NAV

OID: 1.3.112.4.57.3

Notes:

This registry contains allowable values for specifying orbit-relative reference frames in the accompanying referenced standards. These frames can be used to specify maneuver and covariance data.
Note that these orbit-relative local reference frames below are provided in two flavors: inertial and rotating. When transforming velocity terms between inertial and rotating frames, remember to properly incorporate the contribution.

## Contents

16 records in registry

#### Label

1.3.112.4.57.3
Orbit-Relative Reference Frames

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Details Status Name Description Others Have Referred To This As References OID

Assigned

EQW_INERTIAL

Equinoctial Coordinate System, a quasi-inertial, right-handed, Cartesian frame with E aligned with the ascending node direction, W along the orbital angular momentum vector ($$\vec{w} = \vec{r} × \vec{v}$$) and Q completing the set ($$\widehat{Q} = \widehat{W} × \widehat{E}$$). This system is quasi-inertial in the sense that it is treated as an inertial coordinate frame that is redefined at each time of interest.

1.3.112.4.57.3.1

Assigned

LVLH_ROTATING

‘LVLH’ stands for ‘Local Vertical Local Horizontal’. The Z-axis of the rotating LVLH frame is a unit vector collinear and opposite sign of the gravicentric satellite position (planet center, spacecraft gravity center), the Y-axis is a unit vector collinear but with the opposite sign of the orbital kinetic momentum (normal to orbit plane), and the X-axis is the unit vector equal to $$\vec{Y} \times \vec{Z}$$ 1.3.112.4.57.3.2

Assigned

LVLH_INERTIAL

A quasi-inertial version of the LVLH_ROTATING frame. This system is quasi-inertial in the sense that it is treated as an inertial coordinate frame that is redefined at each time of interest.

1.3.112.4.57.3.3

Assigned

NSW_ROTATING

“Nadir, Sun, Normal” – This rotating frame aligns the x-axis in the nadir direction, the y-axis as much as possible toward the Sun while still being normal to the x-axis, and the z-axis completing the right-hand set.

1.3.112.4.57.3.4

Assigned

NSW_INERTIAL

A quasi-inertial version of the NSW_ROTATING frame. This system is quasi-inertial in the sense that it is treated as an inertial coordinate frame that is redefined at each time of interest.

1.3.112.4.57.3.5

Assigned

NTW_ROTATING

A local orbital coordinate rotating frame that has the y-axis along the Tangential (or inertial velocity) vector, z-axis (“W”) along the orbital angular momentum vector ($$\vec{w} = \vec{r} × \vec{v}$$), and N (the x-axis) completing the right handed system (i.e., for a circular orbit “N” generally points in the radial direction and for an eccentric orbit, “N” points as close to radial as possible while still being normal to the T-W plane).

Transverse-Velocity-Normal (TVN) frame (e.g., CCSDS CDM Blue Book 508.0-B-1).

1.3.112.4.57.3.6

Assigned

NTW_INERTIAL

A quasi-inertial version of the NTW_ROTATING frame. This system is quasi-inertial in the sense that it is treated as an inertial coordinate frame that is redefined at each time of interest.

1.3.112.4.57.3.7

Assigned

PQW_INERTIAL

Perifocal Coordinate System, a quasi-inertial frame with P axis pointing to periapsis, W along the orbital angular momentum vector ($$\vec{w} = \vec{r} × \vec{v}$$) and Q completing the set ($$\widehat{Q} = \widehat{W} × \widehat{P}$$). This system is quasi-inertial in the sense that it is treated as an inertial coordinate frame that is redefined at each time of interest.

1.3.112.4.57.3.8

Assigned

RSW_ROTATING

A Radial, Along track, Cross track, local orbital coordinate rotating frame, where the R axis always points out from the satellite along the central body’s radius vector to the satellite as it moves through the orbit. The S axis is in the direction of (but not necessarily parallel to) the velocity vector and is perpendicular to the radius vector. The W axis is aligned with the orbit angular momentum vector.

Note that the RSW_ROTATING frame is also referred to as:
• Gaussian Coordinate System
• ‘Radial, In-track, Cross-track” (RIC)
• ‘Radial, Transverse, Normal’ (RTN)
• The QSW frame • Gaussian Coordinate System
• ‘Radial, In-track, Cross-track” (RIC)
• ‘Radial, Transverse, Normal’ (RTN)
• The QSW frame

1.3.112.4.57.3.9

Assigned

RSW_INERTIAL

A quasi-inertial version of the RSW_ROTATING frame. This system is quasi-inertial in the sense that it is treated as an inertial coordinate frame that is redefined at each time of interest.

• ‘Radial, Down-track, Cross-track’ (UVW)
• ‘Radial, Transverse, Normal’ (RTN), as interpreted by the US Air Force in generation of Conjunction Data Messages per CCSDS CDM Blue Book 508.0-B-1.

1.3.112.4.57.3.10

Assigned

TNW_ROTATING

A local orbital coordinate Tangential, Normal, Cross-track rotating frame that has the x-axis along the Tangential (or velocity) vector, z-axis (“W”) along the orbital angular momentum vector ($$\vec{w} = \vec{r} × \vec{v}$$), and N completing the right handed system (i.e., for a circular orbit “N” generally points in the Nadir direction and for an eccentric orbit, “N” points as close to Nadir as possible while still being normal to the T-W plane). Note that while this frame has the same axes defined as in the NTW frame, the ordering of axes is different (TNW). 1.3.112.4.57.3.11

Assigned

TNW_INERTIAL

A quasi-inertial version of the TNW_ROTATING frame. This system is quasi-inertial in the sense that it is treated as an inertial coordinate frame that is redefined at each time of interest.

1.3.112.4.57.3.12

Assigned

SEZ_ROTATING

The South/East/Zenith (SEZ) topocentric horizon system. This system is a right-handed, Cartesian system rotating with the observing site. The local horizon forms the fundamental plane, with the S axis pointing due south from the site (even in the Southern Hemisphere). The E axis points east from the site and is undefined at the North or South Poles. The Z axis (zenith) points radially outward from the site, along the site’s geodetic local vertical.

1.3.112.4.57.3.13

Assigned

SEZ_INERTIAL

A quasi-inertial version of the SEZ_ROTATING frame. This system is quasi-inertial in the sense that it is treated as an inertial coordinate frame that is redefined at each time of interest.

1.3.112.4.57.3.14

Assigned

VNC_ROTATING

A local orbital coordinate Velocity, Normal, Co-normal rotating frame that has the x-axis along the Velocity (or tangential) vector, y-axis Normal to the orbit along the orbital angular momentum vector ($$\vec{w} = \vec{r} × \vec{v}$$), and z-axis is the “Co-normal” direction completing the right handed system (i.e., for a circular orbit “C” points in the radius vector direction whereas for an eccentric orbit, “C” points as close to radial as possible while still being normal to the V-N plane). Note that while this frame has the same axes defined as in the NTW frame, the ordering of axes is different (i.e., TWN).

‘Velocity, Normal, Bi-normal’ (VNB) x-axis along the Velocity (or tangential) vector, y-axis Normal to the orbit along the orbital angular momentum vector ($$\vec{w} = \vec{r} × \vec{v}$$), and z-axis is the “Bi-normal” direction completing the right handed system.

1.3.112.4.57.3.15

Assigned

VNC_INERTIAL

A quasi-inertial version of the ‘Velocity, Normal, Co-normal’ VNC_ROTATING frame. This system is quasi-inertial in the sense that it is treated as an inertial coordinate frame that is redefined at each time of interest.

‘Velocity, Normal, Bi-normal – quasi-inertial’ (VNQ), as used by NASA/JSC

1.3.112.4.57.3.16