Orbit MFD

Orbit is an MFD mode which is included in the Orbiter Space Flight Simulator. This mode displays a graphic representing a central body, the orbit of the pilot's ship, and the orbit of a target body, and also includes orbital parameters and elements of those orbits. The pilot can select Orbit from the MFD mode selection page.

Orbit MFD displays the osculating orbits at the current epoch (its 2-body orbit) with respect to a celestial body. The orbital parameters may change over time due to perturbations from other gravity sources, nonspherical gravity, atmospheric drag, and thruster action, etc. Any celestial body in the current session can be selected as the reference body.

Orbital elements and graphic display is displayed in one of two frames of reference, Ecliptic (ECL) or Equatorial (EQU) by selecting the FRM button or Shift+F. The current frame is displayed on the top line of the MFD display near the right corner.

Any celestial body may be selected as the reference body by selecting the REF button or Shift+R, displaying a pop-up window where the pilot may select the reference body. Selecting the NT button or Shift+A will autoselect the reference body having the highest gravitational influence on the ship.

The display may project a plane to be projected onto the MFD display by selecting PRJ or Shift+P. Four planes may be selected: Ecliptic (ECL), Equatorial (EQU), the focus ship (SHP), or target ship or celestial body (TGT).

Distance from the focus body may be displayed from the center of the body, indicated by Rad, ApR, PeR, or from the altitude of the mean radius of the body, indicated by Alt, ApA, PeA, by selecting the DTS button or Shift+D.

The orbit of a target ship or body orbiting the same body as the pilot's ship may be selected with the TGT button or Shift+T. The NT button or Shift+N turns off the target orbit and data.

Selecting the HUD button or Shift+H will set the HUD to Orbit MFD mode and copy the orbit reference object.

Key Options
MFD button	Keypress	Description
AR	Shift+A	Autoselect the reference body.
DST	Shift+D	Toggle planetocentric distance or altitude above mean radius
FRM	Shift+F	Toggle frame of reference (ecliptic or reference object equator)
HUD	Shift+H	Set HUD to Orbit mode and copy the current MFD orbit reference object
MOD	Shift+M	Toggle display mode (reference frame, ship's orbital plane, target orbital frame) will show central body with ship's orbit and target orbit if selected; orbital data; both
NT	Shift+N	No target orbit
PRJ	Shift+P	Toggle projection mode of orbit (reference frame, ship's orbital plane, target orbital plane
REF	Shift+R	Select new reference object (celestial object) or orbital data
TGT	Shift+T	Open popup menu to select a target

MFD display components
!Parameter	Nomenclature	Description
SMa	Semimajor axis	longest semi-diameter of the orbit Periapsis + Apoapsis
SMi	Semiminor axis	shortest semi-diameter of the orbit
PeR PeA	Periapsis Radius Periapsis Altitude	Lowest point of the orbit
ApR ApA	Apoapsis Radius Apoapsis Altitude	Highest point of the orbit
Rad Alt	Radius Altitude	Radius from the center of the body Altitude from body mean radius
Ecc	Eccentricity	Circularity of the orbit (0-1)
T	Orbit Period	Time in seconds for one orbit
PeT	Periapsis Time	Time in seconds until the next Periapsis
ApT	Apoapsis Time	Time in seconds until the next Apospsis
Vel	Velocity	Velocity of the ship or target in km/sec
Inc	Inclination	Angle (°) at which orbit deviates from the ecliptic or equator
LAN	Longitude of the Ascending Node	Angle in degrees (°) of the orbit from the Vernal Equinox
LPe	Longitude of Periapsis	Angle (°) along the reference plane from the Vernal Equinox to the Periapsis
AgP	Argument of Periapsis	Angle (°) from the ascending node to the periapsis
TrA	True Anomaly	Angle (°) from the Periapsis to the ship's or target's location along the orbit
TrL	True Longitude
MnA	Mean Anomaly
MnL	Mean Longitude