Scott Manley YouTube Index

OrbitMFD is a multi-functional display that is included in the Orbiter basic package. The MFD displays the central body about which the ship is orbiting, the orbit of the ship as well as the orbit of another ship, space station, or natural body in orbit around the same body. The MFD also displays various orbital elements and parameters of the ship and can also display the elements and parameters of the other aforementioned body.

Display

By default, the body which has the highest gravitational influence on the vessel is the reference body, so, in LEO, the earth would be the reference body as it has the most influence on the vessel. The user can select other reference bodies (any natural body in the simulator) by selecting the REF button and selecting other bodies in the popup menu. The reference body is shown as a gray circle.

The orbits displayed are the orbit of the ship of focus (in green) and the target body (in yellow). The figures on the left column represent orbital parameters for the ship, the figures on the right represent orbital parameters for the target body, station, or vessel. If the ship's orbit intersects and goes below the circle representing the body, the ship is in a suborbital trajectory and will collide with the body unless action is taken. It is shown as an elliptical orbit as if the body is a point mass with the same mass. If the eccentricity of the ship's orbit is greater than 1, the orbit is shown as a hyperbola or may appear as a straight line if the eccentricity as very much greater than 1.

The orbits will also show an open circle representing the apoapsis and a solid circle representing the periapsis of the orbit. If a target is selected, the target orbit will show the line of nodes between the two orbits.

Display Modes

Orbital Elements displayed are:

MFD Label	Element	Unit of Measure	Description
SMa	Semimajor Axis	m, km, AU	One-half the sum of the major diameter (Apoapsis and Periapsis). If Ecc ≥ 1, SMa will show a negative number
SMi	Semiminor Axis	m, km, AU	One-half of the minor axis
PeR PeA	Periapsis Radius Periapsis Distance	m, km, AU	Radial distance from the center of the reference body to the low point of the orbit Radial distance from the surface of the body to the low point of the orbit
ApR ApA	Apoapsis Radius Apoapsis Distance	m, km, AU	Distance from the center of the reference body to the high point of the orbit Radial distance from the surface of the body to the high point of the orbit
Rad Alt	Radius Vector Altitude	m, km, AU	Radial distance from the center of the reference body to the vessel Radial distance from the surface of the reference body to the vessel
Ecc	Eccentricity	0 - ∞	Measure of how circular or non-circular the orbit is. Circle = 0, ellipse = >0 to <1, Parabola = 1, Hyperbola >1
T	Orbital Period (Time)	Seconds	How long it takes to make one revolution
PeT	Time to next Perapsis	Seconds	How long until the next periapsis, if past the periapsis
ApT	Time to next Apoapsis	Seconds	How long until the next apoapsis, if Ecc ≥ will show N/A
Vel	Velocity	m/s	How fast the body is going
Inc	Inclination	Degrees (°)	Vertical tilt of orbit in reference to the ecliptic or the equator of the reference body
LAN	Longitude of Ascending Node	Degrees (°)	Horizontal orientation of the line of ascending node with respect to the vernal equinox
LPe	Longitude of Periapsis	Degrees (°)	Angle measured from the vernal equinox to the peiapsis as if the inclination is zero
AgP	Argument of Periapsis	Degrees (°)	Angle measured from the ascending node to the periapsis
TrA	True Anomaly	Degrees (°)	Position of the body along the orbit from the periapsis
TrL	True Longitude	Degrees (°)	Position of the body along the ecliptic from the vernal equinox
MnA	Mean Anomaly	Degrees (°)	Ficticious position of the body along the orbit from the perapsis as if it was moving at a constant velocity
MnL	Mean Longitude	Degrees (°)	Ficticious position of the body along the orbit from the perapsis as if it was moving at a constant velocity
G	Gravity contributiion		Releative fraction of gravity of the reference body to the total gravitational field of the vessel