Lecture

Orbital Parameters and Calendars

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Description

This lecture covers the classical orbital parameters used in space mission design and operations, including inclination, longitude of ascending node, and argument of periapsis. It also explains the spacecraft's state vector and the difference between mean solar day and sidereal day. Additionally, it discusses Gregorian days versus Julian days and the conversion between them.

In MOOC

Space Mission Design and Operations

Space exploration is a very exciting subject. Consider the achievements of Sputnik 1, Yuri Gagarin's first flight in space, the Apollo missions to the Moon, followed by the Shuttle program, the Hubble Space Telescope launch and maintenance on orbit, and finally the assembly and exploitation of the International Space Station. These were challenging undertakings involving space agencies and industrial teams of several nations, and private companies as well. Space telescopes are in service, and several compon

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Ontological neighbourhood

Astronomy

Astrodynamics: Topics in astrodynamics

Planetary science: Atmosphere

Related concepts (32)

Orbital elements

Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are considered in two-body systems using a Kepler orbit. There are many different ways to mathematically describe the same orbit, but certain schemes, each consisting of a set of six parameters, are commonly used in astronomy and orbital mechanics. A real orbit and its elements change over time due to gravitational perturbations by other objects and the effects of general relativity.

Argument of periapsis

The argument of periapsis (also called argument of perifocus or argument of pericenter), symbolized as ω, is one of the orbital elements of an orbiting body. Parametrically, ω is the angle from the body's ascending node to its periapsis, measured in the direction of motion. For specific types of orbits, terms such as argument of perihelion (for heliocentric orbits), argument of perigee (for geocentric orbits), argument of periastron (for orbits around stars), and so on, may be used (see apsis for more information).

Longitude of the periapsis

In celestial mechanics, the longitude of the periapsis, also called longitude of the pericenter, of an orbiting body is the longitude (measured from the point of the vernal equinox) at which the periapsis (closest approach to the central body) would occur if the body's orbit inclination were zero. It is usually denoted π. For the motion of a planet around the Sun, this position is called longitude of perihelion π, which is the sum of the longitude of the ascending node Ω, and the argument of perihelion ω.

Longitude of the ascending node

The longitude of the ascending node (☊ or Ω) is one of the orbital elements used to specify the orbit of an object in space. It is the angle from a specified reference direction, called the origin of longitude, to the direction of the ascending node, as measured in a specified reference plane. The ascending node is the point where the orbit of the object passes through the plane of reference, as seen in the adjacent image.

Orbit

In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a planet, moon, asteroid, or Lagrange point. Normally, orbit refers to a regularly repeating trajectory, although it may also refer to a non-repeating trajectory.

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