Orbital Mechanics & Spacecraft Operations Flashcards

What is the orbital period of a geostationary satellite?

Answer: 23 hours 56 minutes

A geostationary satellite has a sidereal period of approximately 23 hours 56 minutes (one sidereal day), which keeps it fixed over a point on the equator.

At what altitude do geostationary Earth orbit (GEO) satellites operate?

Answer: 35,786 km

GEO satellites orbit at approximately 35,786 km above the equator, where their orbital period matches Earth's rotation.

Which orbital parameter describes the shape of a satellite's orbit?

Answer: Eccentricity

Eccentricity defines the shape of the orbit, with 0 being a perfect circle and values approaching 1 representing increasingly elongated ellipses.

What is the purpose of a Hohmann transfer orbit?

Answer: To efficiently move a satellite between two circular orbits

A Hohmann transfer orbit uses two engine burns to move a spacecraft between two circular orbits using an intermediate elliptical path, minimizing propellant use.

Which Keplerian element defines the tilt of a satellite's orbital plane relative to the equator?

Answer: Inclination

Inclination is the angle between the orbital plane and Earth's equatorial plane, ranging from 0° (equatorial) to 90° (polar) and beyond.

What causes a satellite in low Earth orbit to gradually lose altitude over time?

Answer: Atmospheric drag

Residual atmospheric drag in LEO continuously removes orbital energy, causing the satellite to spiral inward and eventually re-enter the atmosphere.

What is the semi-major axis of an orbit?

Answer: Half the longest diameter of the elliptical orbit

The semi-major axis is half of the longest dimension (major axis) of the ellipse and is directly related to the orbital period via Kepler's third law.