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Tundra and Molniya orbits are used to provide high-latitude users with higher elevation angles than a geostationary orbit.This is desirable as broadcasting to these latitudes from a geostationary orbit (above the Earth's equator) requires considerable power due to the low elevation angles, and the extra distance and atmospheric attenuation that comes with it.
Low Earth orbit (LEO): geocentric orbits with altitudes below 2,000 km (1,200 mi). [7] Medium Earth orbit (MEO): geocentric orbits ranging in altitude from 2,000 km (1,200 mi) to just below geosynchronous orbit at 35,786 kilometers (22,236 mi). Also known as an intermediate circular orbit.
One complete orbit takes 365.256 days (1 sidereal year), during which time Earth has traveled 940 million km (584 million mi). [2] Ignoring the influence of other Solar System bodies, Earth's orbit, also called Earth's revolution, is an ellipse with the Earth–Sun barycenter as one focus with a current eccentricity of 0.0167. Since this value ...
A highly elliptical orbit (HEO) is an elliptic orbit with high eccentricity, usually referring to one around Earth. Examples of inclined HEO orbits include Molniya orbits , named after the Molniya Soviet communication satellites which used them, and Tundra orbits .
A geostationary orbit, also referred to as a geosynchronous equatorial orbit [a] (GEO), is a circular geosynchronous orbit 35,786 km (22,236 mi) in altitude above Earth's equator, 42,164 km (26,199 mi) in radius from Earth's center, and following the direction of Earth's rotation.
Relatively early in its history, Mars lost its magnetic field, which allowed the solar wind to claw away most of its atmosphere; with that, much of the water sublimed into space.
Extra-close oppositions of Mars happen every 15 to 17 years, when we pass between Mars and the Sun around the time of its perihelion (closest point to the Sun in orbit). The minimum distance between Earth and Mars has been declining over the years, and in 2003 the minimum distance was 55.76 million km, nearer than any such encounter in almost ...
Mars retrograde is as confused as it is confusing. It’s unmooring and can bring waves of utterly unexpected events. You probably don’t need a recap, but let’s take a look at some of what’s ...