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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 ...
The length of time for Mars to complete one orbit around the Sun in respect to the stars, its sidereal year, is about 686.98 Earth solar days (≈ 1.88 Earth years), or 668.5991 sols. Because of the eccentricity of Mars' orbit, the seasons are not of equal length.
If the same sphere were made of lead the small body would need to orbit just 6.7 mm above the surface for sustaining the same orbital period. When a very small body is in a circular orbit barely above the surface of a sphere of any radius and mean density ρ (in kg/m 3), the above equation simplifies to (since M = Vρ = 4 / 3 π a 3 ρ)
The equation of time vanishes only for a planet with zero axial tilt and zero orbital eccentricity. [5] Two examples of planets with large equations of time are Mars and Uranus. On Mars the difference between sundial time and clock time can be as much as 50 minutes, due to the considerably greater eccentricity of its orbit.
The basic time periods from which the calendar is constructed are the Martian solar day (sometimes called a sol) and the Martian vernal equinox year.The sol is 39 minutes 35.244 seconds longer than the Terrestrial solar day, and the Martian vernal equinox year is 668.5907 sols in length (which corresponds to 686.9711 days on Earth).
An areosynchronous orbit that is equatorial (in the same plane as the equator of Mars), circular, and prograde (rotating about Mars's axis in the same direction as the planet's surface) is known as an areostationary orbit (AEO). To an observer on the surface of Mars, the position of a satellite in AEO would appear to be fixed in a constant ...
A mission could have a period of 365 days in a year, a few weeks each month, [6] a few weeks every 26 months (e.g. Mars launch periods), [7] or a short period time that won't be repeated. A launch window indicates the time frame on a given day within the launch period that the rocket can launch to reach its intended orbit.
A synchronous orbit around Earth that is circular and lies in the equatorial plane is called a geostationary orbit. The more general case, when the orbit is inclined to Earth's equator or is non-circular is called a geosynchronous orbit. The corresponding terms for synchronous orbits around Mars are areostationary and areosynchronous orbits.