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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 60,000 years (57,617 BC). The record minimum distance between Earth and Mars in 2729 will stand at 55.65 million km.
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).
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.
A Martian year is equal to 1.8809 Earth years, or 1 year, 320 days, and 18.2 hours. [2] The gravitational potential difference and thus the delta-v needed to transfer between Mars and Earth is the second lowest for Earth. [186] [187] The axial tilt of Mars is 25.19° relative to its orbital plane, which is similar to the axial tilt of Earth. [2]
Mars Year 1 is the first year of Martian timekeeping standard developed by Clancy et al. [1] originally for the purposes of working with the cyclical temporal variations of meteorological phenomena of Mars, but later used for general timekeeping on Mars. Mars Years have no officially adopted month systems.
The maps below were produced by the Mars Global Surveyor ' s Mars Orbiter Laser Altimeter; redder colors indicate higher elevations.The maps of the equatorial quadrangles use a Mercator projection, while those of the mid-latitude quadrangles use a Lambert conformal conic projection, and the maps of the polar quadrangles use a polar stereographic projection.
The primary mission was to begin on November 23, 1993, collecting data during one Martian year (approximately 687 Earth days). The first global map was expected to be completed on December 16, followed by solar conjunction beginning on December 20, and lasting for nineteen days, ending on January 3, 1994; during this time, mission operations ...
Substituting the mass of Mars for M and the Martian sidereal day for T and solving for the semimajor axis yields a synchronous orbit radius of 20,428 km (12,693 mi) above the surface of the Mars equator. [3] [4] [5] Subtracting Mars's radius gives an orbital altitude of 17,032 km (10,583 mi). Two stable longitudes exist - 17.92°W and 167.83°E.