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Mars comes closer to Earth more than any other planet save Venus at its nearest—56 million km is the closest distance between Mars and Earth, whereas the closest Venus comes to Earth is 40 million km. Mars comes closest to Earth every other year, around the time of its opposition, when Earth is sweeping between the Sun and Mars. Extra-close ...
The maximum angular separation of the Earth and Moon varies considerably according to the relative distance between the Earth and Mars: it is about 25′ when Earth is closest to Mars (near inferior conjunction) but only about 3.5′ when the Earth is farthest from Mars (near superior conjunction). For comparison, the apparent diameter of the ...
Several factors make placing a spacecraft into an areostationary orbit more difficult than a geostationary orbit. Since the areostationary orbit lies between Mars's two natural satellites, Phobos (semi-major axis: 9,376 km) and Deimos (semi-major axis: 23,463 km), any satellites in the orbit will suffer increased orbital station keeping costs due to unwanted orbital resonance effects.
Mars's average distance from the Sun is roughly 230 million km (143 million mi), and its orbital period is 687 (Earth) days. The solar day (or sol ) on Mars is only slightly longer than an Earth day: 24 hours, 39 minutes, and 35.244 seconds. [ 185 ]
The diagram shows a Hohmann transfer orbit to bring a spacecraft from a lower circular orbit into a higher one. It is an elliptic orbit that is tangential both to the lower circular orbit the spacecraft is to leave (cyan, labeled 1 on diagram) and the higher circular orbit that it is to reach (red, labeled 3 on diagram).
The orbit of a Mars-crosser is displayed in the bottom row on the right. In generic terms, a Mars-crosser has a smaller perihelion and a larger aphelion compared to Mars. Special cases include inner-grazers (top row, in the middle) and outer-grazers (bottom row, in the middle), which do not completely cross the orbital band described by Mars.
MOLA topographic images of the two hemispheres of Mars. This image appeared on the cover of Science magazine in May 1999. The Mars Orbiter Laser Altimeter (MOLA) was one of five instruments on the Mars Global Surveyor (MGS) spacecraft, which operated in Mars orbit from September 1997 to November 2006. However, the MOLA instrument transmitted ...
The quadrangles appear as rectangles on maps based on a cylindrical map projection, [1] but their actual shapes on the curved surface of Mars are more complicated Saccheri quadrilaterals. The sixteen equatorial quadrangles are the smallest, with surface areas of 4,500,000 square kilometres (1,700,000 sq mi) each, while the twelve mid-latitude ...