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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 prefix areo-derives from Ares, the ancient Greek god of war and counterpart to the Roman god Mars, with whom the planet was identified. The modern Greek word for Mars is Άρης (Áris). As with all synchronous orbits, an areosynchronous orbit has an orbital period equal in length to the primary's sidereal day.
Areosynchronous orbit (ASO): A synchronous orbit around the planet Mars with an orbital period equal in length to Mars' sidereal day, 24.6229 hours. Areostationary orbit (AEO): A circular areosynchronous orbit on the equatorial plane and about 17,000 km (10,557 miles) above the surface of Mars. To an observer on Mars this satellite would appear ...
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.
Deimos (/ ˈ d aɪ m ə s /; systematic designation: Mars II) [11] is the smaller and outer of the two natural satellites of Mars, the other being Phobos. Deimos has a mean radius of 6.2 km (3.9 mi) and takes 30.3 hours to orbit Mars. [5] Deimos is 23,460 km (14,580 mi) from Mars, much farther than Mars's other moon, Phobos. [12]
Observations of Mars had shown that the planet appeared to move 40% faster on one side of its orbit than the other, in conflict with the Aristotelian model of uniform motion. Ptolemy modified the model of planetary motion by adding a point offset from the center of the planet's circular orbit about which the planet moves at a uniform rate of ...
It takes 250 days (0.68 years) in the transit to Mars, and in the case of a free-return style abort without the use of propulsion at Mars, 1.5 years to get back to Earth, at a total delta-v requirement of 3.34 km/s. Zubrin advocates a slightly faster transfer, that takes only 180 days to Mars, but 2 years back to Earth in case of an abort.
[10] [11] Due to the effect of librations and the parallax due to the close distance of Phobos, by observing at high and low latitudes and observing as Phobos is rising and setting, the overall total coverage of Phobos's surface that is visible at one time or another from one location or another on Mars's surface is considerably higher than 50%.