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At the bottom of the mantle lies a basal liquid silicate layer approximately 150–180 km thick. [44] [54] Mars's iron and nickel core is completely molten, with no solid inner core. [55] [56] It is around half of Mars's radius, approximately 1650–1675 km, and is enriched in light elements such as sulfur, oxygen, carbon, and hydrogen. [57] [58]
On this assumption, a two-year return is not possible for some years, and for some years a delta-v kick of 0.6 to 2.7 km/s at Mars may be needed to get back to Earth. [10] NASA published the Design Reference Architecture 5.0 for Mars in 2009, advocating a 174-day transfer to Mars, which is close to Zubrin's proposed trajectory. [11]
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 gravitational constant GM (μ) for Mars has the value of 42 830 km 3 s −2, its equatorial radius is 3 389.50 km and the known rotational period (T) of the planet is 1.025 956 76 Earth days (88 642.66 s). Using these values, Mars' orbital altitude is equal to 17 039 km. [73]
In most situations it is impractical to achieve escape velocity almost instantly, because of the acceleration implied, and also because if there is an atmosphere, the hypersonic speeds involved (on Earth a speed of 11.2 km/s, or 40,320 km/h) would cause most objects to burn up due to aerodynamic heating or be torn apart by atmospheric drag. For ...
Phobos is a small, irregularly shaped object with a mean radius of 11 km (7 mi). It orbits 6,000 km (3,700 mi) from the Martian surface, closer to its primary body than any other known natural satellite to a planet. It orbits Mars much faster than Mars rotates and
Galileo flew by Gaspra on 29 October 1991, passing within 1,600 km (990 mi) at a relative speed of about 8 km/s (18,000 mph). Fifty-seven images were returned to Earth, the closest taken from a distance of 5,300 km (3,300 mi). The best images have a resolution of about 54 meters per pixel (177.16 ft).
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]