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Vesta (radius 262.7 ± 0.1 km), the second-largest asteroid, appears to have a differentiated interior and therefore likely was once a dwarf planet, but it is no longer very round today. [74] Pallas (radius 255.5 ± 2 km ), the third-largest asteroid, appears never to have completed differentiation and likewise has an irregular shape.
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 ...
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.
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 ...
This plot shows a ship capable of 1-g (10 m/s 2 or about 1.0 ly/y 2) "felt" or proper acceleration [6] can travel vast distances, although is limited by the mass of any propellant it carries. A spaceship using significant constant acceleration will approach the speed of light over interstellar distances, so special relativity effects including ...
In gravitationally bound systems, the orbital speed of an astronomical body or object (e.g. planet, moon, artificial satellite, spacecraft, or star) is the speed at which it orbits around either the barycenter (the combined center of mass) or, if one body is much more massive than the other bodies of the system combined, its speed relative to the center of mass of the most massive body.
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]
[2] [3] The general equation describing the radius of the sphere of a planet: [4] / where a {\displaystyle a} is the semimajor axis of the smaller object's (usually a planet's) orbit around the larger body (usually the Sun).