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The launch vehicle's delta-v needed to achieve low Earth orbit starts around 9.4 km/s (5.8 mi/s). The pull of gravity in LEO is only slightly less than on the Earth's surface. This is because the distance to LEO from the Earth's surface is much less than the Earth's radius.
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 ...
Sketch of a circumlunar free return trajectory (not to scale), plotted on the rotating reference frame rotating with the moon. (Moon's motion only shown for clarity) In orbital mechanics, a free-return trajectory is a trajectory of a spacecraft traveling away from a primary body (for example, the Earth) where gravity due to a secondary body (for example, the Moon) causes the spacecraft to ...
The distance traveled, under constant proper acceleration, from the point of view of Earth as a function of the traveler's time is expressed by the coordinate distance x as a function of proper time τ at constant proper acceleration a. It is given by: [8] [9]
Greater flexibility in lunar orbital or landing site coverage (at greater angles of lunar inclination) can be obtained by performing a plane change maneuver mid-flight; however, this takes away the free-return option, as the new plane would take the spacecraft's emergency return trajectory away from the Earth's atmospheric re-entry point, and ...
A menacing asteroid named Apophis is projected to have a close encounter with Earth in 2029, but scientists have long ruled it out as an impact risk. Asteroids safely fly by Earth all the time ...
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).
There are three main "bands" of orbit around the Earth: low Earth orbit (LEO), medium Earth orbit (MEO), and geostationary orbit (GEO). According to orbital mechanics, an orbit lies in a particular, largely fixed plane around the Earth, which coincides with the center of the Earth, and may be inclined with respect to the equator. The relative ...