For instance it is the most common way to transfer satellites into geostationary orbit, after first being " parked " in low earth orbit.

For many of the satellites, it is assumed that the rotation rate is equal to the mean orbital period.

For satellites having a mass less than M μ < sub > err </ sub >/ μ ≈ 10 < sup > 15 </ sup > kg, that is, over a billion times that of the ISS, the error due to the approximation is smaller than the error on the universal geocentric gravitational constant ( and thus negligible ).

For synchronous satellites orbiting Earth, this is also known as a geostationary orbit.

For natural satellites, which can attain a synchronous orbit only by tidally locking their parent body, it always goes in hand with synchronous rotation of the satellite.

For fixed ( point-to-point ) services, communications satellites provide a microwave radio relay technology complementary to that of communication cables.

For this reason, if Venus's slow rotation rate began early in its history, any satellites larger than a few kilometres in size would likely have spiralled into the planet.

For example, the Miura map fold is a rigid fold that has been used to deploy large solar panel arrays for space satellites.

For Ku satellites in DBS ( Direct Broadcast Satellite ) service ( 12. 2-12. 7GHz in the U. S .) dishes much smaller than 1-meter can be used because those satellites are spaced 9 degrees apart.

For satellite communications, the microwave frequencies of the C-band perform better under adverse weather conditions in comparison with K < sub > u </ sub > band ( 11. 2 GHz to 14. 5 GHz ) microwave frequencies, which are used by another large set of communication satellites.

Kate Martin, of the Center For National Security Studies said of the use of military spy satellites being used to monitor the activities of U. S. citizens: " They are laying the bricks one at a time for a police state.

For earth-orbiting satellites, the reference plane is usually the Earth's equatorial plane, and for satellites in solar orbits it is the plane of the ecliptic | ecliptic plane.

For example, the levels of ionizing radiation and radio interference can vary by factors of hundreds to thousands ; and the shape and location of the magnetopause and bow shock wave upstream of it can change by several Earth radii, exposing geosynchronous satellites to the direct solar wind.

For scientific uses, a modern planetary ephemeris comprises software that generates positions of the planets and often of their satellites, or of asteroids or comets at virtually any time desired by the user.

For example, the 1995 declaration cites " observations from earth satellites ," where the 1997 declaration cites " observations from both weather satellites and balloon-borne radiosondes.

For the return signal, ground stations and satellites use a radio signal in the 894 to 896 megahertz range.

For information delivery to end-users, satellite systems, by nature, have relatively long path lengths, even for low earth-orbiting satellites.

For example, astronauts return from missions slightly younger than they would have been if they had remained on Earth, and Global Positioning System | GPS satellites work because they adjust for similar bending of spacetime to coordinate with systems on earth.

For reception of signals from several adjacent satellites, a larger non-parabolic multi-satellite dish ( such as the Simulsat ) that can see up to 3 or more satellites is often used.

For instance, Canada was a founding member of NATO, and was instrumental in the forming of that military alliance against the Soviet Union and its satellites.

Gardner holds up a " For Sale " sign, referring to the Palapa B-2 and Westar 6 satellites.

For example, for ground stations at latitudes of φ = ± 45 ° on the same meridian as the satellite, the time taken for a signal to pass from Earth to the satellite and back again can be computed using the cosine rule, given the geostationary orbital radius r ( derived below ), the Earth's radius R and the speed of light c, as

For areas close to the North ( and South ) Pole, a geostationary satellite may appear below the horizon.

For the geostationary transfer orbit we have

For comparison, geostationary satellites orbit Earth at 35, 790 km.

For geostationary spacecraft the inclination change caused by the gravitational forces of Sun / Moon must be counteracted to a rather large expense of fuel as the inclination should be kept sufficiently small for the spacecraft to be tracked by a non-steerable antenna.

For geostationary spacecraft the eccentricity must be kept sufficiently small for a spacecraft to be tracked with a non-steerable antenna.

For geostationary spacecraft thruster burns orthogonal to the orbital plane must be executed to compensate for the effect of the lunar / solar gravitation that perturbs the orbit pole with typically 0. 85 degrees per year.

For the rest of the two spacecrafts ' pass over the near side of the Moon, Mattingly prepared to shift Casper to a circular orbit while Young and Duke prepared Orion for the descent to the lunar surface.

For example, NASA's workhorse space shuttle used cryogenic hydrogen / oxygen propellant as its primary means of getting into orbit, and all of the rockets built for the Soviet space program by Sergei Korolev used liquid oxygen as their oxidiser.

For a satellite in orbit around a planet, the centripetal force is supplied by gravity.

For non-circular orbits or trajectories, only the component of gravitational force directed orthogonal to the path ( toward the center of the osculating circle ) is termed centripetal ; the remaining component acts to speed up or slow down the satellite in its orbit.

For example, the Ruelle – Takens scenario describes how a periodic orbit bifurcates into a torus and the torus into a strange attractor.

For example, if there is a triple star system in which two stars orbit each other closely while a third star is in a more distant orbit, the two closely orbiting stars would be considered a component with two subcomponents.

For example, the planets that orbit the pulsar PSR 1257 are often referred to with capital rather than lowercase letters.

For example, a detector with the mass of Jupiter and 100 % efficiency, placed in close orbit around a neutron star, would only be expected to observe one graviton every 10 years, even under the most favorable conditions.

For many years economical interplanetary travel meant using the Hohmann transfer orbit.

For instance, the motion of a spacecraft, regarding its orbit and attitude ( rotation ), is described by the relativistic theory of classical mechanics, while the analogous movements of an atomic nucleus are described by quantum mechanics.

For example, perigee and apogee are the lowest and highest parts of an orbit around Earth, while perihelion and aphelion are the closest and farthest points of an orbit around the Sun.

For any specific combination of height above the center of gravity and mass of the planet, there is one specific firing velocity ( unaffected by the mass of the ball, which is assumed to be very small relative to the Earth's mass ) that produces a circular orbit, as shown in ( C ).

# For a given orbit, the ratio of the cube of its semi-major axis to the square of its period is constant.

For example, the 3 numbers which describe the body's initial position, and the 3 values which describe its velocity will describe a unique orbit that can be calculated forwards ( or backwards ).

For example, the orbit of the Moon cannot be accurately described without allowing for the action of the Sun's gravity as well as the Earth's.

For precession of the lunar orbit see lunar precession.

For rocket-powered SSTO, the main challenge is achieving a high enough mass-ratio to carry sufficient propellant to achieve orbit, plus a meaningful payload weight.

For air-breathing SSTO, the main challenge is system complexity and associated research and development costs, material science, and construction techniques necessary for surviving sustained high-speed flight within the atmosphere, and achieving a high enough mass-ratio to carry sufficient propellant to achieve orbit, plus a meaningful payload weight.

For pure rocket approaches Tsiolkovsky's rocket equation shows that dead weight will prevent reaching orbit unless the ratio of propellant to structural mass ( called mass ratio ) is very high — between about 10 and 25 ( i. e. 24 parts propellant weight to 1 part structural weight ; depending on propellant choice ).

For example, no new evidence will demonstrate that the Earth does not orbit around the sun ( heliocentric theory ), or that living things are not made of cells ( cell theory ), that matter is not composed of atoms, or that the surface of the Earth is not divided into solid plates that have moved over geological timescales ( the theory of plate tectonics )... One of the most useful properties of scientific theories is that they can be used to make predictions about natural events or phenomena that have not yet been observed.

For missions beyond low Earth orbit NASA is building the Space Launch System and the Orion spacecraft.