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Topic: High Earth Orbit

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In the News (Wed 20 Mar 19)

 Earth - Open Encyclopedia   (Site not responding. Last check: 2007-11-07)
Earth, also known as the Earth or Terra, is the planet on which humans live, the third planet outward from the Sun.
Thus from Earth the main apparent motion of celestial bodies in the sky (except meteors which are within the atmosphere and low orbiting satellites) is the movement to the west at a rate of 15 °/hr = 15'/min, i.e.
As the Moon orbits Earth, different parts of its face are illuminated by the Sun, leading to the lunar phases: the dark part of the face is separated from the light part by the solar terminator line.
open-encyclopedia.com /Earth   (3015 words)

 Earth orbit - Wikipedia, the free encyclopedia
Earth orbit is an orbit around the planet Earth.
The Moon, Earth's only natural satellite, is in Earth orbit.
Artificial satellites are launched into Earth orbit, and spacecraft bound for other locations in the solar system usually begin their missions by first attaining Earth orbit, before altering course to another planet, moon, or heliocentric (solar) orbit.
en.wikipedia.org /wiki/Earth_orbit   (97 words)

 The Earth [encyclopedia]   (Site not responding. Last check: 2007-11-07)
The Earth orbits the Sun at a mean distance of 149,503,000 kilometers, a distance that is referred to as an "astronomical unit (AU)", and is used as a yardstick for distances to other planets.
This, along with the slight eccentricity of the Earth's orbit, accounts for the Earth's seasons, with the tilt axis causing the Sun to be low in the sky in each hemisphere in alternating cycles during the year.
The mass of the Earth is about 6 x 10^21 tonnes, an unimaginable value, and in considering the planets it is generally more useful to define this value as an "Earth mass (Me)" and to compare the mass of the larger worlds relative to this mass.
kosmoi.com /Science/Earth/more.shtml   (3527 words)

 Orbits in Space
If the Earth were a perfect sphere, orbit calculations could assume that all its mass was concentrated at its center: the force, at least outside the Earth, would have been exactly the same.
However certain orbits exist, passing just a few degrees from the poles, whose planes are rotated by the bulge of the Earth by exactly one rotation per year.
Earth observation satellites such as Landsat and SPOT (Satellite Pour l'Observation de la Terre) also prefer sun-synchronous orbits, which ensure that images from different dates are always taken at the same time of the day.
www-istp.gsfc.nasa.gov /stargaze/Sorbit.htm   (1964 words)

 High Earth Orbit -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-11-07)
High Earth Orbit (HEO) is an (The (usually elliptical) path described by one celestial body in its revolution about another) orbit beyond (Click link for more info and facts about GEO) GEO or (A circular orbit around the Earth having a period of 24 hours) Geosynchronous Orbit.
The disposal orbit of (Click link for more info and facts about geostationary) geostationary satellites fall in the region of HEO.
(A geosynchronous orbit that is fixed with respect to a position on the Earth) Geostationary Orbit (GSO)
www.absoluteastronomy.com /encyclopedia/h/hi/high_earth_orbit.htm   (153 words)

 ESA - Integral - The launcher   (Site not responding. Last check: 2007-11-07)
A powerful launcher is absolutely essential to put the heavy spacecraft into an unusually high Earth orbit which is crucial for the scientific success of the mission.
As part of the arrangement, RSA shall be responsible for placing the satellite in the desired orbit using a Proton launcher, while ESA is responsible for delivering a satellite compatible with the launcher.
The high and eccentric orbit guarantees long periods of uninterrupted observation with nearly constant background and away from trapped radiation in the Earth's proton and electron belts.
www.esrin.esa.it /export/esaMI/Integral/ESAN5RPV16D_0.html   (691 words)

 Providing Global Broadband Internet Access Using Low-Earth-Orbit Satellites
The low orbit and high frequency (30 GHz uplink/20 GHz downlink) allow the use of small, low-power terminals and antennas, with a size and cost comparable to a notebook computer.
A low orbit altitude is used to meet the requirements for low end-to-end delay and reliable communication links that use low power and small antennas.
However, if this small cell pattern swept the Earth's surface at the velocity of the satellite (approximately 25,000 km per hour), a terminal would be served by the same cell for only a few seconds before a channel reassignment or "hand-off" to the next cell would be necessary.
www.isoc.org /inet97/proceedings/F5/F5_2.HTM   (3086 words)

 Low Earth Orbit   (Site not responding. Last check: 2007-11-07)
The high-altitude-elliptical orbit is shown in the figure, the height from the surface is from 1,000km at perigee (when close to the earth) to more than 36,000km of GEO at apogee (when far from the earth).
The orbit of LEO satellites is about 500-1,500km height from the earths surface.
The gravity gradient boom counter acts this force, i.e., the lower left in the figure, therefore the antennas are installed on the opposite side of a gravity gradient boom.
www.uo14.net /about/leo.html   (691 words)

 Space Optics Manufacturing Technology Center - Analyze
Concept studies by NASA and the scientific community for a high earth orbit telescope were conducted in the early 1990’s.
Thermal analyses showed that this telescope would operate at a temperature of 70-100 K. The low temperature can be achieved in a 100 000 km high earth orbit by passive radiative cooling of the optical telescope assembly using multiple radiation shields which are aided by a large sunshield covering one side of the structure.
Initial wavefront corrections and occasional adjustment, when the telescope dwells within short Earth shadow portions of the orbit, are probably the only required corrections.
optics.nasa.gov /concept/heot.html   (358 words)

 Period of the Earth's Orbit
The Earth is one of the nine planets that orbit around the sun in elliptical orbits.
An orbit is the time it takes for a planet or other satellite to go around the sun and end up in the same place it started.
The period of the Earth's orbit is usually thought to be 365 days as calendars show.
www.hypertextbook.com /facts/1999/MitchellKrasnerman.shtml   (338 words)

 NASA scores direct hit on comet / Probe's aim is true at 83 million miles; scientists await data
Comets formed when the solar system was still in its infancy some 4.5 billion years ago and have been frozen from their beginning in the outermost limits of the system.
Scientists have long believed that planets, including Earth, were bombarded intensely for millennia after their formation by wandering comets and asteroids.
High in Earth's orbit, the Hubble Space Telescope has been taking pictures of the comet for weeks and has observed at least three mysterious jets of light bursting from Tempel 1's sunlit side.
sfgate.com /cgi-bin/article.cgi?file=/c/a/2005/07/04/MNGDKDISKQ1.DTL   (1065 words)

 get now: what keeps the earth in its orbit   (Site not responding. Last check: 2007-11-07)
Earth Orbit When a satellite circles close to...
Low Earth Orbit is useful because its nearness to Earth gives it...
After a brief Earth orbit, the object moved to a solar orbit for the...
www.flipper-welt.de /what_keeps_the_earth_in_its_orbit.html   (343 words)

By using information from several of its multiple cameras (each of which looks at the Earth’s surface from a different angle), MISR was able to tell that what looked liked a wavy cloud pattern was actually a wavy pattern on the ice surface.
The rippled area on the surface which could have been mistaken for clouds are actually sastrugi—long, wavelike ridges of snow formed by the wind and found on the polar plains.
Usually sastrugi are only several centimeters high and several meters apart, but large portions of East Antarctica are covered by mega-sastrugi ice fields, with dune-like features as high as four meters separated by two to five kilometers.
terra.nasa.gov   (532 words)

 After nearly forty years of intentional space operations, almost 25,000 objects have been officially catalogued with ...   (Site not responding. Last check: 2007-11-07)
Today, more than 8500 earth orbiting objects are tracked with radar and telescopes of the U.S. Space Surveillance Network, but those account for less than 10 percent of the centimeter-sized objects and, furthermore, they are supposed to be complete up to 90-99 percent for sizes larger than 20 cm in Low Earth Orbit (LEO).
Only about 6 percent of the catalogued objects in earth orbit are operational satellites, about one-sixth are derelict rocket bodies discarded after their use, while over one-fifth are non-operational payloads.
Moreover, propulsion related events have left in orbit the greatest number of large fragments (almost 47%), while, in spite of the great number of deliberate explosions, the number of catalogued debris released in orbit by intentional events is lower.
apollo.cnuce.cnr.it /~pardini/carmen_n/papers_o/c97-020.html   (8032 words)

 High Earth Orbit - Encyclopedia, History, Geography and Biography   (Site not responding. Last check: 2007-11-07)
High Earth Orbit - Encyclopedia, History, Geography and Biography
This rocketry or spacecraft article is a stub.
The article about High Earth Orbit contains information related to High Earth Orbit and See also.
www.arikah.net /encyclopedia/High_Earth_Orbit   (90 words)

 Numerical Computation of Optimal Trajectories for Coplanar, Aeroassisted Orbital Transfer - Baumann, Oberle ...   (Site not responding. Last check: 2007-11-07)
This paper is concerned with the problem of optimal, planar aeroassisted orbital transfer from a high Earth orbit to a low Earth orbit.
It is assumed that initial and final orbits are circular and coplanar, and that the gravitational field is central and governed by the inverse square law.
The whole trajectory is assumed to consist of two impulsive changes of the velocity at the begin and at the end of the trajectory and of one interior atmospheric subarc, where the vehicle is controlled via...
citeseer.lcs.mit.edu /baumann99numerical.html   (471 words)

 The Earth's Atmosphere
Carbon dioxide concentration has increased greatly in the last two centuries.  Living matter, combustion of fossil fuels and volcanic eruptions, produce it.  Large volcanic eruptions can significantly change the relative composition of the upper atmosphere.
Ionosphere.   Above about 80 km, most of the particles are ionized by high-energy light from the Sun as well as cosmic rays.  This vast region is usually broken thermosphere, exosphere and magnetosphere.
Magnetosphere.  (5000 km to >> 60,000 km)  The outermost shell is enormous and is strongly influenced by the interaction of Earth's magnetic field and the solar wind.  It contains the Van Allen radiation belts where high energy charged particles are trapped and concentrated.  This is the region occupied by Geosynchronous Satellites.
scipp.ucsc.edu /outreach/balloon/atmos/The%20Earth.htm   (521 words)

 Howstuffworks "How do satellites orbit the earth?"
In this diagram you can see that the shell is going far enough to actually follow the curve of the earth for a period of time before hitting the ground.
On earth, it's not so easy because satellites have to get up above the atmosphere and into the vacuum of space to orbit for any length of time.
The speed of the satellite is adjusted so that it falls to earth at the same rate that the curve of the earth falls away from the satellite.
www.howstuffworks.com /question378.htm   (501 words)

 LEO (Low Earth Orbit) Satellite (Linktionary term)
There are geostationary satellites flying in high orbit (22,000 miles) where they can maintain the same position above the earth's surface at all times.
In this orbit, the round-trip time for transmission is minimal, as are the power requirements for earth-bound communication devices.
Because of their low orbit, they move faster relative to a point on the surface, so a fleet of LEO satellites is required to maintain communications over a single point.
www.linktionary.com /l/leo.html   (270 words)

 Transterrestrial Musings
Planning to beam vehicles to orbit from the ground, either with thermal rocket or pulsed ablation (they're working on the former).
She expects us to get to orbit much sooner than many do, and we need to start planning now, so that we will have a good handle on the weather issues as we start spending hours and days in space, rather than minutes.
It will be desirable to have earth governments recognize consortia and off-planet governments, with the ability for individuals to be citizens of them.
www.transterrestrial.com   (7962 words)

 CASTOR - A RAVEN System in Canada - Department of Physics of the Royal Military College of Canada
This orbit determination software was used to analyze the astrometry data from the Molniya satellite tracking session of September 16-17, 1998.
RMC noticed that while determining the orbit of this satellite, the residuals in R.A. and Dec. of the RME SDA orbit were generally negligible compared to those of the RMC IRAF orbit.
This is being done in order to determine a method of orbit determination that would entail using the fewest number of observations possible while maintaining the integrity of the determined orbit elements.
www.rmc.ca /academic/physics/castor/castor1_e.html   (5717 words)

 Low Earth orbit microsatellites for data communications using small terminals
The orbital inclination, the angle between the orbital and the equatorial plane, determines the extent of coverage of the earth's surface and also the frequency of visibility for a given latitude.
The polar sun-synchronous circular orbit which is a common low Earth orbit choice for remote sensing satellites has a number of advantages for simple communications services.
Each of the microsatellites currently in-orbit is routinely used to evaluate the interference profile in the uplink channels.
www.ee.surrey.ac.uk /EE/CSER/UOSAT/papers/icdsc10/icdsc10.html   (3294 words)

 CNN.com - Cataloging space junk - Aug 2, 2005
The squadron is charged with detecting, tracking, identifying and cataloging all manmade objects orbiting Earth larger than 10 centimeters (4 inches) long.
According to the Air Force, only a small amount of debris exists where the shuttle orbits and the likelihood of a "significant collision" between a piece of debris and the shuttle is extremely remote.
According to Thurston, satellites in orbit at 350 kilometers altitude, the altitude at which the ISS and most shuttle missions orbit, travel at 7.7 kilometers a second, or more than 16,000 mph.
www.cnn.com /2005/TECH/space/08/02/space.junk/index.html   (881 words)

 Session J8 - First Results from Chandra.
The Chandra X-ray Observatory was launched into a High Earth Orbit on July 23, 1999 by the Space Shuttle Columbia.
During September and October the On-orbit Activation and Calibration Phase of the mission was mostly completed including a number of HRC observations that are publicly available in the CXO Archive.
Early results are being obtained on a variety of sources, demonstrating the power of high resolution spectroscopy to probe the physical and astrophysical properties of celestial objects.
flux.aps.org /meetings/YR00/APR00/abs/S2670.html   (840 words)

 The Space Place :: An Orbit for Every Need
Thus, since Earth rotates once on its axis per day, the GOES satellite seems to hover over the same spot on Earth all the time.
On the other hand, satellites whose job is to make maps or study all different parts of Earth's surface need an orbit that comes as close to passing over the North and South Poles as possible.
However, one is to go into a polar orbit and one is to orbit the equator.
spaceplace.jpl.nasa.gov /goes/goes_poes_orbits.htm   (740 words)

 SPACE.com -- Space Elevator: Next Stop, Earth Orbit
The space elevator concept is based on a structure stretching from the Earth's surface, up through the atmosphere, all the way to geostationary Earth orbit -- 22,300 miles (36,000 kilometers) high above the equator.
The length of the elevator would be busy as electromagnetic passenger pods scoot up and down tracks, traveling at high speeds between Earth and a geostationary transfer station.
Growth of government and industrial infrastructure in space from low Earth orbit to geostationary orbit that would benefit from utilization of the space elevator.
www.space.com /businesstechnology/technology/space_elevator_001226.html   (1109 words)

The story begins in 1952, when the International Council of Scientific Unions decided to establish July 1, 1957, to December 31, 1958, as the International Geophysical Year (IGY) because the scientists knew that the cycles of solar activity would be at a high point then.
In October 1954, the council adopted a resolution calling for artificial satellites to be launched during the IGY to map the Earth's surface.
In July 1955, the White House announced plans to launch an Earth-orbiting satellite for the IGY and solicited proposals from various Government research agencies to undertake development.
www.hq.nasa.gov /office/pao/History/sputnik   (432 words)

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