A low Earth orbit is an Earth-centered orbit with an altitude of 2,000 km or less, or with at least 11.25 periods per day and an eccentricity less than 0.25. Most of the manmade objects in outer space are in LEO. There is a large variety of other sources; the altitude of an object in an elliptic orbit can vary along the orbit. For circular orbits, the altitude above ground can vary by as much as 30 km due to the oblateness of Earth's spheroid figure and local topography. While definitions based on altitude are inherently ambiguous, most of them fall within the range specified by an orbit period of 128 minutes because, according to Kepler's third law, this corresponds to a semi-major axis of 8,413 km. For circular orbits, this in turn corresponds to an altitude of 2,042 km above the mean radius of Earth, consistent with some of the upper altitude limits in some LEO definitions; the LEO region is defined by some sources as the region in space. Some elliptical orbits may pass through the LEO region near their lowest altitude but are not in an LEO Orbit because their highest altitude exceeds 2,000 km.
Sub-orbital objects can reach the LEO region but are not in an LEO orbit because they re-enter the atmosphere. The distinction between LEO orbits and the LEO region is important for analysis of possible collisions between objects which may not themselves be in LEO but could collide with satellites or debris in LEO orbits; the International Space Station conducts operations in LEO. All crewed space stations to date, as well as the majority of satellites, have been in LEO; the altitude record for human spaceflights in LEO was Gemini 11 with an apogee of 1,374.1 km. Apollo 8 was the first mission to carry humans beyond LEO on December 21–27, 1968; the Apollo program continued during the four-year period spanning 1968 through 1972 with 24 astronauts who flew lunar flights but since there have been no human spaceflights beyond LEO. The mean orbital velocity needed to maintain a stable low Earth orbit is about 7.8 km/s, but reduces with increased orbital altitude. Calculated for circular orbit of 200 km it is 7.79 km/s, for 1,500 km it is 7.12 km/s.
The delta-v needed to achieve low Earth orbit starts around 9.4 km/s. Atmospheric and gravity drag associated with launch adds 1.3–1.8 km/s to the launch vehicle delta-v required to reach normal LEO orbital velocity of around 7.8 km/s. The pull of gravity in LEO is only less than on the Earth's surface; this is. However, an object in orbit is, in free fall, since there is no force holding it up; as a result objects in orbit, including people, experience a sense of weightlessness though they are not without weight. Objects in LEO encounter atmospheric drag from gases in the thermosphere or exosphere, depending on orbit height. Due to atmospheric drag, satellites do not orbit below 300 km. Objects in LEO orbit Earth between the denser part of the atmosphere and below the inner Van Allen radiation belt. Equatorial low Earth orbits are a subset of LEO; these orbits, with low inclination to the Equator, allow rapid revisit times of low-latitude places on Earth and have the lowest delta-v requirement of any orbit, provided they have the direct sense with respect to the Earth's rotation.
Orbits with a high inclination angle to the equator are called polar orbits. Higher orbits include medium Earth orbit, sometimes called intermediate circular orbit, further above, geostationary orbit. Orbits higher than low orbit can lead to early failure of electronic components due to intense radiation and charge accumulation. In 2017, "very low Earth" orbits began to be seen in regulatory filings; these orbits, referred to as "VLEO", require the use of novel technologies for orbit raising because they operate in orbits that would ordinarily decay too soon to be economically useful. A low Earth orbit requires the lowest amount of energy for satellite placement, it provides low communication latency. Satellites and space stations in LEO are more accessible for servicing. Since it requires less energy to place a satellite into a LEO, a satellite there needs less powerful amplifiers for successful transmission, LEO is used for many communication applications, such as the Iridium phone system; some communication satellites use much higher geostationary orbits, move at the same angular velocity as the Earth as to appear stationary above one location on the planet.
Satellites in LEO have a small momentary field of view, only able to observe and communicate with a fraction of the Earth at a time, meaning a network of satellites is required to in order to provide continuous coverage. Satellites in lower regions of LEO suffer from fast orbital decay, requiring either periodic reboosting to maintain a stable orbit, or launching replacement satellites when old ones re-enter. Earth observation satellites and spy satellites use LEO as they are able to see the surface of the Earth by being close to it, they are able to traverse the surface of the Earth. A majority of artificial satellites are placed in LEO, making one co
Robert Dennis Latchford is an English former association footballer who played as a centre forward. He made more than 500 appearances in the Football League, playing for Birmingham City, Swansea City and Coventry City in the First Division, won 12 full caps for England. Latchford was the complete centre-forward, able to score or create chances for teammates using either of his feet or his head. Despite his size – 6 feet tall – he was fast over short distances, a quality he used to his advantage when scoring many of his goals. Latchford was born in Birmingham, he was transferred from Birmingham City to Everton for £350,000, a British transfer record at the time. At Everton, Latchford was the top scorer for six successive seasons, he scored 30 goals in the 1977–78 season, winning a £10,000 prize offered by a national newspaper for the first footballer to reach that number in a single season. During the mid-seventies, Latchford was considered as one of the top English forwards of his generation, he earned his first full cap for England in a World Cup qualifier against Italy in 1977.
In April 2006 a book was published telling the story of his 1977/78 season. Co-written with journalist Martin O'Boyle, the book supports Everton's former players charity; the closest he came to a winner's medal at Everton was as a finalist in the League Cup in 1977. Latchford made 268 appearances for Everton scoring 138 goals. After a guest stint in Australia for Brisbane Lions in 1981, scoring 4 goals in as many appearances, Latchford left Everton for Swansea, newly promoted to the top tier of English football, scoring a hat-trick on his debut for the Swans, he also played for Dutch club NAC Breda, Newport County and Merthyr Tydfil before retiring as a player in 1987. During his time at Everton, he was the club's leading post Second World War goalscorer with 138 goals, a record he held until 1989 when Graeme Sharp exceeded Latchford's tally. By the time Latchford left. Latchford played 12 times for England, he represented the players at Professional Footballers' Association, in 1983 was part of a delegation which negotiated improved terms for players in the FA's deal with broadcasters for live coverage of that season's FA Cup.
Now living in Germany with his family, Latchford makes regular trips back to England to speak on the after-dinner circuit and has a regular column on Everton independent website, NSNO.co.uk. Latchford's two brothers and Peter, were both professional goalkeepers. Like Bob, Dave Latchford played for Birmingham City. With Birmingham City FA Youth Cup runners-up 1967. Football League Second Division promotion 1972. Club's top scorer 1972, 1973. With Everton Football League Cup runners-up 1977. Club's top scorer 1975, 1976, 1977, 1978. With Swansea City Welsh Cup winners 1982, 1983. Club's top scorer 1982. With NAC Breda Eerste Divisie promotion 1984. With Merthyr Tydfil Welsh Cup winners 1987. Matthews, Tony. Birmingham City: A Complete Record. Derby: Breedon Books. P. 105. ISBN 978-1-85983-010-9. Bob Latchford at Englandstats.com Profile at Post War English & Scottish Football League A - Z Player's Transfer Database profile Profile at Swansea City A. F. C. Everton Giants at Everton F. C. Aussie Footballers La Butie to Lawrence
The Greater Phoenix Chamber of Commerce is the largest association of businesses in the state of Arizona, one of the largest in the Southwestern United States, with more than 2,900 business members. Founded November 13, 1888 as the Phoenix Chamber of Commerce, the organization was known as the Phoenix Metropolitan Chamber of Commerce from 1973-1987 and adopted its present name in 1998, its mission is to support the growth and development of business, strengthen the quality of life in the community, champion the voice of business in government and keep its members informed and prosperous. The Phoenix Chamber spearheaded efforts towards attracting more settlers to the Valley of the Sun, building a railroad to tap the rich forest country to the north, building better roads and supplying accommodations for those who traveled to Arizona for the winter sunshine; the following year saw the state capitol move from Prescott to Phoenix and marked the beginning of the area's citrus and agriculture industry.
The Chamber of Commerce began the processing of fruits and other products to offer a permanent display for visitors as proof of what the land could produce. If agriculture were to be a permanent success of the area, water storage to carry over during the summer months was crucial. A Chamber committee studied the possibilities of building dams on the Salt River to form reservoirs for water storage, agreed unanimously upon the present site of the Roosevelt Dam, it was through the combined efforts of these businessmen and pioneer farmers that Congress was convinced to bring into effect the plan of Reclamation to capture and hold water from the Colorado River. The hauling of crops to market, along with the growing change in transportation from horse-drawn vehicles to motor travel, created an insistent urge for a paved highway system; that development birthed an expansion of the urban area, building of fine country homes, more schools, more people and more wealth. In addition, Maricopa County became the leader, not only in Arizona but throughout the nation, in building paved highways.
The ease and comfort of traveling over paved highways brought more fine hotels, guest ranches on the city's outskirts, an awakened consciousness to the possibilities of selling the climate to people who lived in less favorable parts of the country. This, in turn, led to the development of the National Advertising Campaign, sponsored by the Chamber of Commerce and supported jointly by Maricopa County and the City of Phoenix. Among the many undertakings of the early organization was the raising of $3,000 for the purchase of a plot of ground, now the historic Phoenix Indian School; this group of business and professional leaders was the greatest factor in determining the location of the Arizona Territorial Capital in Phoenix. It was logical that the Capital should be located in a town where there was promise and people had the vision and energy to behold this promise