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Halo Orbit
A halo orbit is a periodic, three-dimensional orbit near one of the L1, L2 or L3 Lagrange points in the three-body problem of orbital mechanics. Although a Lagrange point is just a point in empty space, its peculiar characteristic is that it can be orbited by a Lissajous orbit or a halo orbit. These can be thought of as resulting from an interaction between the gravitational pull of the two planetary bodies and the Coriolis and centrifugal force on a spacecraft. Halo orbits exist in any three-body system, e.g., a Sun–Earth–orbiting satellite system or an Earth–Moon–orbiting satellite system. Continuous "families" of both northern and southern halo orbits exist at each Lagrange point. Because halo orbits tend to be unstable, stationkeeping may be required to keep a satellite on the orbit. Most satellites in halo orbit serve scientific purposes, for example as space telescopes. Definition and history Robert W. Farquhar first used the name "halo" in 1966 for orbits ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lagrange Points2
Joseph-Louis Lagrange (born Giuseppe Luigi LagrangiaJoseph-Louis Lagrange, comte de l’Empire ''Encyclopædia Britannica'' or Giuseppe Ludovico De la Grange Tournier; 25 January 1736 – 10 April 1813), also reported as Giuseppe Luigi Lagrange or Lagrangia, was an mathematician and astronomer, later naturalized French. He made significant contributions to the fie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kathleen Howell
Kathleen Howell is an American scientist and aerospace engineer known for her contributions to dynamical systems theory applied to spacecraft trajectory design which led to the use of halo orbit in multiple NASA space missions. She is currently the Hsu Lo Distinguished Professor at Purdue University in the School of Aeronautics and Astronautics. In acknowledgment of her many achievements, ''Discover'' magazine recognized her in 2002 as one of the 50 most important women in science. Career She obtained her Bachelor of Science degree in Aerospace Engineering at Iowa State University in 1973. Howell then received her MS and PhD degrees from Stanford University in 1977 and 1983, respectively. Her PhD advisor was John Breakwell and her PhD dissertation was entitled "Three-dimensional, periodic halo orbits in the restricted three-body problem". Howell started as an assistant professor at Purdue University School of Aeronautics and Astronautics in 1982 and is the School's first female t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Near-rectilinear Halo Orbit
A near-rectilinear halo orbit (NRHO) is a halo orbit with slightly curved – or nearly straight – sides between close passes with an orbiting body. The 2022 CAPSTONE mission is the first such orbit in cislunar space, and this Moon-centric orbit will serve as a staging area for future lunar missions. The orbit could be used with other bodies in the Solar System and beyond. A halo orbit is a periodic, three-dimensional orbit associated with one of the L1, L2 and L3 Lagrange points. Near-rectilinear means that some segments of the orbit have a greater curvature than those of an elliptical orbit of the same maximum diameter, and other segments have a curvature less than that of an elliptical orbit of the same maximum diameter (taking maximum diameter as that of the smallest circle that contains the whole of the orbit). In the extreme case all segments have zero curvature with four points with infinite curvature (''i.e.'' a polygon). Such a non-elliptical orbit would require at l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interplanetary Spaceflight
Interplanetary spaceflight or interplanetary travel is the crewed or uncrewed travel between stars and planets, usually within a single planetary system. In practice, spaceflights of this type are confined to travel between the planets of the Solar System. Uncrewed space probes have flown to all the observed planets in the Solar System as well as to dwarf planets Pluto and Ceres, and several asteroids. Orbiters and landers return more information than fly-by missions. Crewed flights have landed on the Moon and have been planned, from time to time, for Mars, Venus and Mercury. While many scientists appreciate the knowledge value that uncrewed flights provide, the value of crewed missions is more controversial. Science fiction writers propose a number of benefits, including the mining of asteroids, access to solar power, and room for colonization in the event of an Earth catastrophe. A number of techniques have been developed to make interplanetary flights more economical. Adva ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interplanetary Transport Network
The Interplanetary Transport Network (ITN) is a collection of gravitationally determined pathways through the Solar System that require very little energy for an object to follow. The ITN makes particular use of Lagrange points as locations where trajectories through space can be redirected using little or no energy. These points have the peculiar property of allowing objects to orbit around them, despite lacking an object to orbit. While it would use little energy, transport along the network would take a long time. History Interplanetary transfer orbits are solutions to the gravitational three-body problem, which, for the general case, does not have analytical solutions, and is addressed by numerical analysis approximations. However, a small number of exact solutions exist, most notably the five orbits referred to as "Lagrange points", which are orbital solutions for circular orbits in the case when one body is significantly more massive. The key to discovering the Interplan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The New York Times
''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid digital media, digital subscribers. It also is a producer of popular podcasts such as ''The Daily (podcast), The Daily''. Founded in 1851 by Henry Jarvis Raymond and George Jones (publisher), George Jones, it was initially published by Raymond, Jones & Company. The ''Times'' has won List of Pulitzer Prizes awarded to The New York Times, 132 Pulitzer Prizes, the most of any newspaper, and has long been regarded as a national "newspaper of record". For print it is ranked List of newspapers by circulation, 18th in the world by circulation and List of newspapers in the United States, 3rd in the U.S. The paper is owned by the New York Times Company, which is Public company, publicly traded. It has been governed by the Sulzberger family since 189 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Webb Space Telescope
The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, distant, or faint for the Hubble Space Telescope. This will enable investigations across many fields of astronomy and cosmology, such as observation of the first stars, the formation of the first galaxies, and detailed atmospheric characterization of potentially habitable exoplanets. The U.S. National Aeronautics and Space Administration (NASA) led JWST's design and development and partnered with two main agencies: the European Space Agency (ESA) and the Canadian Space Agency (CSA). The NASA Goddard Space Flight Center (GSFC) in Maryland managed telescope development, the Space Telescope Science Institute in Baltimore on the Homewood Campus of Johns Hopkins University operates JWST, and the prime contractor was Northrop Grumman. The telescope is named after James E. W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Von Kármán (lunar Crater)
Von Kármán is a large lunar impact crater that is located in the southern hemisphere on the far side of the Moon. The crater is about in diameter and lies within an immense impact crater known as the South Pole–Aitken basin of roughly in diameter and deep. Von Kármán is the site of the first soft-landing on the lunar far side by the Chinese Chang'e 4 spacecraft on 3 January 2019. Overview The northern third of this formation is overlain by the rim and outer rampart of the walled plain Leibnitz, forming a deep indentation in the formation. The remainder of the outer wall is roughly circular in shape, although it is irregular and heavily worn by subsequent impacts. The interior of Von Kármán has been subjected to flooding by lava flows after the original crater formed, leaving the southern portion of the floor nearly flat. This surface has a lower albedo than the surrounding terrain, and is nearly as dark as the interior of Leibnitz. There is a central peak at the l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chang'e 4
Chang'e 4 (; ) is a robotic spacecraft mission, part of the second phase of the Chinese Lunar Exploration Program. China achieved humanity's first soft landing on the far side of the Moon, on 3 January 2019. A communication relay satellite, , was first launched to a halo orbit near the Earth–Moon L2 point in May 2018. The robotic lander and ''Yutu-2'' () rover were launched on 7 December 2018 and entered lunar orbit on 12 December 2018, before landing on the Moon's far side. The mission is the follow-up to Chang'e 3, the first Chinese landing on the Moon. The spacecraft was originally built as a backup for Chang'e 3 and became available after Chang'e 3 landed successfully in 2013. The configuration of Chang'e 4 was adjusted to meet new scientific and performance objectives. Like its predecessors, the mission is named after Chang'e, the Chinese Moon goddess. In November 2019, Chang’e 4 mission team was awarded Gold Medal by the Royal Aeronautical Society. In October ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Queqiao Relay Satellite
''Queqiao'' relay satellite (), also known as the Chang'e 4 Relay, is a communications relay and radio astronomy satellite for the Chang'e 4 lunar farside mission. As part of the Chinese Lunar Exploration Program, the China National Space Administration (CNSA) launched the Queqiao relay satellite on 20 May 2018 to a halo orbit around the Earth–Moon L2 Lagrangian point Queqiao is the first ever communication relay and radio astronomy satellite at this location. The name ''Queqiao'' ("Magpie Bridge") was inspired by and came from the Chinese tale ''The Cowherd and the Weaver Girl''. Design and development Queqiao was designed to function as a communication relay for the Chang'e 4 mission to the far side of the Moon, as well as a deep space radio astronomy observatory for the Chinese space program. Direct communication with Earth is impossible on the far side of the Moon, since transmissions are blocked by the Moon. Communications must go through a communications relay satel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gaia (spacecraft)
''Gaia'' is a space observatory of the European Space Agency (ESA), launched in 2013 and expected to operate until 2025. The spacecraft is designed for astrometry: measuring the positions, distances and motions of stars with unprecedented precision. The mission aims to construct by far the largest and most precise 3D space catalog ever made, totalling approximately 1 billion astronomical objects, mainly stars, but also planets, comets, asteroids and quasars, among others. To study the precise position and motion of its target objects, the spacecraft monitored each of them about 70 times over the five years of the nominal mission (2014–2019), and continues to do so during its extension. The spacecraft has enough micro-propulsion fuel to operate until about November 2024. As its detectors are not degrading as fast as initially expected, the mission could therefore be extended. ''Gaia'' targets objects brighter than magnitude 20 in a broad photometric band that covers the ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar And Heliospheric Observatory
The Solar and Heliospheric Observatory (SOHO) is a European Space Agency (ESA) spacecraft built by a European industrial consortium led by Matra Marconi Space (now Airbus Defence and Space) that was launched on a Lockheed Martin Atlas IIAS launch vehicle on 2 December 1995, to study the Sun. It has also discovered over 4,000 comets.(2,703 discoveries as of 21 April 2014) It began normal operations in May 1996. It is a joint project between the (ESA) and . SOHO was part of the Internat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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