Herschel Space Observatory
Encyclopedia
The Herschel Space Observatory is a European Space Agency
space observatory
sensitive to the far infrared
and submillimetre
wavebands. It is the largest space telescope ever launched, carrying a single mirror of 3.5 metres (11.5 ft) in diameter.
The observatory was carried into orbit in May 2009, reaching the second Lagrangian point
(L2) of the Earth-Sun system, 1500000 kilometres (932,059.1 mi) from the Earth, about two months later. Herschel is named after Sir William Herschel
, the discoverer of the infrared
spectrum and planet Uranus
, and his sister and collaborator Caroline
.
The Herschel Observatory is capable of seeing the coldest and dustiest objects in space; for example, cool cocoons where stars form and dusty galaxies just starting to bulk up with new stars. The observatory will sift through star-forming clouds—the "slow cookers" of star ingredients—to trace the path by which potentially life-forming molecules, such as water, form. The United States through NASA is participating in the ESA-built and -operated observatory. It is the fourth 'cornerstone' mission in the ESA science program, along with Rosetta
, Planck, and the Gaia mission.
. In 2000, FIRST was renamed Herschel. After being put out to tender in 2000, industrial activities began in 2001. Herschel was launched in 2009.
as well as the Milky Way
and even extragalactic
objects billions of light-year
s away, such as newborn galaxies
, and is charged with four primary areas of investigation:
to cover the full far infrared
and submillimetre
waveband. At 3.5 meters wide, its telescope incorporates the largest mirror (made not from glass but from sintered silicon carbide
) ever deployed in space. The light is focused onto three instruments with detectors kept at temperatures below 2 kelvin (-271 °C). The instruments are cooled with liquid helium
, boiling away in a near vacuum at a temperature of approximately 1.4 kelvin (-272 °C). The 2,000-litre supply of helium on board the spacecraft will limit its operational lifetime; nonetheless, it is expected to be operational for at least 3 years.
Herschel carries three detectors:
PACS (Photodetecting Array Camera and Spectrometer): An imaging camera and low-resolution spectrometer
covering wavelengths from 55 to 210 micrometre
s. The spectrometer has a spectral resolution
between R=1000 and R=5000 and is able to detect signals as weak as −63 dB
. It operates as an integral field spectrograph
, combining spatial and spectral resolution. The imaging camera can image simultaneously in two bands (either 60–85/85–130 micrometres and 130–210 micrometres) with a detection limit of a few millijanskys
.
SPIRE (Spectral and Photometric Imaging Receiver): An imaging camera and low-resolution spectrometer covering 194 to 672 micrometre wavelength. The spectrometer has a resolution between R=40 and R=1000 at a wavelength of 250 micrometres and is able to image point sources with brightnesses around 100 millijanskys (mJy) and extended sources with brightnesses of around 500 mJy. The imaging camera has three bands
, centered at 250, 350 and 500 micrometres, each with 139, 88 and 43 pixels respectively. It should be able to detect point source
s with brightness above 2 mJy and between 4 and 9 mJy for extended sources. A prototype of the SPIRE imaging camera flew on the BLAST
high-altitude balloon. NASA's Jet Propulsion Laboratory
in Pasadena, Calif., developed and built the "spider web" bolometer
s for this instrument, which is 40 times more sensitive than previous versions. The Herschel-SPIRE instrument was built by an international consortium comprising more than 18 institutes from eight countries, of which Cardiff University was the lead institute.
HIFI (Heterodyne Instrument for the Far Infrared): A heterodyne
detector which is able to electronically separate radiation of different wavelengths, giving a spectral resolution as high as R=107. The spectrometer can be operated within two wavelength bands, from 157 to 212 micrometres and from 240 to 625 micrometres. SRON Netherlands Institute for Space Research
has led the entire process of designing, constructing and testing HIFI. The HIFI Instrument Control Center, also under the leadership of SRON, is responsible for obtaining and analysing the data.
NASA developed and built the mixers, local oscillator chains and power amplifiers for this instrument.
(SVM) was designed and built by Thales Alenia Space
in its Turin
plant, for the Herschel and Planck missions combined into one single program.
Structurally, the Herschel and Planck SVM's are very similar. Both SVM's are of octagonal shape and for both, each panel is dedicated to accommodate a designated set of warm units, while taking into account the dissipation requirements of the different warm units, of the instruments as well as the spacecraft.
Furthermore, on both spacecraft a common design for the avionics
, the attitude control and measurement system (ACMS) and the command and data management system (CDMS), and power subsystem and the tracking, telemetry and command subsystem (TT&C) has been achieved.
All spacecraft units on the SVM are redundant.
, employing triple-junction solar cell
s, a battery
and the power control unit (PCU). It is designed to interface with the 30 sections of each solar array, provide a regulated 28 V bus, distribute this power via protected outputs and to handle the battery charging and discharging.
For Herschel, the solar array is fixed on the bottom part of the baffle designed to protect the cryostat from the sun. The three-axis attitude control system maintains this baffle in direction of the sun. The top part of this baffle is covered with optical solar reflector (OSR) mirrors reflecting 98% of the sun energy, avoiding heating of the cryostat.
The Herschel spacecraft is three-axis stabilized, the absolute pointing error needs to be less than 3.7 arc sec.
The main sensor of the line of sight in both spacecraft is the star tracker.
, under Thales Alenia Space
Contractorship, was successfully launched from the Guiana Space Centre in French Guiana
at 13:12:02 UTC on 14 May 2009, aboard an Ariane 5
rocket, along with the Planck spacecraft, and placed on a very elliptical orbit (perigee: 270.0 km (intended 270.0±4.5), apogee: 1,197,080 km (intended 1,193,622±151,800), inclination
5.99 deg (intended 6.00±0.06)), on its way towards the second Lagrangian point
.
On June 14, 2009, ESA successfully sent the command for the cryocover to open which will allow the PACS system to see the sky and transmit images in a few weeks. The lid had to remain closed until the telescope was well into space to prevent contamination. Herschel was reported to have completed 90% of the distance to its orbit 1.5 million km away from Earth.
Five days later the first set of test photos, depicting M51 Group
, was published by ESA.
In mid-July 2009, approximately sixty days after launch, it entered a Lissajous orbit
of 800,000 km average radius around the second Lagrangian point
(L2) of the Earth-Sun system, 1.5 million kilometres from the Earth.
shed new light in the way newly forming star regions discard the material which surrounds it.
On July 16, 2010, a special issue of Astronomy and Astrophysics was published with 152 papers on initial results from the observatory.
It was reported on August 1, 2011 that molecular oxygen
had been discovered in space with the Herschel Space Telescope, the first time scientists have found the molecule in space.
Herschel's mesurements of Deuterium levels in a passing comet hint at the idea that much of the Earth's water could have initially come from cometary impacts, result published in Nature.
On October 23rd 2011, it was reported that oceans of water had been discovered in the accretion disc of a nearby star, by measurements of water vapour there.
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...
space observatory
Space observatory
A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects...
sensitive to the far infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
and submillimetre
Submillimetre astronomy
Submillimetre astronomy or submillimeter astronomy is the branch of observational astronomy that is conducted at submillimetre wavelengths of the electromagnetic spectrum. Astronomers place the submillimetre waveband between the far-infrared and microwave wavebands, typically taken to be between a...
wavebands. It is the largest space telescope ever launched, carrying a single mirror of 3.5 metres (11.5 ft) in diameter.
The observatory was carried into orbit in May 2009, reaching the second Lagrangian point
Lagrangian point
The Lagrangian points are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects...
(L2) of the Earth-Sun system, 1500000 kilometres (932,059.1 mi) from the Earth, about two months later. Herschel is named after Sir William Herschel
William Herschel
Sir Frederick William Herschel, KH, FRS, German: Friedrich Wilhelm Herschel was a German-born British astronomer, technical expert, and composer. Born in Hanover, Wilhelm first followed his father into the Military Band of Hanover, but emigrated to Britain at age 19...
, the discoverer of the infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
spectrum and planet Uranus
Uranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...
, and his sister and collaborator Caroline
Caroline Herschel
Caroline Lucretia Herschel was a German-British astronomer, the sister of astronomer Sir Friedrich Wilhelm Herschel with whom she worked throughout both of their careers. Her most significant contribution to astronomy was the discovery of several comets and in particular the periodic comet...
.
The Herschel Observatory is capable of seeing the coldest and dustiest objects in space; for example, cool cocoons where stars form and dusty galaxies just starting to bulk up with new stars. The observatory will sift through star-forming clouds—the "slow cookers" of star ingredients—to trace the path by which potentially life-forming molecules, such as water, form. The United States through NASA is participating in the ESA-built and -operated observatory. It is the fourth 'cornerstone' mission in the ESA science program, along with Rosetta
Rosetta (spacecraft)
Rosetta is a robotic spacecraft of the European Space Agency on a mission to study the comet 67P/Churyumov–Gerasimenko. Rosetta consists of two main elements: the Rosetta space probe and the Philae lander. The spacecraft was launched on 2 March 2004 on an Ariane 5 rocket and will reach the comet by...
, Planck, and the Gaia mission.
Development
In 1982 the Far Infrared and Sub-millimetre Telescope (FIRST) was proposed to ESA. The ESA long-term policy-plan "Horizon 2000", produced in 1984, called for a "High Throughput Heterodyne Spectroscopy mission" as one of its cornerstone missions. In 1986, FIRST was adopted as this cornerstone mission. It was selected for implementation in 1993, following an industrial study in 1992-1993. The mission concept was redesigned from Earth-orbit to the Lagrangian point L2, in light of experience gained from the Infrared Space ObservatoryInfrared Space Observatory
The Infrared Space Observatory was a space telescope for infrared light designed and operated by the European Space Agency , in cooperation with ISAS and NASA...
. In 2000, FIRST was renamed Herschel. After being put out to tender in 2000, industrial activities began in 2001. Herschel was launched in 2009.
Science
Herschel will specialise in collecting light from objects in our Solar SystemSolar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
as well as the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
and even extragalactic
Extragalactic astronomy
Extragalactic astronomy is the branch of astronomy concerned with objects outside our own Milky Way Galaxy. In other words, it is the study of all astronomical objects which are not covered by galactic astronomy, the next level of galactic astronomy....
objects billions of light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s away, such as newborn galaxies
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
, and is charged with four primary areas of investigation:
- Galaxy formation in the early universe and the evolution of galaxies;
- Star formationStar formationStar formation is the process by which dense parts of molecular clouds collapse into a ball of plasma to form a star. As a branch of astronomy star formation includes the study of the interstellar medium and giant molecular clouds as precursors to the star formation process and the study of young...
and its interaction with the interstellar mediumInterstellar mediumIn astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space...
; - Chemical composition of atmospheres and surfaces of Solar System bodies, including planetPlanetA planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
s, cometCometA comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
s and moonsNatural satelliteA natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called its primary. The two terms are used synonymously for non-artificial satellites of planets, of dwarf planets, and of minor planets....
; - Molecular chemistry across the universeUniverseThe Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...
.
Instrumentation
The mission involves the first space observatorySpace observatory
A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects...
to cover the full far infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
and submillimetre
Submillimetre astronomy
Submillimetre astronomy or submillimeter astronomy is the branch of observational astronomy that is conducted at submillimetre wavelengths of the electromagnetic spectrum. Astronomers place the submillimetre waveband between the far-infrared and microwave wavebands, typically taken to be between a...
waveband. At 3.5 meters wide, its telescope incorporates the largest mirror (made not from glass but from sintered silicon carbide
Silicon carbide
Silicon carbide , also known as carborundum, is a compound of silicon and carbon with chemical formula SiC. It occurs in nature as the extremely rare mineral moissanite. Silicon carbide powder has been mass-produced since 1893 for use as an abrasive...
) ever deployed in space. The light is focused onto three instruments with detectors kept at temperatures below 2 kelvin (-271 °C). The instruments are cooled with liquid helium
Liquid helium
Helium exists in liquid form only at extremely low temperatures. The boiling point and critical point depend on the isotope of the helium; see the table below for values. The density of liquid helium-4 at its boiling point and 1 atmosphere is approximately 0.125 g/mL Helium-4 was first liquefied...
, boiling away in a near vacuum at a temperature of approximately 1.4 kelvin (-272 °C). The 2,000-litre supply of helium on board the spacecraft will limit its operational lifetime; nonetheless, it is expected to be operational for at least 3 years.
Herschel carries three detectors:
PACS (Photodetecting Array Camera and Spectrometer): An imaging camera and low-resolution spectrometer
Spectrometer
A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization...
covering wavelengths from 55 to 210 micrometre
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
s. The spectrometer has a spectral resolution
Spectral resolution
The spectral resolution of a spectrograph, or, more generally, of a frequency spectrum, is a measure of its ability to resolve features in the electromagnetic spectrum...
between R=1000 and R=5000 and is able to detect signals as weak as −63 dB
Decibel
The decibel is a logarithmic unit that indicates the ratio of a physical quantity relative to a specified or implied reference level. A ratio in decibels is ten times the logarithm to base 10 of the ratio of two power quantities...
. It operates as an integral field spectrograph
Integral field spectrograph
An integral field spectrograph or a spectrograph equipped with an integral field unit is an optical instrument combining spectrographic and imaging capabilities, used to obtain spatially resolved spectra in astronomy and other fields of research such as bio-medical science and earth observation...
, combining spatial and spectral resolution. The imaging camera can image simultaneously in two bands (either 60–85/85–130 micrometres and 130–210 micrometres) with a detection limit of a few millijanskys
Jansky
The flux unit or jansky is a non-SI unit of spectral flux density equivalent to 10−26 watts per square metre per hertz...
.
SPIRE (Spectral and Photometric Imaging Receiver): An imaging camera and low-resolution spectrometer covering 194 to 672 micrometre wavelength. The spectrometer has a resolution between R=40 and R=1000 at a wavelength of 250 micrometres and is able to image point sources with brightnesses around 100 millijanskys (mJy) and extended sources with brightnesses of around 500 mJy. The imaging camera has three bands
Spectral bands
Spectral bands are part of optical spectra of polyatomic systems, including condensed materials, large molecules etc. Each line corresponding to one level in atom splits in molecules. When the number of atoms is large, one gets continuum of energy levels, so called "spectral bands". They are often...
, centered at 250, 350 and 500 micrometres, each with 139, 88 and 43 pixels respectively. It should be able to detect point source
Point source
A point source is a localised, relatively small source of something.Point source may also refer to:*Point source , a localised source of pollution**Point source water pollution, water pollution with a localized source...
s with brightness above 2 mJy and between 4 and 9 mJy for extended sources. A prototype of the SPIRE imaging camera flew on the BLAST
BLAST (telescope)
The Balloon-borne Large Aperture Submillimeter Telescope is a submillimeter telescope that hangs from a high altitude balloon. It has a 2 meter primary mirror that directs light into bolometer arrays operating at 250, 350, and 500 µm. These arrays were developed for the SPIRE instrument on the...
high-altitude balloon. NASA's Jet Propulsion Laboratory
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...
in Pasadena, Calif., developed and built the "spider web" bolometer
Bolometer
A bolometer is a device for measuring the power of incident electromagnetic radiation via the heating of a material with a temperature-dependent electrical resistance. It was invented in 1878 by the American astronomer Samuel Pierpont Langley...
s for this instrument, which is 40 times more sensitive than previous versions. The Herschel-SPIRE instrument was built by an international consortium comprising more than 18 institutes from eight countries, of which Cardiff University was the lead institute.
HIFI (Heterodyne Instrument for the Far Infrared): A heterodyne
Heterodyne
Heterodyning is a radio signal processing technique invented in 1901 by Canadian inventor-engineer Reginald Fessenden where high frequency signals are converted to lower frequencies by combining two frequencies. Heterodyning is useful for frequency shifting information of interest into a useful...
detector which is able to electronically separate radiation of different wavelengths, giving a spectral resolution as high as R=107. The spectrometer can be operated within two wavelength bands, from 157 to 212 micrometres and from 240 to 625 micrometres. SRON Netherlands Institute for Space Research
Netherlands Institute for Space Research
SRON Netherlands Institute for Space Research is the Dutch expertise institute for space research. The Institute develops and uses innovative technology for groundbreaking research in space, focusing on astrophysical research, Earth science and planetary research...
has led the entire process of designing, constructing and testing HIFI. The HIFI Instrument Control Center, also under the leadership of SRON, is responsible for obtaining and analysing the data.
NASA developed and built the mixers, local oscillator chains and power amplifiers for this instrument.
Service module
A common service moduleService module
A service module is a spacecraft compartment containing a variety of support systems used for spacecraft operations. Usually located in the uninhabited area of the spacecraft, the service module is jettisoned upon the completion of the mission, and usually burns up during atmospheric reentry...
(SVM) was designed and built by Thales Alenia Space
Thales Alenia Space
Thales Alenia Space is an aerospace company born after the Thales Group bought the participation of Alcatel in the two joint-ventures between Alcatel and Finmeccanica, Alcatel Alenia Space and Telespazio.-History:...
in its Turin
Turin
Turin is a city and major business and cultural centre in northern Italy, capital of the Piedmont region, located mainly on the left bank of the Po River and surrounded by the Alpine arch. The population of the city proper is 909,193 while the population of the urban area is estimated by Eurostat...
plant, for the Herschel and Planck missions combined into one single program.
Structurally, the Herschel and Planck SVM's are very similar. Both SVM's are of octagonal shape and for both, each panel is dedicated to accommodate a designated set of warm units, while taking into account the dissipation requirements of the different warm units, of the instruments as well as the spacecraft.
Furthermore, on both spacecraft a common design for the avionics
Avionics
Avionics are electronic systems used on aircraft, artificial satellites and spacecraft.Avionic systems include communications, navigation, the display and management of multiple systems and the hundreds of systems that are fitted to aircraft to meet individual roles...
, the attitude control and measurement system (ACMS) and the command and data management system (CDMS), and power subsystem and the tracking, telemetry and command subsystem (TT&C) has been achieved.
All spacecraft units on the SVM are redundant.
Power subsystem
On each spacecraft, the power subsystem consists of the solar arraySolar panels on spacecraft
Spacecraft operating in the inner solar system usually rely on the use of photovoltaic solar panels to derive electricity from sunlight. In the outer solar system, where the sunlight is too weak to produce sufficient power, radioisotope thermal generators are used as a power source.-History:The...
, employing triple-junction solar cell
Solar cell
A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....
s, a battery
Battery (electricity)
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...
and the power control unit (PCU). It is designed to interface with the 30 sections of each solar array, provide a regulated 28 V bus, distribute this power via protected outputs and to handle the battery charging and discharging.
For Herschel, the solar array is fixed on the bottom part of the baffle designed to protect the cryostat from the sun. The three-axis attitude control system maintains this baffle in direction of the sun. The top part of this baffle is covered with optical solar reflector (OSR) mirrors reflecting 98% of the sun energy, avoiding heating of the cryostat.
Attitude and orbit control
This function is performed by the attitude control computer (ACC) which is the platform for the ACMS. It is designed to fulfil the pointing and slewing requirements of the Herschel and Planck payload.The Herschel spacecraft is three-axis stabilized, the absolute pointing error needs to be less than 3.7 arc sec.
The main sensor of the line of sight in both spacecraft is the star tracker.
Launch and orbit
The spacecraft, built in the Cannes Mandelieu Space CenterCannes Mandelieu Space Center
The Cannes Mandelieu Space Center is an industrial plant dedicated to spacecraft manufacturing, located in both the towns of Cannes and Mandelieu in France...
, under Thales Alenia Space
Thales Alenia Space
Thales Alenia Space is an aerospace company born after the Thales Group bought the participation of Alcatel in the two joint-ventures between Alcatel and Finmeccanica, Alcatel Alenia Space and Telespazio.-History:...
Contractorship, was successfully launched from the Guiana Space Centre in French Guiana
French Guiana
French Guiana is an overseas region of France, consisting of a single overseas department located on the northern Atlantic coast of South America. It has borders with two nations, Brazil to the east and south, and Suriname to the west...
at 13:12:02 UTC on 14 May 2009, aboard an Ariane 5
Ariane 5
Ariane 5 is, as a part of Ariane rocket family, an expendable launch system used to deliver payloads into geostationary transfer orbit or low Earth orbit . Ariane 5 rockets are manufactured under the authority of the European Space Agency and the Centre National d'Etudes Spatiales...
rocket, along with the Planck spacecraft, and placed on a very elliptical orbit (perigee: 270.0 km (intended 270.0±4.5), apogee: 1,197,080 km (intended 1,193,622±151,800), inclination
Inclination
Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...
5.99 deg (intended 6.00±0.06)), on its way towards the second Lagrangian point
Lagrangian point
The Lagrangian points are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects...
.
On June 14, 2009, ESA successfully sent the command for the cryocover to open which will allow the PACS system to see the sky and transmit images in a few weeks. The lid had to remain closed until the telescope was well into space to prevent contamination. Herschel was reported to have completed 90% of the distance to its orbit 1.5 million km away from Earth.
Five days later the first set of test photos, depicting M51 Group
M51 Group
The M51 Group is a group of galaxies located in Canes Venatici. The group is named after the brightest galaxy in the group, the Whirlpool Galaxy...
, was published by ESA.
In mid-July 2009, approximately sixty days after launch, it entered a Lissajous orbit
Lissajous orbit
In orbital mechanics, a Lissajous orbit, , named after Jules Antoine Lissajous, is a quasi-periodic orbital trajectory that an object can follow around a Lagrangian point of a three-body system without requiring any propulsion. Lyapunov orbits around a libration point are curved paths that lie...
of 800,000 km average radius around the second Lagrangian point
Lagrangian point
The Lagrangian points are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects...
(L2) of the Earth-Sun system, 1.5 million kilometres from the Earth.
Operational mission
On 21 July 2009, Herschel commissioning was declared successful, allowing the start of the operational phase. A formal handover of the overall responsibility of Herschel was declared from the programme manager Thomas Passvogel to the mission manager Johannes Riedinger.Discoveries
Herschel was instrumental in the discovery of an unknown and unexpected step in the star forming process. The initial confirmation and later verification via help from ground based telescopes of a vast hole of empty space, previously believed to be a dark nebula, in the area NGC 1999NGC 1999
NGC 1999 is a dust filled bright nebula with a vast hole of empty space represented by a black patch of sky, as can be seen in the photograph. It is a reflection nebula, and shines from the light of the variable star V380 Orionis....
shed new light in the way newly forming star regions discard the material which surrounds it.
On July 16, 2010, a special issue of Astronomy and Astrophysics was published with 152 papers on initial results from the observatory.
It was reported on August 1, 2011 that molecular oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
had been discovered in space with the Herschel Space Telescope, the first time scientists have found the molecule in space.
Herschel's mesurements of Deuterium levels in a passing comet hint at the idea that much of the Earth's water could have initially come from cometary impacts, result published in Nature.
On October 23rd 2011, it was reported that oceans of water had been discovered in the accretion disc of a nearby star, by measurements of water vapour there.
See also
- Atacama Large Millimeter ArrayAtacama Large Millimeter ArrayThe Atacama Large Millimeter/sub-millimeter Array is an array of radio telescopes in the Atacama desert of northern Chile. Since a high and dry site is crucial to millimeter wavelength operations, the array is being constructed on the Chajnantor plateau at 5000 metres altitude...
(ALMA) - List of largest optical reflecting telescopes