The Herschel Space Observatory was a
space observatory
A space telescope (also known as space observatory) is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first operational telescopes were the American Orbiting Astronomical Observatory, OAO ...
built and operated by the
European Space Agency
The European Space Agency (ESA) is a 23-member International organization, international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 ...
(ESA). It was active from 2009 to 2013, and was the largest
infrared telescope
An infrared telescope is a telescope that uses infrared light to detect celestial bodies. Infrared light is one of several types of radiation present in the electromagnetic spectrum.
All celestial objects with a temperature above absolute zero ...
ever launched until the launch of the
James Webb Space Telescope
The James Webb Space Telescope (JWST) is a space telescope designed to conduct infrared astronomy. As the largest telescope in space, it is equipped with high-resolution and high-sensitivity instruments, allowing it to view objects too old, Lis ...
in 2021.
Herschel carries a mirror
and instruments sensitive to the
far infrared
Far infrared (FIR) or long wave refers to a specific range within the infrared spectrum of electromagnetic radiation. It encompasses radiation with wavelengths ranging from 15 μm ( micrometers) to 1 mm, which corresponds to a freque ...
and
submillimetre wavebands (55–672 μm). Herschel was the fourth and final cornerstone mission in the
Horizon 2000
The Science Programme of the European Space Agency is a long-term programme of Outline of space science, space science and space exploration missions. Managed by the agency's Directorate of Science, The programme funds the development, launch, ...
programme, following ''
SOHO
SoHo, short for "South of Houston Street, Houston Street", is a neighborhood in Lower Manhattan, New York City. Since the 1970s, the neighborhood has been the location of many artists' lofts and art galleries, art installations such as The Wall ...
''/''
Cluster II'', ''
XMM-Newton
''XMM-Newton'', also known as the High Throughput X-ray Spectroscopy Mission and the X-ray Multi-Mirror Mission, is an X-ray space observatory launched by the European Space Agency in December 1999 on an Ariane 5 rocket. It is the second corners ...
'' and ''
Rosetta
Rosetta ( ) or Rashid (, ; ) is a port city of the Nile Delta, east of Alexandria, in Egypt's Beheira governorate. The Rosetta Stone was discovered there in 1799.
Founded around the 9th century on the site of the ancient town of Bolbitine, R ...
''.
The observatory was carried into orbit by an
Ariane 5
Ariane 5 is a retired European heavy-lift space launch vehicle operated by Arianespace for the European Space Agency (ESA). It was launched from the Guiana Space Centre (CSG) in French Guiana. It was used to deliver payloads into geostationar ...
in May 2009, reaching the
second Lagrangian point (L2) of the
Earth–Sun system, from Earth, about two months later. Herschel is named after
Sir William Herschel, the discoverer of the
infrared
Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...
spectrum and planet
Uranus
Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a Supercritical fluid, supercritical phase of matter, which astronomy calls "ice" or Volatile ( ...
, and his sister and collaborator
Caroline Herschel
Caroline Lucretia Herschel ( , ; 16 March 1750 – 9 January 1848) was a German astronomer, whose most significant contributions to astronomy were the discoveries of several comets, including the periodic comet 35P/Herschel–Rigollet, which b ...
.
The observatory was 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 sifted 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 telescope's lifespan was governed by the amount of
coolant
A coolant is a substance, typically liquid, that is used to reduce or regulate the temperature of a system. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, chemically inert and neither causes nor promotes corr ...
available for its instruments; when that coolant ran out, the instruments would stop functioning correctly. At the time of its launch, operations were estimated to last 3.5 years (to around the end of 2012). It continued to operate until 29 April 2013 15:20 UTC, when ''Herschel'' ran out of coolant.
NASA was a partner in the Herschel mission, with US participants contributing to the mission; providing mission-enabling instrument technology and sponsoring the NASA Herschel Science Center (NHSC) at the
Infrared Processing and Analysis Center
The Infrared Processing and Analysis Center (IPAC) provides science operations, data management, data archives and community support for astronomy and planetary science missions. IPAC has a historical emphasis on infrared-submillimeter astronomy a ...
and the Herschel Data Search at the
Infrared Science Archive
The Infrared Science Archive (IRSA) is the primary archive for the infrared and submillimeter astronomical projects of NASA, the space agency of the United States. IRSA curates the science products of over 15 missions, including the Spitzer Space T ...
.
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 Observatory
The Infrared Space Observatory (ISO) was a space telescope for infrared light designed and operated by the European Space Agency (ESA), in cooperation with ISAS (now part of Japan Aerospace Exploration Agency, JAXA) and National Aeronautics and ...
2.5–240 μm) 1995–1998 In 2000, FIRST was renamed Herschel. After being put out to tender in 2000, industrial activities began in 2001. Herschel was launched in 2009.
The Herschel mission cost . This figure includes spacecraft and payload, launch and mission expenses, and science operations.
Science
Herschel specialised in collecting
light
Light, visible light, or visible radiation is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400– ...
from objects in the
Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...
as well as the
Milky Way
The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galax ...
and even
extragalactic objects billions of
light-year
A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...
s away, such as newborn
galaxies
A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar Sys ...
, and was charged with four primary areas of investigation:
*
Galaxy formation
In cosmology, the study of galaxy formation and evolution is concerned with the processes that formed a Homogeneity and heterogeneity, heterogeneous universe from a Big Bang, homogeneous beginning, the formation of the first galaxies, the way ga ...
in the
early universe and the evolution of galaxies;
*
Star formation
Star formation is the process by which dense regions within molecular clouds in interstellar space—sometimes referred to as "stellar nurseries" or "star-forming regions"—Jeans instability, collapse and form stars. As a branch of astronomy, sta ...
and its interaction with the
interstellar medium
The interstellar medium (ISM) is the matter and radiation that exists in the outer space, space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as cosmic dust, dust and cosmic rays. It f ...
;
* Chemical composition of
atmospheres and surfaces of Solar System bodies, including
planet
A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...
s,
comet
A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...
s and
moons
A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are colloquially referred to as moons, a deriva ...
;
* Molecular chemistry across the
universe
The universe is all of space and time and their contents. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from s ...
.
During the mission, Herschel "made over 35,000 scientific observations" and "amass
dmore than 25,000 hours' worth of science data from about 600 different observing programs".
Instrumentation
The mission involved the first
space observatory
A space telescope (also known as space observatory) is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first operational telescopes were the American Orbiting Astronomical Observatory, OAO ...
to cover the full
far infrared
Far infrared (FIR) or long wave refers to a specific range within the infrared spectrum of electromagnetic radiation. It encompasses radiation with wavelengths ranging from 15 μm ( micrometers) to 1 mm, which corresponds to a freque ...
and
submillimetre waveband.
At , Herschel carried the largest optical telescope ever deployed in space.
It was made not from glass but from
sintered
Sintering or frittage is the process of compacting and forming a solid mass of material by pressure or heat without melting it to the point of liquefaction. Sintering happens as part of a manufacturing process used with metals, ceramics, pla ...
silicon carbide
Silicon carbide (SiC), also known as carborundum (), is a hard chemical compound containing silicon and carbon. A wide bandgap semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mass-produced as a powder a ...
. The mirror's blank was manufactured by Boostec in
Tarbes
Tarbes (; Gascon language, Gascon: ''Tarba'') is a Communes of France, commune in the Hautes-Pyrénées Departments of France, department in the Occitania (administrative region), Occitanie Regions of France, region of southwestern France. It is ...
,
France
France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
; ground and polished by Opteon Ltd. in
Tuorla Observatory
Tuorla Observatory is the Department of Astronomy at the University of Turku, southwest Finland. It is the largest astronomical research institute in Finland. Together with the Space Research Laboratory at the Physics Department of the University o ...
,
Finland
Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...
; and coated by vacuum deposition at the
Calar Alto Observatory
The Calar Alto Observatory (Centro Astronómico Hispano en Andalucía or "Spanish Astronomical Centre in Andalusia") is an astronomical observatory located in Almería province in Spain on Calar Alto, a mountain in the Sierra de Los Filabre ...
in
Spain
Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...
.
The light reflected by the mirror was focused onto three instruments, whose detectors were kept at temperatures below . The instruments were cooled with over of
liquid helium
Liquid helium is a physical state of helium at very low temperatures at standard atmospheric pressures. Liquid helium may show superfluidity.
At standard pressure, the chemical element helium exists in a liquid form only at the extremely low temp ...
, boiling away in a near vacuum at a temperature of approximately . The supply of helium on board the spacecraft was a fundamental limit to the operational lifetime of the space observatory;
[ it was originally expected to be operational for at least three years.
Herschel carried three detectors:
; PACS (Photodetecting Array Camera and Spectrometer): An imaging camera and low-resolution ]spectrometer
A spectrometer () is a scientific instrument used to separate and measure Spectrum, spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomeno ...
covering wavelengths from 55 to 210 micrometre
The micrometre (English in the Commonwealth of Nations, Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a uni ...
s, which was designed and built by the Max Planck Institute for Extraterrestrial Physics
The Max Planck Institute for Extraterrestrial Physics is part of the Max Planck Society, located in Garching, near Munich, Germany.
In 1991 the Max Planck Institute for Physics and Astrophysics split up into the Max Planck Institute for Extraterr ...
. The spectrometer had a 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. It is usually denoted by \Delta\lambda, and is closely related to the resolvi ...
between R=1000 and R=5000 and was able to detect signals as weak as −63 dB. It operated as an integral field spectrograph, combining spatial and spectral resolution. The imaging camera was able to 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 had a resolution between R=40 and R=1000 at a wavelength of 250 micrometres and was able to image point sources with brightnesses around 100 millijanskys (mJy) and extended sources with brightnesses of around 500 mJy. The imaging camera had three bands Bands may refer to:
* Bands (song), song by American rapper Comethazine
* Bands (neckwear), form of formal neckwear
* Bands (Italian Army irregulars)
Bands () was an Italian military term for Irregular military, irregular forces, composed of nati ...
, centred at 250, 350 and 500 micrometres, each with 139, 88 and 43 pixels respectively. It was able to detect point source
A point source is a single identifiable ''localized'' source of something. A point source has a negligible extent, distinguishing it from other source geometries. Sources are called point sources because, in mathematical modeling, these sources ...
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
The Jet Propulsion Laboratory (JPL) is a Federally funded research and development centers, federally funded research and development center (FFRDC) in La Cañada Flintridge, California, Crescenta Valley, United States. Founded in 1936 by Cali ...
in Pasadena, Calif., developed and built the "spider web" bolometer
A bolometer is a device for measuring radiant heat by means of a material having a temperature-dependent electrical resistance. It was invented in 1878 by the American astronomer Samuel Pierpont Langley.
Principle of operation
A 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
Cardiff University () is a public research university in Cardiff, Wales. It was established in 1883 as the University College of South Wales and Monmouthshire and became a founding college of the University of Wales in 1893. It was renamed Unive ...
was the lead institute.
; HIFI (Heterodyne Instrument for the Far Infrared): A heterodyne
A heterodyne is a signal frequency that is created by combining or mixing two other frequencies using a signal processing technique called ''heterodyning'', which was invented by Canadian inventor-engineer Reginald Fessenden. Heterodyning is us ...
detector able to electronically separate radiation of different wavelengths, giving a spectral resolution as high as R=107. The spectrometer was operated within two wavelength bands, from 157 to 212 micrometres and from 240 to 625 micrometres. SRON Netherlands Institute for Space Research led the entire process of designing, constructing and testing HIFI. The HIFI Instrument Control Center, also under the leadership of SRON, was responsible for obtaining and analysing the data.
NASA developed and built the mixers, local oscillator chains and power amplifiers for this instrument. The ''NASA Herschel Science Center'', part of the Infrared Processing and Analysis Center at the California Institute of Technology, also in Pasadena, has contributed science planning and data analysis software.
Service module
A common service module
A service module (also known as an equipment module or instrument compartment) is a component of a crewed space capsule containing a variety of support systems used for spacecraft operations. Usually located in the uninhabited area of the spacec ...
(SVM) was designed and built by Thales Alenia Space
Thales Alenia Space () is a joint venture between the French technology corporation Thales Group (67%) and Italian defense conglomerate Leonardo (company), Leonardo (33%). The company is headquartered in Cannes, France.
It provides space-based ...
in its Turin
Turin ( , ; ; , then ) is a city and an important business and cultural centre in northern Italy. It is the capital city of Piedmont and of the Metropolitan City of Turin, and was the first Italian capital from 1861 to 1865. The city is main ...
plant for the Herschel and ''Planck
Max Karl Ernst Ludwig Planck (; ; 23 April 1858 – 4 October 1947) was a German theoretical physicist whose discovery of energy quanta won him the Nobel Prize in Physics in 1918.
Planck made many substantial contributions to theoretical p ...
'' missions, as they were combined into one single program.
Structurally, the Herschel and ''Planck'' SVMs are very similar. Both SVMs are of octagonal shape and, for both, each panel is dedicated to accommodate a designated set of warm units, while taking into account the heat dissipation requirements of the different warm units, of the instruments, as well as the spacecraft.
Furthermore, on both spacecraft a common design has been achieved for the avionics
Avionics (a portmanteau of ''aviation'' and ''electronics'') are the Electronics, electronic systems used on aircraft. Avionic systems include communications, Air navigation, navigation, the display and management of multiple systems, and the ...
systems, attitude control and measurement systems (ACMS), command and data management systems (CDMS), power subsystems and the tracking, telemetry, and command subsystem (TT&C).
All spacecraft units on the SVM are redundant.
Power subsystem
On each spacecraft, the power subsystem consists of the solar array
A photovoltaic system, also called a PV system or solar power system, is an electric power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to abs ...
, employing triple-junction solar cell
A solar cell, also known as a photovoltaic cell (PV cell), is an electronic device that converts the energy of light directly into electricity by means of the photovoltaic effect. 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's 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 seconds.
The main sensor of the line of sight in both spacecraft is the star tracker
A star tracker is an optical device that measures the positions of stars using photocells or a camera.
As the positions of many stars have been measured by astronomers to a high degree of accuracy, a star tracker on a satellite or spacecraft may ...
.
Launch and orbit
The spacecraft, built in the Cannes 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. After a long history in aircraft manufacturing, starting in 1929, the center became incr ...
, under Thales Alenia Space
Thales Alenia Space () is a joint venture between the French technology corporation Thales Group (67%) and Italian defense conglomerate Leonardo (company), Leonardo (33%). The company is headquartered in Cannes, France.
It provides space-based ...
Contractorship, was successfully launched from the Guiana Space Centre
The Guiana Space Centre (; CSG), also called Europe's Spaceport, is a spaceport to the northwest of Kourou in French Guiana, an Overseas departments and regions of France, overseas region of France in South America. Kourou is located approxim ...
in French Guiana at 13:12:02 UTC on 14 May 2009, aboard an Ariane 5
Ariane 5 is a retired European heavy-lift space launch vehicle operated by Arianespace for the European Space Agency (ESA). It was launched from the Guiana Space Centre (CSG) in French Guiana. It was used to deliver payloads into geostationar ...
rocket, along with the Planck spacecraft, and placed on a very elliptical orbit on its way towards the second Lagrangian point.[Herschel Latest News]
on line herschel.esac.esa.int
/ref> The orbit's perigee
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values.
Apsides perta ...
was 270.0 km (intended ), apogee
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values.
Apsides perta ...
1,197,080 km (intended ), inclination
Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object.
For a satellite orbiting the Eart ...
5.99 deg (intended ).
On 14 June 2009, ESA successfully sent the command for the cryocover to open which allowed 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.
Five days later the first set of test photos, depicting 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 (M51A). Other notable members include the companion galaxy to the Whirlpool Galaxy ( M51B) and the ...
, was published by ESA.
In mid-July 2009, approximately sixty days after launch, it entered a halo orbit
A halo orbit is a periodic, non-planar orbit associated with 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 th ...
of 800,000 km average radius around the second Lagrangian point (L2) of the Earth-Sun system, 1.5 million kilometres from the Earth.
Discoveries
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.
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
A dark nebula or absorption nebula is a type of interstellar cloud, particularly molecular clouds, that is so dense that it obscures the visible wavelengths of light from objects behind it, such as background stars and emission or reflection ...
, in the area of NGC 1999 shed new light in the way newly forming star regions discard the material which surround them.
In July 2010 a special issue of ''Astronomy and Astrophysics'' was published with 152 papers on initial results from the observatory.
A second special issue of ''Astronomy and Astrophysics'' was published in October 2010 concerning the sole HIFI instrument, due its technical failure which took it down over 6 months between August 2009 and February 2010.
It was reported on 1 August 2011, that molecular oxygen
Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
had been definitively confirmed in space with the Herschel Space Telescope, the second time scientists have found the molecule in space. It had been previously reported by the Odin
Odin (; from ) is a widely revered god in Norse mythology and Germanic paganism. Most surviving information on Odin comes from Norse mythology, but he figures prominently in the recorded history of Northern Europe. This includes the Roman Em ...
team.
An October 2011 report published in ''Nature'' states that Herschel measurements of deuterium levels in the comet Hartley 2 suggests that much of Earth's water could have initially come from cometary impacts. On 20 October 2011, it was reported that oceans-worth of cold water vapor had been discovered in the accretion disc of a young star. Unlike warm water vapor, previously detected near forming stars, cold water vapor would be capable of forming comets which then could bring water to inner planets, as is theorized for the origin of water on Earth
The origin of water on Earth is the subject of a body of research in the fields of planetary science, astronomy, and astrobiology. Earth is unique among the Terrestrial planet, rocky planets in the Solar System in having oceans of liquid water on ...
.
On 18 April 2013, the Herschel team announced in another ''Nature'' paper that it had located an exceptional starburst galaxy
A starburst galaxy is one undergoing an exceptionally high rate of star formation, as compared to the long-term average rate of star formation in the galaxy, or the star formation rate observed in most other galaxies.
For example, the star format ...
which produced over 2,000 solar mass
The solar mass () is a frequently used unit of mass in astronomy, equal to approximately . It is approximately equal to the mass of the Sun. It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxie ...
es of stars a year. The galaxy, termed HFLS3, is located at '' z ='' 6.34, originating only 880 million years after the Big Bang
The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models based on the Big Bang concept explain a broad range of phenomena, including th ...
.
Just days before the end of its mission, ESA announced that Herschel observations had led to the conclusion that water on Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...
had been delivered as a result of the collision of Comet Shoemaker–Levy 9
Comet Shoemaker–Levy 9 ( formally designated D/1993 F2) was a comet that broke apart in July 1992 and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of Solar System objects. ...
in 1994.
On 22 January 2014, ESA scientists using Herschel data reported the detection, for the first definitive time, of water vapor
Water vapor, water vapour, or aqueous vapor is the gaseous phase of Properties of water, water. It is one Phase (matter), state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from th ...
on the dwarf planet
A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be hydrostatic equilibrium, gravitationally rounded, but insufficient to achieve clearing the neighbourhood, orbital dominance like the ...
, Ceres, largest object in the asteroid belt
The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids ...
. The finding is unexpected because comets
A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or coma surrounding the nucleus, an ...
, not asteroids
An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...
, are typically considered to "sprout jets and plumes". According to one of the scientists, "The lines are becoming more and more blurred between comets and asteroids."
End of mission
On 29 April 2013, ESA announced that Herschel supply of liquid helium
Liquid helium is a physical state of helium at very low temperatures at standard atmospheric pressures. Liquid helium may show superfluidity.
At standard pressure, the chemical element helium exists in a liquid form only at the extremely low temp ...
, used to cool the instruments and detectors on board, had been depleted, thus ending its mission.[ At the time of the announcement, Herschel was approximately 1.5 million km from Earth. Because Herschel orbit at the L2 point is unstable, ESA wanted to guide the craft on a known trajectory. ESA managers considered two options:
*Place Herschel into a ]heliocentric orbit
A heliocentric orbit (also called circumsolar orbit) is an orbit around the barycenter of the Solar System, which is usually located within or very near the surface of the Sun. All planets, comets, and asteroids in the Solar System, and the Sun ...
where it would not encounter Earth for at least several hundred years.
*Guide Herschel on a course toward the Moon for a destructive high-speed collision that would help in the search for water at a lunar pole. Herschel would take about 100 days to reach the Moon.
The managers chose the first option because it was less costly.
On 17 June 2013, Herschel was fully deactivated, with its fuel tanks forcibly depleted and the onboard computer programmed to cease communications with Earth. The final command, which severed communications, was sent from European Space Operations Centre
The European Space Operations Centre (ESOC) serves as the main mission control centre for the European Space Agency (ESA) and is located in Darmstadt, Germany. ESOC's primary function is the operation of uncrewed spacecraft on behalf of ESA and ...
(ESOC) at 12:25 UTC.
The mission's post-operations phase continued until 2017. The main tasks were consolidation and refinement of instrument calibration, to improve data quality, and data processing, to create a body of scientifically validated data.
After Herschel
Following Herschel demise, some European astronomers have pushed for the joint European-Japanese SPICA
Spica is the brightest object in the constellation of Virgo and one of the 20 brightest stars in the night sky. It has the Bayer designation α Virginis, which is Latinised to Alpha Virginis and abbreviated Alpha Vir or α Vir. Analys ...
far-infrared observatory project, as well as ESA's continued partnership in NASA's James Webb Space Telescope
The James Webb Space Telescope (JWST) is a space telescope designed to conduct infrared astronomy. As the largest telescope in space, it is equipped with high-resolution and high-sensitivity instruments, allowing it to view objects too old, Lis ...
. James Webb covers the near-infrared spectrum from 0.6 to 28.5 μm, and SPICA covers the mid-to-far-infrared spectral range between 12 and 230 μm. While Herschel dependence on liquid helium coolant limited the design life to around three years, SPICA would have used mechanical Joule-Thomson coolers to sustain cryogenic temperatures for a longer period of time. SPICA's sensitivity was to be two orders of magnitude higher than Herschel.
NASA's proposed Origins Space Telescope (OST) would also observe in the far-infrared
Far infrared (FIR) or long wave refers to a specific range within the infrared spectrum of electromagnetic radiation. It encompasses radiation with wavelengths ranging from 15 μm ( micrometers) to 1 mm, which corresponds to a freque ...
band of light. Europe is leading the study for one of OST's five instruments, the Heterodyne Receiver for OST (HERO).
See also
*Atacama Large Millimeter Array
The Atacama Large Millimeter/submillimeter Array (ALMA) is an astronomical interferometer of 66 radio telescopes in the Atacama Desert of northern Chile, which observe electromagnetic radiation at millimeter and submillimeter wavelengths. The ar ...
(ALMA)
*Spitzer Space Telescope
The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003, that was deactivated when operations ended on 30 January 2020. Spitzer was the third space telescope dedicate ...
*List of largest infrared telescopes
The largest infrared telescopes for infrared astronomy are listed in terms of diameter of primary mirror. The infrared spectrum with its longer wavelength than visible light has a number of challenges, especially for ground-based observatories ...
*List of largest optical reflecting telescopes
This list of the largest optical reflecting telescopes with Objective (optics), objective diameters of or greater is sorted by aperture, which is a measure of the light-gathering power and resolution of a reflecting telescope. The mirrors themse ...
*List of space telescopes
This list of space telescopes (astronomy, astronomical space observatory, space observatories) is grouped by major frequency ranges: gamma ray, x-ray, ultraviolet, visible light, visible, infrared, microwave and radio. Telescopes that work in mult ...
References
Further reading
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External links
*ESA
Herschel mission website
Herschel science website
Herschel operations website
Herschel science results website
*NASA
Herschel mission website
Herschel Science Center
United Kingdom outreach website
{{Authority control
European Space Agency space probes
Space telescopes
Infrared telescopes
Submillimetre telescopes
Derelict satellites in heliocentric orbit
Spacecraft using Lissajous orbits
Space probes launched in 2009
Space probes decommissioned in 2013
2013 disestablishments in Europe
Artificial satellites at Earth-Sun Lagrange points