The Herschel Space Observatory was a
space observatory
A space telescope or 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-2 launche ...
built and operated by the
European Space Agency (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 in 2021.
Herschel carries a mirror
and instruments sensitive to the
far infrared
Far infrared (FIR) is a region in the infrared spectrum of electromagnetic radiation. Far infrared is often defined as any radiation with a wavelength of 15 micrometers (μm) to 1 mm (corresponding to a range of about 20 THz to ...
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 space science and space exploration missions. Managed by the agency's Directorate of Science, The programme funds the development, launch, and operation of missions ...
programme, following ''
SOHO
Soho is an area of the City of Westminster, part of the West End of London. Originally a fashionable district for the aristocracy, it has been one of the main entertainment districts in the capital since the 19th century.
The area was develo ...
''/''
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 cornerst ...
'' and ''
Rosetta
Rosetta or Rashid (; ar, رشيد ' ; french: Rosette ; cop, ϯⲣⲁϣⲓⲧ ''ti-Rashit'', Ancient Greek: Βολβιτίνη ''Bolbitinē'') is a port city of the Nile Delta, east of Alexandria, in Egypt's Beheira governorate. The Ro ...
''.
The observatory was carried into orbit by an
Ariane 5 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
Frederick William Herschel (; german: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline H ...
, the discoverer of the
infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
spectrum and planet
Uranus
Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus ( Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars), grandfather of Zeus (Jupiter) and father of ...
, and his sister and collaborator
Caroline Herschel
Caroline Lucretia Herschel (; 16 March 1750 – 9 January 1848) was a German born British astronomer, whose most significant contributions to astronomy were the discoveries of several comets, including the periodic comet 35P/Herschel–Rigolle ...
.
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 corrosi ...
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 Sp ...
.
Development
In 1982 the Far Infrared and Sub-millimetre Telescope (FIRST) was proposed to
ESA
, owners =
, headquarters = Paris, Île-de-France, France
, coordinates =
, spaceport = Guiana Space Centre
, seal = File:ESA emblem seal.png
, seal_size = 130px
, image = Views in the Main Control Room (120 ...
. 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 JAXA) and NASA. The ISO was designed to study infrared light at wavelengt ...
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 or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 te ...
from objects in the
Solar System
The Solar System Capitalization 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 "Solar ...
as well as the
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...
and even
extragalactic objects billions of
light-years away, such as newborn
galaxies, and was charged with four primary areas of investigation:
*
Galaxy formation
The study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have ge ...
in the
early universe
The chronology of the universe describes the history and future of the universe according to Big Bang cosmology.
Research published in 2015 estimates the earliest stages of the universe's existence as taking place 13.8 billion years ago, wit ...
and the evolution of galaxies;
*
Star formation and its interaction with the
interstellar medium;
* Chemical composition of
atmospheres and surfaces of Solar System bodies, including
planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
s,
comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ...
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 often colloquially referred to as ''moons'' ...
;
* Molecular chemistry across the
universe
The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. ...
.
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 or 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-2 launche ...
to cover the full
far infrared
Far infrared (FIR) is a region in the infrared spectrum of electromagnetic radiation. Far infrared is often defined as any radiation with a wavelength of 15 micrometers (μm) to 1 mm (corresponding to a range of about 20 THz to ...
and
submillimetre waveband.
At , Herschel carried the largest optical telescope ever deployed in space.
It was made not from glass but from
sintered silicon carbide
Silicon carbide (SiC), also known as carborundum (), is a hard chemical compound containing silicon and carbon. A semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mass-produced as a powder and crystal s ...
. The mirror's blank was manufactured by Boostec in
Tarbes
Tarbes (; Gascon: ''Tarba'') is a commune in the Hautes-Pyrénées department in the Occitanie region of southwestern France. It is the capital of Bigorre and of the Hautes-Pyrénées. It has been a commune since 1790. It was known as ''Turba ...
,
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...
; 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 ...
,
Finland
Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of B ...
; and coated by vacuum deposition at the
Calar Alto Observatory in
Spain
, image_flag = Bandera de España.svg
, image_coat = Escudo de España (mazonado).svg
, national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond")
, national_anthem = (English: "Royal March")
, i ...
.
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 spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomenon where the ...
covering wavelengths from 55 to 210 micrometre
The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...
s, which was designed and built by the Max Planck Institute for Extraterrestrial Physics. The spectrometer had a spectral resolution between R=1000 and R=5000 and was able to detect signals as weak as −63 dB. It operated as an integral field spectrograph
Integral Field Spectrographs (IFS) combine spectrographic and imaging capabilities in the optical or infrared wavelength domains -from 0.32 μm to 24 μm- to get from a single exposure spatially resolved spectra in a bi-dimensional region. Develop ...
, 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, 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 ''localised'' source of something. A point source has negligible extent, distinguishing it from other source geometries. Sources are called point sources because in mathematical modeling, these sources ca ...
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 or The Blast may refer to:
*Explosion, a rapid increase in volume and release of energy in an extreme manner
*Detonation, an exothermic front accelerating through a medium that eventually drives a shock front
Film
* ''Blast'' (1997 film), ...
high-altitude balloon. NASA's Jet Propulsion Laboratory
The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States.
Founded in the 1930s by Caltech researchers, JPL is owned by NASA an ...
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 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 u ...
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 Franco-Italian aerospace manufacturer. A joint venture between the French technology corporation Thales Group (67%) and Italian defense conglomerate Leonardo (33%), the company is the largest satellite manufactur ...
in its Turin
Turin ( , Piedmontese: ; it, Torino ) 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 ...
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 blend of ''aviation'' and ''electronics'') are the electronic systems used on aircraft. Avionic systems include communications, navigation, the display and management of multiple systems, and the hundreds of systems that are fit ...
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 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 absorb and ...
, employing triple-junction solar cell
A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon. s, a battery
Battery most often refers to:
* Electric battery, a device that provides electrical power
* Battery (crime), a crime involving unlawful physical contact
Battery may also refer to:
Energy source
*Automotive battery, a device to provide power t ...
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
Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle/satellite) with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, et ...
. 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 incre ...
, under Thales Alenia Space
Thales Alenia Space () is a Franco-Italian aerospace manufacturer. A joint venture between the French technology corporation Thales Group (67%) and Italian defense conglomerate Leonardo (33%), the company is the largest satellite manufactur ...
Contractorship, was successfully launched from the Guiana Space Centre
The Guiana Space Centre (french: links=no, Centre spatial guyanais; CSG), also called Europe's Spaceport, is a European spaceport to the northwest of Kourou in French Guiana, a region of France in South America. Kourou is located approximatel ...
in French Guiana at 13:12:02 UTC on 14 May 2009, aboard an Ariane 5 rocket, along with the Planck spacecraft
''Planck'' was a space observatory operated by the European Space Agency (ESA) from 2009 to 2013, which mapped the anisotropies of the cosmic microwave background (CMB) at microwave and infrared frequencies, with high sensitivity and small angu ...
, 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. For example, the apsides of the Earth are called the aphelion and perihelion.
General description
There are two apsides in any ell ...
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. For example, the apsides of the Earth are called the aphelion and perihelion.
General description
There are two apsides in any ell ...
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 S ...
, was published by ESA.
In mid-July 2009, approximately sixty days after launch, it entered a halo 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.
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 nebu ...
, 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 the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
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 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 rocky planets in the Solar System in that it is the only planet known to have oceans of ...
.
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 formatio ...
which produced over 2,000 solar masses of stars a year. The galaxy, termed HFLS3, is located at '' z ='' 6.34, originating only 880 million years after the Big Bang.
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 largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...
had been delivered as a result of the collision of Comet Shoemaker–Levy 9
Comet Shoemaker–Levy 9 ( formally designated D/1993 F2) 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. This generated a ...
in 1994.
On 22 January 2014, ESA
, owners =
, headquarters = Paris, Île-de-France, France
, coordinates =
, spaceport = Guiana Space Centre
, seal = File:ESA emblem seal.png
, seal_size = 130px
, image = Views in the Main Control Room (120 ...
scientists using Herschel data reported the detection, for the first definitive time, of water vapor
(99.9839 °C)
, -
, Boiling point
,
, -
, specific gas constant
, 461.5 J/( kg·K)
, -
, Heat of vaporization
, 2.27 MJ/kg
, -
, Heat capacity
, 1.864 kJ/(kg·K)
Water vapor, water vapour or aqueous vapor is the gaseous p ...
on the dwarf planet
A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun, smaller than any of the eight classical planets but still a world in its own right. The prototypical dwarf planet is Pluto. The interest of dwarf planets to ...
, Ceres
Ceres most commonly refers to:
* Ceres (dwarf planet), the largest asteroid
* Ceres (mythology), the Roman goddess of agriculture
Ceres may also refer to:
Places
Brazil
* Ceres, Goiás, Brazil
* Ceres Microregion, in north-central Goiás ...
, largest object in the asteroid belt
The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, c ...
. The finding is unexpected because comets
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...
, not asteroids
An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...
, 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 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 unmanned 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. 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
Origins Space Telescope (Origins) is a concept study for a far-infrared survey space telescope mission.[far-infrared
Far infrared (FIR) is a region in the infrared spectrum of electromagnetic radiation. Far infrared is often defined as any radiation with a wavelength of 15 micrometers (μm) to 1 mm (corresponding to a range of about 20 THz to ...]
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 ...
(ALMA)
* Spitzer Space Telescope
*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
A ''list'' is any set of items in a row. List or lists may also refer to:
People
* List (surname)
Organizations
* List College, an undergraduate division of the Jewish Theological Seminary of America
* SC Germania List, German rugby unio ...
*List of space telescopes
This list of space telescopes (astronomical space observatories) is grouped by major frequency ranges: gamma ray, x-ray, ultraviolet, visible, infrared, microwave and radio. Telescopes that work in multiple frequency bands are included in all ...
References
Further reading
*
*
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