GAIA :

LAUNCH DATE:	2013
MISSION END:	nominal mission end after 5 years (2018)
LAUNCH VEHICLE:	Soyuz-Fregat
LAUNCH MASS:	2030 kg
MISSION PHASE:	Implementation

ORBIT: Lissajous-type orbit around L2
OBJECTIVES: To create the largest and most precise three dimensional chart of our Galaxy by providing unprecedented positional and radial velocity measurements for about one billion stars in our Galaxy and throughout the Local Group.

Un nou proiect, intitulat Gaia, va studia timp de 5 ani Calea Lactee, cartografiind întreaga galaxie şi obţinând răspunsuri la cele mai importante întrebări despre evoluţia şi structura sa. „Va fi fenomenal. Va schimba totul”, a declarat astronomul Barry F. Madore de la Observatorul Carnegie din Pasadena, California.

Dezvoltată de Agenţia Spaţială Europeană şi construită de EADS, naveta Gaia valorează 700 de milioane de euro. Gaia va fi doar cel de-al doilea satelit dedicat astrometriei (ştiinţa care se ocupă de studierea mişcărilor, poziţiilor şi distanţelor dintre diferite obiecte astronomice) lansat pe orbită. Astrometria este o ştiinţă practicată de câteva secole, însă acurateţea telescoapelor situate pe planeta noastră este limitată de turbulenţele atmosferice. Până acum, oamenii de ştiinţă au măsurat cu o precizie de 1% distanţa către mai puţin de 1.000 de stele. Cu Gaia, însă, cercetătorii estimează că vor putea măsura cu această fidelitate distanţa către mai bine de 10 milioane de stele. În cuvintele lui Timo Prusti, un cercetător implicat în acest proiect, „va fi o lovitură de baros pentru astronomia fundamentală”.

Naveta Gaia urmează să fie lansată în cursul acestui an din Kourou, Guiana Franceză, urmând să intre în orbită în punctul L2 (Lagrange 2), la 1,5 milioane de kilometri

Technical Info : Fully-integrated Gaia Protoflight Payload Module with all the Multi-Layer Insulation (MLI) installed, with the exception of the covering for the bipods. The optical bench is now shrouded with MLI. Nearest to the camera, the rear of one of the primary mirrors and one of the tertiary mirrors are visible. Beneath the tertiary (smaller) mirror, the Radial Velocity Spectrometer (RVS) can be seen. To the right of the RVS is the Focal Plane Assembly (FPA) with its Charge-Coupled Device (CCD) sensors (blue). The focal plane array, with 106 CCDs, a total of almost 1 Gigapixels, is the largest ever developed.

PLANK & HERSCHEL:

Herschel reflected in Planck mirror

Planck will offer vastly improved performance in measuring the Cosmic Microwave Background (CMB) radiation compared to balloon-borne and ground-based experiments and will exceed the performance of any previous space-based instruments of this kind.

The spacecraft revolves about its Sun-pointing axis once per minute to stabilise its attitude. Planck will use this stabilisation spin to scan the sky, observing at least 95% of it through two separate observation periods in a span of 15 months.

The Planck spacecraft
Dimensions	4.20 x 4.22 m (height x width)
Mass	1.95 tonnes at launch
Spacecraft	Spin stabilised, 1 rpm
Telescope mirror	1.9 x 1.5 m primary reflector
Telescope mass	205 kg with focal plane unit
Lifetime	A minimum of 15 months, limited by degradation of cooling system
Operational orbit	Lissajous orbit at an average distance of 400 000 km from L2
Propulsion	Hydrazine, 12 thrusters x 20 N each, 4 thrusters x 1 Newton each
Solar arrays	Flat, fixed triple-junction Gallium-Arsenide cell panels on rear of spacecraft
	Solar array area: 13m²
Batteries	39 Ah lithium ion batteries
Planck will study the Cosmic Microwave Background by measuring its temperature all over the sky. Planck’s large telescope will collect light from the CMB and focus it onto two arrays of radio detectors, which will translate the signal into a temperature reading. The detectors on board Planck are highly sensitive. They will look for variations in the temperature of the CMB of about a million times smaller than one degree – this is comparable to measuring from Earth the heat produced by a rabbit sitting on the Moon. The Planck spacecraft consists of two main elements: a warm satellite bus, or service module, and a cold payload module, which includes the two scientific instruments and the telescope. The service module is octagonal in shape. It houses the data handling systems and subsystems essential for the spacecraft to function and communicate with Earth, and the electronic and computer systems of the instruments. At the base of the service module is a flat, circular solar panel that generates power for the spacecraft and protects it from direct solar radiation. Planck’s cooling system - cut view The baffle is an important part of the payload module. It surrounds the telescope, limiting the amount of stray light incident on the reflectors. It also helps radiate excess heat into space, cooling the focal plane units of the instruments and the telescope to a stable temperature of about –223ºC (or 50 K). The baffle forms part of the passive cooling system for the satellite, which supports the active cooling system. The solar array, located at the bottom of the service module at one end of the spacecraft, is permanently illuminated by sunlight. Three reflective thermal shields isolate the service module from the payload module at the opposite end. This prevents heat generated by the solar array and the electronic boxes inside the service module from diffusing to the payload module. This passive cooling system brings the temperature of the telescope down to around 50 K. The temperature of the detectors is further decreased to levels as low as 0.1 K by a three-stage active refrigeration chain. The resulting difference in temperature between the warm and cold ends of the satellite is an astounding 300 K.	3 x low gain antennae 1 x medium gain antenna

http://youtu.be/Es4sjgq-_EE

JWST :

September 2009 artist conception of JWST.

The James Webb Space Telescope (JWST) is designed to expand the scientific success of the Hubble Space Telescope. Being a 'cool' telescope, JWST is designed to operate at very low temperatures (around -230° C). This will give it an unprecedented view of the Universe at infrared wavelengths and will allow it to observe a wide variety of celestial objects, ranging from planets in the Solar System to nearby stars, from neighbouring galaxies to galaxy clusters, and out to the farthest reaches of the very distant Universe. It is planned to operate for five years, possibly ten.

What’s special?

JWST is also very big, as its primary mirror has an area seven times larger than that of Hubble, which will make it much more sensitive. JWST will combine superb image quality, a large field of view, and a low level of background light with a highly stable environment away from the turbulence of the Earth's atmosphere that blurs images collected on the ground. All of these characteristics set JWST apart from other existing or planned observatories and will be instrumental in the search for the faintest stars and galaxies.

Spacecraft

September 2009 artist conception of JWST.

JWST will be launched on board an Ariane V ECA rocket from the European Spaceport of Kourou, in French Guiana. One technical challenge is trying to pack a 6.5-m spacecraft into a 5 m diameter rocket, described as ‘a bit like designing a ship in a bottle’. Besides the telescope mirrors, the spacecraft, and the large sun shield, the JWST observatory has four scientific instruments mounted behind the telescope itself:

The Near Infrared Camera (NIRCam) is mainly designed for imaging studies and the detection of faint objects. The topics for which NIRCam will be invaluable include the search for the first stars, star clusters and galaxy cores that formed after the Big Bang; the study of far distant galaxies seen in the process of formation or merging; the detection of light distortion due to dark matter; the discovery of supernovae in remote galaxies; studies of the stellar population in nearby galaxies, of young stars in the Milky Way and of Kuiper Belt objects in our Solar System.

The Near-Infrared Spectrograph (NIRSpec) will obtain spectra of more than 100 galaxies or stars simultaneously and is sensitive over a wavelength range that matches the peak emission from the most distant galaxies. The key scientific objectives of NIRSpec are the study of star formation and chemical abundances of young distant galaxies; tracing the creation of the chemical elements back in time; exploring the history of the intergalactic medium, i.e. the gaseous material that fills the vast volumes of space between the galaxies; characterising the atmospheres of extra-solar planets.

The Mid-Infrared Camera and Spectrograph (MIRI) is an essential tool for studying extremely old and distant stellar populations; regions of intense star formation that are hidden behind thick layers of obscuring dust; hydrogen emission from previously unthinkable distances; the physics of protostars; Kuiper Belt objects and faint comets.

The Fine Guidance Sensor (FGS) will provide high-precision signals to the observatory to enable stable pointing at the milli-arcsecond level. It will also support star field identification via correlation with a star catalogue as well as spatial and radiometric calibrations.

Journey

JWST must be cooled so that the instruments’ own infrared emission cannot overwhelm the faint signals from observed objects. The JWST orbit will be 1.5 million km away from Earth, at Lagrange Point 2 (L2), so it must be extremely reliable, even though it is using new and innovative technology, because it will be too far away for astronauts to service it.

History

The James Webb Space Telescope was formerly known as the Next Generation Space Telescope (NGST). Due for launch on an Ariane 5, it will follow in HST’s footsteps. ESA has participated actively in both missions from the very beginning, bringing huge scientific benefits to European astronomers, while promoting competitiveness and cross-border collaboration within European science as a whole. NASA and ESA, joined by the Canadian Space Agency, have collaborated on JWST since 1997.

Partnerships

JWST is a partnership between ESA, NASA and the Canadian Space Agency.

Last update: 14 November 2011

HST - old Hubble for ya '

EUCLID :

How did the Universe originate and what is it made of?

Primary Goal

To understand the nature of dark energy and dark matter by accurate measurement of the accelerated expansion of the Universe through different independent methods.

Targets

Galaxies and clusters of galaxies out to z~2,
in a wide extragalactic survey covering 15 000 deg², plus a deep survey covering an area of 40 deg²

WavelengthVisible and near-infrared
Telescope1.2 m Korsch
OrbitSecond Sun-Earth Lagrange point, L2
Lifetime6 years
TypeM-class mission

Euclid

20 June 2012

ESA’s Euclid mission to explore the hidden side of the Universe – dark energy and dark matter – reached an important milestone today that will see it head towards full construction.

Selected in October 2011 alongside Solar Orbiter as one of the first two medium-class missions of the Cosmic Vision 2015–25 plan, Euclid received final approval from ESA’s Science Programme Committee to move into the full construction phase, leading to its launch in 2020.

The committee also formalised an agreement between ESA and funding agencies in a number of its Member States to develop Euclid’s two scientific instruments, a visible-wavelength camera and a near-infrared camera/spectrometer, and the large distributed processing system needed to analyse the data they produce.Finally, the committee agreed on a Memorandum of Understanding between ESA and NASA that will see the US space agency help to provide infrared detectors.Nearly 1000 scientists from 100 institutes form the Euclid Consortium building the instruments and participating in the scientific harvest of the mission.

“This formal adoption of the mission is a major milestone for a large scientific community, their funding agencies and also for European industry,” said Alvaro Giménez Cañete, ESA’s Director of Science and Robotic Exploration.

“It took a lot of hard work to get this far, but we now have a solid blueprint for a feasible space telescope which enables very accurate measurements that will bring to light the nature of dark energy,” said Yannick Mellier, the Euclid Consortium lead.In the coming months, industry will be asked to make bids to supply spacecraft hardware, such as the telescope, power systems, attitude and orbit controls, and communications systems.Euclid will use a 1.2-m diameter telescope and the two instruments to map the 3D distribution of up to two billion galaxies and dark matter associated with them, spread over more than one third of the whole sky.Stretched across ten billion light-years, the mission will plot the evolution of the Universe’s structure over three-quarters of its history.Euclid is optimised to answer one of the most important questions in modern cosmology: why is the Universe expanding at an accelerating rate, rather than slowing down due to the gravitational attraction of all the matter in it?

The discovery of this cosmic acceleration in 1998 was rewarded with the Nobel Prize for Physics in 2011 and yet we still do not know what causes it.

The term ‘dark energy’ is often used to signify this mysterious force, but by using Euclid to study its effects on the galaxies and clusters of galaxies across the Universe, astronomers hope to come much closer to understanding its true nature and influence.“Euclid addresses the cosmology-themed questions of ESA’s Cosmic Vision and it’s fantastic that we are moving forward into the next stage of development – we’re one step closer to learning more about the Universe’s darkest secrets,” said René Laureijs, ESA’s Euclid project scientist.

Spacecraft

Introduction

The Euclid spacecraft will have a launch mass of around 2100 kg. It will be about 4.5 metres tall and 3.1 metres in 'diameter' (with appendages stowed). The nominal mission lifetime is six years.

The Euclid spacecraft will be made up of two major assemblies:

payload module – houses the telescope, the focal plane components of the instruments and some of the data processing electronics;
service module – contains the satellite systems: power distribution, attitude control, propulsion, telecommand, telemetry and data handling.

Two spacecraft concepts have been studied during the assessment phase: (left) concept from EADS Astrium, and (right) concept from Thales Alenia Space. Credit: ESA

Euclid

Mission Status

The Euclid mission has been adopted with launch planned for 2020.

Euclid, a mission devised to provide insight into the nature of dark energy and dark matter by accurate measurement of the accelerated expansion of the Universe, emerged from two mission concepts that were proposed in response to the ESA Cosmic Vision 2015-2025 Call for Proposals, issued in March 2007: the DUNE - Dark Universe Explorer - mission proposed to measure the effects of weak gravitational lensing; the SPACE - Spectroscopic All Sky Cosmic Explorer - mission, aimed at measuring the baryonic acoustic oscillations and redshift-space distortion patterns in the Universe.

In October 2007 the ESA advisory structure selected both proposals to enter the assessment study phase, considering them as equally relevant to the investigation of dark energy. ESA then appointed a Concept Advisory Team with the task of identifying the best possible concept for the dark energy mission to be studied during this phase. This team recommended a combined mission which could simultaneously measure weak lensing and baryonic acoustic oscillations (BAOs). The new mission concept was called Euclid, honouring the Greek mathematician Euclid of Alexandria (~300 BC) who is considered as the father of geometry.

The ESA internal pre-assessment phase for Euclid ran from November 2007 until May 2008. The outcome of this study was a preliminary design for the Euclid mission and its payload which formed the basis for the Invitation to Tender that was issued to Industry in May 2008. A parallel competitive contract was awarded to EADS Astrium Friedrichshafen (Germany) and Thales Alenia Space (Italy); these industrial activities were concluded in September 2009.

Two instrument consortia responded to ESA's call for Declaration of Interest for payload studies issued in May 2008. The consortium for the visual and near-infrared imaging photometer for the weak-lensing experiment is led by A. Réfrégier from CEA Saclay. The consortium providing the NIR spectrometer for the Baryonic Acoustic Oscillations experiment is led by A. Cimatti from Bologna University. These studies ran from October 2008 until August 2009.

The report of the assessment study, which includes the Euclid science case together with a synthesis of the industrial and instrument consortium studies, was presented to the scientific community in December 2009. In addition, an independent technical review of the assessment study was conducted by ESA. The recommendations of the review board were presented to the scientific community also in December 2009.

In early 2010 ESA's Science Programme Committee recommended that Euclid, along with two other M-class candidate missions (PLATO and Solar Orbiter) proceed to the next phase: a more detailed definition phase during which period the cost and implementation schedule for the mission must be established. This detailed definition phase was completed in mid 2011.

In October 2011, Euclid was selected by the SPC as one of the first two medium-class missions of the Cosmic Vison 2015-2025 plan; Solar Orbiter was the other mission selected at the time. Euclid received final approval to move into the full construction phase at the SPC meeting in June 2012.

Science Goals

Euclid is an ESA mission to map the geometry of the dark Universe. The mission will investigate the distance-redshift relationship and the evolution of cosmic structures. It achieves this by measuring shapes and redshifts of galaxies and clusters of galaxies out to redshifts ~2, or equivalently to a look-back time of 10 billion years. It will therefore cover the entire period over which dark energy played a significant role in accelerating the expansion.

Until about thirty years ago astronomers thought that the Universe was composed almost entirely of ordinary matter: protons, neutrons, electrons and atoms. In the intervening years the emerging picture of the composition of the Universe has changed dramatically. It is now assumed that ordinary matter makes up only about 4% of the Universe, and that the mass-energy budget of the Universe is actually dominated by two mysterious components: dark energy and dark matter.
Dark energy, which accounts for the vast majority (76%) of the energy density of the Universe, is causing the expansion of the Universe to accelerate. The existence and energy scale of dark energy cannot be explained with our current knowledge of fundamental physics.

The Universe evolves from a homogeneous state after the big bang through cooling and expansion. The small initial inhomogeneities grow through gravity to produce the large-scale structures that we see today. Credit: Euclid Assessment Study Report

The remaining 20% of the energy density is in the form of dark matter, which, like ordinary matter, exerts a gravitational attraction, but unlike normal matter does not emit light. The nature of dark matter is unknown, although several candidates are predicted by supersymmetric extensions of the standard model of particle physics. Plausible candidates for the cold dark matter are the axion and the lightest super¬symmetric particle; massive neutrinos can account for the hot dark matter. One possibility to explain one or both of these puzzling components is that Einstein's Theory of General Relativity, and thus our understanding of gravity, needs to be revised on cosmological scales. Together, dark energy and dark matter pose some of the most important questions in fundamental physics today.

Euclid's cosmological probes

Euclid will map the large-scale structure of the Universe over the entire extragalactic sky - or half of the full sky excluding the regions dominated by the stars in our Milky Way. It will measure galaxies out to redshifts of ~2, which corresponds to a look-back time of about 10 billion years, thus covering the period over which dark energy accelerated the expansion of the Universe.
Euclid is optimised for two primary cosmological probes:

Weak gravitational Lensing (WL): Weak lensing is a method to map the dark matter and measure dark energy by measuring the distortions of galaxy images by mass inhomogeneities along the line-of-sight.
Baryonic Acoustic Oscillations (BAO): BAOs are wiggle patterns, imprinted in the clustering of galaxies, which provide a standard ruler to measure dark energy and the expansion in the Universe.

Weak gravitational lensing requires extremely high image quality because possible image distortions by the optical system must be suppressed or calibrated-out to be able to measure the true distortions by gravity.

(Left) Illustrations of the effect of a lensing mass on a circularly symmetric image. (Right) In galaxy cluster Abell 1689, strongly lensed arcs can be seen around the cluster. Every background galaxy is weakly lensed.

The Euclid baryonic acoustic oscillations experiment involves the determination of the redshifts of galaxies to better than 0.1%, this can only be accomplished through spectroscopy.


Illustration of the two primary cosmological probes of Euclid: weak gravitational lensing (left) and Baryonic Acoustic Oscillations (right).Credit: (right) NASA, ESA, and R. Massey.

Surveyed in the same cosmic volume, these techniques not only provide systematic cross-checks but also a measurement of large scale structure via different physical fields (potential, density and velocity), which are required for testing dark energy and gravity on cosmological scales.
With its wide-field capability and high-precision design, Euclid will:

Investigate the properties of the dark energy by accurately measuring both the acceleration as well as the variation of the acceleration at different ages of the Universe
Test the validity of general relativity on cosmic scales
Investigate the nature and properties of dark matter by mapping the 3-dimensional dark matter distribution in the Universe
Refine the initial conditions at the beginning of our Universe, which seed the formation of the cosmic structures we see today.

Euclid is therefore poised to uncover new physics by challenging all sectors of the cosmological model. The Euclid survey can thus be thought of as the low-redshift, 3-dimensional analogue and complement to the map of the high-redshift Universe provided by ESA's Planck mission.

Additional science with Euclid

Euclid will produce a massive legacy of deep images and spectra over at least half of the entire sky. This will be a unique resource for the astronomical community and will impact upon all areas of astronomy. Euclid’s spatial resolution of 0.2 seconds of arc is only achievable from space, and is comparable to the Hubble Space Telescope. With Euclid, the majority of the new sources identified by future imaging observatories, from radio to X-rays, will be readily associated to a known redshift, out to a redshift z~2. This adds an enormous power to the science return of these other projects, as it eliminates the time-consuming phase of redshift follow-up. Euclid will be a discovery machine on an unprecedented scale, and may well be the major feeder for more detailed studies both with ground-based facilities and future satellites.

INTEGRAL :

Artist's impression, showing Integral instruments

Integral is the first space observatory that can simultaneously observe objects in gamma rays, X-rays and visible light. Its principal targets are violent explosions known as gamma-ray bursts, powerful phenomena such as supernova explosions, and regions in the Universe thought to contain black holes.

Gamma rays are even more powerful and penetrating than the X-rays used in medical examinations. Fortunately, the Earth's atmosphere acts as a shield to protect us from this dangerous cosmic radiation.

This means that gamma rays from space can only be detected above the Earth’s atmosphere. Integral is the most advanced gamma-ray observatory ever launched. It can detect radiation from events far away and from the processes that shape the Universe.

History

Integral launch

Integral was selected by the ESA in June 1993 as the next ESA medium-size scientific mission (M2) of its Horizon 2000 programme. The mission was conceived as an observatory led by ESA with contributions from Russia (Proton launcher) and NASA (Deep Space Network ground station)

SPI will gauge gamma-ray energies with exceptional precision

Standing 5 metres high and more than 4 tonnes in weight, the Integral spacecraft is impressive. The satellite has two main parts. The service module is the lower part of the satellite and contains all spacecraft subsystems. The payload module is mounted on the service module and carries the scientific instruments.

To limit the costs of the mission the service module is a rebuild of the one developed for XMM-Newton, ESA's X-ray Multi-Mirror satellite. It is a closed structure made of composite material, a combination of aluminium and carbon fibre. It houses the satellite systems, including solar power generation, power conditioning and control, data handling, telecommunications and thermal, attitude and orbit control.

The sharpest gamma-ray images to this day will come from IBIS

The four scientific instruments of Integral's payload module weigh 2 tonnes, making this payload the heaviest ever placed in orbit by ESA. This is due to the need to shield the detectors from background radiation in order to make them sensitive. There are two main instruments detecting gamma rays. An imager will give the sharpest gamma-ray images so far. A spectrometer will gauge gamma-ray energies extremely precisely. Two other instruments, an X-ray monitor and an optical camera, will help to identify the gamma-ray sources.

There is a special support structure 4 metres above the platform with the instrument detectors. This carries so-called 'coded masks'. These metal masks produce the images of the gamma-ray sources. Since gamma rays cannot be focussed by conventional lenses or mirrors, Integral has to use an entirely different technique to make its images, known as the coded mask technique. A coded-mask telescope is a pinhole camera with not just one but many pinholes.

Light, or electromagnetic radiation, comes in many forms. There are radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays and gamma rays, all of which form what is known as the 'electromagnetic spectrum'.

Oddly enough, visible light – to which human eyes are sensitive - is the smallest band of radiation. To our eyes, what we see seems like the entire Universe; yet there is much more out there.

Different types of objects in the Universe emit different types of radiation. Our Sun is a rather obvious source of visible light. But it also glows in radio waves, infrared, ultraviolet light and X-rays. Some objects emit only radio waves or only X-rays. This is why it is important to study the Universe with various kinds of space observatories.

Artist's impression of a gamma-ray burst

ESA’s Integral satellite is looking at the Universe, mainly concentrating on the gamma rays. These are produced by spectacular events in the Universe such as stars exploding, matter falling into black holes and celestial objects colliding. By collecting gamma rays, astronomers are able to see these violent events and can judge exactly how they shape the Universe.

For example, some chemical elements are created during explosions in which individual stars blow themselves to pieces. The new chemicals leave gamma-ray fingerprints in the fireball for astronomers to find. By studying these, Integral is piecing together how these chemicals are created.

Integral is also studying the mysterious blasts known as gamma-ray bursts. These explode at random in distant realms of the Universe and are probably caused by the collision of neutron stars (the hearts of dead stars) or may be the explosion of very massive stars.

Integral is designed to capture not just gamma rays but also X-rays and visible light. This complementary data is also helping astronomers identify the celestial object that is releasing the gamma rays and allow it to be more fully analysed.

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Merging neutron stars are probably responsible for some gamma-ray bursts

Astronomical satellites register sudden bursts of gamma rays, always from a random direction, roughly once a day. These bursts may last a hundredth of a second, or anything up to 90 minutes. They become, briefly, the brightest objects in the gamma-ray sky but are never seen to repeat.

For over 20 years, astronomers had no clues about how far away these explosions occurred. Until in 1997, the Italian-Dutch satellite BeppoSAX provided accurate X-ray measurements so quickly that a burst’s location could be pinpointed, enabling follow-up observations with optical and other telescopes.

These observations confirmed that the gamma-ray bursts are extremely distant and therefore must be caused by tremendous explosions equal to the radiance of millions of millions of stars.

An image of the full sky, showing gamma rays from radioactive aluminium, produced in supernovae

Where does this energy come from? This colossal amount of energy may be released when compact objects collide, such as neutron stars or black holes. Astronomers know of a small number of neutron stars in our galaxy that are in orbit around one another and may merge in the far future.

There is also mounting evidence that incredibly powerful supernovae, called ‘hypernovae’, are the source of the gamma-ray bursts.

Integral will be able to look at the glowing debris for the telltale signs of elements created when a star explodes.

XMM - NEWTON

Artist's impression of XMM-Newton

XMM-Newton is detecting more X-ray sources than any previous satellite and is helping to solve many cosmic mysteries of the violent Universe, from what happens in and around black holes to the formation of galaxies in the early Universe. It is designed and built to return data for at least a decade.

It is the biggest science satellite ever built in Europe. Its telescope mirrors are the most sensitive ever developed in the world, and with its sensitive detectors, it sees much more than any previous X-ray satellite.

XMM-Newton’s high-technology design uses over 170 wafer-thin cylindrical mirrors spread over three telescopes. Its orbit takes it almost a third of the way to the Moon, so that astronomers can enjoy long, uninterrupted views of celestial objects.

What's special?

XMM-Newton has been able to measure for the first time the influence of the gravitational field of a neutron star on the light it emits. This measurement provides much better insight into these objects.

Neutron stars are among the densest objects in the Universe — a sugarcube-sized piece of a neutron star would weigh over a thousand million tonnes. Neutron stars are the remnants of heavy stars that end their life in a supernova explosion. In such cataclysmic events, most of the stellar matter is ejected into space (to eventually become the building blocks of all matter in the Universe, including ourselves). Part of what remains then collapses under its own gravity.

Scientists believe that, in a neutron star, the density and the temperatures are similar to those existing a fraction of a second after the Big Bang when the primordial soup of matter in the Universe was ‘broken’ into its most fundamental constituents. They assume that when matter is tightly packed as it is in a neutron star, it goes through important changes. Protons, electrons, and neutrons — the components of atoms — fuse together. It is possible that even the building blocks of protons and neutrons, the so-called quarks, get crushed together.

Scientists have spent the last decades trying to identify the nature of matter in neutron stars. To do this, they need to know some important parameters, very precisely. If you know a star’s mass and radius, or the relationship between them, you can obtain its density. However, no instrument was advanced enough to perform the measurements needed, until now. Thanks to ESA’s XMM-Newton observatory, astronomers have been able to obtain the mass-to-radius ratio of a neutron star for the first time and acquire the first clues about its composition. These clues suggest that neutron stars contain normal, non-exotic matter, although they are not conclusive. Scientists say this is a ‘key first step’ and that they will keep on with the search.

This measurement was a first in astronomical observation and it is considered a huge achievement. The method consists of determining the compactness of the neutron star in an indirect way. The gravitational pull of a neutron star is immense — thousands of million times stronger than the Earth’s. This makes the light emitted by the neutron star lose energy. This energy loss is called a gravitational ‘redshift’. The measurement of this redshift by XMM-Newton indicated the strength of the gravitational pull, and revealed the star’s compactness.