IMAGE CAPTIONS:
Image 1:
A simulated EPIC p-n camera deep-field exposure.
Image 2:
Simulation of an XMM RGS observation of Capella.
ESA
Paris, 20 December 1999
XMM flying beautifully
The European Space Agency's new X-ray space telescope has reached its operational orbit less than a week after being launched from Kourou on 10 December. The XMM spacecraft, which is being controlled by teams at the ESA's Space Operations Centre, ESOC in Darmstadt Germany, is functioning admirably.The early orbit phase came to an end on 16 December after XMM had been manoeuvred to its final orbit. This required four firings of its thrusters, on successive passages at apogee, in order to increase XMM's velocity, thus elongating its orbit and raising the perigee from 826 km to 7,365 km. One burn was then made to fine tune the apogee to around 114,000km. The spacecraft, being tracked by ground stations in Perth, Kourou and Villafranca, is now circling the Earth in this highly elliptical orbit once every 48 hours.
The XMM flight operations staff have found themselves controlling a spacecraft that responds exceptionally well. During these first orbits, the satellite has been oriented several times with razor-sharp precision. On board systems have responded without incident to several thousand instructions sent by controllers. "XMM is flying so beautifully" says Dietmar Heger, XMM Spacecraft Operations Manager. "The satellite is behaving better in space than all our pre-launch simulations and we have been able to adjust our shifts to this more relaxed situation".
On his return from French Guiana, Robert Lainé, XMM Project Manager immediately visited the Darmstadt Mission Control Centre, at ESOC. "The perfect behaviour of XMM at this early stage reflects the constructive cooperation of European industrial companies and top scientists. Spacecraft operations are in the hands of professionals who will endeavour to fulfill the expectations of the astronomers and astrophysicists of the world. I am very happy that ESA could provide them with such a wonderful precision tool".
During the early orbit phase, controllers have activated part of XMM's science payload. The three EPIC X-ray cameras have been switched on and vented. On 17 December the telescope doors were opened allowing the spacecraft's golden X-ray Multi Mirror modules to see the sky. The Optical Monitor telescope door was opened on 18 December. During this last weekend, XMM's Radiation Monitor which records the flux of cosmic particles and radiations was switched on.
Mission controllers have now placed XMM in a quiescent mode for the Christmas and New Year period. Full operations will resume on 4 January with the start of the spacecraft commissioning phase due to last until 15 February. ESA's XMM Science Operations Centre at Villafranca will be brought online early January allowing the start of the exhaustive calibration and performance verification phase of XMM's science instruments. Progress on this calibration should allow the telescope to target and take "firstlight pictures" of its first X-ray sources next March.
Further information on XMM and the ESA Science Programme can be found on the Worldwide Web at: http://www.sci.esa.int/.
13 Dec 1999
XMM into operational orbit
Over the weekend, the extreme tension of the launch itself disappeared. The XMM satellite is now in the safe hands of the ESOC control teams. In their Main Control Room, XMM has yet to be chalked up on the record board. It is the 42nd mission to be handled by ESOC since 1968.Since first acquisition of the spacecraft telemetry, XMM is being gradually manoeuvred to reach its definitive operational orbit. Saturday midday, 24 hours after liftoff, the satellite was at its first apogee, the furthest point from Earth.
The large display screens on the wall indicate the precise distance, 113,850 km. A planisphere indicates where the satellite's position in space relative to Earth and the visibility for each ground station. The display shows that Perth is being used and that the satellite is high in the night sky over Australia.
The atmosphere is calm in the Darmstadt control centre. Some operators appear to be so relaxed than an observer might get the impression that nothing is really happening. But no, with a clockwork rigour following their pre-established flight plan, the ESOC flight control teams are preparing for the second of two perigee boost manoeuvres on this first orbit. The first took place two hours earlier.
The spacecraft is behaving perfectly. As an illustration, during its first 24 hours in space XMM had received some 1240 tele-commands and none had been rejected on-board. Amongst these commands were the activation of the small Visual Monitoring Cameras (VMC). Their pictures created great excitement when they were displayed for the first time after being sent back by the spacecraft.
The perigee boosts are crucial if XMM is to reach its definitive orbit. Each time the operation consists in activating the spacecraft thrusters in order to increase the spacecraft's velocity. This additional speed elongates the orbit so that at its closest point to Earth, XMM will pass at a higher altitude. After launch, XMM had been released by Ariane 5 at 826 km. The first boosts raised the perigee to 4900 km.
Three perigee boosts (the first in two parts) are required to raise XMM's perigee to the nominal 7000 km of its operational orbit. A final manoeuvre will then adjust the apogee to precisely 114,000 km.
Brightly coloured schematics and graphs are displayed on the consoles of the Flight Operations Director, and those of the XMM Project team representatives. On these, can read the temperature and pressure throughout the propulsion system, for example for each of the thrusters as they are firing and the four hydrazine propellant tanks.
Controllers can also obtain a graphic view of what the spacecraft's star trackers are seeing. For example, on this apogee passage, five stars are represented. It is to these points in space that XMM's Attitude and Orbit Control system has locked-on to maintain the spacecraft attitude.
XMM has eight main thrusters in two redundant sets. For each perigee boost, one set is activated, the other remain as a backup. All four thrusters work at the same time, providing not only the increase in velocity but also maintaining XMM's orientation.
The thruster firings last quite long. 53 and 98 minutes on the first orbit, 40 minutes on the second orbit, 55 minutes for the final manoeuvre. Each time the spacecraft's velocity is increased, for example by 87 m/sec on the longest burn. During these manoeuvres, the greater part of XMM's 530 kg of hydrazine will be consumed. For instance 276 kg were used on the first orbit burns.
When XMM is at its furthest distance from Earth, it is travelling at some 670 m/sec, 2400 km/hour. Certainly very fast in human terms, but when it returns at its perigee passage, it whizzes past Earth nine times faster!
By Thursday 16 December, after fine tuning the apogee on orbit 4, the spacecraft will have been placed in its operational orbit. The Launch and Early Operations Phase of the mission will be over. XMM will then have a few days of relative calm whilst the ESOC teams enjoy a well-deserved Xmas and New Year holiday.
Images supporting this release.
13 Dec 1999
ESOC and XMM teams celebrate Santa Lucia
Some very special "rocket fuel" was awaiting the B-team XMM flight controllers when they came off shift, midday on December 13. Swedish staff had organised a gathering to celebrate Santa Lucia, Sweden's traditional remembrance of the Sicilian saint.XMM's Anders Elfving (Attitude and Orbit systems engineer) and Anders Karlsson (TTC & software engineer) had prepared the potent beverage, called "gl=F6gg", a mixture of wine, spices and a dash of vodka. They were assisted by Swedish colleagues from ESOC Mats Rosengren and Boris Smeds, Tommy Strandberg from Dornier and Andreas Hedqvist from XMM contractor VEGA.
Whilst the XMM spacecraft continued on its second orbit, the corridor outside
the Main Control room resounded to the strains of a violin and the song of
Santa Lucia. Everyone heartily enjoyed the gl=F6gg and gingerbread cookies.
XMM was a few hours away from another boost of its thrusters, to again
raise its perigee. People at the small party joked about the effects the
beverage might have on the increase in speed, but Flight Operations
management assured everyone that there was no gl=F6gg on board the
spacecraft -- and that the A-team about to take responsibility for XMM
were following a dry path into the control room!
Images supporting this release
11 Dec 1999
The photographs were taken by two micro-cameras placed on the exterior
of the spacecraft's focal plane assembly. Provided by OIP, subsidiary of
Delft Sensor Systems, Antwerp, Belgium, the two cameras (10 x 6 x 6cm)
each weigh but 430 grams.
The cameras are of two types: the FUGA camera has a logarithmic
response, with a high dynamic range, providing a black and white picture.
The exposure time of the second IRIS camera with a colour filter, can be
modified. The field of view of both cameras is fixed (approx. 40 deg x
40 deg), giving a view along the telescope tube towards the service
platform and the solar arrays.
These pictures were taken just under five hours after liftoff, at 19:25 UT
(20:25 CET). XMM was then at an altitude of 55,300 km above the Earth's
surface. Because of constraints due to the spacecraft's orientation at
this time, the cameras could not have a view showing our planet.
IMAGE CAPTIONS:
Image 1:
Image 2:
11 Dec 1999
On a large screen in the Main Control Room, an animation showed XMM's
position in space, moving away from Earth on its first orbit. Dietmar
Heger, spacecraft controller commented: "It's going very, very nicely.
Almost better than the simulations we have been through before launch".
To reach its definitive orbit, commands will be sent to the satellite to fire
its onboard motors several times. On the first orbit, in two burns some 22
and 24 hours after liftoff, the velocity of the spacecraft will be increased
so as to start raising the perigee. A second perigee raising manoeuvre will
take place at +69 hours and a third at +117 hours. At the start of orbit 4
another manoeuvre will fine-tune the apogee, before XMM is configured for
its definitive operational orbit (114,000 x 7,000km)
During the early orbit phase, part of XMM science payload (notably the three
EPIC cameras) are to be switched on, in order to vent the instruments of
any residual air. On orbit 5, the radiation monitor will be switched on (to
start collecting data on the passages through the Earth's radiation belts)
and on the sixth orbit, the door to the Optical Monitor will be opened.
XMM will be placed in a "sleep mode", pointing at a bright star that will
not be occulted during this period over the Xmas and New Year holidays.
Operations will resume on 4 January. A long phase of commissioning the
spacecraft in orbit and calibration of the instruments will precede the
start of the first science observations, scheduled next spring.
IMAGE CAPTIONS:
Image 1:
Image 2:
10 Dec 1999
"XMM is the biggest and most innovative scientific spacecraft developed by
ESA so far," said Roger Bonnet, ESA's Director of Science. "The world's space
agencies now want the new technology that ESA and Europe's industries
have put into XMM's amazingly sensitive X-ray telescopes. And the world's
astronomers are queuing up to use XMM to explore the hottest places in
the universe. We must ask them to be patient while we get XMM fully
commissioned."
XMM's initial orbit carries it far into space, to 114,000 kilometres from
the Earth at its most distant point. On its return the satellite's closest
approach, or perigee, will be at 850 kilometres.
The next phase of the operation, expected to take about a week, will raise
that perigee to 7000 kilometres by repeated firing of XMM's own thrusters.
The spacecraft will then be on its intended path, spending 40 hours out of
every 48-hour orbit clear of the radiation belts which spoil the view of
the X-ray universe. Technical commissioning and verification of the
performance of the telescopes and scientific instruments will then
follow. XMM should be fully operational for astronomy in the spring of
2000.
All of ESA's science missions present fresh technological challenges to
Europe's aerospace industries. In building XMM, the prime contractor
Dornier Satellitensysteme in Friedrichshafen in Germany (part of
DaimlerChrysler Aerospace) has led an industrial consortium involving
46 companies from 14 European countries and one in the United States.
XMM stands for X-ray Multi-Mirror Mission. Its main telescopes will
gather X-rays from the cosmos with 120 square metres of gold-coated
surfaces, in 174 mirrors fashioned, smoothed and nested together with
high precision by contractors in Germany and Italy.
With XMM, Europe has taken the lead in X-ray missions and X-ray detectors:
the most sensitive and largest ever made. The four complex scientific
instruments on XMM have been developed and led by European scientists
with participation from institutes worldwide.
Compared with NASA's Chandra X-ray telescope launched earlier this year,
XMM is at least 5 times more sensitive. The gain in sensitivity is 15-fold,
at high X-ray energies. But Chandra has a sharper view, so the two missions
are complementary and there is close transatlantic collaboration among the
scientists involved.
Prime scientific objectives for XMM are to find out exactly what goes on
in the vicinity of black holes, and to help to clear up the mystery of the
stupendous explosions called gamma-ray bursts. Other hot topics for
investigation include cannibalism among the stars, the release of newly
made chemical elements from stellar explosions, and the origin of the
cosmic rays that rain on the Earth.
XMM is one of a carefully-planned series of scientific satellites built in
Europe by which ESA has established a pioneering role in space astronomy.
Recently completed missions include the very successful star-mapping
satellite Hipparcos, and the Infrared Space Observatory which
revolutionized astronomers' knowledge of the cool parts of the universe.
Coming along after XMM are Integral for gamma-ray astronomy, FIRST for
the far-infrared, and Planck for examining the entire cosmic microwave
background far more accurately than ever before.
Images supporting this release.
Satellites Business Unit
December 10, 1999
The XMM telescope (X-ray Multi Mirror) is almost eleven meters high and
has a mass of nearly four tons. Over a period of ten years it will explore
the universe for X-rays emitted by spectacular celestial sources such as
exploding stars, pulsars and black holes.
Astronomers hope that XMM will detect over one million unknown X-ray
sources. Under DSS' industrial lead, over 35 companies were involved in
building the space telescope with an order volume of 230 million euros,
on behalf of the European Space Agency ESA.
In ESA's satellite control center (ESOC) in Darmstadt, nearly three
hundred visitors from politics, industry and science witnessed on video
the event at the launch center in Kourou, French Guyana.
"The successful launch of the XMM telescope substantiates Dornier
Satellitensysteme GmbH's lead role in Europe in the field of science
satellites", stated a happy Alfred Setzer of the DSS board of management.
In the presence of journalists in Darmstadt he continued that Dornier
Satellitensysteme GmbH was also the contractor for two other extremely
challenging science missions of ESA, namely the Cluster II satellite fleet
for the exploration of solar influences on the Earth's magnetosphere, and
the cometary explorer Rosetta.
"We hope that XMM will achieve the same success for the astronomers'
community as did the German X-ray satellite Rosat." Rosat, too had been
built under the industrial lead of DSS and had been operational for over
eight years. Over 100,000 new X-ray sources were discovered in that
mission and recorded on an X-ray map of the universe.
Within the next hours, the XMM ground crew will unfold the spacecraft's
solar array with a 16.1-meter span and deploy the sunshield. Within
approximately 24 hours, and after three orbital correction maneuvers,
they will move the observatory from its transfer orbit to its final high
eccentric orbit (7,000 km perigee / 114,000 km apogee).
NASA
Dec. 10, 1999
The XMM spacecraft, an X-ray satellite designed to provide high quality
X-ray spectra of X-ray sources from black holes to very hot objects
created when the Universe was very young, is a European Space Agency
project with contributions from NASA. NASA's involvement in the
mission includes provision of critical components for two of the
spacecraft's three science instruments and participation in the
science-observing program. Based upon the initial competition for
observing time, U.S. scientists will receive about one fifth of the
observing time on the spacecraft during its first two years in orbit.
NASA's Goddard Space Flight Center (Greenbelt, Md.) provided technical
oversight of the U.S. provided hardware that is flying aboard the
spacecraft. Goddard also will oversee the U.S. guest observer program
wherein selected scientists are awarded observing time on the new
observatory to gather science data. Goddard will provide support to
U.S. guest scientists in the form of data archives, technical guidance
and software support.
"Goddard will be providing support for U.S. scientists using this world
class observatory and we are extremely optimistic that this will result
in first class science," said Goddard scientist Dr. Richard Mushotzky
who is part of the XMM science team.
U.S. hardware co-investigator, Dr. France Cordova from the University
of California at Santa Barbara, contributed to the construction of two
of the European instruments. Cordova and co-workers provided the data
processing unit, the digital electronics modules, software and science
support for the Optical Monitor (OM) instrument. Another U.S.
co-investigator, Dr. Steve Kahn from Columbia University in New York
City, provided two reflection grating assemblies for the Reflection
Grating Spectrometer, data analysis software and science support.
"Both of these instruments are state-of-the-art and the Reflection
Grating Spectrometer in particular has advanced new technology," said
Mushotzky.
The third instrument comprising the science payload, the European
Photon Imaging Camera (EPIC), has silicon chips that can obtain medium
spectral resolution x-ray spectra from sources much fainter than ever
before. The RGS will analyze the spectra in more detail and with
greater resolution. The Optical Monitor will observe the same part of
the sky as the x-ray telescopes but in the ultraviolet and optical
wavelengths. This will give astronomers complementary data on the X-ray
sources observed with the EPIC and RGS instruments.
The spacecraft has four telescopes. Three of them are X-ray telescopes
with the combined surface area of a tennis field, 120 square meters.
However, due to the fact that the x-rays are focussed via reflection at
very shallow angles, the effective collecting area for x-rays is 100
times less. In addition to the large collecting area afforded by XMM,
the spacecraft will operate in an orbit that will allow it to take long
and uninterrupted observations. The fourth telescope is a 30-centimeter
optical telescope, which, by virtue of its operation above the
atmosphere, is much more sensitive than a similar telescope on the
ground.
The name of XMM stems from its multiple mirrors. XMM, with the largest
x-ray collecting area flown to date, will allow astronomers to gather
and analyze more
X-ray sources quicker than with previous space observatories.
Scientists expect XMM will explain a number of cosmic mysteries,
ranging from black holes to the origin of the universe. XMM will
investigate supernova remnants, black holes, magnetically active flare
stars and more.
XMM, a world-class observatory, is the second cornerstone mission of
ESA's Horizon 2000 program. Its large effective area and soft x-ray
spectroscopic capabilities very nicely complement the high
angular-resolution and higher energy x-ray spectroscopic capabilities
of NASA's recently launched Great Observatory for x-ray astronomy, the
Chandra X-ray Observatory. The minimum mission life of the spacecraft
is two years but it is expected to last much longer.
SRON
23 november 1999
XMM is letterlijk een "multi mirror". Niet alleen heeft de satelliet drie
spiegeltelescopen om de röntgenstraling waar te nemen, maar elke telescoop
bestaat uit 58 spiegels. De spiegels passen in elkaar zoals een set met
steeds kleinere pannen. De telescopen zijn door een koolstof-fiber buis
van 7 meter verbonden met de röntgendetectoren. De detectoren worden met
hoge precisie, d.w.z. met een afwijking van minder dan 0.1 mm, op hun plaats
gehouden ten opzichte van de spiegels. Dit ondanks de extreme temperaturen
waaraan de tussenliggende buis wordt blootgesteld.
Stichting Ruimte Onderzoek Nederland (SRON) heeft een belangrijke
wetenschappelijke bijdrage geleverd aan XMM in de vorm van de Reflectie
Tralie Spectrometer, oftewel de RGS (tralie=grating). Deze röntgenspectrometer
kan het röntgenlicht van sterren en sterstelsels uitéén rafelen in
verschillende 'kleuren' net zoals een prisma dat kan met zichtbaar licht.
De RGS bestaat uit een traliedeel dat het röntgenlicht in de verschillende
golflengtes ontleedt en een cameradeel dat met behulp van speciale detectoren
uiteindelijk het röntgenlicht registreert.
Stichting Ruimte Onderzoek Nederland (SRON) is een instituut van de
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) en
initieert, ontwikkelt, bouwt en gebruikt instrumenten voor wetenschappelijk
onderzoek in en vanuit de ruimte. Nadere informatie over SRON activiteiten
SRON internetsite.
European Space Agency
22 November 1999
ESA's X-ray Multi Mirror mission -- XMM -- is the second Cornerstone in
ESA's Long Term Scientific Programme (*). This new X-ray space telescope
promises even more discoveries. With the large collecting area of its
mirrors and the high sensitivity of its cameras, XMM is expected to
increase radically our understanding of high-energy sources -- clues to
a mysterious past, and keys to understanding the future of the Universe.
The space observatory combines three barrel-shaped telescope modules. In
each are nested 58 wafer-thin concentric mirror shells highly polished and
subtly shaped. Passing through at an extremely shallow angle, the so-called
"grazing incidence", the X-rays will be beamed to the science instruments
situated on the focal plane at the other extremity of the satellite.
The three mirror modules have a total mirror surface of over 120m2 --
practically the size of a tennis court. The collecting power of XMM's three
telescopes is the greatest ever seen on an X-ray space mission, many times
more than the most recently launched X-ray satellite.
The design and assembly of the mirror modules, their testing for operation
in space and their precise calibration constitute one of the greatest
achievements of the XMM programme. The flimsy mirror shells, with their
gold reflective surface on a nickel backing, were made by replication like
carbon copies from master moulds. They were shaped to an accuracy of a
thousandth of a millimetre, and then polished to a smoothness a thousand
times better than that.
Packaged one within another like Russian dolls, each mirror was focused
and centred with respect to its neighbour to an accuracy of 25 microns --
a quarter of the width of a human hair.
At the prime focus of each of the telescopes are three European Photon
Imaging Cameras. With silicon chips that can register extremely weak X-ray
radiation, these advanced cameras are capable of detecting rapid variations
in the intensity of a source.
Grating structures at the exit of two mirror modules will reflect about
half the incoming rays to a secondary focus, with its own cameras. This
Reflection Grating Spectrometer will "fan out" the various wavelengths
(much like a prism with visible light), and indicate in more detail the
presence of individual elements, such as oxygen and iron.
The third instrument aboard XMM is a conventional but very sensitive optical
telescope. It will observe simultaneously the same regions as the X-ray
telescopes but in the ultraviolet and visible wavelengths, giving
astronomers complementary data about the X-ray sources being studied.
In orbit, this 30-cm telescope will be as sensitive as a 4-m instrument
on the Earth's surface.
Astronomers will use XMM to resolve the mysteries of stars that exploded
long ago as supernovae and whose remnants, glowing with X-rays, may be
supplying material for new planets and stars. They will study regions of
supernova remnants that are still hot and may hold the key to understanding
the origin of the enigmatic cosmic rays that pervade the Universe.
The mission will study X-rays that originate from "vampire stars" that feed
upon their companions, where intense gravitational fields swirl matter from
one sphere to the other in strange and terrifying ballets.
XMM's high-speed cameras will examine celestial sources whose X-rays
pulse rhythmically and mysteriously, and those that flash briefly, pinpointing
perhaps gigantic explosions that result from colliding black holes in far off
galaxies.
XMM will delve into enigmatic black holes, cosmic dustbins that consign
matter and light to oblivion, where tired X-rays have lost energy and time
itself is slowing down.
The golden X-ray eyes of ESA's observatory will try to make sense of a
'bigger picture', ascertaining how galaxies aggregate millions of stars, how
these galaxies themselves form clusters and groups scattered across cosmic
space. XMM will also attempt to understand the nature of the invisible dark
matter that fills interstellar space.
After being released by the launcher, XMM will be placed in a highly
eccentric 48-hour orbit, rising to a distance of 114,000 km from the
Earth, then returning to within 7,000 km of our planet.
This orbit has been chosen for several reasons. It offers an optimal contact
between ground tracking stations and the satellite; it will allow the
satellite to pass rapidly through the Earth's radiation belts which could
harm its delicate science instruments; and above all it will offer
astronomers the longest possible observation periods.
Notes:
No X-rays from space can penetrate the Earth's atmosphere so all X-ray
astronomy is carried out with instruments on rockets, stratospheric
balloons or satellites. X-rays from the Sun were first detected during
sounding rocket flights in the 1950s. By 1970, more than forty X-rays
sources had been detected during rocket-borne experiments.
Satellites have since conducted more extensive surveys. The first satellite
dedicated to X-ray astronomy was Uhuru. Launched in 1970 it mapped the
sky identifying 339 sources. Several others were to follow, including
Einstein which carried grazing incidence mirrors and detectors capable of
recording images of cosmic X-ray sources. Einstein studied more than ten
thousand sources.
EXOSAT (1983-1986) was the European Space Agency's first X-ray
observatory mission. Placed on a highly eccentric orbit reaching out
191,700 km from Earth, it allowed very long observations above the
radiation belts and greatly enlarged our understanding of many classes
of X-ray sources.
The German/US/UK ROSAT launched in 1990 was another big step forwards.
Until its recent switch off it carried out a complete sky survey identifying
100,000 X-ray sources.
XMM will be opening up a golden age of X-ray astronomy alongside two other
major missions. Launched in July 1999, Chandra is the third of NASA's Great
Observatories. It is exploring X-rays from space with images 25 times
sharper than previously obtained. ASTRO-E is Japan's fifth X-ray astronomy
mission and is due to be launched early in 2000.
Europe has already begun studying a next generation X-ray astrophysics
facility, XEUS. By making use of the International Space Station and by
ensuring significant potential for growth and evolution, XEUS will offer
vastly expanded capabilities allowing the study of the very first black
holes created when the Universe was just a few percent of its present age.
Further information on XMM and the ESA Science Programme can be found on
the Worldwide Web at:
http://sci.esa.int/categories/scienceprograms/ and
click << Horizon 2000 >> on the left-hand bar.
12 Nov 1999
The ESA Director of Science Roger-Maurice Bonnet has given the green
light to Robert Laine, the XMM Project Manager, to proceed to the next
phase in preparing XMM for launch. This means that the XMM spacecraft
is confirmed for a launch on 10 December 1999.
M. Lainé, currently in French Guiana overseeing the final operations
before launch, is delighted. "All actions on the flight hardware of
our spacecraft are closed, the science instruments are in flight
configuration, everything is on schedule for the big day."
The next milestones in the satellite campaign will be the fuelling of
the spacecraft, due to start on Monday 15th November, followed on the
19th by the arrival of the Ariane 504 launcher in the Final Assembly
building, where the satellite is being prepared.
IMAGE
CAPTION:
XMM being prepared for hydrazine loading. In the foreground the
(transfert) tank containing the hydrazine.
Satellites Business Unit
Munich, Germany
05/10/99
In Überlingen, DSS submitted the satellite test and analysis results to
its customer, the Paris-based space agency ESA. In the last months the
spacecraft had undergone a thorough check. A space simulation test (at
various temperatures and under vacuum conditions), vibration tests (to
simulate the ascent loads during launch) and extensive functional checks
were performed.
"All tests were completed successfully; in part the results are better than
the requirements posed by the customer", is the proud statement of the DSS
project manager, Uwe Minne. Robert Lainé, the XMM project manager on
behalf of ESA, agrees: "I am highly satisfied with the achievements of the
industry consortium. On the one hand, the cost target was observed and on
the other hand, we are ahead of schedule because according to the original
schedule, the launch had been planned for January 21, 2000. On top of
this, all system requirements were met. I congratulate DSS on their
outstanding team."
Soon, an approximate fourteen-member team of space engineers and
technicians from Dornier Satellitensysteme GmbH will prepare for its
journey to South America, for the XXM launch preparations. The spacecraft
will be deployed into space with Ariane flight no. 504 from the space
center Kourou in French Guiana.
Among other things, astronomers hope that XMM (X-ray Multi Mirror) will
provide conclusive evidence of the existence of black holes.
Under the leadership of DSS, an industrial consortium of 35 European
companies developed and built the 230-million Euros spacecraft. With a
length of almost eleven meters, a diameter of four meters and a total mass
of nearly four tons, this is the largest satellite ever built under ESA's
science program.
Similar to the color of visible light which provides important information
on the temperature, composition and dynamics of cosmic objects, X-rays
offer a wealth of chemical and physical data over a much wider energy
range. XMM, with a far better resolution than its precursors, will
substantially advance the "decoding" of X-ray sources. A marked increase
in the number of detected sources is also expected. In a single day, XMM
will detect more X-rays than the first US X-ray mission did 25 years ago
in three years.
On account of the high packing density in the mirror assemblies, these
mirror shells must be extremely thin and, at the same time, lightweight
to ease their transport into space. DSS in Friedrichshafen performed early
feasibility studies on how to comply with these exacting structural
requirements ten years ago. The studies showed both carbon-fiber reinforced
plastics (CFRP) and nickel to be suitable materials. They offer extreme
long-term surface accuracy and the mirrors can still be manufactured much
thinner than those of Rosat, which were made of glass-ceramics. ESA finally
opted for nickel mirrors. A thin gold film is deposited on their internal
surface for maximum reflection.
The mirror assemblies' focal length of 7.5 meters necessitates the
spacecraft's uncommonly large dimensions of four by ten meters and a total
mass of four tons. In the telescope's focal plane three imaging CCD cameras
and, for the first time for X-rays, two high-resolution reflection grating
spectrometers are installed. In the X-ray spectrum of 0.35 to 2.5 keV, the
latter are to provide data on the composition, temperature, dynamics and
other properties of the investigated astronomical objects. Scientists from
Europe and the USA, involved in the project, hope to capture approximately
30,000 X-ray spectra in unprecedented detail during the spacecraft's
planned ten-year mission life.
The electronic cameras, too, discriminate X-rays of different energy levels.
They can view X-rays between 0.1 and 10 keV (wavelength of 12 to 0.12
nanometers) "in color". Using the so-called spectrophotometry, astronomers
will obtain a wealth of information that has been inaccessible so far.
In addition to those instruments for detection of X-ray photons, an optical
camera is being developed for observations in the visible and ultraviolet
light. It will allow astronomers to perform simultaneous visual observations
of the sources scanned with "X-ray eyes". All three scientific instruments,
which are currently under development at various European and American
institutes, will be simultaneously operated and will transmit real-time
data down to Earth.
The list of observation objects however is not only made up of potential
black hole candidates but also includes neutron stars, supernova remnants,
the center of the Milky Way and cores of distant galaxies.
ESA Science News
27 Sep 1999
On the quayside were Arianespace Mission Director for the XMM launch,
Philippe Rolland; Jean-Yves Trébaol, the Launch Range Manager for the XMM
flight from the French Space Agency (CNES); and Robert Lainé and Uwe Minne,
XMM Project Managers respectively from ESA and prime-contractor Dornier.
They were glad also to see that their two colleagues accompanying the
spacecraft appeared to have survived their transatlantic trip!
The Toucan first unloaded its hazardous items, such as propellant-filled
rocket stages, and the XMM trailer was only rolled out at the next high
tide the following morning. Local television and press media were there
to cover the event.
The XMM container then led an exceptional convoy of nine vehicles. Escorted
by police, it left through the small harbour's industrial estate, rejoining
the 'Space Road' which first passes the technical complex of the Guiana
Space Centre (where the Jupiter Mission Control is situated) before
reaching the launch complex itself a further 13 kilometres along the
coast road.
Upon entering the forward zone of the European spaceport, XMM headed for
the largest building, the Ariane-5 Final Assembly Building (BAF). It is an
impressive cathedral-like structure, 90m tall, fully air-conditioned with a
volume of 123,000 cubic metres! It is from the BAF that the Ariane launch
vehicles, ready for lift-off, are taken to their launch site.
The BAF also accommodates clean rooms where exceptionally sized satellites
can be prepared for launch. The XMM trailer reversed into the building's
air lock, the protective tarpaulin was removed and an over-head gantry
crane transferred the long container.
The XMM launch campaign starts practically immediately as much work remains
before the launch in December. First activities will see the unloading of
mechanical and electrical ground support equipment, and removal of the
spacecraft from its container. Numerous system checks on the satellite
will take place before fuelling in mid-November.
Eight members of the ESA team and 15 colleagues from Dornier have already
arrived for the long campaign in French Guiana. Others are arriving soon.
It is all too clear: with their spacecraft now only 5 km away from its
launch site, the mood is good and everyone is highly motivated.
Images supporting this release.
IMAGE CAPTIONS:
[IMAGE 1]
[IMAGE 2]
[IMAGE 3]
[IMAGE 4]
11 Jun 1999
Explaining the decision to bring the launch forward, ESA's XMM Project
manager Robert Lainé said: "It was a result of the extra capability provided
by Ariane 5. A greater knowledge of the launcher after the 502 and 503
qualification missions allowed Arianespace to tell us that the vehicle
could carry XMM to a higher altitude before it is released. Our spacecraft
is also lighter than originally expected, approximately 100 kg."
This good news allowed the XMM project team to open the launch window
a month earlier. The spacecraft will also be carrying more fuel for its
in-orbit life. Another factor allowing the launch to take place sooner,
according to Robert Lainé, is an uneventful series of tests upon the
spacecraft with no surprises, allowing the team to have XMM ready
earlier. But he insisted: "We have cut no corners. All the tests that
were planned have been completed successfully."
The spacecraft, whose two halves were mated on 26 May, will now
complete its final tests at ESA's ESTEC technical centre in Noordwijk,
including electrical verifications and accoustic tests at the start of
July. There will be a solar array deployment test in mid-August. By
then a giant satellite container will have been delivered and the
spacecraft will be packed for shipping on one of the Arianespace
vessels to French Guiana. Departure from Rotterdam is scheduled for
mid-September.
The launch campaign, starting end of September, will take place entirely
in the satellite preparation area of the Ariane 5 Final Assembly Building
(BAF), leading up to a launch now nominally set for the 15th December.
The prospect of having XMM in orbit sooner also greatly pleases the
scientific community, eagerly waiting to use the space observatory.
Images supporting this release
01 Apr 1999
The telescopes have now all been fitted to the spacecraft's lower platform,
which has completed most of its environmental tests at ESA's ESTEC Technical
Centre at Noordwijk in the Netherlands. At the end of February, the three
structural and thermal models of the telescopes, used during these tests,
were removed to make way for those that will fly on the spacecraft.
The positioning of the first of XMM's 'golden eyes' began on 24 March.
Operations took place in an ultra-clean 'class 100' tent situated in the
ESTEC satellite test area. A small team of engineers from prime contractor
Daimler-Chrysler Aerospace (Dornier) and from ESA wore special suits to
avoid any contamination of the flight hardware as they carefully moved the
telescope vertically into the waiting orifice on the satellite. Once slotted
in, the first telescope was fixed to its mounting interface by means of six
bolts and 3 centring pins around its external circumference.
These delicate operations were repeated for the second telescope on 26 March,
and the third telescope was placed in position on 30 March. After each
mounting, precise measurements were taken with micrometer gauges to evaluate
any deformation to the satellite platform due to the added mass of the
telescopes, weighting in total 1420 kg. When all was finished, engineers were
pleased to announce that the deformation of the platform was low, below 10
microns, and they confirmed that there were no undue loads on the spacecraft.
Before the lower half of XMM is mated to the focal plane assembly, scheduled
at the end of May, one further XMM 'eye' will be added: the Optical Monitor.
This telescope which will observe the heavens in the visible and ultraviolet,
is due to be fitted in the third week of April.
Images supporting this article
Testing XMM
(ESA Bulletin 94, pdf-format)
ESA
Paris, 10 February 1998
XMM, the X-ray Multi-Mirror mission, is due to be launched in 1999. It is a European conception with innovative telescopes. XMM will revolutionize the study of X-rays coming from the Universe, by harvesting far more X-rays per hour than any previous mission. Its enormous capacity will enable astronomers to analyse many strong sources of cosmic X-rays very quickly, and to discover and characterize many faint sources previously beyond their reach.
As the most popular and competitive branch of space astronomy, X-ray astronomy reveals special places in the Universe where very high temperatures or violent forces generate energetic radiation. These sources include black holes, exploding stars, pairs of stars orbiting very close together, and the central regions of clusters of galaxies.
XMM's optical monitor, viewing the scenes by visible light, will help in the interpretations. The combination of X-ray telescopes and optical monitoring should be well-suited to tracking down gamma-ray bursters -- extraordinary explosions in space that mystify the astronomers.
Full descriptions of the X-ray sources will depend on precise spectral analysis of the relative intensities of X-rays of different energies, including the signatures of identifiable chemical elements. Such spectral analysis is XMM's task, using instruments of the highest quality fed by the remarkable telescopes.
As seen at ESTEC today, the spacecraft stands upside down. Its front end, where the mirror modules of the X-ray telescopes pass through the satellite's service module, is closest to the ground. At the top is the section containing detectors at the focus of the X-ray telescopes.
Surmounting the assembly, a pair of cones will carry heat away from the detectors. XMM's appearance is, though, dominated by the long tube that spans the telescopes' focal length, and by the black thermal blanket that will protect the spacecraft from unequal heating on the sunny and shaded sides.
"You have to imagine the big tube of XMM filled with focused X-rays en route to the detectors," says Robert Laine ESA's project manager for XMM. "That's the whole purpose of the mission, and our chief preoccupation has been with the three multi-mirror modules that accomplish it. Critics thought we were too ambitious, trying to nest 58 precisely formed mirrors together in each module. No one had ever attempted such a feat before. It wasn't easy, but thanks to excellent innovative work by European industry, XMM's telescopes are even better than we hoped."
X-rays are focused by glancing them off a carefully shaped mirror, like a bucket without a bottom. In a single-mirror telescope, most of the incoming X-rays miss the mirror. To catch more of them, designers nest multiple mirrors inside one another. Before XMM, astronomers had to choose between many mirrors with relatively poor focusing, or a very few mirrors with a sharp focus. With 58 precision-made mirrors in each of its three X-ray telescopes, XMM combines enormous gathering power with accurate focusing.
Carl Zeiss in Germany made shaped and polished mandrels (moulds) for mirrors of 58 different diameters, up to 70 cm for the widest. Media Lario in Italy made the mirrors by electrodeposition of nickel on the mandrels, coated their inner surfaces with gold, and carefully assembled them in their nested configuration, in a high accuracy structure fabricated by APCO in Switzerland.
The performance of each XMM mirror module has been verified in special facilities of the Centre Spatiale de Liege in Belgium and the Max-Planck-Institut fur extraterrestriche Physik in Germany. The first flight model conformed with the specification, and the second and third were even better.
The total surface area of the extremely thin mirror that gathers X-rays in XMM's three multi-mirror telescopes (taken together) is larger than 120m2.
Two of the three X-ray telescopes are fitted with reflection grating spectrometers for the most detailed analysis of the X-ray energies. XMM is designed to fit in the fairing of Europe's new Ariane 5 launcher.
Some 46 companies in 14 European countries (and 1 in the USA) have contributed to XMM's construction. The investigators responsible for the instruments in XMM come from the Netherlands and the UK, with investigators in Belgium, France, Germany, Italy, Switzerland and the USA. XMM will spend most of its time south of the Earth, travelling quite slowly out to distances of more than 100,000 kilometres, well clear of the Earth's radiation belts.
XMM will be controlled by ESA's satellite operations centre (ESOC) from Darmstadt (Germany) and Villafranca (Spain) via ground stations in Perth (Australia) and Kourou (French Guiana).
XMM takes pictures of itself!
The XMM spacecraft, launched on 10 December from Kourou, has sent back
pictures of itself in space.USEFUL LINKS FOR THIS STORY
XMM launch clips and more images
Picture taken by XMM's FUGA camera showing the telescope tube and one
solar array on the left. At the top of the picture, one sees the edges of
the now deployed telescope sunshield. What appears as a white boom in
centre is in fact one of the fixed lateral sunshield panels, seen side-on.
10 December 1999, 5 hours after launch.
Picture taken by XMM's IRIS camera show the other solar array on right.
At the bottom of the photograph (below the ESA flags) is the MLI thermal
insulation just under the lens of the camera.XMM in safe hands
During the first hours after XMM's acquisition by the Perth ground station,
the spacecraft control teams at ESOC nursed their baby through its initial
in-orbit sequences. Triggered by the onboard timer, the two wings of the
solar array opened faultlessly, the telescope sunshield equally well. The
star trackers were switched on and the spacecraft's reaction wheels were
spun up.USEFUL LINKS FOR THIS STORY
Dietmar Heger (XMM spacecraft controller) and his "baby in space". "It's going
better than the simulations". ESOC main control room, 10 December 1999.
Alan Smith, flight operations manager (on right) explaining XMM first
sequences to Jocelyne Landeau (ESOC PR) and Martin Huber. Mission control
room at ESOC, 10 December 1999.Europe's latest space telescope is off to a good start
The world's most powerful observatory for X-ray astronomy, the European
Space Agency's XMM satellite, set off into space from Kourou, French Guiana,
at 15:32 Paris time on 10 December. The mighty Ariane 5 launcher, making
its very first commercial launch, hurled the 3.9-tonne spacecraft into a
far-ranging orbit. Within one hour of lift-off the European Space Operations
Centre at Darmstadt, Germany, confirmed XMM was under control with
electrical power available from the solar arrays.
DaimlerChrysler Aerospace AG
Munich, Germany
Europe's Biggest Space Observatory, XMM, in Orbit: Ariane 5 Successfully
Deploys Supertelescope, DSS Bolsters Lead in Science Satellites
Darmstadt -- Europe's largest research satellite, the X-ray observatory,
XMM, is in space. Today, Friday, December 10, 1999, at 3:52 pm (CET), an
Ariane 5 launch vehicle injected the spacecraft into a transfer orbit. 29
minutes after lift-off, XMM was released from the upper stage of Ariane
5 in a height of 2350 kilometers. Only one minute later, the
communications signal of XMM was received. The supertelescope was
developed and built under the industrial lead of Dornier Satellitensysteme
GmbH (DSS, Friedrichshafen), a member of DaimlerChrysler Aerospace AG
(Dasa, Munich).NASA TO SUPPORT EUROPEAN SPACE AGENCY'S
X-RAY MULTI MIRROR TELESCOPE MISSION
American scientists are anxiously awaiting the launch of the European Space
Agency's X-Ray Multi Mirror (XMM) spacecraft, set to lift off Dec. 10
from French Guyana on an Ariane 5 launch vehicle.Lancering van Europese röntgentelescoop
Op 10 december 1999 zal in Frans Guyana een Ariane 5 gelanceerd worden met
aan boord de XMM (X-ray Multi Mirror) satelliet. De telescopen van XMM gaan
kijken naar röntgenstraling afkomstig uit het heelal. Voor de röntgenastronomie
breken nu dan ook spannende tijden aan. Drie grote observatoria zullen
namelijk vanaf begin volgend jaar gegevens verzamelen: XMM, als één van de
grote 'corner stone' missies van de Europese Ruimtevaart Organisatie (ESA),
Chandra van NASA (met ook een belangrijke Nederlandse bijdrage) en Astro-E
van Japan. De drie satellieten vullen elkaar aan en iedere satelliet heeft
zijn eigen sterke punten. Voor XMM is dat zijn grote gevoeligheid. Hierdoor
kunnen sterrenkundigen voor het eerst in groot detail fysische
karakteristieken van hete kosmische gassen bepalen.
Paris, FranceLifting the veil on the X-ray universe
X-ray astronomy is a relatively young branch of astrophysics which today
is one of the most competitive and popular. In the few decades since the
discovery of X-ray radiation from cosmic X-ray sources, this field has
grown at an astonishing rate leading to the identification of numerous
exciting new phenomena.174 wafer-thin X-ray mirrors
X-rays coming from celestial objects are highly energetic and elusive. They
can best be measured and studied after focusing a sufficient number upon
sensitive detectors. To achieve this, XMM's Mirror Modules have been given
a gargantuan appetite for X-rays.A multi-spectral space telescope
The spacecraft carries three sets of science instruments, not only capable
of making images of an X-ray source but also able to precisely distinguish
the "colour" of the X-rays being viewed.The mysteries of the X-ray sky
XMM will explore the hidden depths of the Universe, its violent hotspots
where stars and galaxies are formed, and where worlds and matter itself
disappear. Much as the colour of a street lamp can indicate which gas it
uses, the science instruments on board XMM will reveal the deepest secrets
of X-ray objects, their chemical composition and temperatures -- clues to
the physical processes that are taking place.A high-flying mission
The XMM spacecraft, the largest science satellite ever built in Europe, is
due to be launched in December 1999 by an Ariane-5 from the European
Spaceport in Kourou.BREAKING NEWS
Green light for XMM launch on 10 December
All lights are green to launch ESA's X-ray Space Observatory on 10
December with a launch window starting at 14:32 GMT.
USEFUL LINK FOR THIS STORY
DaimlerChrysler Aerospace AG"Green Light" for Europe's Space Telescope XMM:
Überlingen -- Europe's largest science satellite, XMM, has received the
"green light" for launch. Today, Tuesday, October 5, approximately 120
space experts will convene in Überlingen on Lake Constance for the
so-called "Flight Acceptance Review". The prime industrial contractor for
the spacecraft, measuring 11 meters, is Dornier Satellitensysteme GmbH
(DSS, Friedrichshafen), a member of DaimlerChrysler Aerospace AG (Dasa,
Munich). The launch of XMM onboard an Ariane 5 launch vehicle is
scheduled for December 8, 1999.
DSS Team Embarking For
Launch Campaign in KourouX-rays from space
X-rays are a result of high-energy processes, for example in supernovas.
These are high-density stars which explode in the final stage of their
development, releasing clouds of gas at temperatures of many millions of
degrees, and generating high-energy X-rays in the process. The centers of
galaxies, clusters of galaxies, and quasars -- even normal stars like the
Sun -- all emit X-rays. The relatively weak X-rays emitted by the Sun were
detected as early as 1948 by an upper atmosphere sounding rocket. These
short-wave X-rays from space cannot penetrate the Earth's atmosphere as
they are absorbed in high altitudes by air molecules. Therefore, the best
approach to detect their cosmic origin is through the use of satellites. A
major breakthrough in the generation of a sky map of X-ray sources was
achieved nine years ago with the launch of the German X-ray satellite Rosat,
also a DSS development. 120,000 cosmic X-rays have been detected so far.
After far exceeding its specified life span, Rosat was switched off in
December 1998, as the gas supply needed for the detector was depleted.Mapping of X-rays
Apart from the fact that the X-rays of cosmic objects do not penetrate the
Earth's atmosphere, it is very complicated to focus and record them using
satellite instruments. X-ray photons can only be focused by optical mirrors
on the scientific instruments when they hit the metallic mirrors at a grazing
incidence angle. This requires a special design for the X-ray optical system.
The barrel-shaped mirror consists of two segments, with the first segment
formed according to a paraboloid and the second to a hyperboloid mirror.
The effective area of these is only a small, few-millimeter-wide ring.
In order to focus as many X-rays as possible, one XMM mirror assembly
consists of 58 nested mirror shells. The XMM telescope contains three
identical X-ray mirror assemblies with an outer diameter of 70 centimeters
each. With a total of 174 mirror shells, this new telescope has an enormous
throughput and high sensitivity compared to all previous projects, which is
what is primarily required for spectroscopy.Black holes in focus
Black holes are the remnants of past explosions of stars. Some scientists
presume that black holes also formed shortly after the big bang and are still
wandering through the universe. As they emit no radiation at all, these black
holes are invisible. It is only their enormous gravitational force that acts
on the environment. They continuously absorb gas and dust. Before matter
drops into a black hole, where it is lost forever, it revolves around this
strange object virtually at the speed of light. The frictional forces among
these accelerated gas particles generate temperatures of several million
degrees. It is precisely then that this cosmic swirl emits X-rays, which
can be detected with special spacecraft telescopes. Astrophysicists hope
to examine the physical processes at the "edges" of black holes with the
help of XMM. The expected data could provide conclusive evidence of the
existence of these "gravitational monsters" which were theoretically
calculated by the German physicists Albert Einstein and Karl Schwarzschild.XMM arrives in French Guiana
As scheduled, the Arianespace MN Toucan berthed at Kourou's Pariacabo
harbour on the afternoon of 23 September after a ten-day crossing from
Europe. A welcoming party was present as the ship lowered its rear access
ramp, revealing its full load: the XMM giant container and eight others
with various Ariane-4 and Ariane-5 rocket stages.USEFUL LINKS FOR THIS STORY
XMM launch preparations
Ariane homepage
XMM leads convoy to the Kourou spaceport.
MN Toucan preparing to unload at Pariacabo harbour.
The XMM container arrives at the Ariane 5 Final Assembly Building (BAF).
The Ariane 5 Final Assembly Building, where XMM is being prepared for its
launcher.XMM ready for launch in December, a month earlier than envisaged!
The European Space Agency's XMM mission had until very recently been
officially set to liftoff on 21 January 2000. Now, with a common accord
between the ESA project management and Arianespace, the launch of the
X-ray astronomy mission by an Ariane 5 has been rescheduled to mid-
December this year.XMM receives its golden eyes!
ESA's X-ray space observatory XMM, currently being assembled in view of
a launch from Kourou next January, has been fitted with its three X-ray
telescopes -- the extremely high-precision Mirror Modules, each with its
58 wafer-thin gold-covered mirror shells which will give the mission its
unprecedented vision of the X-ray universe.ESA unveils its big XMM spacecraft
Looking like a black pillar more than 10 metres tall, Europe's largest scientific spacecraft now stands in a test bay at ESTEC, ESA's space and technology centre at Noordwijk in the Netherlands.A miracle of telescope engineering
Some facts about XMM
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