A Galactic Crash Investigation

ESO - European Southern Observatory logo.

22 June 2011

 X-rays, dark matter and galaxies in the cluster Abell 2744

A team of scientists has studied the galaxy cluster Abell 2744, nicknamed Pandora’s Cluster. They have pieced together the cluster’s complex and violent history using telescopes in space and on the ground, including ESO’s Very Large Telescope and the Hubble Space Telescope. Abell 2744 seems to be the result of a simultaneous pile-up of at least four separate galaxy clusters and this complex collision has produced strange effects that have never been seen together before.

Pandora’s Cluster — a galactic crash investigation

When huge clusters of galaxies crash together, the resulting mess is a treasure trove of information for astronomers. By investigating one of the most complex and unusual colliding clusters in the sky, an international team of astronomers has pieced together the history of a cosmic crash that took place over a period of 350 million years.

 Pandora’s Cluster — the merging galaxy cluster Abell 2744

Julian Merten, one of the lead scientists for this new study of cluster Abell 2744, explains: “Like a crash investigator piecing together the cause of an accident, we can use observations of these cosmic pile-ups to reconstruct events that happened over a period of hundreds of millions of years. This can reveal how structures form in the Universe, and how different types of matter interact with each other when they are smashed together.”

 Wide-field view of Abell 2744

“We nicknamed it Pandora’s Cluster because so many different and strange phenomena were unleashed by the collision. Some of these phenomena had never been seen before,” adds Renato Dupke, another member of the team.

Simulation of the merging events in Abell 2744

Abell 2744 has now been studied in more detail than ever before by combining data from ESO’s Very Large Telescope (VLT), the Japanese Subaru telescope, the NASA/ESA Hubble Space Telescope, and NASA’s Chandra X-Ray Observatory.

Zooming in on Pandora’s Cluster

The galaxies in the cluster are clearly visible in the VLT and Hubble images. Although the galaxies are bright they make up less than 5% of the mass there. The rest is gas (around 20%), which is so hot that it shines only in X-rays, and dark matter (around 75%), which is completely invisible. To understand what was going on in the collision the team needed to map the positions of all three types of matter in Abell 2744.

Pan across Abell 2744, Pandora’s Cluster

Dark matter is particularly elusive as it does not emit, absorb or reflect light (hence its name), but only makes itself apparent through its gravitational attraction. To pinpoint the location of this mysterious substance the team exploited a phenomenon known as gravitational lensing. This is the bending of light rays from distant galaxies as they pass through the gravitational fields present in the cluster. The result is a series of telltale distortions in the images of galaxies in the background of the VLT and Hubble observations. By carefully plotting the way that these images are distorted, it is possible to map quite accurately where the hidden mass — and hence the dark matter — actually lies.

By comparison, finding the hot gas in the cluster is simpler as NASA’s Chandra X-ray Observatory can observe it directly. These observations are not just crucial to find out where the gas is, but also to show the angles and speeds at which different components of the cluster came together.

When the astronomers looked at the results they found many curious features. “Abell 2744 seems to have formed from four different clusters involved in a series of collisions over a period of some 350 million years. The complicated and uneven distribution of the different types of matter is extremely unusual and fascinating,” says Dan Coe, the other lead author of the study.

It seems that the complex collision has separated out some of the hot gas and dark matter so that they now lie apart from each other, and from the visible galaxies. Pandora’s Cluster combines several phenomena that have only ever been seen singly in other systems.

Near the core of the cluster is a “bullet”, where the gas of one cluster collided with that of another to create a shock wave. The dark matter passed through the collision unaffected [1].

In another part of the cluster there seem to be galaxies and dark matter, but no hot gas. The gas may have been stripped away during the collision, leaving behind no more than a faint trail.

Even odder features lie in the outer parts of the cluster. One region contains lots of dark matter, but no luminous galaxies or hot gas. A separate ghostly clump of gas has been ejected, which precedes rather than follows the associated dark matter. This puzzling arrangement may be telling astronomers something about how dark matter behaves and how the various ingredients of the Universe interact with each other.

Galaxy clusters are the biggest structures in the cosmos, containing literally trillions of stars. The way they form and develop through repeated collisions has profound implications for our understanding of the Universe. Further studies of the Pandora’s Cluster, the most complex and fascinating merger yet found, are in progress.

Notes:

[1] This effect has been seen before in a few galaxy cluster collisions, including the original "Bullet Cluster", 1E 0657-56.

More information:

This research is presented in a paper entitled “Creation of cosmic structure in the complex galaxy cluster merger Abell 2744”, to appear in Monthly Notices of the Royal Astronomical Society.

The team is composed of J. Merten (Institute for Theoretical Astrophysics, Heidelberg, Germany; INAF-Osservatorio Astronomico di Bologna, Italy), D. Coe (Space Telescope Science Institute, Baltimore, USA), R. Dupke (University of Michigan, USA; Eureka Scientific, USA; National Observatory, Rio de Janeiro, Brazil), R. Massey (University of Edinburgh, Scotland), A. Zitrin (Tel Aviv University, Israel), E.S. Cypriano (University of Sao Paulo, Brazil), N. Okabe (Academia Sinica Institute of Astronomy and Astrophysics, Taiwan), B. Frye (University of San Francisco, USA), F. Braglia (University of British Columbia, Canada), Y. Jimenez-Teja (Instituto de Astrofisica de Andalucia, Granada, Spain), N. Benitez (Instituto de Astrofisica de Andalucia), T. Broadhurst (University of Basque Country, Spain), J. Rhodes (Jet Propulsion Laboratory/Caltech, USA), M. Meneghetti (INAF-Osservatorio Astronomico di Bologna, Italy), L. A. Moustakas (Caltech), L. Sodre Jr. (University of Sao Paulo, Brazil), J. Krick (Spitzer Science Center/IPAC/Caltech, USA) and J. N. Bregman (University of Michigan).

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

ESOcast 31: Pandora's Cluster video: http://www.eso.org/public/videos/eso1120a/

Links:
    Research paper: http://www.eso.org/public/archives/releases/sciencepapers/eso1120/eso1120.pdf

    Photos of the VLT: http://www.eso.org/public/images/archive/category/paranal/

Images, Text, Credits: NASA / ESA, ESO / CXC & D. Coe (STScI) / J. Merten (Heidelberg / Bologna) / ESA / Hubble & Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble) / Videos: ESO/L. Calcada and J. Merten (Heidelberg / Bologna) / NASA  / D. Coe (STScI) / Digitized Sky Survey 2 / A. Fujii. Music: Music: John Dyson (from the album Moonwind).

Best regards, Orbiter.ch

The end for ATV Johannes Kepler

ESA - ATV-2 Johannes Kepler Mission patch.

21 June 2011

Europe’s unmanned ATV space freighter plunged on command into Earth’s atmosphere today to end its mission as a spectacular shooting star over the southern Pacific Ocean. Contact with the spacecraft was lost at 20:41:39 GMT (22:41:39 CEST) at an altitude of 80 km.

Illustration of ATV-2 reentry

After a flawless undocking from the International Space Station on Monday at 14:46 GMT (16:46 CEST), the Automated Transfer Vehicle (ATV) flew solo while its mission control centre in Toulouse, France, prepared the craft for its fiery end.

There was one unplanned manoeuvre: dodging a piece of space debris about two hours after leaving the Station.

After a warning from NASA that an object would zip past to within 50 m, ATV-2 fired its thrusters briefly to move out of danger.

The tonne of propellant remaining in its tanks was plenty for the reentry manoeuvres and any contingencies. The ad hoc avoidance again demonstrated ATV’s adaptability to changing situations.

Last moments of Johannes Kepler

Today, at 17:07 GMT (19:07 CEST), ATV fired its engines to enter an elliptical orbit leading to the second burn at 20:04 GMT (22:04 CEST), which precisely targeted its Pacific goal.

  Mission directors signalling the spirit at the ATV-CC

The first burn lasted for 10 min 9 sec and the second for 14 min and 9 sec.

Just before hitting the atmosphere, Johannes Kepler was commanded to begin tumbling to ensure it would disintegrate and burn up safely.

Surviving pieces such as the heavy docking adapter and main engines – designed to withstand extreme heat – struck the ocean at around 21h GMT (23h CEST). There were no hazardous materials aboard ATV.

The destructive reentry happened exactly as planned over an uninhabited area of the south Pacific, about 2500 km east of New Zealand, 6000 km west of Chile and 2500 km south of French Polynesia.

"The mission of ATV-2 has been very smooth and we have encountered during these four months only very minor issues that were quickly taken care of by our teams," said Nico Dettmann, Head of ESA’s ATV Programme.

Johannes Kepler docking with the Space Station on 24 February

"ATV has shown again its capabilities in servicing the Station and we are looking forward to the next, Edoardo Amaldi, which will be shipped to Kourou in August for launch in early 2012."

"We broke many records with ATV-2," continued Alberto Novelli, Head of ESA’s ATV Mission Operations.

"Not only was this the heaviest payload ever launched by ESA and the Ariane 5 rocket, but the ATV’s engines also achieved the biggest boost for human spaceflight since the Apollo missions to the Moon: we raised the Space Station’s orbit by more than 40 kilometres."

Reentry being analysed

ATV’s last moments were recorded by a prototype ‘black box’ provided by the US Center for Orbital and Reentry Debris Studies. A similar recorder was carried by Japan’s HTV-2 ferry during its reentry on 28 March.

ATV-1 burning during the reentry in 2008

The small device collected information on acceleration, roll, pitch and yaw rates, temperatures and GPS coordinates.

It was then left to decend on its own, protected by its own heatshield, and transmit the stored data via the Iridium satphone system.

The information will help to predict what happens to space hardware as it reenters and comes apart under aerodynamic heating and loads.

This will help in designing future spacecraft to break up into less hazardous fragments on reentry.

Related links:

International Space Station: http://www.esa.int/esaHS/iss.html

EADS Astrium: http://www.astrium.eads.net/

Arianespace: http://www.arianespace.com/index/index.asp

Automated Transfer Vehicle (ATV): http://www.esa.int/SPECIALS/ATV/index.html

Credits: ESA / D. Ducros / Jari Makinen / NASA.

Greetings, Orbiter.ch

Soyuz-U with Progress M-11M Successfully Lifts Off from Baikonur

ROSCOSMOS logo.

21 June 2011

Soyuz-U with Progress M-11M Successfully Lifts Off from Baikonur

Soyuz-U rocket with Progress M-10M atop successfully lifted off today at 18.38 MSK, from launch pad 1, Baikonur.

Launch of Progress M-11M

Progress M-11 which is to deliver about 2.6t of cargo to the International Space Station is due to dock to Zvezda module on June 23, at 20:37 MSK.

Progress M-11M is Flying Towards the ISS

In line with the International Space Station mission plan, Progress M-11M  cargo vehicle was launched from Baikonur yesterday.
The rocket successfully injected  the vehicle into the orbit with the following parameters:

• min altitude – 193,96 km;
• max altitude – 240,09 km;
• revolution – 88,54 min;
• inclination – 51,64 deg.

The vehicle is due to dock to the station’s Zvezda module on June 23, at 20:37 MSK (Moscow Time).

Text, Video, Credit: Roscosmos PAO / Photo Credit: Yuzhny Space Center.

Best regards, Orbiter.ch

ESA reentry vehicle on track for flight in 2013

ESA logo.

21 June 2011

ESA and Thales Alenia Space Italia announced an agreement today at the Paris Air & Space Show to begin building the IXV Intermediate eXperimental Vehicle for its mission into space in 2013.

Europe’s ambition for a spacecraft to return autonomously from low orbit is a cornerstone for a wide range of space applications, including space transportation, exploration and robotic servicing of space infrastructure.

IXV Intermediate eXperimental Vehicle

This goal will be achieved with IXV, which is the next step from the Atmospheric Reentry Demonstrator flight of 1998. More manoeuvrable and able to make precise landings, IXV is the ‘intermediate’ element of Europe’s path to future developments with limited risks. 

Launched into a suborbital trajectory on ESA’s small Vega rocket from Europe’s Spaceport in French Guiana, IXV will return to Earth as if from a low-orbit mission, to test and qualify new European critical reentry technologies such as advanced ceramic and ablative thermal protection.

The 2 t lifting body will attain an altitude of around 450 km, allowing it to reach a velocity of 7.5 km/s on entering the atmosphere. It will collect a large amount of data during its hypersonic and supersonic flight, while it is being controlled by thrusters and aerodynamic flaps.

IXV launched into space

The craft will then descend by parachute and land in the Pacific Ocean to await recovery and analysis.

The detailed design and critical technologies are ready. Today’s agreement allows the vehicle’s manufacturing, assembly, integration and qualification to begin.

Procurement of the ground network will also begin, including the mission control centre, ground station telemetry kits, transportable antennas and communication network.

Formal approval for signing the contract will come at the end of June from ESA’s Industrial Policy Committee.

Signature of agreement to build IXV

“Less than two years after the Agency requested industry to quote the activities for IXV, the progress made is remarkable. The achievement of major milestones, such as the Critical Design Review, gives us the confidence to believe that the vehicle will be ready in two years,” says Antonio Fabrizi, ESA Director of Launchers.

“Today’s agreement confirms that ESA and industry are committed to keep up with the challenging schedule and be ready for flight in 2013.”

“Thanks to this agreement, the IXV mission into space has become a near-term reality. Its success will provide Europe with valuable know-how on reentry systems and flight-proven technologies that are necessary to support the Agency’s future ambitions, including return missions from low Earth orbit,” says Giorgio Tumino, IXV Project Manager.

 

ESA's Intermediate eXperimental Vehicle

“In the long term, studies on the evolution of IXV will be consolidated and proposed to Member States, focusing on an affordable reusable craft for operating and servicing payloads in orbit before returning to touch down on land.”

Related link:

Intermediate eXperimental Vehicle (IXV): http://www.esa.int/SPECIALS/Launchers_Technology/SEMDPQ2PGQD_0.html

Images, Video, Text, Credits: ESA / J.Huart / S. Corvaja.

Cheers, Orbiter.ch

Galileo’s Soyuz launchers arrive at French Guiana

ESA - GALILEO logo / Roscosmos - Soyuz at CSG (Kourou) patch.

21 June 2011

The two Soyuz launchers that will fly the first four satellites of Europe’s Galileo navigation system into orbit have arrived at Kourou harbour in French Guiana, completing a journey that took them halfway round the world.

The first two Galileo In Orbit Validation satellites are set to be launched from Europe’s Spaceport on 20 October, with two more following them into orbit by mid-2012.

The October launch will be the first flight of a Soyuz rocket from French Guiana. 

 Soyuz rockets being unloaded

The two Soyuz ST-B launchers and their Fregat-MT upper stages were carried across the Atlantic aboard Arianespace vessel MN Colibri, arriving on 18 June.

The rocket hardware left by train from the Soyuz manufacturing plant in Samara, Russia and the Fregat factory in Moscow to St Petersburg harbour, where it was loaded for shipment, leaving on 3 June for French Guiana.

First Soyuz launch this October

The next step will be the Launcher Flight Readiness Review, due to take place on 21 July. Authorisation will then be given to begin assembling the rocket hardware and deployingthe initial Soyuz ST-B launcher for the first Galileo campaign.

The first two Galileo satellites – known as PFM and FM2, for Protoflight Model and Flight Model 2 – are currently undergoing their final qualification and acceptance tests at Thales Alenia Space in Rome, Italy.

Soyuz ST-B launchers at Kourou harbour

Once Satellite Flight Readiness Review has given the green light, both satellites and their ground equipment and launch teams will arrive at the beginning of September for the launch campaign.

Soyuz ST-B is the most powerful version of the famous Soyuz launcher, while the Fregat-MT is an upgraded version of the Fregat upper stage.

Soyuz on pad in dry run for launch

Other Soyuz hardware is already in storage at Kourou but only the combination of Soyuz ST-B and Fregat-MT was up to the demanding task of conveying the Galileo satellites into their circular 23 222 km orbits.

A European dispenser will hold the satellites in place as they share their ride to orbit, and then release them into their final orbits.

Baseline versions of the reignitable Fregat were previously employed to deliver ESA’s GIOVE-A and -B experimental satellites in 2006 and 2008, which secured the rights to Galileo’s radio frequencies. Fregat-MT carries an additional 900 kg of propellants for its double-satellite load.

Soyuz from French Guiana

October’s launch will be a historic occasion, the first time that a Soyuz launcher lifts off from a spaceport other than Baikonur in Kazakhstan or Plesetsk in Russia.

Because French Guiana is so close to the equator each launch will benefit from Earth’s spin, increasing the maximum payload to geostationary transfer orbit from 1.7 tonnes to three tonnes. As a medium-class launcher, Soyuz will complement Ariane and Vega to enhance the flexibility and competitiveness of Europe’s launcher family.

Soyuz transported to pad in mobile gantry

Each three-stage rocket will be assembled horizontally in the traditional Russian manner, transferred to the launch site and moved to the vertical so that its payload can be mated onto it from above. A new mobile launch gantry enables this process, while protecting the satellites and the launcher from the humid tropical environment.

Fully assembled Soyuz at Europe's Space Port

Galileo IOV

These first four Galileo satellites will form the operational nucleus of the full Galileo satnav constellation.

First two Galileo IOV satellites

They are fully representative of the others that will follow them into orbit, combining the best atomic clock ever flown for navigation – accurate to one second in three million years – with a powerful transmitter to broadcast precise navigation data worldwide.

Related links:

Arianespace: http://www.arianespace.com/index/index.asp

Roscosmos: http://www.roscosmos.ru/main.php?lang=en

Soyuz: http://www.esa.int/SPECIALS/Launchers_Access_to_Space/SEM6JRS4LZE_0.html

Galileo: http://www.esa.int/esaNA/galileo.html

Images, Video, Text, Credits: ESA / D. Ducros / S. Corvaja / P. Carril / Arianespace.

Greetings, Orbiter.ch

Johannes Kepler has left the Station

ESA - ATV-2 Johannes Kepler Mission patch.

20 June 2011

Europe’s Johannes Kepler ATV cargo ferry undocked from the International Space Station today at 14:46:30 GMT (16:46:30 CEST). The craft is now leaving the orbital outpost far behind and will end its mission on Tuesday evening as a shooting star over the Pacific Ocean.

After spending almost four months as an important part of the International Space Station, ESA’s second Automated Transfer Vehicle is ending its days as a rubbish truck – another critical role because the 1200 kg of waste bags and discarded equipment cannot just be thrown out of the Station.

ATV after undocking

The crew closed the hatches between the two vehicles on Sunday afternoon at 15:30 GMT (17:30 CEST).

Undocking came today, with ATV’s thrusters gently increasing the distance from the outpost, towards a path leading to its deliberate destruction. Before the undocking, all electical and data connections between the two spacecraft were disconnected at 14:39 GMT (16:39 CEST).

ATV Johannes Kepler delivered more than seven tonnes of dry cargo, propellants and air in February.

ATV’s last major job was to boost the complex to a higher orbit. The vehicle also assisted Station attitude control several times during its mission.

Fireball over the Pacific

Tomorrow, Johannes Kepler will fire its engines twice to descend from orbit.

The first burn, at 17:07 GMT (19:07 CEST), will drop it towards Earth. The second burn, at 20:52 GMT (22:52 CEST), will direct it precisely towards its South Pacific target.

This area is used for controlled reentries of spacecraft because it is uninhabited and outside shipping lanes and airplane routes. Extensive analysis by ESA specialists will ensure that the trajectory stays within safe limits.

ATV Contol Centre preparing for undocking

The same area was also used for the descents of ATV-1 in September 2008 and Russia’s Mir space station in 2001.

Air and sea traffic has been warned and a no-fly zone will prevent any accidents.

The 14-tonne ATV is now empty of hazardous materials and it will almost completely burn up – like a meteor, hitting the atmosphere at high speed.

Each year, about 40 000 tonnes of meteoroids and interplanetary dust fall to Earth with no ill effect.

End of the ATV-1 over Pacific, 2008

The freighter will hit the outer layers of the atmosphere at an altitude of about 100 km. It will start tumbling at about 20:24 GMT (22:24 CEST), disintegrate, burn and any remains will strike the ocean at around 20:59 GMT (22:59 CEST).

Only a few hardy pieces might survive the fiery reentry and splash harmlessly into the ocean.

Last call home

The last moments of Johannes Kepler will be carefully captured by its Reentry Breakup Recorder, collecting information on its position, attitude, temperature, pressure and other aspects of its breakup.

The 9 kg ‘black box’ will start recording automatically for ATV’s last five minutes.

Heatshield of a Reentry Breakup Recorder

It will then be jettisoned, protected by its own heatshield. At an altitude of 18 km it will transmit the stored data via the Iridium satphone system for analysis. The recorder will not be recovered.

Some aspects of controlled destructive entries are still not well known so all in-situ measurements are welcome.

Similar recorders may be used in future on satellites and spacecraft like black boxes on aircraft.

Related links:

International Space Station: http://www.esa.int/esaHS/iss.html

EADS Astrium: http://www.astrium.eads.net/

Arianespace: http://www.arianespace.com/index/index.asp

Images, Text, Credits: ESA / J. Makinen / NASA / The Aerospace Corporation.

Best regards, Orbiter.ch

Cassini Captures Ice Queen Helene

NASA - Cassini Insider's Mission patch.

20 June 2011

NASA's Cassini spacecraft successfully completed its second-closest encounter with Saturn's icy moon Helene on June 18, 2011, beaming down raw images of the small moon. At closest approach, Cassini flew within 4,330 miles (6,968 kilometers) of Helene's surface. It was the second closest approach to Helene of the entire mission.

Image, Text, Credits: NASA / JPL-Caltech / Space Science Institute.

Cheers, Orbiter.ch