With today's contribution I want to fulfil the promise I made in the blog entry I wrote on 12 July 2011 to inform you about the results of the tests on the usability of the German Aerospace Center's (Deutsches Zentrum für Luft und- Raumfahrt; DLR) new web portal.

On 18 September 2011, German Aerospace Day, DLR and ESA staged the first European SpaceTweetup. A tweetup is an event in which users of the social media platform Twitter meet up. Together with ESA, we invited our Twitter followers to come and find out more about the European aerospace industry, meet scientists and astronauts and have a look at our research facilities and aircraft.

The German ROSAT research satellite was launched on 1 June 1990 on a Delta II launcher and successfully scanned space for X-ray sources for nine years. Its record of achievements extends from discovering countless X-ray sources to analysing galactic clusters, X-ray binary stars and black holes to discovering the reflection of the Sun's X-ray radiation by the Moon. The findings by the scientists involved in the mission have appeared in over 7000 publications. After orbiting Earth for 21 years, ROSAT re-entered the atmosphere over the Bay of Bengal. It is not known whether any parts reached the Earth's surface.

The airborne observatory SOFIA will arrive at Cologne-Bonn Airport on Saturday 17 September 2011 at about 06:50 CEST. The aircraft will be one of the attractions during German Aerospace Day, which takes place on the following day. The flight from the United States to Germany can be followed live online from 19:10 CEST – learn how in this blog post.

Here is a list of the social media channels for German Aerospace Day and the associated SpaceTweetup; nearly all the events can be followed in (almost) real time.

Camilla Corona SDO is ready for the Space Tweetup! File this one under ‘humour’: A fabulous and very tongue-in-cheek press release has been issued by one of our favourite rubber chickens.

On 18 September 2011 DLR is hosting, for the eleventh time, German Aerospace Day in Cologne, offering young and old alike the opportunity to take a look behind the scenes of DLR's research work. For those interested in following this special day online and those active in social networks, we will be reporting live throughout the event here on this blog as well as on Facebook, Twitter, YouTube and Flickr.

A great deal has happened since DLR’s participation in the Aerospace trade show at Le Bourget in June, and it can all be followed on the recently revamped DLR homepage. Last week’s events mainly focused on the MAKS Aviation and Space Salon in Moscow, the third trade fair for the international aerospace industry, where DLR has been showcasing its work, following its appearances at Le Bourget (Paris) and ILA in Berlin. Just as at the Le Bourget trade fair, at MAKS we were once again able to engage in many interesting and important talks.

After more than 5 months of successful flight operations by GSOC, the operational control was re-handed over again to the control center in Solna, Sweden. Since handover to GSOC in March this year, various experiments could be performed. My colleagues already reported corresponding details within the Blog. I’ll now try to describe the topic of a satellite mission handover.

The new version of DLR's iOS App provides a wealth of information right at your fingertips - now also supporting the features of the iPad.

Today we sent off the last invitation letters for the first european SpaceTweetup, jointly organised by DLR and ESA. I cannot make clear enough how happy I am to organise and host this event together with our friends from ESA's communication department. But before I give you a little bit of background information on how the event came about, let me first answer the often heard question:

The Space Shuttle Atlantis announced its arrival at the Kennedy Space Center (KSC) in the early morning hours of 21 July 2011 with a double sonic boom. Just over three minutes later, the spaceship touched down on the runway and at 05:57:54 local time "wheels stop" was called for the last time. Atlantis and its crew had safely returned to Earth. NASA's space shuttles have travelled into orbit 135 times; this era ended today. The space shuttles have shaped US space policy for the last 30 years and have stood as an icon of human spaceflight for a whole generation.

Finished at last! The redesigned web portal for the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) is ready to receive the first of its close to 500,000 visitors per month. We have been working on the redesign for some time now, and are more than pleased with the result.

Astronomers on board SOFIA fly over most of the water vapour in the atmosphere; it is precisely this that makes the desired infrared observations possible. But the fact that SOFIA flies has another major advantage: it is a mobile observatory. In contrast to ground-based observatories, it can be used at different locations around the globe. This can be very useful, for example, for the Pluto occultation that will take place these days.

In my last blog entry, I focussed on a farewell to the shuttle fleet and some observations on the paradigm shift occurring in the space sector. Space Shuttle Endeavour has now landed safely and Atlantis is being prepared for launch. Images of the International Space Station (ISS) with Space Shuttle Endeavour and docked with the European space transporter ATV 'Johannes Kepler', taken from a Soyuz capsule as it was departing, already have historical value. This time, I would like to focus on my reappointment as Chairman of the DLR Executive Board and on the aspects that will be of central importance in my ongoing work.

I had already been working on the SOFIA project for some years, when back in 1998, a consortium of German research institutes (Max-Planck Institute of Radio Astronomy in Bonn, University of Cologne, Max-Planck Institute of Solar System Research and the DLR Institute of Planetary Research) decided to develop the German Receiver for Astronomy at Terahertz Frequencies (GREAT) as the Principal Investigator-class Science Instrument for the first generation at the SOFIA Observatory. At this time, the aim was for the observatory to be operational by the end of 2001. It was not only the optimists who were expecting the GREAT spectrometer to soon enter operational service. Back then, who could have thought that it would take 13 years for GREAT to fly on SOFIA for the first time?

On 16 May, the Space Shuttle Endeavour was launched en route to the International Space Station (ISS). On board was the large science experiment, AMS, designed to look for evidence of dark matter and antimatter. The flight is Endeavour's last, and it heralds the end of the shuttle era. In parallel with this somewhat technical farewell, we have also had to say goodbye to Thomas Reiter, who has been Director of Human Spaceflight and Operations for the European Space Agency (ESA)since mid-April. Two departures in the area of space exploration were sufficient reason for me to start reflecting on fundamental issues in spaceflight.

From the 14th of April the ECAPS High Performance Green Propulsion System (HPGP) experiment started its final campaign HPGP-4, the one planned for the extended mission period.

The small space shop on site at the Kennedy Space Center gives an indication of the fast-approaching end of space shuttle flights from the cape; everything is reduced in price. Although many people here on the ‘Space Coast’ are unsure about the coming months and years, the spirit needed to carry this historic space location into the future of spaceflight is unbroken. The day before the launch of STS-134, the press conferences were not just looking forward to the imminent mission.

SSC (Swedish Space Corporation) performed a remarkable autonomous close approached to bring MANGO and TANGO to a distance of less than 15 m. The maneuvers needed for that approach were computed by their autonomous formation flying (AFF) software on-board of MANGO. During an experiment of 8 days duration SSC performed numerous formation keeping and formation configuration maneuvers to verify the handling of different formation scenarios.

The alarm clock goes off at 04:45 Eastern Daylight Time (EDT). At 05:30, breakfast. At 06:00, the ESA-DLR media delegation, consisting of a dozen journalists and a number of 'Public Affairs Officers' (as NASA calls them) is on the move. At 08:40, after obtaining additional accreditation at two badging stations, we finally arrive at the Kennedy Space Center (KSC) press site.

Ever since the discovery of the telescope, man has been fascinated by the observation of the surface of the Moon. The constantly changing light coming from the Sun causes craters, mountains, valleys and plains to take on continuously varying appearances. Yet, as we look at this atmosphereless natural satellite, we get the impression that the Moon has not changed, even over the span of a human lifetime. But is this really the case?

The goal of PRISMA is to demonstrate sensors and flight software needed to perform formation flight and rendezvous missions. With respect to future on-orbit servicing missions, PRISMA is a milestone in developing and demonstrating the required technologies in orbit. The experiment operations started after commissioning and separation of the two spacecraft, Mango and Tango, in August 2010 . The basic experiment programme is planned to last ten months, with an additional two months for an extended campaign. The first half of this timeline was successfully executed by the Swedish Space Corporation, and after the transfer of operations on 14 March it is now GSOC's turn to conclude the nominal first year of operations. Let's have a closer look at the project structure, the experimenter's contributions and the experiment operations to be conducted at GSOC.

Since yesterday's Flight Readiness Review (FRR) confirmed a "Go" for Endeavour's Launch on 29 April it's now certain that we (me, that is) will continue blogging here starting next Thursday, 28 April, where there will be first photo opportunities at Kennedy Space Center. Unfortunately my DLR colleague Thilo Kranz, fellow blogger and excellent shuttle photographer, will not be there this time.

On 14 March 2011, the German Space Operations Center (GSOC) took over operations of PRISMA. Despite my 20 years of service, I must say that even though every mission launch is special, the transfer of operations for an ongoing mission has a very new ‘feel’ about it. PRISMA has been different in many ways. The aim of this mission is to demonstrate various formation flying and rendezvous scenarios at separations of as little as a few metres with satellites Tango and Mango.

On 26 December 2004, a devastating tsunami destroyed large parts of the coastline of the Indian Ocean. It is estimated that 250,000 people lost their lives because there was no early warning system. Shortly afterwards, the German government decided to spend 50 million Euros to develop a tsunami early warning system in Indonesia, the most severely affected country. Scientists from major German research centres presented innovative concepts for such a system to the political decision makers. Convinced of the feasibility of the proposal, the German Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung; BMBF) decided to support the project, now named the German-Indonesian Tsunami Early Warning System (GITEWS), as a joint development led by the German Research Centre for Geosciences (Deutsches GeoForschungsZentrum; GFZ) in Potsdam.

On 19 March 2011 everything came together perfectly – in a completely clear sky there was a full Moon and, what is more, at almost the exact time, the Moon passed through the point of closest approach to Earth on its elliptical orbit. This meant we were able to admire an unusually large and bright full Moon. Not wanting to let this opportunity pass, I photographed the Moon through my telescope.

An important meeting of the ESA Council took place on 16 and 17 March in Paris. Among other matters, it dealt with the International Space Station (ISS), ensuring European access to space, and the appointment of ESA Directors. On the first evening of the Council meeting, I was invited by the Ambassador of the Federal Republic of Germany in Paris, Reinhard Schäfers, to visit his official residence. It was a good opportunity to speak, not only about German space strategy in general, but also about the coordination of space activities at a time when we are all concerned regarding the news about the events in Japan.

NASA's Tom Speer used to be a pilot for commercial aircraft. He now works in the SOFIA project, training new SOFIA crew members on aircraft operations. I asked Tom for an interview and he was kind enough as to answer my questions.

With this new set of images that Thilo recently sent, we start to tie in with Space Shuttle Mission STS-134 which will carry the European-built Alpha Magnetic Spectrometer (AMS) to the International Space Station. The mission won't launch before 19 April 2011, but we already have some great images.