Monthly Archives: September 2013

Another day in the life of a Gaia test engineer

In the middle of last night, we received in Kourou a disturbing call from the Gaia control centre, located in Darmstadt, Germany. Although for us it was middle of the night, it was already morning in the control centre. So what happened? Although often announced in the media as having the biggest camera on board that has ever flown in space, Gaia does not actually take pictures in the sense as you and me taking pictures on a holiday trip. Instead, it rather tracks the stars across its sensors as the telescopes rotates and the field of view moves across the star filled sky. In order to do so, a constant readout...

Inspecting the Soyuz facilities

The previous blog entries have given an overview of the activities of the last few weeks: from the arrival of the spacecraft in Kourou to the successful test of the Launch and Acquisition Mode (LAM) - the initial operational mode of the spacecraft during and after launch up to the contact with the ground stations. Another recent activity was the inspection of the Soyuz facilities and especially the VS06 rocket (Soyuz Flight number 6), which will now launch Gaia, after the switch with the O3B project. The first thing that catches your eye is a depot with 40 massive containers that are shipped from St. Petersburg by boat. The Soyuz facility stores...

Gaia data processing

In a previous blog entry you have learned about the rehearsals taking place in preparation for the Gaia data processing. Unlike a mission such as the Hubble Space Telescope, Gaia does not produce data that is immediately scientifically useful. The raw telemetry must first be processed before we can obtain the sought after distances, motions, and properties of the stars observed by Gaia. This immense task will be undertaken by a pan-European collaboration, the Gaia Data Processing and Analysis Consortium (DPAC). The DPAC consists of about 450 persons, spread over academic institutes and space agencies throughout Europe and beyond, who are actively contributing to writing the millions of lines of code needed...

Successful system test

Few people realize how complicated a launch actually is. Gaia is launched with a Russian-built Soyuz rocket, which has three stages. In fact, it ignites the first and second stage at the same time and the third stage is ignited before the second stage is burned out. The three main stages take the payload (spacecraft) into orbit around Earth. Then the Fregat upper stage takes over. The Fregat stage is also Russian-built. With some complicated manoeuvres, it brings the satellite on course to its final destination, the L2 point. Once the Fregat has done its job, it separates from the satellite, and the satellite starts working autonomously from then on. When the...

IT Phone home

Being an Information Technology (IT) specialist may not sound as glamorous as some of the other roles that people have out here in Kourou, but it is just perhaps just as important since we all rely heavily on our computers and online communications, not only for a successful launch campaign, but also to stay connected with our families thousands of miles away back home. Being an IT specialist in the jungle also presents with it some unique challenges, but the unusual technical problems are probably the most interesting to deal with! I’m no stranger to Kourou launch campaigns, having worked on Rosetta and Herschel and Planck in the past. Before the Gaia...

From VS-07 to VS-06

Last week was busy with a number of electrical tests performed in two shifts. In practice it has been busier than anyone could have expected. Of course, electrical tests and the life of a team of more than 50 persons inevitably leads daily to a number of questions needing to be answered generally sooner than later. Our preparation was good enough to cover most of this. However, when postponement of the launch of four O3B satellites – originally planned for 30 September – was confirmed, adaption from all parties was necessary. We were originally assigned VS-07 (Vol Soyuz 7) and suddenly became VS-06. Just one digit change should not be dramatic but...

Operations rehearsal 4

Once Gaia is flying it will send a daily stream of scientific data to Earth. The Missions Operations Centre receive this and transfer it to the Science Operations Centre in the European Space Astronomy Centre (ESAC), the ESA establishment near Madrid in Spain.  At ESAC, “Initial Data Treatment” is carried out as well as running the First Look software to assess the instrument health. The processed data is then sent to the other data processing centres around Europe (Barcelona, Cambridge, Geneva, Turin and Toulouse).  A group of payload experts also look at this data to confirm the performance of the instrument. Depending on what the payload experts find, small changes or calibration...

Spacecraft switch on

Activities are progressing well. The electrical team has set up all the electrical test equipment in the control room. This control room is adjacent to the cleanroom, where the spacecraft is, with a window in between. This makes it easy to communicate visually. Then a big bundle of cables runs from the control room to the satellite through a hole in the wall. The first switch on after transportation is always an exciting moment. You never know what might have happened during transport and packing/unpacking – a loose screw, a broken connector... you just don't want to end up with smoke coming out of the spacecraft! There are however numerous safety mechanisms...

Gaia goes to L2 - what's an "ell-two"?

Just like observatories on Earth, space observatories like Gaia like it quiet and dark. In space "quiet and dark" means far away from Earth. At large distances from Earth, the motion of spacecraft are no longer controlled only by the gravity of Earth, but also by other gravitational sources – most prominently by the Sun. The orbital motion of Earth around the Sun also influences the motion of spacecraft. The good thing about these forces – if you are a spacecraft – is that in five locations, all these forces balance out to create a stable location from which to study the wider Universe. These points are called the "Lagrange points", or...

Update from the Gaia Operations team

There's a detailed technical backgrounder today over at ESA's Rocket Science blog reporting on the Gaia mission operations testing campaign. It was written by the Spacecraft Operations Manager, Dave Milligan, and covers what's happening at ESA's ESOC Operations Centre as the mission gets closer to lift off. Well worth a read! Access full report

Gaia comes to life - spacecraft ready for switch-on

As soon as brought out of its transport container, Gaia's verification and preparation for launch could start. The first verification activity allowed to confirm that transport did not impact the alignment of some sensitive equipment like thrusters and star trackers. Then, the Astrium Stevenage team took over and verified the functionality and leak tightness of Gaia's propulsion systems. This is a must to comply to safety before pressurising gas tanks and loading propellant tanks with dangerous fluids. The picture shows the set-up of the spacecraft in the S1B clean room connected to its fluidic equipment. The next step is the electrical verification. A number of new participants just arrived to support the...

Out of the box - Gaia unveiled

The transport container with the spacecraft was opened on Monday last week in the clean room of the launch centre. In the clean room the air is strictly controlled to a very high level of purity,  the temperature is kept stable at 21 °C and the humidity below 60%. These conditions are very important for Gaia which has very delicate optical systems. Here are some photos showing the phase of opening the container. Above: The container has just been opened and the cover is ready to be lifted. On the left wall one can see the two fans of the redundant air conditioning system. Also the air inside the container has been...