Tag Archives: Operations

‘Go’ for science

Following the extensive in-orbit commissioning review and after encountering the unexpected challenges highlighted previously on the blog, Gaia is now ready to begin its science mission. Read the announcement published today on the ESA Portal: Gaia: ‘Go’...

Gaia lift-off time

Launching a satellite seems fairly simple: put it onto a rocket and launch it into space. Of course it’s a bit more complicated than this and some missions are more complex than others. In the case of Gaia we have to launch at a very specific time each day. This lift-off time is determined by the Libration Point Mission Analysis Group of ESOC. In this blog entry I’ll explain why this launch time is so constrained and how we determine the exact lift-off time. There are three major factors that contribute to this launch: – The destination of Gaia, the Sun-Earth libration point, or Lagrange point 2 – The programming of the...

Some Gaia numbers

We have heard and read many numbers about Gaia: the number of stars and other objects that it will observe, the maximum observable magnitude, the microarcsecond of accuracy and the remarkable focal length of 35 m. We have also read that such a powerful telescope on Earth would be able to detect a button on the spacesuit of an astronaut on the Moon. But let’s look at more hidden numbers. It took over 3.5 million hours to study, design, build and test Gaia. That’s about 300 people working full time for 7 years, spread over 74 different companies and 16 countries. Meanwhile the design and implementation of the science and the operations...

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...

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...

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...

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...

Gaia – Surveying a billion stars

Welcome to ESA’s Gaia blog! Gaia is a global space astrometry mission. It will make the largest, most precise three-dimensional map of our Galaxy by surveying more than a thousand million stars. In this blog we’ll cover the activities from Kourou from once the spacecraft has left the clean room in Toulouse until launch. And we’ll include guest blogs from outside of Kourou – to give you an idea of the other things that are happening in the wider Gaia community. Details shortly…Watch this space!