Recent News On Nasa

Eye of Gaia: billion-pixel camera to map Milky Way

The largest digital camera ever built for a space mission has been painstakingly mosaicked together from 106 separate electronic detectors. The resulting “billion-pixel array” will serve as the super-sensitive ‘eye’ of ESA’s Galaxy-mapping Gaia mission.

While the naked human eye can see several thousand stars on a clear night, Gaia will map a billion stars within our own Milky Way Galaxy and its neighbors over the course of its five-year mission from 2013, charting their brightness and spectral characteristics along with their three-dimensional positions and motions.

In order to detect distant stars up to a million times fainter than the eye can see, Gaia will carry 106 charge coupled devices (CCDs), advanced versions of chips within standard digital cameras.
Developed for the mission by e2v Technologies of Chelmsford, UK, these rectangular detectors are a little smaller than a credit card, each one measuring 4.7x6 cm but thinner than a human hair.
The 0.5x1.0 m mosaic has been assembled at the Toulouse facility of Gaia prime contractor Astrium France.  
Technicians spent much of May carefully fitting together each CCD package on the support structure, leaving only a 1 mm gap between them. Working in double shifts in strict cleanroom conditions, they added an average four CCDs per day, finally completing their task on 1 June.
“The mounting and precise alignment of the 106 CCDs is a key step in the assembly of the flight model focal plane assembly,” said Philippe Garé, ESA’s Gaia payload manager.

The completed mosaic is arranged in seven rows of CCDs. The main array comprises 102 detectors dedicated to star detection. Four others check the image quality of each telescope and the stability of the 106.5º angle between the two telescopes that Gaia uses to obtain stereo views of stars.
In order to increase the sensitivity of its detectors, the spacecraft will maintain their temperature of –110ºC.

Gaia’s CCD support structure, like much of the rest of the spacecraft, is made of silicon carbide – a ceramic like material, extraordinarily resistant to deforming under temperature changes.
 
First synthesized as a diamond substitute, SiC has the advantage of low weight: the entire support structure with its detectors is only 20 kg.
Gaia will operate at the Earth–Sun L2 Lagrange point, 1,5 million kilometers behind the earth, when looking from the sun, where Earth’s orbital motion balances out gravitational forces to form a stable point in space. As the spinning Gaia’s two telescopes sweep across the sky, the images of stars in each field of view will move across the focal plane array, divided into four fields variously dedicated to star mapping, position and motion, colour and intensity and spectrometry.

Scheduled for launch in 2013, Gaia’s three-dimensional star map will help to reveal the composition, formation and evolution of the Milky Way, sampling 1% of our Galaxy’s stars.

Gaia should also sample large numbers of other celestial bodies, from minor bodies in our own Solar System to more distant galaxies and quasars near the edge of the observable Universe.

--------------------------------------------------------------------

Last Space Shuttle mission launched

Space Shuttle Atlantis was launched today at 17:29 CEST (15:29 GMT) to the International Space Station on a mission that will end the multi-purpose space plane programmer’s three-decade era of human spaceflight.

 

Atlantis will dock after about 2 days with the orbital outpost on Sunday at 17:09 CEST (15:09 GMT) and the four new astronaut arrivals will float into the Station about two hours later where currently the ISS Expedition 28 crew consisting of two American and one Japanese astronauts and 3 Russian cosmonauts permanently live and work in space.

Atlantis is carrying the Italian-built Raffaello pressurized logistics module filled with vital supplies and spares. On the journey down, it will return a range of items to Earth. Also all the samples from the on-board MELFI freezers will be returned to Earth in thermally conditioned state for analysis by the scientists.

Raffaello will be berthed at the Node-2 port on Monday and, after unloading its precious cargo, it will be detached again on Sunday 17 July and put back by the Space Station robotic arm into the Shuttle cargo bay.  

Two of the Shuttle astronauts will make a spacewalk on Tuesday 12 July to recover a Station ammonia pump that recently failed. It will be returned to Earth for engineers to probe the causes.

Atlantis will leave the Station again on Monday 18 July at 07:59 CEST (05:59 GMT).

The final Shuttle landing at the Kennedy Space Center is planned for Wednesday 20 July at 13:06 CEST (11:06 GMT).