Today Space Event Is

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http://www.space.com/24292-rosetta-spacecraft.html

 

 

An artist's impression of the Rosetta orbiter deploying the Philae lander to comet 67P/Churyumov–Gerasimenko in 2014.
Credit: ESA–C. Carreau/ATG medialab

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Rosetta is a spacecraft on a 10-year mission to catch a comet. Launched in 2004, the spacecraft will soon make its rendezvous with Comet 67P/Churyumov-Gerasimenko.

Rosetta will be the first spacecraft to accompany a comet as it enters the inner solar system. After meeting up with the comet, it will begin a two-year study of the comet's nucleus and environment, observing how a frozen comet changes as it approaches the heat of the sun. Rosetta will also deploy a robot to make the first controlled landing on a comet. [Photos: Europe's Rosetta Comet Mission in Pictures]

Rosetta is named for the Rosetta Stone, a block of black basalt that was inscribed with a royal decree in three languages — Egyptian hieroglyphics, Egyptian Demotic and Greek. The spacecraft's robotic lander is called Philae, named after a similarly inscribed obelisk found on an island in the Nile River. Both the stone and the obelisk were key to deciphering ancient Egyptian hieroglyphs. Scientists hope the mission will provide a key to many questions about the origins of the solar system and, perhaps, life on Earth.

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ESA > Our Activities > Space Science > Rosetta

 

 

 

 

 

How Rosetta wakes up from deep space hibernation

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THE MOST IMPORTANT ALARM CLOCK IN THE SOLAR SYSTEM

16 January 2014

At 10:00 GMT on Monday, the most important alarm clock in the Solar System will wake up ESA’s sleeping Rosetta spacecraft.

Rosetta is chasing comet 67P/Churyumov–Gerasimenko and, since its launch in 2004, has made three flybys of Earth and one of Mars to build up enough speed and get on a trajectory towards the comet. It has also encountered asteroids Steins and Lutetia along the way.

Operating on solar energy alone, the spacecraft was placed into a deep space slumber in mid-2011 as it cruised far from the Sun and out towards the orbit of Jupiter. To prepare for its long sleep, Rosetta was oriented so that its solar arrays faced the Sun and put into a once per minute spin for stability.

The only devices left running were its computer and several heaters.

 

 

Chasing a comet

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Thirty-one months later, Rosetta’s orbit has brought it back to within ‘only’ 673 million kilometres of the Sun, and there is finally enough solar energy to power the spacecraft fully again. It is time to wake up.

Rosetta’s computer is programmed to carry out a sequence of events to re-establish contact with Earth on 20 January, starting with an ‘alarm clock’ at 10:00 GMT.

Immediately after, the spacecraft’s startrackers will begin to warm up, taking around six hours.

Then its thrusters will fire to stop the slow rotation. A slight adjustment will be made to Rosetta’s orientation to ensure that the solar arrays are still facing directly towards the Sun, before the startrackers are switched on to determine the spacecraft’s attitude.

Once that has been established, Rosetta will turn directly towards Earth, switch on its transmitter and point its high-gain antenna to send its signal to announce that it is awake.

Because of Rosetta’s vast distance – just over 807 million kilometres from Earth – it will take 45 minutes for the signal to reach the ground stations. The first opportunity for receiving a signal on Earth is expected between 17:30 GMT and 18:30 GMT.

Deep space tracking dishes will be listening out for the signal, starting with NASA’s ‘big ears’ – the 70 m-diameter station at Goldstone, California, followed by, as the Earth rotates, the Canberra station in eastern Australia. ESA's New Norcia 35 m antenna, in Western Australia, would be next in line to await the signal's arrival. 

Whenever the signal is received, it will be relayed immediately to ESOC, ESA’s Operations Centre in Darmstadt, Germany.

This exciting moment will be announced to the world straightaway via the @ESA_Rosetta twitter account.

 

[pinky123]

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