Posts Tagged ‘Rosetta’

Philae unanchored and bounced – but now stable – on 67P/Churyumov-Gerasimenko

November 13, 2014

Philae successfully separated from Rosetta and arrived at Comet 67P/Churyumov-Gerasimenko. It did land but its anchoring harpoons apparently failed to fire.  Magnetic field data indicates that Philae has touched down at least 3 times. After the first, the lander bounced and took over 2 hours to touch down again. It bounced again and then touched down 7 minutes later. It is hoped that it has come to rest with the 3rd touchdown but this will not be confirmed till this morning. (Update! It has just been confirmed that the lander is on the surface, stable and sending pictures. Its attitude is not known but full data transmission seems to have been established. Data on the tomography of the comet’s nucleus is also being transmitted).

A remarkable achievement after a 10 year journey. Now the Rosetta orbiter will remain in close proximity to the comet and will accompany it as it approaches the Sun. The Rosetta mission is due to end in December 2015. “By then, both the spacecraft and the comet will have circled the Sun and be on their way out of the inner Solar System”.

Philae bouncing

The Rolis instrument on Philae took this picture on descent:

 

The image shows comet 67P/CG acquired by the ROLIS instrument on the Philae lander during descent on Nov 12, 2014 14:38:41 UT from a distance of approximately 3 km from the surface. The landing site is imaged with a resolution of about 3m per pixel.

The ROLIS instrument is a down-looking imager that acquires images during the descent and doubles as a multispectral close-up camera after the landing. The aim of the ROLIS experiment is to study the texture and microstructure of the comet’s surface. ROLIS (ROsetta Lander Imaging System) is a descent and close-up camera on the Philae Lander. It has been developed by the DLR Institute of Planetary Research, Berlin. The lander separated from the orbiter at 09:03 GMT (10:03 CET) and touched down on Comet 67P/Churyumov–Gerasimenko seven hours later.

Rosetta finds its new stone

August 8, 2014

The Original Rosetta Stone – BBC

The new stone is a comet identified as 67P/Churyumov-Gerasimenko

  • It was first observed in 1969 and named after its Russian discoverers
  • The comet is in an elliptical 6.45-year orbit that takes it from beyond Jupiter at its furthest point, to between the orbits of Mars and Earth at its closest to the Sun.
  • It is approximately 3.5 x 4 km in size, has a rotational period of 12.7 hours and a mass of 3.14±0.21×1012 kg
  • The surface temperature appears to be around -70ºC, which is warmer than expected
  • It is currently about 405 million km from earth (about 22.5 light-minutes) and moving at 55,000 km/hr

The European Space Agency’s Rosetta craft has now arrived at 67P/Churyumov-Gerasimenko after a 10 year, 6.4 billion km long journey and has entered orbit around its new stone

Rosetta is a cornerstone mission to chase, go into orbit around, and land on a comet. It will study the Jupiter-family comet 67P/Churyumov-Gerasimenko with a combination of remote sensing and in situ measurements. The spacecraft will orbit the comet and release the Philae lander, which carries a suite of instruments for imaging and sampling the comet nucleus. The mission will track the comet through perihelion, examining its behaviour before, during and after.

Rosetta Trajectories by Christian Simoes astronoo.com

Rosetta Trajectories by Christian Simoes astronoo.com

The spacecraft was launched from Kourou aboard an Ariane 5G+ on 2 March 2004. It required four gravity assists for its journey, one by Mars and three by Earth. Rosetta had already flown by the asteroids 2867 Steins (in 2008) and 21 Lutetia (in 2010), before entering deep space hibernation in June 2011.

Rosetta’s main goals will be reached in 2014. Following a planned exit from hibernation on 20 January, the spacecraft’s instruments were checked as it continued on its journey to 67P/Churyumov-Gerasimenko. The spacecraft arrives at the comet in August 2014, and deploys the lander in November 2014.

Comet 67P-CG on 3rd August 2014 ESA

Comet 67P-CG on 3rd August 2014 ESA

Rosetta is just 100 km from the comet’s surface, but it will edge closer still. Over the next six weeks, it will describe two triangular-shaped trajectories in front of the comet, first at a distance of 100 km and then at 50 km.

At the same time, more of the suite of instruments will provide a detailed scientific study of the comet, scrutinising the surface for a target site for the Philae lander.

Rosetta awakes

January 21, 2014

The European Space Agency is – justifiably – feeling pleased with itself:

Rosetta wake-up signal

It was a fairy-tale ending to a tense chapter in the story of the Rosetta space mission this evening as ESA heard from its distant spacecraft for the first time in 31 months.

Rosetta is chasing down Comet 67P/Churyumov-Gerasimenko, where it will become the first space mission to rendezvous with a comet, the first to attempt a landing on a comet’s surface, and the first to follow a comet as it swings around the Sun.

Since its launch in 2004, Rosetta has made three flybys of Earth and one of Mars to help it on course to its rendezvous with 67P/Churyumov-Gerasimenko, encountering asteroids Steins and Lutetia along the way.

Operating on solar energy alone, Rosetta was placed into a deep space slumber in June 2011 as it cruised out to a distance of nearly 800 million km from the warmth of the Sun, beyond the orbit of Jupiter.

Now, as Rosetta’s orbit has brought it back to within ‘only’ 673 million km from the Sun, there is enough solar energy to power the spacecraft fully again.

Thus today, still about 9 million km from the comet, Rosetta’s pre-programmed internal ‘alarm clock’ woke up the spacecraft. After warming up its key navigation instruments, coming out of a stabilising spin, and aiming its main radio antenna at Earth, Rosetta sent a signal to let mission operators know it had survived the most distant part of its journey.

The signal was received by both NASA’s Goldstone and Canberra ground stations at 18:18 GMT/ 19:18 CET, during the first window of opportunity the spacecraft had to communicate with Earth. It was immediately confirmed in ESA’s space operations centre in Darmstadt and the successful wake-up announced via the @ESA_Rosetta twitter account, which tweeted: “Hello, World!”

Rosetta will be woken up Monday at 1000GMT after a two-and-a-half year sleep

January 19, 2014

The European Space Agency will try and wake-up its sleeping Rosetta spacecraft on Monday at 1000 GMT. The spacecraft entered deep space hibernation in June 2011 when it was too far away from the sun to capture much solar energy. If this works it will be a considerable achievement considering that Rosetta was launched 10 years ago  and the communications technology on board is effectively at least two  “generations” old!

Rosetta trajectory till June 2011

ESA:

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.

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.

Graphic of mission

Rosetta Mission (ESA via BBC)


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