Historic Comet Landing Wednesday Nov 12,2014

 

Philae made incredible landing on comet 67P today at 3.30pm GMT making it first craft in history to land on a comet

Probe separated from the Rosetta spacecraft seven hours earlier after 10 year mission to comet

'It's a big step for human civilisation,' said Esa director general as control room erupted with applause
 

First image by Philae showed Rosetta 50 seconds after separation as it headed towards planet

Five simple words marked the fulfilment of an extraordinary feat of space exploration yesterday when scientists announced: ‘We are on the comet.’

At the European Space Agency’s mission control, a faint radio signal came back from the Philae lander at 4pm – proof that it had finally reached the surface of the comet 67P/Churyumov-Gerasimenko after a decade-long chase through space.

Dr Stephan Ulamec, who ran the audacious landing programme, said early tests suggested the craft had bounced softly before turning and settling again. 

He said: ‘It touched down and was re-bouncing. So maybe today, we didn’t just land, we landed twice.’

TIMELINE OF THE LANDING 

Time is when confirmation on Earth will be received.  All times in GMT

0903 - Philae will separate from the main Rosetta spacecraft.

0904 - First 'farewell images' received from Philae of Rosetta.

0912 - Philae will be 100 metres from Rosetta.

0943 - Loss of signal expected due to manoeuvre of spacecraft.

1053 - Signal link re-stablished.

1458 - Philae's harpoon anchor system will be turned on.

1501 - Images of landing site will be taken.

1517 - Final pre-touchdown operations.

1522 - Start of lander's touchdown window.

1602 - Expected time of landing on the surface.

1607 - First images of the surface sent back to Earth.

The mission control team in Darmstadt, Germany celebrating immediately after the announcement that
Rosetta's probe, Philae, has successfully landed on its comet 67P/Churyumov-Gerasimenko

 

  

Esa director general Jean-Jacques Dordain (pictured) said: 'This is a big step for human civilisation'

WHAT COULD HAVE HAPPENED IF THE THRUSTER DIDN'T WORK?

When Philae touched the surface of the comet it fired harpoons into the surface to keep it anchored there.

To keep it attached to the surface a thruster at the top was mean to push it down as the harpoons fired.

But this morning, the thruster didn't appear to be working - and it was confirmed the harpoons didn't fire.

This meant the lander may have had to rely solely on screws on its legs. 

The surface was much softer than they expected, so there were some concerns that Philae was not securely fixed on the comet – although from a software point of view things seemed to be fine.

Engineers may attempt to fire the anchors again soon in order to keep Philae attached to the surface of the comet.

'It's complicated to land on a comet, and complicated to understand what has happened during this landing,' said Dr Stefan Ulamec, Philae Lander Manager. 

'The good news is we touched down, we had a clear signal and recieved data.

'The not so good news is that the anchoring harpoons did not fire. We looked into the data, and we don't fully understand what has happened.

We had fluctuations in the radio link, but it always came back again.

'Some of the details indicate the lander may have lifted off again, it is bouncing. 

'Two hours later, this stopped. We may have landed not once, but twice.'

 

This morning it was revealed that the cold thruster - a nitrogen thruster - on top of the Philae lander was not working properly. This meant the Philae lander relied solely on its screws and harpoons (illustration shown) to ensure it did not bounce off the surface of the comet

Google Doodle Celebrates Europe's Comet Landing

WHAT IS A COMET? 

Comets are remnants of the early solar system that remain in orbit around the sun.

Most are found in two specific regions of the solar system. The first region is the Kuiper belt, just beyond the orbit of Neptune, which is thought to contain about 200 million objects.

Much further out, extending to 50,000 times the distance from Earth to the sun, is a vast region known as the Oort Cloud where hundreds of millions of comets are present.

Comet are often called 'dirty snowballs' because they are made of ice and rock. At their core they have a solid nucleus.

But as they approach the sun, the ice on their surface melts and a 'coma' of gas forms around the comet.

They also have two main tails. The dust tail is made of small, solid particles that are pushed back from the sun.

The gas tail, meanwhile, forms behind the comet from the melted ice on its surface.

A third tail known as a sodium tail has been detected around some comets, but less is known of it.

WHY ARE COMETS IMPORTANT? 

Comets are of great interest to scientists because they are the oldest and most primitive bodies in the solar system that we know of.

They preserve the earliest record of material from the nebula from which our sun and planets formed.

While the planets in the solar system have gone through chemical transformations, comets have remained almost unchanged in the 4.5 billion year history of the solar system.

It is also thought that they brought certain elements to planets, including water.

They also carry complex organic molecules that may triggered life on Earth.

67P/CHURYUMOV-GERASIMENKO 

The comet is named after astronomers Klim Ivanovych Churyumov and Svetlana Ivanovna Gerasimenko who identified it in 1969.

It is believed to originate from the Kuiper Belt, a large reservoir of small icy bodies located just beyond Neptune. 

Scientists describe it as a 'Jupiter class' comet which takes 6.45 years to complete one full circuit of the sun

The icy core, or nucleus, is about 2.4 miles (4km) across and the comet takes around 12.4 hours to rotate fully.

The comet has now been observed from Earth on seven approaches to the Sun: in 1969, 1976, 1982, 1989, 1996, 2002 and 2009.

Over an entire year, as it approaches the sun, Rosetta will orbit the comet, mapping its surface and studying changes in its activity.

As its ices evaporate, instruments on board the orbiter will study the dust and gas particles that surround the comet and trail behind it