All systems GO for Rosetta's touchdown! Esa gives the green light for humanity's first ever comet landing on 12 November
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To date, humanity has landed spacecraft on the moon, Venus, Mars, Saturn's moon, Titan and two asteroids - Eros and Itokawa.
But one month from today, a new celestial body will hopefully be added to that list: a comet, namely 67P/Churyumov-Gerasimenko.
Esa has today confirmed that the landing attempt of the Philae probe on 12 November will go ahead, and engineers will be holding their breath in the run up to the attempt in the hope it is successful.
Esa, headquartered in Paris, has confirmed Rosetta will attempt to land on a comet on 12 November. The daring descent its Philae probe (artist's impression shown) will take seven hours from separation. It will be exactly nine years to the day that a similar landing attempt on an asteroid by Japan's Hayabusa failed in 2005
Philae's landing site, currently known as Site J and located on the smaller of the comet's two 'lobes', was confirmed following a comprehensive readiness review.
Since the arrival on 6 August 2014, the mission has been conducting an unprecedented survey and scientific analysis of the comet, a remnant of the early phases of the Solar System's 4.6 billion-year history.
At the same time, Rosetta has been moving closer to the comet: starting at 62 miles (100km) on 6 August, it is now just 6.2 miles (10km) from the centre of the body.
This allowed a more detailed look at the primary and backup landing sites in order to complete a hazard assessment, including a detailed boulder census.
'Now that we know where we are definitely aiming for, we are an important step closer to carrying out this exciting - but high-risk - operation,' says Dr Fred Jansen, Esa's Rosetta mission manager.
'However, there are still a number of key milestones to complete before we can give the final Go for landing.'
The relatively smooth landing region, identified for the moment simply by the letter 'J', is located on the smaller of the duck-shaped comet's two lobes. An inset showing a close up of the landing site is also shown
A series of Go/No-Go decisions must be taken before separation, starting on 11 November with a confirmation from the flight dynamics team that Rosetta is on the right trajectory ahead of delivery of the lander.
Further Go/No-Go decisions will be made during the night of 11-12 November concerning readiness and uplink of commands, culminating in confirmation of the lander's readiness for separation.
A short manoeuvre must then take place around two hours before separation. This will set Rosetta on course to release Philae on the right trajectory to land on the comet.
The final critical Go/No-Go for separation occurs shortly after this manoeuvre.
After the release of Philae, Rosetta will manoeuvre up and away from the comet, before reorienting itself in order to establish communications with Philae.
'If any of the decisions result in a No-Go, then we will have to abort and revise the timeline accordingly for another attempt, making sure that Rosetta is in a safe position to try again,' says Dr Jansen.
Close-up of Philae's primary landing site J, which is located on the 'head' of Comet 67P/Churyumov–Gerasimenko. Site J offers the minimum risk to the lander in comparison to the other candidate sites, and is also scientifically interesting, with signs of activity nearby
The agency had been quick to select a landing site and prepare for the touch down since Rosetta arrived in orbit around the comet on 6 August 2014.
This is because they want to attempt the landing before the comet gets closer to the sun and becomes more active.
When this happens it is thought it will release more water vapour, which may be hazardous to the lander's health.
The landing itself even without this hazardous water vapour will be incredibly tense, as such an endeavour has never been successfully completed before.
The closest comparison is the attempting landing on an asteroid of a probe called Minerva attached to Japan's Hayabusa spacecraft on 12 November 2005.
However, in that instance the lander was released at too great a height - and it floated off into space instead of drifting towards the asteroid.
Mission operators for the Rosetta mission will be hoping such a fate does not befall the Philae lander.
Nonetheless, Rosetta will still be continuing to study the comet into the future regardless of the outcome of the landing attempt.
It will use its 11 scientific instruments to study the comet as it orbits the sun.
The agency had been quick to select a landing site and prepare for the touch down since Rosetta arrived in orbit around the comet on 6 August 2014. This is because they want to attempt the landing before the comet gets closer to the sun and becomes more active (jets of vapour shown shooting into space here)
The high-risk manoeuvre, if successful, will be the first time in history that a probe has been landed on a comet.
Scientists at mission control in Germany hope the spider-like probe will send back data that could answer questions on the origin of Earth's water and perhaps even life.
But they've warned that the landing should be seen as an 'exciting extra' on the Rosetta mission as the mission carries a 'high risk'.
Comet 67P/Churyumov-Gerasimenko is currently travelling through space some 297 million miles (478 million km) from Earth.
The relatively smooth landing region, identified for the moment simply by the letter 'J', is located on the smaller of the duck-shaped comet's two lobes.
A further back up site has been chosen on the larger of 67P's lobes, and is currently being marked by Esa with the letter 'C'.
'As we have seen from recent close-up images, the comet is a beautiful but dramatic world - it is scientifically exciting, but its shape makes it operationally challenging,' Dr Stephan Ulamec, Philae Lander Manager, said earlier this month.
'None of the candidate landing sites met all of the operational criteria at the 100 per cent level, but Site J is clearly the best solution.'
Rosetta took an incredible selfie of its 131ft (40 metre) solar wings gleaming against the darkness of space last week. In the background is the duck-shaped comet, Comet 67P/Churyumov-Gerasimenko, with its distinct 'head' and 'body' clearly visible
At Site J, the majority of slopes have an angle less than 30º, reducing the chances of Philae toppling over during touchdown.
Site J also appears to have relatively few boulders, and receives sufficient daily sunlight to recharge Philae and continue science operations on the surface beyond the initial battery-powered phase.
Site C was chosen as a backup because of more sunlight hours and fewer boulders.
But even the flat surface chosen contains potentially dangerous boulders and cracks.
These include a mysterious 'pyramid', in the words of Esa, named Cheops that was spotted on the surface of the comet earlier this week.
At around 82ft-tall (25 metres), the structure is one of the larger boulders seen on the comet and could help scientists better understand its history.
Boulder Cheops, taken by Rosetta's OSIRIS camera on 19 September , from a distance of 17.7 miles (28.5km)
The 'pyramid' stood out among a group of boulders on the lower side of 67P/C-G's larger lobe - an area that has reminded scientists of the famous pyramids at Giza near Cairo in Egypt
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