In a press conference held yesterday, ESA announced the choice of the primary site on the comet 67P/Churyumov-Gerasimenko where the lander Philae will land, according to the plans on November 11. Among the five sites that were selected as candidates, the one selected was indicated by the letter J and was voted unanimously. As a backup site the one that was indicated by the letter C was selected.

As it was immediately clear when the very irregular shape of the comet 67P/Churyumov-Gerasimenko was discovered, the choice wasn’t easy. None of the candidate sites fully satisfied the required criteria and the site J was considered the best solution after an analysis of the images obtained in recent weeks.

The J site offers a good lighting that will allow the lander Philae’s solar panels to be active for most of the time allowing to recharge the batteries. In that area, the slope generally don’t exceed 30°, reducing the danger for Philae to topple over before it can activate the harpoon that will fix it to the ground.

The sites indicated by the letters B and C were examined as backup sites. Eventually, the C site was preferred for its more light and less boulders. The sites A and I were discarded because during new examination didn’t meet several important criteria.

Now that the choice has been made, ESA begins planning the descent of the lander Philae. According to an initial assessment, it will take about seven hours, a duration that doesn’t compromise the observations using too much battery power during that operation. It will still need to be planned in detail.

The comet 67P/Churyumov-Gerasimenko is approaching the Sun so is becoming active with the sublimation of ice that gets heated and turned into steam. This may cause unpredictable movements of the comet changing the position of the Rosetta spacecraft, which is carrying the Philae lander.

The consequence is that the planning of the landing of Philae carries a risk margin. That’s something that has never been attempted before so each phase will be carefully considered but eventually it will have to be programmed and carried out automatically. The date is not yet certain and on September 26 it will be announced for good whether it will be November 11 or another one.

[ad name=”AmazonScience”]