Agilkia
The place chosen, after two months of observation, was Agilkia. The choice was linked to safety criteria for the lander: it had to allow Philae to descend without suffering damage, carry out two phases of scientific measurements, one with the comet far from the Sun and another closer to perihelion. And it had to guarantee at least partial illumination from Philae’s solar panels during these two phases. The uncertainty about the exact landing point was 500 meters. The Lander would arrive very slowly, at a speed of 1 meter per second, taking a total of 6 hours and 59 minutes to perform the maneuver.
ESA/ROSETTA/MPS by the OSIRIS Team; MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
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What was Philae like?
Little Philae was a little robot equipped with 10 scientific instruments intended to study the comet’s nucleus, its surface and internal structure, its composition and its chemical and physical properties. Once landed, Philae was to collect data for three months. It would brake and correct its trajectory with a small propellant, the Active Descent System.. Once near the comet, it would fire two harpoons to lock onto the surface. At 15:34 pm on November 12, Philae landed at Agilkia just 112 meters from the predetermined point. Thus it became the first human artifact in history to touch the surface of a comet.
ESA/ROSETTA/MPS by the OSIRIS Team; MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
The landing
It was historic, although with certain setbacks: the Active Descent System did not work and Philae could only rely on the two anchor harpoons. But they didn’t work either. It fell to the surface, bounced and circled the comet for about two hours. After one or two bounces, at 17:31 pm, it fell into a niche in the rock called Abydos. For more than two days, 56 hours in total, it continued sending data. However, Abydos was almost in shadow and the solar panels could not recharge the batteries. Therefore, in the first minutes of November 15, Philae entered hibernation and contact with the lander was lost.
ESA/Rosetta/MPS by the OSIRIS Team; MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
The swan song
In June 2015, months after the iconic descent, the Sun once again illuminated the panels of the small lander for a while. Philae managed to send one last data packet about the status of its instruments to Rosetta. But after that delivery, the lander returned to silence. Thus ended the mission of the ill-fated small robot, one of the most exciting anecdotes of the interplanetary exploration of the Solar System.
ESA/Rosetta/MPS by the OSIRIS Team; MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
Article originally published in WIRED Italy. Adapted by Alondra Flores.
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