Philae (spacecraft)
Philae (/ˈfaɪliː/ or /ˈfiːleɪ/) was a robotic European Space Agency lander that accompanied the Rosetta spacecraft until it separated to land on comet 67P/Churyumov–Gerasimenko, ten years and eight months after departing Earth. On 12 November 2014, Philae touched down on the comet, but it bounced when its anchoring harpoons failed to deploy and a thruster designed to hold the probe to the surface did not fire. After bouncing off the surface twice, Philae achieved the first-ever "soft" (nondestructive) landing on a comet nucleus, although the lander's final, uncontrolled touchdown left it in a non-optimal location and orientation.
Illustration of Philae | |||||||||||||||||||||||||||||
| Mission type | Comet lander | ||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Operator | European Space Agency / DLR | ||||||||||||||||||||||||||||
| COSPAR ID | 2004-006C | ||||||||||||||||||||||||||||
| Website | www | ||||||||||||||||||||||||||||
| Mission duration | Planned: 1–6 weeks Active: 12–14 November 2014 Hibernation: 15 November 2014 – 13 June 2015 | ||||||||||||||||||||||||||||
| Spacecraft properties | |||||||||||||||||||||||||||||
| Manufacturer | DLR / MPS / CNES / ASI | ||||||||||||||||||||||||||||
| Launch mass | 100 kg (220 lb) | ||||||||||||||||||||||||||||
| Payload mass | 21 kg (46 lb) | ||||||||||||||||||||||||||||
| Dimensions | 1 × 1 × 0.8 m (3.3 × 3.3 × 2.6 ft) | ||||||||||||||||||||||||||||
| Power | 32 watts at 3 AU | ||||||||||||||||||||||||||||
| Start of mission | |||||||||||||||||||||||||||||
| Launch date | 2 March 2004, 07:17 UTC | ||||||||||||||||||||||||||||
| Rocket | Ariane 5G+ V-158 | ||||||||||||||||||||||||||||
| Launch site | Kourou ELA-3 | ||||||||||||||||||||||||||||
| Contractor | Arianespace | ||||||||||||||||||||||||||||
| End of mission | |||||||||||||||||||||||||||||
| Last contact | 9 July 2015, 18:07 UTC | ||||||||||||||||||||||||||||
| 67P/Churyumov–Gerasimenko lander | |||||||||||||||||||||||||||||
| Landing date | 12 November 2014, 17:32 UTC | ||||||||||||||||||||||||||||
| Landing site | Abydos | ||||||||||||||||||||||||||||
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Despite the landing problems, the probe's instruments obtained the first images from a comet's surface. Several of the instruments on Philae made the first direct analysis of a comet, sending back data that would be analysed to determine the composition of the surface. In October 2020, scientific journal Nature published an article revealing what Philae had discovered while it was operational on the surface of 67P/Churyumov–Gerasimenko.
On 15 November 2014 Philae entered safe mode, or hibernation, after its batteries ran down due to reduced sunlight and an off-nominal spacecraft orientation at the crash site. Mission controllers hoped that additional sunlight on the solar panels might be sufficient to reboot the lander. Philae communicated sporadically with Rosetta from 13 June to 9 July 2015, but contact was then lost. The lander's location was known to within a few tens of metres but it could not be seen. Its location was finally identified in photographs taken by Rosetta on 2 September 2016 as the orbiter was sent on orbits closer to the comet. The now-silent Philae was lying on its side in a deep crack in the shadow of a cliff. Knowledge of its location would help in interpretation of the images it had sent. On 30 September 2016, the Rosetta spacecraft ended its mission by crashing in the comet's Ma'at region.
The lander is named after the Philae obelisk, which bears a bilingual inscription and was used along with the Rosetta Stone to decipher Egyptian hieroglyphs. Philae was monitored and operated from DLR's Lander Control Center in Cologne, Germany.