Philae awake (cartoon). Image Credit: ESA

As you may have heard, the European Space Agency’s (ESA) stranded Philae lander has finally woken up after seven long months of hibernation. The probe, released from ESA’s Rosetta spacecraft, went silent three days after landing on the surface of comet 67P/Churyumov-Gerasimenko on Nov. 12, 2014. The new, long-awaited signals were received by the European Space Operations Centre in Darmstadt, Germany at 22:28 CEST (4:28 p.m. EST) on Saturday, June 13. The data packets have been analyzed by the teams at the Lander Control Center at the German Aerospace Center (DLR), and the scientists can confirm that the lander has successfully phoned home, reporting its current status.

Issues arose months ago because the lander settled in a spot that didn't receive much sunlight, which made it difficult to recharge with solar energy, and also plunged the tiny craft into a deep cold. However, things have been heating up as the comet continues its orbit. "Philae is doing very well: It has an operating temperature of -35ºC and has 24 Watts available," said Stephan Ulamec, DLR Philae Project Manager. "The lander is ready for operations."

Fortunately, it seems that the lander's solar panels are now receiving power for over 135 minutes during each illumination period, which is twice what it was receiving in November. Sadly, that's not enough power to make drilling into the comet a viable option.

“We are still examining the housekeeping information at the Lander Control Centre in the DLR German Aerospace Center’s establishment in Cologne, but we can already tell that all lander subsystems are working nominally, with no apparent degradation after more than half a year hiding out on the comet’s frozen surface,” Ulamec continues.

Finding Philae:


Philae’s waking up ends a long-lasting ESA campaign to find the wayward probe and determine its current position. For months the scientists has been studying high-resolution imagery of the comet’s terrain, provided by Rosetta spacecraft, to locate the lander. More recently the Philae team released pictures on which probably the probe is seen as a bright spot, resting on a frigid terrain of the comet.

Is the bright spot really the Philae lander? ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

“Although the pre- and post-landing images were taken at different spatial resolutions, local topographic details match well, except for one bright spot present on post-landing images, which we suggest is a good candidate for the lander,” said Philippe Lamy this week, member of the OSIRIS team. “This bright spot is visible on two different images taken in December 2014, clearly indicating that it is a real feature on the surface of the comet, not a detector artifact or moving foreground dust speck.”

The Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS), onboard the Rosetta orbiter, is a dual camera, imaging system operating in the visible, near infrared and near ultraviolet wavelength ranges. OSIRIS consists of two independent camera systems sharing common electronics. The narrow angle camera is designed to produce high spatial resolution images of the nucleus of the target comet. It is constantly searching for the signs of Philae lander.

But the scientists are not absolutely sure that this bright spot is really Philae. Rosetta’s closer flybys will be needed to provide higher-resolution imaging. However, due to the recent high cometary activity, when jets of gas and dust could be hazardous for the spacecraft’s navigation systems.

Philae, as seen by Rosetta’s OSIRIS narrow-angle camera nearly two hours after separation. The image shows details of the lander structure, including its three relatively bright legs. Image Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Now, with the data being received after the lander’s waking up, Philae’s current location will be much easier to pin down.

What's Next for Philae?

And ultimately, this is one of the most important next steps—figuring out how to improve Rosetta’s orbit to cement contact with the lander so that we can conduct advanced science investigations.  Rosetta it set to adopt a new orbit from June 16 to 19. This location is 12 miles (20 km) closer to the comet, bringing the spacecraft down to a distance of about 110 mi (180 km) from the surface. Moreover, Rosetta will be turned so that it will continuously have its communication device turned towards the comet, making contact more likely; however, there is an issue with, rising temperatures. As the comet gets closer to the sun, it has started to heat up and give off jets of vapor and dust, which are dangerous for Rosetta's systems.

However, the increased heat might mean good things for Philae. “We know now that we can get in touch with Philae,” the ESA’s director general, Jean-Jacques Dordain, stated during a press conference. “It will be getting warmer and warmer on the surface of the comet because, until the 13th of August, the comet will get closer and closer to the sun, so we should have more and more opportunities to get in touch with Philae.”

If all goes well, Rosetta may may get its next communications signal from the lander on Friday, and science experiments could commence in less than a week.

For now, we play the waiting game.


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