- NEW: Philae's operators satisfied that the probe completed its mission on the comet
- Philae's landing didn't go as planned, leaving it in the shade, ESA says
- It is supposed to run on solar power, but now there's not enough sunlight for that
- Philae's primary battery was running out and is expected to be dead
(CNN) -- After an improbable 10-year, 310-million-mile journey to become the first ever space vehicle to make a soft landing on a comet, the Philae probe may have ended its mission prematurely.
Its batteries have run down, said the European Space Agency.
"Philae has fallen into 'idle mode' for a potentially long silence. In this mode, all instruments and most systems on board are shut down," ESA said.
This might not change.
Philae was supposed to transmit data from Comet 67/P for nine months as it passed the sun, running on solar power, but it did not get its place in the sunlight that scientists had hoped for.
How Rosetta lands on the comet Bounce landing
The probe's landing didn't go as planned this week, after Philae detached from the Rosetta orbiter. It took two bounces away from its designated landing spot, and never fired its anchoring harpoon.
"The lander remains unanchored to the surface at an as yet undetermined orientation," ESA said.
Rosetta's lander Philae is on the surface of Comet 67P/Churyumov-Gerasimenko on Thursday, November 13, and sending back images. One of the lander's three feet can be seen in the foreground. While Philae is the first probe to land on a comet, Rosetta is the first to rendezvous with a comet and follow it around the sun. The information collected by Philae at one location on the surface will complement that collected by the Rosetta orbiter for the entire comet. 
Rosetta's lander Philae captured this image during its descent to the comet from a distance of 3 kilometers (1.8 miles) from the surface on Wednesday, November 12. 
Philae took this parting shot of its mother ship shortly after separation on November 12, as Philae headed for a landing on Comet 67P. The lander touched down on the comet seven hours after separating from the orbiter. 
Rosetta's OSIRIS camera captured this parting shot of the Philae lander after separation. 
This mosaic is made of four individual images taken 31.8 kilometers (about 20 miles) from the center of Comet 67P/Churyumov-Gerasimenko on November 4. 
Rosetta took this image of comet 67P/Churyumov-Gerasimenko on September 15. The box on the right shows where the lander will touch down. 
The spacecraft sent this image as it approached the comet on August 6. From a distance of 130 kilometers (nearly 81 miles), it reveals detail of the smooth region on the comet's "body" section. 
This image, captured August 7, shows the diversity of surface structures on the comet's nucleus. 
The comet's "head" can be seen in the left of the frame as it casts a shadow over the "body" in this image released August 6. 
This image of the comet was taken on August 1. 
Rosetta's mission started on March 2, 2004, when it was launched on a European Ariane 5 rocket from Kourou, French Guiana. 
Rosetta is named after the Rosetta Stone, the black basalt that provided the key to deciphering Egyptian hieroglyphs. Scientists think the mission will give them new clues about the origins of the solar system and life on Earth. The mission is spearheaded by the European Space Agency with key support from NASA. 
This photo shows Rosetta being tested before it was wrapped in insulating blankets and loaded on a rocket for launch. 
Rosetta has massive solar wings to power the spacecraft. They were unfurled and checked out at the European Space Agency's test facilities before being packed up for liftoff. 
After its closest approach to Earth in November 2007, Rosetta captured this image of the planet. 
Rosetta snapped this image of Earth in November 2009. The spacecraft was 393,328 miles from Earth. 
Rosetta passed asteroid Steins in September 2008, giving scientists amazing close-ups of the asteroid's huge crater. The asteroid is about 3 miles in diameter. 
Rosetta took this image of Mars as it looped through the solar system. 
This image was taken by an instrument on Rosetta's Philae lander just minutes before the spacecraft made its closest approach to Mars. Part of Rosetta and its solar arrays are visible. 
On July 10, 2010, Rosetta flew about 1,864 miles from asteroid Lutetia, which is 10 times larger than asteroid Steins. 
Look closely at the top of this picture. See that dot? That's Saturn. Rosetta snapped the picture of asteroid Lutetia and captured Saturn in the background. 
After taking pictures of Earth, Mars and asteroids, Rosetta was put into hibernation in May 2011 after it reached the outer part of the solar system. Mission managers woke it January 20, 2014. 
In November, Rosetta will become the first spacecraft to deploy a robot for a soft landing on a comet. It also will be the first probe to escort a comet into our inner solar system. This drawing shows how Rosetta will drop its robot lander, Philae, onto the comet. 
The robot lander will fire harpoons to anchor itself to the comet. Scientists expect the lander to send back data to Earth for at least a week and possibly for many months as the comet heads toward the sun. 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Rosetta: The comet chaser It ended up in a shady spot of Comet 67P/Churyumov-Gerasimenko, ESA said, likely without enough sunlight to keep functioning.
Originally, it was supposed to have seven hours of light per comet day -- which lasts just 12.4 hours. Now it is exposed only 1.5 hours a day. That's likely not enough to juice up Philae's rechargeable secondary battery, ESA said.
There is one last hope.
"Mission controllers sent commands to rotate the lander's main body, to which the solar panels are fixed," ESA says in on its blog. "This may have exposed more panel area to sunlight."
Despite its walleyed positioning, Philae transmitted data and black-and-white photos back to Earth and ESA scientists.
The pictures appear to indicate it landed in some sort of shadow, possibly the shadow of a cliff.
Opinion: The big lesson from comet landing
Lander stable on comet's surface Race to transmit data
How Philae space probe docked on comet Philae turned on its instruments, drilling for samples, and while there was still time, transferred data. Now, the lander has fallen silent. Its operators on Earth lost contact with it early Saturday.
Built by a European consortium, led by the German Aerospace Research Institute, the landing probe has nine experiments.
"The lander (was) racing against the clock to meet as many of the core science goals as possible before the primary battery (was) exhausted," ESA said.
Its operators are satisfied with the results, and praised Philae for completing its mission slated for the comet's surface, before it went into hibernation.
Opinion: How comet mission helps in search for alien life
The German space agency, which operates Philae for ESA, has taken a light-hearted approach to the battery's impending doom, putting out witty messages on a confirmed Twitter account in Philae's name.
"I'm feeling a bit tired, did you get all my data? I might take a nap," a post read.
"So much hard work.. getting tired... my battery voltage is approaching the limit soon now," another read.
So much hard work.. getting tired... my battery voltage is approaching the limit soon now http://ift.tt/1vemO0I
— Philae Lander (@Philae2014) November 14, 2014 It's possible that the conditions may change as the comet moves closer to the sun, making it possible to charge the secondary battery.
Then Philae could awaken from its deep slumber and send data and photo surprises back to Earth, ESA said.
Even with the lander out of commission, the Rosetta orbiter that carried the Philae lander will continue to transmit observations of the comet.
Elated scientists show off latest pics from historic comet mission
Rosetta team celebrates landing Ten year voyage
Rosetta took off from Earth 10 years ago, aboard an Ariane 5 rocket, and traveled 6.4 billion miles before rendezvousing with the comet in August.
The Philae lander separated from the orbiting Rosetta about 3:30 a.m. ET Wednesday and first landed on the comet seven hours later.
The lander weighs about 220 pounds and is the size of a domestic washing machine. The target comet is only 4 kilometers, or 2.5 miles, in diameter.
The spaceship is named after the Rosetta Stone, an inscribed piece of volcanic rock found in Egypt in 1799 that allowed scientists to decipher hieroglyphics and thus understand the ancient Egyptian culture, ESA said. The lander is named after an island in the Nile River where an obelisk was found that helped decipher the Rosetta Stone, ESA said.
Led by ESA with a consortium of partners including NASA, scientists on the Rosetta comet-chasing mission hoped to learn more about the composition of comets and how they interact with the solar wind: high energy particles blasted into space by the sun.
Opinion: Philae's comet landing is amazing
CNN's Ed Payne, Ashley Fantz, Fred Pleitgen and Dave Gilbert contributed to this report.
