The Philae lander’s depleted batteries has forced the probe to go silent, and the Rosetta team acknowledged that may be the last they hear from Philae. But it has completed its primary mission of returning data from the surface of the comet it landed on, making the decade-long effort a success no matter what.

The Rosetta mission hasn’t been a perfect one, as despite the historic landing on a comet 300 million miles away a few days ago, the failure of some of Philae’s systems caused it to bounce off the surface and land in an area where its solar panels are exposed to much less light than planned, limiting what scientists can do with it. However, the European Space Agency has been able to complete the primary mission of exploring the comet’s surface, according to the Associated Press.

ESA landed the probe Wednesday on comet 67P/Churyumov-Gerasimenko after a 10-year journey from Earth. So far, the lander has performed a few tests and sent back reams of data, including photos of the comet’s rocky surface.

Operators also lifted the lander by about 4 centimeters and rotated it 35 degrees in hopes of better exposing the solar panels to the sun so its batteries could be recharged. Had it landed where it was supposed to, it would have received 6-7 hours of sunlight, as opposed to just an hour or so now.

ESA isn’t sure if the operation to maneuver Philae into a better position worked. Even if it did, it could be weeks or even months until the batteries recharge to a point that it can send out new signals, although scientists will regularly check for new signals.

The last signals from Philae were received at 7:36 p.m. EST on Friday, or early Saturday morning in ESA’s mission control center in Darmstadt, Germany.

The lander transmitted scientific data from some experiments on the surface, which is what the mission had planned on.

ESA mission chief Paola Ferri was quoted by the Associated Press as saying they don’t know if the lander will have a high enough charge for them to operate ever again, and that it is “highly unlikely” the team will reestablish communication anytime soon.

For now, ESA’s scientists will examine the data closely to find out if the experiments were actually a successful. Of great importance is a difficult operation that took place Friday when the lander attempted to drill a 10-inch hole in the comet to grab a sample of the material that makes up the comet. If successful, scientists would salivate over the opportunity to directly examine material beneath the surface of the comet, which has been virtually unchanged since the solar system began 4.5 billion years ago.

While ESA knows that the lander performed the necessary operations, the agency doesn’t know if it actually succeeded and whether the drill even touched the ground.

The science team still doesn’t know exactly where Philae landed. They are examining high-resolution images from the orbiter that launched the lander to try to spot it.

The goal of the $1.6 billion project is to provide insight on the origin of the universe, and perhaps life itself on Earth. Specifically, scientists suspect that comets contain the building blocks of wife, such as organic matter and water, and they brought them to Earth. Comets contain amino acids, which are key to the construction of cells. A breakthrough in understanding that better would mark a huge leap forward in human understand of the origins of life.