The European Space Agency's (ESA) comet-chasing probe Rosetta needed a few extra minutes when waking up from its three-year hibernation.

According to New Scientist, Rosetta was 18 minutes late in sending its wakeup message to Earth because of an unidentified glitch. ESA officials said they are still investigating the glitch, but said it has not compromised the mission at all.

The internal alarm went off at 10:00 GMT, as scheduled, but ESA spacecraft operations manager Andrea Accomazzo told New Scientist the glitch was likely present while Rosetta was sleeping.

"We now know that there were a few hiccups during hibernation, but that doesn't affect anything we are doing now," she said.

A decade old this year, Rosetta was launched in 2004 with one ultimate goal in mind: be the first spacecraft to latch onto a comet. According to the Associated Press, Rosetta's systems were powered down in 2011 as it drifted through space to conserve energy. Now, it begins the final phase of its mission.

With a comet named 67P/Churyumov-Gerasimenko in sight, Rosetta would end up rewarding ESA's billion-dollar mission of learning virtually everything there is to know about comets with a successful landing.

Rosetta will spend the following months observing its target as well as running tests and practice maneuvers. Around summer, Rosetta will deploy its Philae lander toward the 2.5-mile-wide ball of ice and rock.

"Over the millennia, comets have actually affected our evolution," said Paolo Ferri, ESA head of mission operations. "There are many theories about comets hitting the Earth and causing global catastrophes. So understanding comets is also important to see in the future what could be done to defend the Earth from comets."

The earliest the wakeup signal could have reached Earth was 6:30 p.m. at ESA mission control in Germany and had a one-hour window. The signal came in sometime around 7:15 p.m.

"The spacecraft decided to make us suffer after two and half year," Ferri, told CNN. "We came almost to the end of the window, we were very tense."