From the drug lord who pulled off an impossible escape to an extraterrestrial ocean containing clues to alien life, here are the baffling mysteries the world will try to solve this year.

WTF space junk: What was that debris?

A group of scientists in a plane caught sight of a mysterious piece of space junk right as it burned up in Earth's atmosphere above the Indian Ocean in November.

NASA and other space agencies around the world monitor a large percentage of the millions of bits of space debris that orbit the planet, and researchers had been expecting the object — appropriately named WT1190F — to re-enter Earth's atmosphere when it was first spotted in October.

But nearly two months later, they still aren’t sure what the object actually was. They do have some ideas. The leading theory is that it’s the second stage of a rocket — though they have no idea which rocket.

Wanted woman: Where is Hayat Boumeddiene?

A woman reported to be Hayat Boumeddiene brandishes a crossbow in this 2010 photograph.

Hayat Boumeddiene baffled investigators from the start.

The 26-year-old is suspected of helping plan the deadly attacks in Paris between Jan. 7 and 9 that targeted the offices of Charlie Hebdo, a kosher market and a police officer. She was the common-law wife of Amedy Coulibaly, one of the three attackers, but the level of her involvement remains unclear.

What we do know is that the three attackers were killed, and Boumeddiene escaped. Authorities believe she left Paris just before the attacks, traveled to Turkey and then crossed over into Syria. A month later, ISIS propaganda magazine Dabiq published an alleged interview with Boumeddiene, saying she is now with the group in Syria.

Today, Boumeddiene is one of the most wanted criminals on the planet.

8,000-year-old puzzle: What are these patterns in remote Kazakhstan?

Image: NASA/GSFC/Digital Globe

Some blame aliens. Others say Nazis were behind it. But the mysterious earthworks, known as the Steppe Geoglyphs, are thousands of years in the making.

Scattered throughout remote parts of Kazakhstan and only visible from high above, their patterns vary in shapes — from giant rings to swastikas.

Image: NASA/GSFC/Digital Globe

There are nearly 300 of these strange works, the oldest of which was constructed at least 8,000 years ago. And no one, including scores of scientists who have studied them, really knows why they’re there. The theory is that they came from an ancient settlement.

Dmitriy Dey, who first spotted them in 2007 on Google Earth — he was looking for ancient pyramids at the time — thinks they may have been built as “horizontal observatories to track the movements of the rising sun,” according to a New York Times interview in October.

The ancient relics are so puzzling that NASA is now working to unravel the mystery. From 430 miles above the Earth, the space agency captured some of the clearest images, which were released in late 2015.

The great escape: Where is El Chapo?

Update: Solved!

The tunnel El Chapo used to escape. Image: Jan-Albert Hootsen, Mashable

One minute Joaquín Guzmán was locked up in a Mexican prison, pacing the floor of his small cell. Then he was gone.

In July, Guzmán — the Sinaloa drug cartel's infamous leader known as "El Chapo" — pulled off an elaborate escape from the Altiplano maximum security prison with bravado. He slipped through a small hole drilled into in his shower cell and then sped away on a motorcycle through an underground tunnel. By the time he emerged in a safe house outside prison walls, guards hadn’t even started their search.

El Chapo (a modern-day Pablo Escobar for fans of Netflix's Narcos) has been on the run ever since. Some believe the Mexican government may be letting him live free to bring some sort of balance to the chaotic narco wars.

So where is Guzmán now? Nobody with the gall to recapture him knows. He's back in prison — and may be extradited to the U.S.

Ghost boats: Who is sending ships filled with corpses to Japan?

One of the mystery boats that has washed up in Wajima.

Mysterious "ghost boats" — wrecked wooden ships with decaying corpses on board — are washing up on the shores of Japan.

Nearly a dozen boats carrying decomposing bodies were found off the country's northwestern coast in just one month, the coast guard said in December. The first boat was found in October, and in November officials discovered 10 bodies in three boats at Ishikawa prefecture. Later, they found another boat with six skulls and a body that was nearly intact.

Several signs point to North Korea. Most of the boats carried equipment and signs written in Korean, and one was had a scrap of cloth resembling a torn bit of the North Korean flag. However, authorities have not been able to confirm their origin or why the people on board perished.

More than 30 boats were found in 2015. There were 65 the year before and 80 in 2013.

Alien ocean: Is there life on Saturn's moon?

Enceladus, one of Saturn's 62 moons, shines as a crescent above the planet's rings.

In October, NASA's Cassini spacecraft, which has been exploring Saturn since 2004, got closer than ever to an extraterrestrial ocean on Enceladus, one of the planet's 62 moons. During its daring dive into an icy plume erupting from the moon's south pole, Cassini sampled the spray to figure out what's lurking beneath the surface.

"Enceladus is not just an ocean world. It's a world that might provide a habitable environment for life as we know it," Cassini program scientist Curt Niebur said at the time.

But even if the ocean material is chock-full of little lifeforms, Cassini won't know it. The spacecraft wasn't built to actually detect life. Its instruments don't have the ability to parse out sure signs, like DNA, from the icy spray.

A Cassini view of Saturn's moon Enceladus on Oct. 14, 2015.

Instead, scientists are hoping to learn more about the pH balance and molecular composition of the water. NASA is still analyzing the data from that October flyby. In the best-case scenario, the spacecraft might be able to determine if the small moon's ocean could be habitable.

Cassini's mission will end when it runs out of fuel sometime in 2017. Until then, the probe will be making its final observations of many of Saturn's moons.

Catastrophic collapse: What killed 120,000 antelopes in just a few days?

Dead Saiga antelopes in Kazakhstan. Image: Sergei Khomenko/FAO

In a span of less than two weeks in May, there was a widespread die-off of critically endangered saiga antelope throughout central Kazakhstan. The United Nations reported that more than 120,000 of the animals — that's more than a third of the global population — died from mid-May through the end of the month.

It's the largest die-off event of the species ever recorded.

While scientists have not yet pinpointed the cause of the deaths, a preliminary analysis showed that a combination of environmental and biological factors were involved, as mainly mothers and calves were among the dead. Two pathogens — one known as Pasteurella and the other as Clostridia — contributed to the rapid and widespread die-off. However, this discovery fails to solve the mystery.

One possible suspect in the die-off event is rocket fuel from decades of launches from facilities in central Kazakhstan. Currently, Russia launches crewed and uncrewed missions to the International Space Station from the Baikonur Cosmodrome in Kazakhstan.

Still missing: What happened to MH370?

A tiny piece of the puzzle that is Malaysia Airlines Flight 370 washed up on Reunion island in the Indian Ocean in July. Investigators believe the piece of debris was a flaperon that came from the missing plane.

Image: EPA/RAYMOND WAE TION

Though we finally have a piece of tangible evidence, we still have no real answers as to what happened after MH370 took off from Kuala Lumpur in March 2014 and vanished into the night. The mere fact that a modern airliner could simply disappear has led to several conspiracy theories. Was it hijacked? Did it catch fire and crash? Did Putin orchestrate its capture?

Nearly two years have passed since the plane went missing and we’re no closer to cracking the case. Maybe 2016 will shine more light on one of the modern world’s biggest aviation mysteries.

DUSTWUN: Why did Bowe Bergdahl walk away?

Bergdahl went missing from his outpost in Afghanistan in June 2009. This photo is undated. Image: U.S. Army/Associated Press

Sgt. Bowe Bergdahl was captured by the Taliban in 2009 and held prisoner for five years, the longest any soldier has been kept as a POW since the Vietnam War. In 2014, the U.S. made a deal with the Taliban and Bergdahl was released in a prisoner swap.

But what should have been a joyous homecoming quickly turned dark after it was revealed that Bergdahl walked off his base in Afghanistan. He was labeled as a deserter, and he vanished from the public eye. America didn't see or hear from him for over a year.

Until this December.

The popular podcast Serial debuted its second season with a focus on Bergdahl’s disappearance. His side of the story is told through hours of conversations he's been having with filmmaker Mark Boal (of Zero Dark Thirty). The Army has since announced that Bergdahl will be court-martialed, meaning that the man who spent half a decade with the Taliban could spend even more time behind bars on American soil.

But the question remains: Is Bergdahl a deserter? A whistleblower? Or somewhere in between?

That final scene: Is Jon Snow dead?

That final Game of Thrones scene ended on a close-up shot of Jon Snow, lying face-up on the snowy ground, with hauntingly vacant eyes open.

We figured this was it. Jon Snow was dead…

… Well, maybe.

Kit Harrington, the actor who plays Jon Snow, was spotted on the set of Game of Thrones later in the year — man bun and all. Then HBO released a poster for the upcoming season, and it features a bloody Jon Snow.

This all leads us to believe that Jon Snow has a chance. Or maybe he’ll just return in flashbacks. Or as a ghost. Or as a White Walker.

The good thing about this mystery is we know 100% that it will be solved in 2016. Game of Thrones Season 6 premieres in April.

The fugitive: Where is Salah Abdeslam?

Among the attackers who took part in the Paris attacks on Nov. 13 that left 130 dead, just one made it out alive. Salah Abdeslam, 26, may have handled logistics for the group, and is now believed to have fled for Syria. While he escaped the French and Belgian dragnet, it's unclear if he ever made it into territory held by Islamic State militants.

Abdeslam, who is originally from Brussels, rented a car in Belgium and drove it to Paris to help carry out the attacks. But if he ever intended to be one of the killers, it appears he changed his mind at the last minute. An explosives-laden vest was later found in Paris, as well as the abandoned car. He fled the city in the early morning after the attack with help from friends. They passed through three checkpoints on their drive, but were never detained.

Despite several police raids in his old Brussels neighborhood of Molenbeek, authorities have yet to find Abdeslam. Though some have speculated he fled to Turkey or Syria, no solid information has surfaced.

Additional reporting by Miriam Kramer, Andrew Freedman and Victoria Ho.