SC ocean exploration company believes they found Amelia Earhart's aircraft. What to know.

The disappearance of Amelia Earhart, the first female to fly solo across the Atlantic Ocean in 1932, remains a mystery. What happened to her has unraveled many different theories over the years: Was she a government agent who met her untimely demise while spying on the Japanese? Could she have come in contact with extraterrestrial beings? Did her plane crash? And if so, where?

According to South Carolina-based marine robotics company Deep Sea Vision, the truth might be buried at the bottom of the Pacific Ocean floor. They believe they may have discovered Earhart's long-lost aircraft, adding another layer of mystique to the legend.

On Sunday, the Charleston company announced via social media they captured a sonar image of what "appears to be Earhart's Lockheed 10-E" aircraft, which Earhart disappeared with 86 years ago in 1937. Earhart's navigator Captain Fred Noonan, who was onboard, also disappeared.

Deep Sea Vision's 16-person crew "scanned more than 5,200 square miles of ocean floor" using the Kongsberg Discovery HUGIN 6000, "the most advanced unmanned underwater drone, before finding what could be the legendary American aviator's Lockheed 10-E Electra."

Deep Sea Vision's "Search for Amelia Earhart" mission

Tony Romeo, based in Charleston, is chief executive officer of Deep Sea Vision, a company that provides clients access to deep ocean Autonomous Underwater Vehicles and quality-controlled data. Services offered by the company include wreck-hunting and deep sea cable and pipe route surveys, as well as deep sea mineral, habitat and bathymetric seabed mapping.

Romeo, who is also a pilot and former U.S. Air Force intelligence officer, sold his commercial real-estate properties to raise the $11 million required to embark on the mission "Search for Amelia Earhart."

In September, he and his team began their expedition from Tarawa, Kiribati, a port near Howland Island in the central Pacific Ocean. Radio messages were received by Itasca, the U.S. Coast Guard vessel stationed near Howland Island to assist with Earhart's landing and refueling. The messages were used by Romeo's team to determine Earhart's route, and where her plane may have crashed.

Thirty days later, a discovery was made by the team's drone, which "captured a fuzzy sonar image of an object the size and shape of an airplane resting some 5,000 meters underwater within 100 miles of Howland Island." Unfortunately, the team found the image in the drone's data around 90 days into the trip. They were unable to turn back to investigate further but have made plans to launch another expedition later this year with a camera. In particular, the team will be searching for the plane tail's number: NR16020.

Romeo told the Charleston Post and Courier he is "optimistic" that the discovered objects are from Earhart's plane.

Who was Amelia Earhart?

The National Air and Space Museum listed five things you may not know about Earhart.

Here are some of the highlights:

Amelia Earhart was a record-setter. She was the first female American aviator to fly solo across the Atlantic and the first person to fly solo from Hawaii to the U.S. mainland. In 1930, Earhart became the first woman to fly an autogiro after only 15 minutes of instruction.

She went on to become the first woman vice president of the National Aeronautic Association. In her role, she pushed for the organization to establish separate female records apart from men, giving women an equal chance to compete for world titles.

In 1935, Earhart became a visiting professor at Purdue University. With her background as a former premed student, she served as a counselor for women and a lecturer in aeronautics.

Aviation aside, Earhart was an entrepreneur and fashion designer who created a line of functional women's clothing, using her sewing machine to make blouses, dresses, pants, suits, hats and luggage. To promote her work, she even modeled her designs for spreads.

A woman of many feats, Earhart's life would be tragically cut short at the age of 39 when she disappeared and was declared legally dead.

When did Amelia Earhart disappear?

On May 20, 1937, she set out to become the first woman to complete a circumnavigation flight around the globe, departing from Oakland, California on a Lockheed Electra aircraft alongside Noonan. The two would make 29 additional stops on their journey, with their last known refuel being in Lae, New Guinea on July 2 at 10 a.m. local time.

Earhart and Noonan were due on Howland's Island, which was about 2,500 miles away from Lae, 18 hours later. They never arrived.

Awaiting their arrival with fuel was Coast Guard cutter Itasca, who received intermittent voice messages from Earhart as her signal increased. According to the Smithsonian Institute’s analysis of government records, there was no two-way contact since neither Earhart nor Noonan knew Morse code. Earhart may have never heard the transmissions at all.

The Navy and Coast Guard searched about 250,000 square miles of ocean for Earhart and Noonan, which Time reported cost $250,000 a day. Eighteen months after the disappearance, Earhart and Noonan were declared dead by the Navy, who determined their plane had crashed into the Pacific after running out of fuel.

To see more photos from Deep Sea Vision's "Search for Amelia Earhart" mission, visit their website. Check back on their website for updates regarding their second expedition to confirm Earhart's plane tail number later this year.

USA Today contributed to this article

Nina Tran covers trending topics. Reach her via email at ntran@gannett.com

This article originally appeared on Greenville News: Was Amelia Earhart's plane found? SC's Deep Sea Vision may have