HOUSTON (AP) ― Jon Thompson has traveled the world collecting art and artifacts for museum exhibits, seen the remains of the Titanic on the sea floor and participated in two unsuccessful missions to find Amelia Earhart.

Aged 72 and battling prostate cancer, Thompson is convinced he and a team from deep-sea exploration company Nauticos will finally be successful in finding the Kansas-born aviator’s plane, which disappeared with Earhart and navigator Fred Noonan in July 1937. He’s among the researches looking for Earhart as the 75th anniversary of her disappearance approaches, and competition between search parties is fierce.

“Admittedly, it’s a needle in a haystack, but with the technology we have employed and the brains we have involved, if we don’t find it, no one will,” Thompson said.

Theories about what happened to Earhart and Noonan are varied. They disappeared while flying from New Guinea to Howland Island as part of the adventurer’s attempt to become the first female pilot to circumnavigate the globe.

Last month, the International Group for Historic Aircraft, headed by longtime Earhart seeker Ric Gillespie, said a U.S. State Department analysis of an image off the remote island of Nikumaroro, in what is now the Pacific nation of Kiribati, looks like it could be aircraft landing gear. Gillespie’s team will return in July to renew their search.

A few months later, Thompson will be a sonar operator on a ship headed by David Jourdan, a deep-sea explorer who used high-tech equipment in 1999 to find the Israeli submarine, the Dakar, which went missing in 1968.

“It seems to be the greatest unsolved mystery of the last century,” Thompson said.

Thompson and Jourdan are among the many historians and researchers who believe Earhart’s plane crashed into the ocean, which they say explains why extensive searches shortly after the disappearance failed to uncover remains or debris.

Gillespie’s group believes Earhart and Noonan may have managed to land on a reef abutting the atoll, then known as Gardner Island, and survived for a short time. They surmise the plane was washed off the reef shortly after landing and that the wreckage may be in the deep waters nearby. That is what they will look for during their 10-day expedition in July.

Conspiracy theories that Earhart and Noonan were U.S. government agents captured by the Japanese before the World War II have been largely debunked.

Thompson and his group plan to spend two months searching an area up to 1550 square kilometers within 32 kilometers of Howland Island. It’s the final section of an area where research from three institutions suggests the plane could have crashed. Thompson’s two previous missions searched about 5,700 square kilometers nearby.

Before fall, Thompson will complete proton therapy treatment for prostate cancer at Houston’s MD Anderson Cancer Center. He will also work with students at the University of Texas’ Cockrell School of Engineering to analyze two theories about Earhart. One investigates how far the plane would glide before sinking based on ocean drifts and other aspects of crashing on water. The other looks at where the aircraft could have flipped and broken on impact if Earhart were too exhausted and weak to operate the machine.

Vishnu Jyothindran, a senior studying aerospace engineering who is leading the research, is excited by the uncertainty.

“In class, you expect you’ll get a question that you can solve with data in the textbook,” he said in a statement. “We don’t have that guarantee here and that’s unfortunate, but it’s also just reality.”

If artifacts are found, Thompson already knows what the exhibit would look like. The artifacts would travel on a three-story barge and dock at dozens of North American cities.