KITTERY – The Navy’s only research submarine is coming to the Portsmouth Naval Shipyard where it will be inactivated after nearly 40 years in service.

Shipyard spokesman Gary Hildreth says NR-1, a 150-foot nuclear-powered exploration sub that was launched in 1969, will arrive at the Kittery shipyard sometime this month.

Over the years, the vessel has been used to search for artifacts and wrecks and to map the ocean floor. After the space shuttle Challenger explosion in 1986, the sub helped search for and recover parts of the Challenger spacecraft.

After the sub is inactivated at the Portsmouth Naval Shipyard, it will be transported to Puget Sound Naval Shipyard in Washington state.