HUNTSVILLE, Alabama — NASA has demolished a 239-foot-tall structure that engineers once used to test rocket engines that sent astronauts to the moon, toppling it with explosives on Friday despite reservations from state history officials who wanted it preserved.

Contractors working for the National Aeronautics and Space Administration took down the remaining concrete towers of Test Stand 4696 at Redstone Arsenal, home of NASA's Marshall Space Flight Center.

The tower was built in the early 1960s to test F-1 engines, which helped power Saturn V rockets to the moon. Documents show the tower hadn't been used for an F-1 test since February 1969, five months before astronauts first landed on the lunar surface.

NASA said it needed to demolish the concrete-and-steel tower to save on maintenance costs and make way for a new structure for testing rocket engines.

"It will be replaced with a more modern one," said Marshall spokeswoman Jennifer Stanfield.

But the decision was disappointing to Elizabeth Brown, preservation director for the Alabama Historical Commission.

While NASA did a "very good job" documenting the history of the tower in photos and words after the state objected to the demolition, Brown said, losing a structure of such technological importance still hurts.

"I would much rather this test stand stay where it is," Brown said.

Made of four concrete pillars and a steel superstructure, the stand was capable of holding an F-1 liquid fuel motor as it pushed upward with 1.5 million pounds of thrust. A massive shield at the bottom deflected the fiery rocket blast to the side.

A history of the tower compiled by NASA called it a "prominent artifact and icon of the Cold War and vestige of the United States' successful effort to outpace Soviet Union's space program." Documents show NASA considered the tower to be of "exceptional" historic significance in 2003 and eligible for inclusion on the National Register of Historical Places.

But the space agency wanted to demolish the structure within a few years, and state preservation officials objected to the plan in 2009.

Brown said the state eventually agreed to drop its objections after NASA documented the history of the structure, but she was still sorry to see it go.

"Here is a story from Alabama that everyone could be proud of. It's of national importance," she said.

Marshall has test stands of even greater historical significance, she said, including one that tested entire Saturn V rockets and another that fired engines for the first Mercury rockets.