A piece of the space shuttle Columbia, which broke apart and burned on re-entry more than eight years ago, has been found in a drought-stricken East Texas lake, NASA officials said Tuesday.

The spherical object, about 40 inches in diameter, was exposed by low levels at Lake Nacogdoches, about 140 miles northeast of Houston. NASA spokeswoman Lisa Malone said the object was one of 16 tanks that flew aboard Columbia.

The aluminum tank was part of the shuttle's electrical power distribution system. Now full of mud, the tank either held liquid hydrogen or liquid oxygen when it operated on Columbia.

Officials said they are working on a plan to recover the tank and bring it back to Kennedy Space Center in Florida, where other debris from Columbia's wreckage that's been previously found is stored.

"We are working out the details with local authorities," Malone said. "It's not toxic or hazardous in any way. We're not in a big rush to get it back over."

The shuttle broke apart and burned on Feb. 1, 2003, killing all seven astronauts aboard and scattering shuttle pieces across East Texas. The shuttle had been damaged at launch by foam insulation that fell off an external fuel tank.

Nacogdoches police Sgt. Greg Sowell said his department reported the then-mystery object to NASA on Friday after an officer who patrols the lake area saw it.

"It had been out of the water for some time," Sowell said. "It had been seen by local sportsmen. ... People didn't know what they were looking at."

The northern area of the lake where the tank was found is 9 to 10 feet below its normal levels because of the drought, he said.

Police are not guarding the tank because it is in a very remote area that is not accessible by vehicle or boat, Sowell said.

"We're reminding everyone that it's a federal offense to tamper with it," he said.

NASA does not plan to send a team to recover the tank but will let local authorities do that, Malone said.

About 40 percent of the shuttle has been recovered since the accident, she said.

"From time to time, several times a year, we get phone calls and e-mails and letters from citizens that say, 'We think we found a piece of the Columbia debris.' We analyze the pictures and talk to them. Some of the items do end up being actual debris pieces from Columbia," Malone said.