PORTLAND – A mystery ship that has been cloaked in secrecy since it docked in Portland Harbor three weeks ago may carry equipment used to observe an Air Force rocket on a top-secret mission, a newspaper reported Wednesday.

The rocket’s flight path would take it over the ocean on a trajectory parallel to the East Coast, the Portland Press Herald reported. The Air Force could launch the rocket from Cape Canaveral, Fla., as early as Friday.

The Sage has been tied up in Portland Harbor for about three weeks, and people on the waterfront have been speculating about the nature of its mission. Some believe it is here to track the space shuttle Discovery.

Anyone in the loop about the ship’s mission is keeping mum.

The ship’s captain is not talking, and neither are the Air Force, NASA or Lockheed Martin, a defense contractor that apparently leased the vessel.

Earlier this month, the Air Force postponed the launch of the Titan IVB rocket after the Canadian government expressed concern that 11-ton booster engines jettisoned from the main rocket could crash into the ocean near Newfoundland’s offshore oil platforms, Oil companies planned to evacuate 325 crewmen from the oil platforms.

The Titan rocket is carrying a satellite for the U.S. National Reconnaissance Organization. The Air Force has told the Canadians it will destroy the rocket if there is a problem.

Peter Brown, senior multimedia editor for VIA Satellite Magazine, has examined photos of the Sage, which is equipped with two large domes on its deck. He said it appears to have a large telemetry antenna that could gather a stream of data from the shuttle or the Titan rocket as it proceeds on a projected flight path up the East Coast.

In addition, it has equipment that could beam high-resolution, real-time video by satellite back to NASA or the Air Force, he said.

The Coast Guard Marine Safety Office has received numerous calls from people wondering about the Sage, which is tied up in a secure area at the Portland Ocean Terminal.

Todd Bagetis, a Coast Guard petty officer, said the Coast Guard knows the ship’s mission, but he would not describe what it is.

“I don’t want a lot of citizens to get all worried about nothing,” he said.

The Sage, registered in New Orleans, is about 180 feet long and is one of 530 vessels owned by Tidewater, an offshore marine-services provider. Stephen Dick, the company’s executive vice president, said he believes Lockheed Martin, a defense contractor, is leasing the vessel.