U.S. astronaut Lisa Nowak, already accused of trying to kidnap a romantic rival, has been charged with attempted murder and now faces an additional US$10,000 bond for her release.

Police say U.S. Navy Capt. Lisa Nowak drove more than 1,000 kilometres from her Houston home to the Orlando International Airport to confront Colleen Shipman, a woman she believed was a rival for the affections of Navy Cmdr. William Oefelein.

She wore a diaper on the long journey so she wouldn't have to stop to urinate, and police say they found a steel mallet, knife, rubber tubing and garbage bags in her possession.

"The intent was there to do serious bodily injury or death," claimed Orlando Police Sgt. Barb Jones.

Orange County Circuit Judge Mike Murphy had earlier granted $15,500 bail for Nowak, 43, who was arrested Monday on charges including battery and attempted kidnapping.

But shortly before she was to be released, police charged her with attempted first-degree murder and bail was raised by US$10,000.

Nowak, a married flight engineer with three children, was initially charged with destruction of evidence, but the judge said he found no probable cause for that charge.

Chief astronaut Steve Lindsey, who flew with Nowak to the international space station last July aboard space shuttle Discovery, and fellow astronaut Chris Ferguson attended the hearing.

"Our primary concern is her health and well-being and that she get through this," Lindsey told reporters afterward.

Oefelein, Nowak's apparent love interest, was a pilot during space shuttle Discovery's trip to the space station last December.

But in a taped statement given to police, Nowak described her connection to Oefelein as "more than a working relationship but less than a romantic relationship."

The arrest affidavit says that when she found out that Shipman was flying to Orlando from Houston, Nowak decided to confront her.

Nowak raced from Houston to Orlando. And then, dressed in a dark wig, glasses and a trench coat, she boarded an airport bus that Shipman took to her car in an airport parking lot.

Shipman told police she noticed someone following her, hurried inside the car and locked the doors, according to the arrest affidavit.

Nowak tapped on the window, tried to open the car door and asked for a ride.

Shipman refused but rolled down the car window a few centimetres when Nowak started crying. Nowak then sprayed a chemical into Shipman's car that burned her eyes, the affidavit said.

Shipman drove away and called the police at about 3:50 a.m., the affidavit says.

Shipman told authorities she had been followed from the airport to a parking lot by a woman wearing a trench coat with a hood pulled over her head.

An officer who followed Nowak spotted her throw away a bag containing the wig and a BB gun, police said.

Inside Nowak's vehicle, which was parked at a nearby motel, authorities uncovered a pepper spray package, an unused BB-gun cartridge, latex gloves and emails between Shipman and Oefelein.

They also discovered directions to Shipman's house and receipts indicating Nowak paid only in cash during her trip from Houston, including for her hotel stay.

They also found Shipman's home address and handwritten directions to the address, the arrest affidavit said.

In her statement to police, Nowak said she did not intend to physically harm Shipman, but only wanted to scare Shipman into talking with her.

"If you were just going to talk to someone, I don't know that you would need a wig, a trench coat, an air cartridge BB gun and pepper spray,'' said Sgt. Barbara Jones, a spokeswoman for the Orlando Police Department.

"It's just really a very sad case. ... Now she ends up finding herself on the other side of the law with some very serious charges.''

Nowak could face a maximum of life in prison if convicted of attempted kidnapping.

According to NASA's official biography, Nowak is married with three children. During her 13-day mission on Discovery in July she operated the robotic arm during three spacewalks.

Oefelein is unmarried. He piloted Discovery in December as part of a separate mission that continued construction on the International Space Station. He has two children, according to a NASA biography.

The Orlando Sentinel described Shipman as a captain in the U.S. Air Force assigned to the 45th Launch Support Squadron at Patrick Air Force Base, near the Kennedy Space Center.

Nowak and Oefelein trained together but never flew together.

NASA spokesperson Doug Peterson told CTV Newsnet that Nowak's status with the astronaut corps will be "on hold" for a while -- "until we find out ... how this is all going to turn out. Those particular issues are being worked out now within NASA and the astronaut office," Peterson said in a phone interview from Johnson Space Station in Houston, Texas.

Peterson said his organization is "stunned" by the whole situation.

"We're perplexed by it and also deeply concerned about Lisa Nowak and everyone else involved in this situation," he said.

"It's just an amazing turn of events -- something we've never seen before."

With files from The Associated Press