The medical specialist who awaited Columbia’s astronauts in Florida said there was no way they could have ejected from the craft as it dived at supersonic speed.

“I can only imagine that death would have been rapid. I certainly hope so,” said Dr. Kim Prisk, a pulmonary physiologist from the University of California, San Diego, who is working with an international team studying the dynamic effects of space travel on the human body.

Prisk said the heat and pressure in the craft were so extraordinary that consciousness would have been impossible as the burning vehicle streaked across the morning Texas sky.

“When the vehicle broke up it was traveling at about Mach 6. You can’t do anything at Mach 6,” Prisk said. “The reason it was visible on television was because it was traveling in a fireball. At that point it was in a ferocious cloud of ionized gas.”

Prisk and his medical colleagues were awaiting the crew’s arrival at the Kennedy Space Center in Cape Canaveral Saturday to continue an intricate cardiovascular and cardiopulmonary research project.

Latest information from CNNStories: ‘Columbia is lost’ Astronauts accepted risks of duty Americans stunned by shuttle disaster Mission Control calls go unanswered by shuttle Shuttle’s age wasn’t a factor, experts say Escape from craft was impossible, specialist says Future of shuttles comes into question Disaster revives town’s heartache Investigators focusing on tiles hit during liftoff Astronaut brought joy, tears to Israel Crews collecting scattered debris Flights had nearly lost mystique TV brought crash images into homes The world reactsPhotos: Photo galleryVideo: Columbia breaks apart over Texas (CNN)Links: Latest information from NASA NASA background information on the Columbia crew and its missionTexas media: Nacogdoches, Texas DailySentinel.com HoustonChronical.com DallasNews.comIsrael news: Jerusalem Post