If Columbia’s tiles or wing section were damaged on liftoff, that fear could have been allayed by in-flight robotic inspection. For years, NASA has been testing robotic devices for any number of tasks, including inspection and repair duties.

Columbia was without a Canadian-built robot arm. In the past, that arm has been used to bend its way to various parts of the vehicle for a TV look. However, even if the robot arm had been installed on the ill-fated space plane, its reach to view the entire suite of underside tiles, including those on wing bottoms, is restricted.

NASA officials have stated that it is far too risky to send an astronaut overboard to eye or repair damage in out-of-the-way locations on a space plane. In fact, a space walker could possibly create more damage to the sensitive tiles in attempting to survey or fix the heat-thwarting material, space agency engineers have stated.

Once system, the AERCam-SPRINT has already proven its robotic right stuff. It flew on STS-87 in 1997.

AERCam -- short for Autonomous Extra-vehicular Robotic Camera -- is a small, hand deployed and captured remote controled inspection tool. It carries its own avionics and nitrogen-gas propulsion. The surface of the ball-shaped robot is covered with cushions to prevent damage in case of collisions with other space hardware. It weighs a little less than 38 pounds (17 kilograms), and is outfitted with two cameras, position lights and a floodlight. The AERCam is designed to fly very slowly – just less than one-quarter of a foot per second.

During an STS-87 space walk, astronaut Winston Scott released the oversized soccer ball of a robot. It flew freely within the shuttle’s cargo bay for about one-half hour. Meanwhile, shuttle pilot Steve Lindsey from the space plane’s aft flight deck using a hand controller, two laptop computers and a window-mounted antenna remotely controlled the free-flyer.

David Akin, a leading space robotic expert at the University of Maryland in College Park, said AERCam "demonstrated that free-flying cameras can be easily controlled and provide wonderful external views of the space shuttle."

Although its flight was restricted to just above the cargo bay, Akin told SPACE.com , feasibility studies have been done by NASA to fly AERCam underneath the vehicle to image tiles.

"There are concerns about loss of signal…but it is possible to use orbital dynamics effects to put the vehicle in a ‘free orbit’ of the orbiter at a distance of a couple of hundred feet," Akin said.

"With some modifications to the orbiter communications systems, or better placement of dedicated antennas, it should be possible to do remotely-controlled close inspections of the tiles," Akin said.

AERCam could show other types of external damage too, Akin said.

In the future, a device like AERCam could be stowed inside a container in a space plane’s cargo bay. No need for spacewalking astronauts to deploy the robot. From inside the space plane, astronauts would pop out the robot, let it do its duties, then fly back the hardware to its container.

Can a robot do tile repair in orbit? Akin believes so, but a good dose of advanced research and development is needed.

"I believe it would be possible to have a robotic system that could actually repair tiles, using a spray-in-place ablative material," Akin said. What are needed are high-reliability manipulator controls, collision detection and avoidance, and a way for the robot to keep itself in position while working on the tiles.

"But we know enough about all those problems to begin working toward a feasible solution," Akin concluded.

NASA has investigated a mini-armada of robots, some more sophisticated than AERCam.

As example, a joint effort between NASA and the Defense Advanced Research Projects Agency (DARPA) has created Robonaut - designed to work side by side with spacewalking humans. The goal is to build a machine with dexterity that exceeds that of a suited astronaut.

Yet another robot being pursued is the Personal Satellite Assistant, or PSA. This tiny robot is under study for use inside the International Space Station, but shows the trend toward highly capable robots looking for missions.

PSA is equipped with cameras, sensors, speakers, microphones, a display panel, and a fan for propulsion. PSAs are looked upon as trusty servants for astronauts onboard the ISS and the space shuttle. Work on this softball-sized space pal has been underway at NASA's Ames Research Center at Moffett Field, California.

"There have been many other inspection and repair robots that have made it through various stages of design and prototype, said David Miller, a robot specialist and Professor at the School of Aerospace and Mechanical Engineering at the University of Oklahoma in Norman. But no robots, that he is aware of, are as close to flight at AERCam and Ranger – a vehicle developed at the University of Maryland.

"Of course it is not at all clear that the ability to inspect the tile system would have been able to change Columbia's fate," Miller told SPACE.com .