"Let's go all the way around on the scooters. Those guys may have bungled the job of numbering the photos."
They began a slow circuit, making certain they glimpsed all the facets from a height of only ten feet.
"It's not here," Underwood agreed at last. "Let's talk to the crew that took the shots."
They headed towards the equipment platform, floating in free space, from which Mason, one of the Senior Physicists, was directing operations. Mason signaled for the radiations to be cut off as the men approached.
"Find any clues, Chief?" he asked Underwood. "We've done our best to fry this apple, but nothing happens."
"Something did happen. Did you see it?" Underwood extended the photograph with the mechanical fingers of the spacesuit. Mason held it in a light and stared at it. "We didn't see a thing like that. And we couldn't have missed it." He turned to the members of the crew. "Anyone see this writing on the thing?"
They looked at the picture and shook their heads.
"What were you shooting on it at the time?"
Mason glanced at his records. "About a hundred and fifty angstroms."
"So there must be something that becomes visible only in a field of radiation of about that wave length," said Underwood. "Keep going and see if anything else turns up, or if this proves to be permanent after exposure to that frequency."