Under the dark, starry sky stretched the forbidding deserts of Erebus, dim wastes whose every grain of sand throbbed with a faint blue radiance that gathered in drifting azure haze. The shining blue mists swirled and pulsated slowly, wrapping the whole dusky landscape before them, veiling the mountains westward.
They knew that when they stepped out on that blowing waste, into those shining mists, they would be stepping into a hell of radiation streaming ceaselessly from the radioactive mass of the planet — a torrent of alpha particles and of beta rays and of hard gamma radiation as withering as super X-rays.
Determinedly, John Thorn strode forward. The other two Planeteers followed. Their feet sinking slightly into the glowing sand, they trudged westward.
"They felt no change. But when Thorn tried to use his suit-audio, there came from it only a shattering roar. He linked hands with his comrades, speaking to them by conduction of sound.
"The radiation kills our audios completely,” he said. “It's what deadened all our instruments as we approached Erebus."
Sual Av nodded his black-helmeted head vigorously. “The gamma. radiation alone from this mass would do that."
"How in hell's name does this whole world come to be radioactive?” Gunner muttered. “If it was thrown off the sun in a tidal disturbance like the other planets, it should consist of the same kind of matter."
"I believe Erebus is the product of an older and deeper disturbance than that which produced the other planets,” Sual AV said keenly. “A disturbance so deep that it hurled out a mass of the heavier radioactive elements at the sun's heart, which formed a huge radioactive core for this world when it hardened."
"But there must have been some non-radioactive elements here originally, even so,” objected Gunner.
"Yes, but they would inevitably be made radioactive also by the radiation from the core,” Sual Av replied. “You know, the familiar phenomenon of induced radioactivity, which was discovered by the old Earth scientists way back in the first third of the twentieth century. The phenomenon by which a sheet of aluminum or some other normally non-radioactive element will become itself radioactive if subjected to radiation from radioactive elements."