"I suspect that religion is a necessary evil in the childhood of our particular species. And that's one of the interesting things about contact with other intelligences: we could see what role, if any, religion plays in their development."
- Arthur C. Clarke

From Niven's 1968 story A Gift from Earth:

Ramrobots had been first visitors to all the settled worlds.

The interstellar ramscoop robots, with an unrestricted fuel supply culled from interstellar hydrogen, could travel between stars at speeds approaching those of light. Long ago, the UN had sent ramrobots to nearby stars to search out habitable planets...

Interstellar ramscoop robot #143 left Juno at the end of a linear accelerator. Coasting toward insterstellar space, she looked like a huge metal insect, makeshift and hastily built. Yet, except for the contents of her cargo pod, she was identical to the last forty of her predecessors. Her nose was the ramscoop generator, a massive, heavily armored cylinder with a large orifice in the center. Along the sides were two big fusion motors, aimed ten degrees outward, mounted on oddly jointed metal structures like the folded legs of a praying mantis. The hull was small, containing only a computer and an insystem fuel tank.

Juno was invisible behind her when the fusion motors fired. Immediately the cable at her tail began to unroll. The cable was thirty miles long and was made of braided Sinclair molecule chain. Trailing at the end was a lead capsule as heavy as the ramrobot itself.