question:  How do Svan and his five fellow insurgents find out that the people of Earth no longer think of
  
  Venusians as human?
context: DOUBLECROSS by JAMES Mac CREIGH Revolt was brewing on Venus, led by the descendant of the first Earthmen to land. [Transcriber's Note: This etext was produced from Planet Stories Winter 1944. The Executive Officer was moodily smoking a cigarette in the open lock, staring out over the dank Venusian terrain at the native town. "Everything shipshape, I take it!" But after all, they're human beings, just like us—" "Not any more. Four or five generations ago they were. "They had to acclimate themselves to Venus's climate. He stared at the wooden shacks that were the outskirts of the native city, dimly visible through the ever-present Venusian mist. The native guard of honor, posted a hundred yards from the Earth-ship, stood stolidly at attention with their old-fashioned proton-rifles slung over their backs. A few natives were gazing wonderingly at the great ship, but made no move to pass the line of guards. They think there will be hordes of immigrants from Earth, now that we know Venus is habitable. And there's some sort of a paltry underground group that is spreading the word that the immigrants will drive the native Venusians—the descendants of the first expedition, that is—right down into the mud. That's a basic law of—" The annunciator over the open lock clanged vigorously, and a metallic voice rasped: "Officer of the Deck! "From their own mouths you have heard it. "Then we must act. We have agreed that, if the Earth-ship returns, it means disaster for Venus. Therefore, it must not return." "The Council did not know what we would face. The Councilmen could not come to the city and see what strength the Earth-ship has." It will be set by means of this dial—" he touched a spot on the surface of the globe with a pallid finger—"to do nothing for forty hours. There will be danger, I think...."
output:  They use a spy ray, which allows hem to listen in on a conversation happening on an official
options:  They are informed by fellow Venusian rebels, who themselves heard from the council.  They already know. Racism and prejudice runs rampant in all Venusian and Earth towns.  They intercept a galactic transmission, which explains it all.  They use a spy ray, which allows hem to listen in on a conversation happening on an official