question:  What is the purpose of “touching helmets”?
context: Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] The glowing semi-disk of Jupiter was more than half a million miles distant. "Try not to be simple—for once!" growled Jeffers. "You know I took this piloting job just to scrape up money for an advanced engineering degree back on Earth. "You can ease out whenever your contract's up. Five hundred credits a week base pay, five hundred for hazardous duty. His contract guaranteed a pilot's rating, but someone had neglected to specify the type of craft to be piloted. On the bulletin board, Tolliver's name stood out beside the number of one of the airtight tractors used between the dome city and the spaceport, or for hauling cross-country to one of the mining domes. He soon found that there was nothing for him to do but hang around the garage in case a spaceship should land. Sometimes there's no reason but them for sending a ship back with a crew instead of in an economy orbit. Under a portable, double-chambered plastic dome blown up outside the ship's airlock, a crewman helped him load two trunks and a collection of bags into the tractor. Trying already to be just one of the gang, instead of Lady Betty! They found they could send back loaded ships by 'automatic' flight—that is, a long, slow, economical orbit and automatic signalling equipment. Then they're boarded approaching Earth's orbit and landed by pilots who don't have to waste their time making the entire trip." "Square dances with champagne?" "Don't be silly. When the rock and ice are set to sliding, they come at you practically horizontally. He enlarged upon other dangers to be encountered on the satellite, taking care to impress the newcomer with the daredeviltry of John Tolliver, driver of "missions" across the menacing wastes between dome and port. It did not, naturally, indicate he was drawing the salary of a space pilot.
output:  To communicate without using the radio.
options:  To communicate without using the radio.  To share oxygen.  To maintain the vacuum seal of the suits.  To keep the dust out.