AKRON-The old saying about gravity isn't necessarily true. Not everything that goes up must come down. Consider, for example, the two Goodyear tires that traveled to the moon 25 years ago. They're still up there.
The National Aeronautics and Space Administration used two Goodyear XLTs (Experimental Lunar Tires) on a rickshaw cart Apollo 14 astronauts used to transport rock samples.
Goodyear would have loved to get the XLTs back, but NASA termed the pneumatic tires and the cart-called METS (modular equipment transporter system)-disposable, said Goodyear's John E. ``Jack'' Lynch and Stan M. Mezynski, who worked on the moon tire project.
``It would have cost a fortune to bring the cart back,'' Mr. Mezynski said. ``The postage was too much.''
Returning to Earth with the cart would have cost NASA precious time, as the astronauts would have had to dismantle and store the cart, Mr. Lynch said. Also, the cart would have increased the mission's fuel costs by ``an astronomical amount,'' he said.
``Weight is at a premium; every ounce counts,'' Mr. Lynch said. ``They already were bringing back a couple hundred pounds of rock samples. And every ounce added to the payload increases the risks during liftoff.''
Mr. Mezynski and Mr. Lynch spent more than 50 percent of their work time for nine months developing the moon tire. Nearly 100 other Goodyear employees also contributed to the project, including: more than 50 people in Akron developing, mixing and testing the compounds and end product; about five at the firm's New Bedford, Mass., plant making valves for inner tubes used in the moon tires; and another 35 making the tubes in Gadsden, Ala.
NASA and Goodyear began discussing the possibility of using tires on the moon in 1960. Some prototypes from these earlier days existed when Goodyear officially embarked on the moon tire project in November 1969. But these earlier prototypes were of little help, Mr. Mezynski said.
One 1960s prototype consisted of a wire-mesh wheel covered with a fabric coated with Neoprene rubber. The tire was 16 feet in outside diameter and 5 feet wide. Very little was known about the moon's surface in the early 1960s, and NASA wanted a tire that could move in up to 8 feet of surface dust, Mr. Lynch said. Moon surface dust later was found to be just a couple of inches, and NASA reduced the required tire size to a 16-inch outside diameter.
NASA makes much of its equipment in-house, Mr. Lynch said, but after several unsuccessful attempts to develop a moon tire, the government finally called in the tire makers in 1969.
``They had a state-of-the-art facility and it was `spare no expense,' but they couldn't make a tire,'' Mr. Lynch said. ``They didn't have the equipment, technology or materials. That's when they decided to ask the tire makers to participate. They needed us.''
At least three other tire makers bid to participate in the project, but Goodyear won, Mr. Lynch said.
Goodyear's moon tire development cycle wasn't far off some of its passenger tire concept-to-end-product times, but it was a little more frustrating, as NASA continuously changed its specification demands, Mr. Mezynski said.
``We went through a real learning process on this,'' Mr. Lynch said.
First, NASA told Goodyear it needed an all-white tire to reflect the heat-estimated at up to 250 degrees Fahrenheit depending on the time of day and the tire's angle to the sun. Then NASA officials decided they needed an all-black tire to withstand the shade, where temperatures dropped below -85 F.
After Goodyear had met all the specifications, NASA said carbon black couldn't be used to make the tire because the government planned to use a carbon dating process to determine the age of the moon. So Goodyear re-developed compounds for the tires, tubes, beads and valves, with silica replacing the carbon black.
NASA specifications also required that the inner tube be inflated to 1.5 psi on the moon surface-a difficult task. A tire with 1.5 psi on Earth has an inflation pressure of 16.2 psi on the moon because atmospheric pressure (14.7 psi) isn't a factor there.
Goodyear solved the gauge pressure problem by having NASA partially inflate the inner tube with nitrogen so that on the moon it reached 1.5 psi. The tire maker gave the synthetic rubber tube a special coating to improve gas retention.
Although at times frustrating, being part of a national defense project such as Apollo 14 had its fringe benefits, Mr. Mezynski said.
``The interesting thing is: We were allowed to violate any U.S. patent to develop the tire, but we weren't allowed to patent anything we developed,'' he said.
Goodyear's participation in the moon tire project sends a message to customers about the firm's willingness and technical capability to meet stringent specifications, Mr. Lynch said.
Goodyear also is able to tell rubber industry execs it equipped the pull cart used by the world's first lunar golfer, Mr. Lynch said. On Apollo 14, astronaut Alan B. Shepard Jr. pulled out a specially adapted No. 6 golf club head, placed it on the end of one of the excavating tools and hit three golf balls.
NASA hasn't used carts or land rovers on its missions since 1973, but Mr. Lynch is optimistic the government will call upon the tire makers again.
``One of these days we'll do it again,'' Mr. Lynch said. ``It might be 50 years, but I expect they'll come back to the tire companies.''
When that happens, the tire's specifications won't be the only thing that changes. The bidding process likely will be different, Mr. Mezynski said.
``I don't know if they'll maintain their position that it has to be an American company that supplies the tires,'' Mr. Mezynski said. ``If so, we'd be OK there. We'd only have to beat out one small company-Cooper.''