Booster rockets in those days were still relatively weak, so Rosen’s satellite had to be lightweight. It had to be able to move itself out of the elliptical launch orbit and establish a circular orbit above the equator. There, it would have to remain stable, stay on station, resist the forces of gravity exerted by Earth, the sun, and the moon, and continue facing its ground antenna—all while traveling at a precise 6,878 miles per hour to remain in sync with Earth’s rotation.
Rosen’s plan was to design lighter-weight communications gear and to stabilize the satellite with spin, like a thrown football. The technique had been used to stabilize early booster rockets but to employ it on a satellite still required a leap of faith. A spinning satellite could aim no more than a third of its solar cells toward the sun at one time, and the omnidirectional antennas would broadcast signals indiscriminately in all directions, wasting a lot of the power the satellite collected.
So the team devised an antenna that broadcast a wide, flattened signal rather than a spherical, omnidirectional one, to better focus radio waves. And because transistors didn’t exist that could amplify a signal to cover such vast distances at the necessary frequencies, the team employed a type of vacuum tube called a traveling wave tube, which used high-voltage electrons to increase the power of electronic signal waves. Pierce had worked on the tube, but now Mendel designed a lighter, more efficient version.
Once the electronics were sorted out, the satellite still had to be shot into an elliptical orbit and then somehow moved precisely into a circular path around the equator. Then it had to be stopped, turned to orient its antenna toward Earth, set to spinning again, and kept there. To steer the satellite, Don Williams designed an ingenious two-thruster pulse rocket system, controlled from the ground, that would move it around in space with spurts of compressed nitrogen at just the right points in the satellite’s spin cycle—Rosen’s idea.
Rosen had imagined a 20-pound, 17-inch cube. He ended up with a 25-pound cylinder, 30 inches in diameter and 15 inches tall. Meanwhile, Hughes often withheld funds and support. Pierce thought the concept was impractical. Years later, Rosen says, Pierce apologized. By the time John Rubel, the Defense Department’s research and development chief, visited in the spring of 1961, Rosen had the satellite’s control mechanism working and had transmitted television signals in the lab using its communications equipment. Rubel liked what he saw.
