Science: Rocket from Balloon

Space flight enthusiasts talk confidently about trips to the moon, but so far no rocket, even an unmanned one, has climbed more than 0.25% of the distance—about 600 miles, unofficially credited to the Lockheed X17. The first vehicle to make a really big stride into space will probably be a cheap, unstreamlined, unglamorous, four-stage job assembled out of familiar rocket hardware by Aeronutronic Systems, Inc., a Ford Motor Co. subsidiary at Glendale, Calif. Its gimmick: it will start at 100,000 ft. from a balloon.

Battling Air. When rockets are fired from the earth’s surface, they cannot start fast. If they move too fast too soon, the dense, low-altitude air battles back ferociously, wasting the rocket’s fuel and heating the structure to the disaster point. But slow starting has disadvantages too. Rocket motors are less efficient at slow speed, and a slow-starting vehicle wastes energy because it has to carry the fuel it needs for later acceleration to high altitude against the earth’s gravitation.

Asked by the Air Force to design an extreme high-altitude research vehicle, Aeronutronic rocketeers concluded that if the vehicle could be lifted above the densest part of the stratosphere before it was fired, they could get the advantages of high-speed starting without the disadvantages of drag and heat. They got in touch with General Mills, Inc., which had developed enormous balloons of polyethylene film, asked if the company could design a balloon that could serve as a launching platform. General Mills could, and did.

Aeronutronic’s rocket, named Far Side, lacks the streamlined style of surface-starting rockets. Its first stage is a cluster of four Recruit solid-propellant rocket motors, made by Thiokol Chemical Corp. at Elkton, Md., each with 40,000 lbs. of thrust. Stage Two is a single Recruit. Stage Three is four clustered Arrow II rockets (thrust: 250 lbs. each). The last stage is a single Arrow II which pushes the payload—a tube containing 3.5 lbs. of instruments—to final speed. The whole assembly looks like a graceless bundle of pipes, weighs 1,900 lbs.

4,000 Miles Up. Hanging nose-up below its balloon, Far Side will be lifted nearly 19 miles above the earth, where the air has one-hundredth the density of sea-level air. A radio signal from the ground will set an igniting system in motion. The four Stage One Recruits will roar into life, concentrating their 160,000 lbs. of thrust on the small rocket and snapping it upward with 70 g. of acceleration. It will shoot through the filmy balloon as if it were not there. The first stage fuel will be burned in 1.5 sec., giving Far Side a speed of 3,500 m.p.h. Stage Two, igniting a few seconds after the separation of Stage One, will double the speed. Stage Three will raise it to 11,000 m.p.h., and finally Stage Four will fire. When it burns out at 75 miles above the earth, Far Side will be climbing at about 18,000 m.p.h., and it will not stop until it has climbed 4,000 miles. When it falls back, the friction of the atmosphere will burn Far Side like a meteor before it can reach the earth.

The Air Force has ordered six Far Sides (price: less than $1 million for the lot), and the first test will probably be made from a Pacific island next September. From the gawky Far Side, the Air Force hopes to get information on cosmic rays, the earth’s magnetic field and space temperature that will be sorely needed when the glossier and more expensive military rockets begin to navigate space.