HOW TO GO WEIGHTLESS

In dozens of military and civilian laboratories across the U.S., researchers are working under pressure to perfect ways of keeping a human being alive and functioning efficiently when he soars into the void of space (TIME, May 26). None of their problems is as will-o'-the-wispy as weightlessness, the gravity-free state that will envelop man when he orbits around the earth or reaches for the moon and planets. Reason: in the earth's atmosphere and gravity belt, this unearthly state can be created only for a fraction of a minute at a time. To learn at firsthand how it is done and what it feels like, TIME's Medicine Editor Gilbert Cant went weightless in one of the Air Force's fast jet fighters. His account:

AT 500 knots the F-100F Super Sabre pulled out of its dive and rocketed upward. Up went the needle on the accelerometer or "g meter," which gauges the piling up of gravity forces. In a "g suit" hooked up to an automatic air-compressor system, I felt a giant's fist pressing into my belly, two pairs of giant hands around my thighs and calves, to retard the flow of blood to the feet and reduce the risk of blackout. Belatedly I remembered to try the "M1 maneuver"--tensing the abdominal muscles to reduce the blood drainage still more. The g-meter needle crept up past 2 to 3 and on to 4. My normal 145 lbs. now weighed 580: I felt compressed, depressed. Even the light rubber ball of the pneumatic release for my camera shutter, held in my hand, seemed unbearably heavy. With the eyeballs tugged downward, with eyelids feeling like rusty iron curtains, it was an intense effort to peek "up" to keep watching the meters.

As we approached the peak of our climb, the relentless 4-g pressure was lifted and suddenly we slipped through a man-made loophole in the law of gravity: we weighed nothing at all.

Stringless Yo-Yo. We were in a weird state whose most experienced explorer is Major Herbert Stallings Jr. of the School of Aviation Medicine at Randolph A.F.B. (Texas). He has racked up a total of about 38 weightless hours. But bad weather and reassignment of planes had ruled out Major Stallings as my guide. Instead, I became the guest of the Tactical Air Command at Langley A.F.B., just inside the Virginia capes. Assigned to the project was Lieut. Colonel Devol ("Rock") Brett, skipper of the 355th Fighter Squadron and son of World War II's Lieut. General George H. Brett, now retired. West Pointer Brett, 34, veteran jet pilot, had hit the zero-gravity state for a few seconds on countless occasions, especially at the beginning of an outside loop, but he had never before been asked to try for zero gravity and hold it as long as possible. So the mission developed into a new experience for both pilot and passenger.

A few minutes out of Langley, our Super Sabre whooshed over Virginia's Dismal Swamp to the cirrus-dappled air over North Carolina's Chowan River. This area was set aside for acrobatics, cleared of other aircraft. In the Super Sabre, Brett could have wafted into weightlessness by flying high and level, faster than sound, and pushing the plane's nose up into the Keplerian trajectory, in which centrifugal force exactly cancels the earth's gravitational pull. Despite his plane's vast speed reserve, he chose to work at lower altitudes, enter the parabola from a power dive (see diagram). Over "hot mikes" (both microphones always switched on, so that each of us could hear the other's breathing), he asked simply: "Ready?"

Like a Lead Balloon. Gripped in my hand as we went through the power dive and pullout was a 4-oz. lead sinker of the kind used by bottom fishermen. Though it cost only 7-c- at the base PX, it made a far more vivid indicator of the zero-gravity state than the electronic accelerometer in which the Air Force has invested millions. As my bottom, squeezed to insensible bloodlessness during the 4-g pullout, rose from the seat cushion, I felt the exhilaration of restored circulation (and noted the lasting aptness of the old barnstormer's motto: you fly by the seat of your pants). I "dropped" the sinker in front of my masked face. It stayed there, floating. The merest delicate touch sent it gliding, featherlike, right or left, up or down, forward or aft. I was as happy as I would have been with a stringless yoyo. This was one place where a lead balloon would make a hit.

It was over too soon. Pilot Brett had been too busy with his controls and indicators, and I had been too bemused by the otherworldliness of the phenomenon, to time our first excursion into weightlessness. Colonel Brett pulled up the nose again, regained altitude, and within a minute or so was asking: "Ready to try it again?" Down we dived and up into another pullout. Up went the g needle. I felt a crushing force, and then the ineffable relief of subgravity and the euphoria of zero gravity. This time it lasted longer. Again I toyed with the stringless yoyo, so delightedly that I did not notice when we began to slow down. By inertial force, the sinker glided forward from my upraised left hand. My grab for it was defeated by the shoulder harness. Over the hot mike I warned Brett: "There's a lead slug corning over your left shoulder." He looked up, saw the sinker gliding past his head in slow motion, bided his time and coolly upped the plane's nose. The movement dropped the sinker gently into his lap. As he passed it back, he also gave me a short piece of string, with an invitation to use it.

With different starting altitudes, angles of climb and speeds, we repeated the maneuver 18 times in little more than an hour's flying. The 4-g phase was miserable for me, unaccustomed to it, and I felt befuddled for a few seconds after each pullout. As we homed to Langley (going supersonic on the way), Brett told me that he had felt as clearheaded during weightlessness as in any other acrobatic flight, had never for an instant forgotten his oil-pressure gauge, which might easily have dipped dangerously low in these maneuvers. His clearheadedness showed that training can make a big difference.

2 Plus 2=What? Now that Pilot Brett had the feel of it, we tried some experiments. With the plane refueled, we headed back to the acrobatic area. Brett's usual rear-seat man, ist Lieut. Arthur Brattkus, had prepared a mental-alertness test for me during our coffee break. On the back pages of a scratch pad he had written three elementary problems in arithmetic. These represented a mild foretaste of what a space pilot might have to do in the weightless state. Would my gravity-free brain be clear enough to solve them?

In the first parabola of the second series, I flipped over the thigh pad to tackle the first problem: multiply 13 by .9. The reaction was surprising. Squinting over the oxygen mask, I could not be sure whether there was a decimal point in the multiplier or just a speck in the paper. Irrationally, I felt hostile to Brattkus for not having been more careful. Just as irrationally, the decision I had to make (was it a decimal point or wasn't it?) seemed momentously important. I got off this dilemma by doing the multiplication, writing the answers for both possibilities. The problem for the next parabola was equally simple: divide 4.5 into 22. Determined to take a short cut and do it in my head, I goofed, gave the wrong answer: 5. The third parabola's problem (adding five numbers up to four digits) was no trouble. It was all probably a matter of getting used to the conditions and the job.

In his 31st and last parabolic curve of the morning, Brett approached Veteran Stallings' record of 43 seconds: he maintained a state of negligible gravity for 40 seconds, of which I would testify that 27 seconds were true zero gravity. As closely as Brett and I could figure, we had floated virtually weightless for seven minutes and in true zero gravity for five. From our two-man, 2 1/2-hour survey, we could obviously not make even tentative assumptions about possibly grave long-term effects (over days, weeks or months) of weightlessness on the human circulatory and respiratory systems. But these suggestions emerged: a weightless man in space need not be witless if he has had time to recover from the probable dulling effect of massive g forces during blastoff; his reasoning powers should be unimpaired; he need be in little danger of injuring himself from muscular overshooting--neither of us overshot objects that we reached for, though we did our reaching gingerly.

As for the sensation, I felt buoyant to the point of exaltation. And not necessarily because of the novelty alone. To Stallings, after 38 hours, zero gravity is old hat, yet he still feels exhilarated by it, aptly calls it "like swimming without getting wet." Airman Brett got no such emotional lift, only a solid, 4-g satisfaction from a job well done. It depends on who you are.

This file is automatically generated by a robot program, so reader's discretion is required.