60 years ago today: Mercury rising

            We’re at the Cape, December 19, 1960, for the first of the real Mercury missions.  In an unmanned test, a Redstone rocket is set to propel a fully functional Mercury capsule (production capsule #2) on a suborbital trajectory, an arc to an altitude of 130 miles before streaking to a splashdown in the Atlantic — all in just 15 minutes.  

            It’s same ride one of us will soon make in the diminutive Mercury, which stands about 9 ft. tall and 6 ft. in diameter at its blunt base and weighs about one ton.  The bell-shaped capsule, built by McDonnell Aircraft in St. Louis, sits on a pencil-thin Redstone.  The rocket alone stands 58-ft. tall and it’s single A-7 engines provides a thrust of 78,000 lbs.  That’s enough to toss the Mercury on its short suborbital arc — just long enough to give a five-minute taste of space and test all systems.    

            The rocket/spacecraft combination stands 83 ft. tall.  That includes the red, 15-ft.-tall escape tower above the capsule, a solid-fueled rocket that can produce a swift kick of 50,000 lbs. of thrust to lift the capsule away in an emergency.

            The count proceeds smoothly . . . 

            Until the dreaded call: We have a hold.  We are holding, due to unacceptable high level winds. The pressure increases on the launch team because . . .

            We’re here, but not for the first time.  Mercury Redstone one (MR-1) counted toward launch on November 7, the day before the presidential election.   Just 22 minutes before launch, the launch team detected a leak in the helium system used to pressurize the capsule’s thrusters.  The capsule had to be taken from the pad, the heat shield removed and the helium system repaired.

            So now we wait. After 40 minutes, the winds fall into limits.  We resume the count . . .

            We are ready in the new Mercury Control Center at the Cape to be used for the first time.  The added pressure we’re feeling comes not from that November 7 attempt but what happened next.  The bird was ready for flight again on November 21.  That day, a perfect countdown drained toward a 9 a.m. launch.

            The final seconds — everything was go.  Three . . . Two . . . One

            Fire!

            Smoke boils from the base of the Redstone, it’s single engine building up thrust.  The rocket lifts with a mighty roar.

            For an instant.

            For maybe four inches.

            The engine shuts down, the roar squelched.

            The Redstone settles back on it’s four fins onto the ring-like launch pedestal.  Sways a bit, and . . .

            With a flash and fury and rush, something shoots sheets of smoke down the sides of the rocket and soars away in a blink.  What? — it’s the solid-rocket escape tower. It’s flown off — leaving the capsule behind solidly clamped to the rocket.

            Crazy!

            Yet the crazy has just begun. Three seconds after the escape tower flashes away, the small antenna can at the top of the capsule pops off, pulling out the small drogue parachute, 6-ft. in diameter.  Which is followed by the main parachute, 63 ft. in diameter, and then the reserve chute, like a magician pulling scarves from his sleeve.

            The damn capsule is acting like it’s returning from space.  It deploys radar tracking chaff, like a shower of strips of tinfoil, a packet of dye marker that is suppose to mark its position in the water, and a sonar bomb.

            All the while, a slight breeze is tugging at the parachutes draped down the side of the rocket.

            The rocket — fully fueled and armed.  The parachutes could be dragged over and explode.

            For a moment, everyone in Mercury Control is stunned into silence.

            What to do?   It’s a “hang fire” situation. There’s no way to disarm the thing, drain the fuel.

            Jesus, voices come on the loop, from the blockhouse near the pad where the Redstone team is located. All sorts of crazy ideas — even a suggestion that someone use a rifle to shoot holes in the Redstone’s tanks to drain the fuel.

            A resounding NO comes from Mercury Control.  If you don’t have a clear plan, it’s best to do nothing.   Think it through.  When pressure builds in the liquid oxygen tank, relief valves will open.  The wind is calm — the parachutes won’t tip the stack over.  The self destruct system is armed, as are all the pyrotechnics.  Wait until the next morning when the vehicle’s batteries run down and it is safe.

            And that’s what we did. But nothing will ease the public humiliation of that rocket sitting there shedding parts impotently.

            And that’s why we have to get this third attempt right today.

            The problem was traced to two plug-like connections at the base of the rocket, where a tail umbilical is supposed to pull out when the Redstone is an inch off the pad.  The two connections are supposed to pull out in a precisely time sequence milliseconds apart.  This did not happen at the correct interval.  The rocket’s electronics lost grounding early, causing an abort shutdown and also sending a stray signal through a relay to the spacecraft’s automatic programmer indicating a normal shutdown.   Thus, the programmer jettisoned the escape tower as if in normal flight.  Then the programmer received a signal from the capsule’s pressure sensors that the capsule is in the lower atmosphere — so initiated the normal landing sequence.  

            An erroneous gap in the timing of the two disconnects occurred because the Redstone for the Mercury is heavier than the military model, its fuel tanks lengthened by 6 ft. to add 20 sec. of burn time.  Therefore lifts off slower, throwing off the timing.   And that’s how the whole mess happened.  

            The problem was easy to fix by adjusting the umbilical length.   In addition, a long grounding strap has been added to the base of the booster.  As an added safeguard, the event electronics are changed so that a “normal shutdown” signal cannot be sent until at least 130 seconds into the Redstone’s planned 140-second engine burn.

            . . . And with that, less than a month after the four-inch fiasco, we’re back here, still red-faced but counting down.  In just four weeks, the MR-1 booster, which suffered minor tail damage, was replaced with the Redstone that had been designated for MR-3, the first manned flight. The same capsule, #2, refurbished with a new escape tower, sits atop the stack, and carries a new mission designation, MR-1A.

            The count ticks away, only seconds away from launch.   And then . . .

            A hold.  We have another hold.  It’s the capsule’s hydrogen peroxide thruster system again. A valve must be replaced — but by good luck, it can be done quickly, on the pad.

            Yet what else could go wrong?  An hour passes . . .

            And we’re go. We’re counting.  We’re in the final seconds.  

            Zero.  Fire!   Smoke billows, and this time . . .   Out of the smoke, the Mercury Redstone rises for the first time in history.  Straight and true — she’s looking good.  

            The Redstone’s single engine shuts down at an altitude of 35 miles, out of fuel after 143 seconds, velocity 4,909 mph, somewhat higher than planned, .  The capsule’s posigrade rockets fire, separating the capsule from the rocket.  Perfect — on the dot the capsule’s automatic control system turns the capsule around, blunt end forward, call retro attitude.  It soars to a height of 130 miles.  Three retrorockets in the pack strapped to the heat shield fire — a test of the system needed in orbital flights.  Again, everything works.

            And after five minutes of weightlessness, down she comes, due to the overthrust, pulling 12.4 Gs, more than the planned 11 Gs, a level which would be near an astronaut’s limits.  The parachute and recovery systems — which you could say were proven out in the November 21 fiasco! — work perfectly.   Splashdown, at a range from launch of 234 miles, 18 miles further than planned, after a flight of 15 minutes and 45 seconds.

            Despite the slight overshoot, the mission has proven the Mercury/Redstone system, just 18 months after the program was formally initiated.  NASA officials proclaim the flight an “unqualified success.”

            One more Mercury Redstone flight is required — carrying a chimpanzee — before an astronaut will ride the rocket — and, we hope become the first man in space.

            For the moment, no one is thinking too much about that slight over-thrust by the Redstone.

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