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The Launchbox, PoD 11: The Near Misses of Mercury

By Andy Cooke

When you’re pushing the limits of human knowledge – and doing so in a race, to boot – you’re going to be raking some risks.

Such was the situation with the Mercury Project.

Remember – by the time this started, no-one had ever sent a human into space. The entire endeavour was an exercise in learning-by-doing. Monkeys and then chimpanzees were sent into space and recovered without serious ill-effects (apart from a very grumpy monkey when an abort on a trial flight sent poor Ham into a far higher and faster trajectory than planned), and the Americans knew that dogs had successfully flown in Sputniks in the Soviet Union. Some had even come back from the experience!

It should not be a surprise to learn that almost every Mercury mission flirted very closely with disaster.

This article will, instead of covering a single PoD in detail, give a flavour of some of the many PoDs that were possible during the Mercury Programme. The potential for significant changes in the Space Race is at its greatest early on - as Francis Castanos pointed out in last week's excellent article.

Gus Grissom being airlifted (belatedly) from the water; Liberty Bell 7 has sunk. Image: NASA

Liberty Bell 7

Following Al Shepard’s successful suborbital lob in Freedom 7 (just a few weeks too late to be the first human into space), Gus Grissom was launched on a near-identical repeat of the mission in Liberty Bell 7.

Which sank.

The escape hatch fired after splashdown and before the spacecraft was secured by a helicopter and Grissom swam clear to avoid going down with his ship. And then his spacesuit (open at the neck) started to fill with water and he nearly drowned before the helicopter realised that his frantic waving wasn’t just to say “hi” or to encourage them to pick up the rapidly sinking spacecraft (which they finally aborted trying to do when the helicopter itself was nearly dragged under) but to say “Ahem, I’m drowning here, would you be so good as to, you know, save my life?”

There was a long investigation as to whether or not Grissom fired the escape hatch himself or whether it was a random electrical short. NASA bosses privately assumed it was the former, despite the astronaut’s vociferous denials (and, to be fair, Grissom’s hands both lacked any mark from the detonator bursting back and scoring the skin on activation, which would be virtually unique in any firing of the Mercury escape hatch) but couldn’t risk it was the latter. If it was due to an electrical short, couldn’t it happen in flight? Okay, the astronauts were suited up for Mercury, but for the already-planned Apollo missions, they’d be in shirtsleeves for most of the mission. Accordingly, an explosive escape hatch was deleted from future planned spacecraft like Apollo – something that would later cost Grissom his life.

  • But what if Grissom had drowned here? Or, conversely, if the hatch hadn’t fired at all and changed opinions as to the utility of exploding escape hatches?

Friendship 7 is launched from Pad 14, boosting John Glenn into orbit. Image: NASA

Friendship 7

Then John Glenn leapfrogged Al Shepard in the public consciousness by actually flying into orbit and immortality (and out of active service as NASA would never risk losing their first orbital astronaut). But towards the end of his flight, NASA control received alarming telemetry from the spaceship Friendship 7 (Note – all Mercury spacecraft had a “7” designation, to denote the Original Seven astronauts). The airbag that would soften the impact with the ocean in splashdown had deployed – or so the telemetry said. This meant the heat shield wasn’t locked in position any more – which would be a very bad thing for Glenn.

Perhaps the retrorocket pack – which was strapped on to the rest of the spacecraft as if an afterthought – would be able to hold it on? They were supposed to jettison it after retrofire (any remaining unburned solid propellant might explode, which could equally spoil the level of success of the mission, resulting in the Original Seven becoming a Less-Original Six), but the straps holding the rocket pack onto the lower end of the spacecraft would also hold the heatshield on. At least until the straps burned through in the re-entry firestorm, but hopefully the air pressure would hold the heatshield on by that point…

They did keep the retropack on through re-entry, and there was a lack of exploding retrorockets or burning-up spacecraft, which was somewhat a relief to NASA.

Afterwards, it was determined that it was just a faulty sensor.

  • But what if it had been real – and the retrorocket strap trick hadn’t worked?

Photo taken by Scott Carpenter during the flight of Aurora 7. Image: NASA, astronaut Scott Carpenter

Aurora 7

The planned Delta 7 was scrubbed – which was originally to be the follow-up flight to Friendship 7. Astronaut Deke Slayton had a minor heart fibrillation. With possibly excessive caution, flight surgeons grounded him and Scott Carpenter was moved into his place. Aurora 7 was next.

Aurora 7 went well – apart from Carpenter using too much manoeuvring fuel in his curiosity to solve the “fireflies mystery”, to carry out scientific experiments, to explore the capabilities of the spacecraft, and to be honest – to sightsee a little. Glenn had reported clouds of luminescent dots occasionally accompanying the spacecraft, which baffled NASA until Carpenter worked out that they were particles of ice being knocked loose.

Carpenter had already fallen behind in his struggle to keep up with the busy science plan - much of which had been amended late in the day, giving him little time to try to memorise what to do. In addition, he was distracted by watching the “frostflies” and began his re-entry procedure late. The automatic stabilization system failed and, using manual control, and having burned through so much of his manouevring fuel during his flight, Carpenter ran out of fuel during re-entry.

After they lost contact with him and couldn’t find him in the landing area, NASA began to suspect he’d been burned up on re-entry, unable to hold the correct attitude to have the heatshield protect him.

Almost an hour of frantic searching located him 400 km off target. Carpenter never flew another space mission.

  • But what if Carpenter running out of fuel in re-entry had caused the loss of the vehicle?

  • Or what if Slayton had not been grounded - what would his mission have been like?

Sigma 7 splashing down close to the recovery ship (photographed from the deck of the USS Kearsarge). Image: NASA

Sigma 7

Wally Schirra, next up in Sigma 7, noted Carpenter’s problems and ruthlessly pruned the experiments from his own mission down to a minimum and then, unlike Carpenter, refused to let there be any additions and revisions to the flight plan (reasoning that this had caused Carpenter to be overloaded). The point of his mission, as he saw it, was simply to prove that the spacecraft could fly safely throughout the mission with no headaches for NASA.

Accordingly, he sat there in orbit and allowed the spacecraft to drift (without using fuel) for prolonged periods. He completed the mission with no alarms, re-entered with almost all his fuel still remaining, and splashed down within half a mile of the recovery carrier (at one point, while under parachute and asked where he expected to come down, Schirra joked, “Ah – on your number three elevator, I think”).

Schirra then insisted on the spacecraft being lifted onto the carrier’s deck before deliberately firing the escape hatch in a final engineering test. The detonator’s recoil caused unavoidable clear bruising to his hand, demonstrating to his own satisfaction that Grissom’s escape hatch firing had indeed been due to an electrical short and not the astronaut (Grissom remained the only astronaut whose hatch had fired and who had not received bruises or scratches to his hand from a recoiling detonator). Practically the only “what-if” of this mission is:

  • What if he hadn’t done so well in keeping things unexciting?

Cooper inside Faith 7 on the deck of the recovery ship, after the hatch was blown. Image: NASA

Faith 7

The final Mercury mission was that of Gus Cooper: Faith 7 (named over the rumoured objections of some at NASA who feared the headlines if they lost the vehicle: “NASA loses Faith”).

Faith 7 was to be the long-duration day-long-plus mission that would finally put the Americans on a similar level to the Soviets (who had first flown a day-long mission as early as Vostok 2 – before America had even orbited a man). Cramming in more batteries and oxygen tanks would do the trick.

It took a few attempts to launch the Atlas rocket (as an aside, the Atlas boosters were notoriously unreliable. With gas pressure used to help support the metal skin of the rocket when fully fuelled – whose mass had been reduced to an absolute minimum – it had an uncomfortable habit of exploding part way through launch. With utmost quality control, the Atlas rockets for Friendship 7, Aurora 7, and Delta 7 had gone off flawlessly (Freedom 7 and Liberty Bell 7 had used the less powerful but less fragile Redstone rockets for their suborbital lobs). Cooper’s rocket even had to be sent back for wiring repairs, but eventually it was ready.

Mission Control was then a bit nonplussed to find out that during one prolonged hold, the famously relaxed Cooper actually fell asleep on top of the fully fuelled rocket, taking “laid back” to an improbable degree.

Eventually he launched – successfully – and orbited. And orbited again. And again. And again…

Following Schirra’s lead, he let it drift as much as he could, but carried out quite a few scientific experiments as well. Then things started to go wrong. Faulty indicators. Loss of attitude readings. Short-circuits in the main power supply. More and more started going wrong, but the phlegmatic Cooper shrugged and carried on. Glenn had flown three orbits, as had Carpenter. Schirra had doubled that by flying 6 orbits. Cooper passed their combined total and just kept going. Twelve orbits. Thirteen. Fourteen. Fifteen... Eventually, and after 22 orbits, and using a hastily revised checklist (bypassing the many faults that had shut down whole chunks of the spacecraft), Cooper manually flew the capsule through re-entry flawlessly.

  • But what if the rickety spacecraft had finally given out completely towards the end and either the re-entry had gone wrong – or the spacecraft been unable to re-enter at all?

It would eventually have had its orbit deteriorate to naturally re-enter, but this could have been well out of the timescales of the onboard oxygen.

The Mercury Logo (designed retroactively in 1964). Image: NASA

What Could Have Been...

There are a number of potential What-Ifs, all of which could have changed the direction of the American Space Programme at the start:

  • What if Grissom had drowned? Would splashdowns themselves have been looked at again? Would the entire programme have been paused for the investigation as it was later for the Fire?

  • Conversely, what if the hatch had not fired? Would NASA have incorporated an emergency explosive escape hatch into Apollo Block I – thereby saving the lives of the Apollo 1 astronauts?

  • What if one of the Atlas rockets used for the last four Mercury missions had exploded? Would the escape system (using a solid-rocket booster to yank the capsule clear) have worked?

  • What if the indications of problems with the heatshield on Glenn’s mission had been real? Would the strap really have held it on? Or what if the solid fuel residuals had exploded? Losing the first American in orbit during the mission could have killed the manned space programme.

  • What if Carpenter had been lost in re-entry as was feared?

  • What if Slayton had flown his mission in Delta 7? What would it have been like? An unflown mission gives an author a lot of freedom.

  • What if Schirra had had a similar mission to Carpenter, having not been so ruthless in rejecting experiments and changes, or as much discipline with the fuel?

  • What if Cooper’s mission had ended in tragedy in a progressively failing capsule?

Any of these, so early in the manned space programme, could have caused significant reactions (or overreactions) from NASA and from the political leadership, who were watching closely.

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Andy Cooke has written the sci-fi Endeavour trilogy (The End and Afterwards, Diamond in the Dark, Beyond the Sunset) and the political alternate history Lectern books (The Fourth Lectern, The Fifth Lectern), published by SLP