by Jeff Pollard
The crew comforted themselves with thoughts about how well tested this rocket is, and even if it explodes in a blaze of glory, the capsule could escape and fly away by itself. This was not true of Space Shuttle flights, which had quite a lot of black-zones in its flight plan. A black zone is a time during a mission in which there is no way to abort. For the Griffin, there weren't any black regions in their flight plan. But of course, having an abort option doesn't necessarily mean the abort option would work, and they all knew that.
The three soon-to-be private astronauts, were about to rocket into the sky, destined to be the first people to be sent to orbit by an entity other than a government. At this point, only the US, Russia, and China have ever put people in space. And China only joined that party in 2003, and have only flown people to space five times. Now that list would look like this: Russia, USA, China, and SpacEx.
Checklists complete, fuel tanks filled, the men have nothing to do but wait as the countdown ticks through T-minus 20 minutes. At that point, the three of them had been strapped in and waiting for more than five hours.
“I gotta piss,” Tim says.
“Just wait until orbit,” Travis replies.
“Al Shepard, first American in space, flew the whole way up with a space-suit full of urine,” Kingsley says.
“You can pee at t-plus-20 minutes,” Travis adds.
“Just thirty-some minutes. I can hold that,” Tim says, trying to convince himself.
“Here, maybe this'll distract you. Kingsley reaches to an out of the way panel, activating a music player that starts in with “Life on Mars?” by David Bowie. The three men listen at first, slowly joining in until they're singing in unison with David Bowie, shouting really.
“Launch Control, Griffin.”
“Go ahead Launch Control,” Tim says. Tim Bowe, as the most experienced pilot, is technically the mission commander, while Travis is flight engineer, and second in command, in charge of the spacecraft systems. Kingsley has no official capacity, and thus is not technically in charge of anything. Though in reality, he could fly the Griffin by himself if he needed to; they all could.
“Coming up on T-minus-12-minutes, all systems are green. We are go for launch. Set computer to terminal launch,” says Launch Control a few miles away at the Launch Control Facility.
“Roger, computer is in charge,” Tim says.
“Let's light this-” Travis starts to say.
“Don't say candle,” Kingsley interrupts.
“Let's light this bitch,” Tim says.
“Say again Griffin?” Launch Control asks over the radio.
(T-10:50) Launch Control: Terminal count launch has started.
(T-10:48) Mission Director (in Hawthorne, California, at Mission Control): If a hold is called from this point forward, the terminal count auto-sequence will be aborted, indicate a hold condition by saying hold-hold-hold on the primary countdown net. In this event, the vehicle control will immediately abort the terminal count auto-sequence. If a hold is called, all operators proceed to the terminal count abort steps in section 10-dot-59.
K, Travis, and Tim watch the clock as it ticks down towards the t-minus-10-minute mark.
“Have you ever seen a clock tick so slowly in your life?” Tim asks.
“Time is relative,” K adds.
(T-10:00) Launch Control: Terminal launch count auto-sequence has started.
(T-9:59) Payload Control: Griffin, confirm computer has started auto-sequence.
(T-9:57) Flight Engineer, Travis Clayton: Confirm, clock is counting.
(T-9:52) Launch Control: Range Officer, activate downrange video recorders.
(T-9:48) Payload Control: Griffin, switch launch enable to flight.
(T-9:45) Flight Engineer, Travis Clayton: Launch enable to flight.
(T-9:40) Rocket Control: Pre-valves coming open.
(T-9:29) First Stage Control: Chilling first stage engines.
(T-8:00) Flight Engineer, Travis Clayton: Griffin internal auto-sequence has started.
(T-7:25) Payload Control: Griffin, set batteries to bus.
(T-7:20) Flight Engineer, Travis Clayton: Roger, Griffin batteries to bus.
(T-7:00) Launch Control: Griffin on internal power. All systems go.
The clock ticks down as all the dozens of systems have to start-up and work together, work perfectly, at precise times, and it all has to align with external factors like wind conditions, local air-traffic, etc. But for now, no holds are called, no aborts triggered.
(T-4:45) Launch Control: Switch Eagle 9 to internal power.
(T-4:25) Rocket Control: Stage 1 and stage 2 on internal power.
(T-4:17) Rocket Control: Vehicle release auto-sequence has started.
(T-3:00) Launch Control: We are go for launch.
(T-2:45) Rocket Control: Stage 2 heaters closing out.
(T-2:00) Launch Control: Range, verify go for launch.
(T-1:56) Range Officer: Range is green.
(T-1:39) First Stage Control: Helium loads closing out.
(T-1:29) Rocket Control: Pre-valves coming open.
(T-1:23) First Stage Control: OX bleed open for final engine chill.
(T-1:03) Guidance: Flight computer has entered auto-idle.
(T-0:59) Flight Engineer, Travis Clayton: Vehicle is in startup.
(T-0:57) Pilot, Commander Tim Bower: Flight computer is in control.
The crew look to each other, everything is working perfectly.
“We're going to space boys,” Travis says.
Kingsley watches his panels, overseeing everything. His whole life he has worked toward this goal. Now it was real. It was happening. His Griffin spaceship was about to fly to space. The thousands of hours in simulators, the years of training, designing, all lead up to this moment. He imagined a complete and total focus on the mission at hand and the gauges in front of him, but instead he closes his eyes and turns off his senses. He remembers being just a boy, watching the first Space Shuttle launch on television while sitting on his father's lap and his dad explaining to little Kingsley what was happening. The first shuttle launch was a major event, the first NASA launch of a manned spacecraft since 1975. The curious little boy had never seen a rocket launch before. When the orbiter disappeared into the distance a few minutes after launch, after the SRBs fell away, Kingsley was entranced. He turned to his dad and declared, “I'm gonna go to space when I grow up.” Only months later his parents would be dead, but his interest in space would never die. That's what he remembered most about his father, little moments like that.
(T-0:38) First Stage Control: Helium checkout closing out.
(T-0:36) Rocket Control: Tank press systems setting up.
(T-0:30) Mission Director: t-minus 30 seconds.
(T-0:22) Rocket Control: All tanks at pressure.
The four main tanks, first stage LOX, first stage kerosene, second stage LOX, and second stage kerosene, were all full, at pressure, ready to go. To squeeze every last bit of fuel from the tanks, they are topped off with Helium, a light inert gas that would push out the last of the oxidizer and fuel as the tanks emptied. From t-minus-20-seconds down, Launch Control announced each second over the radio. Every technician had their telemetry to monitor, and a moment's notice to call an abort or a hold if something was off.
At t-minus-3-seconds, the turbo-pumps spin up, sending fuel and oxidizer through the delicate plumbing to the nine Arthur engines of the first stage. At t-minus-1-second, the triethylaluminum and triethylborane igniters are injected into the combustion chambers, reacting with each other and the ambient oxygen at a high temperature and emitting a bright green light that is immediately followed by ignition of all nine engines, shooting flames into the flame bucket, redirecting the exhaust horizontally.
The computers watch the combustion stability of all nine rocket engines, checking for any anomaly. It takes only a fraction of a second for each engine to come online. This split-second is the most delicate of the whole operation. If one of the engines
doesn't light correctly, the computer will instantly shut down all nine engines, and the launch will be aborted. Depending on the issue, they could try again within a few hours. But the instant they abort, the hundreds of systems and sub-systems are no longer in sync. The engines start to warm up, the tanks need to relieve the pressure, as they cannot stay at full pressure for very long without danger of cracking. Ice begins to accumulate on the exterior of the rocket, near the cryogenically cold liquid oxygen tanks. The Griffin has to be put back on external power so they don't drain their batteries, same goes for the computer in the first and second stage. Needless to say, an abort does not lead to a simple do-over.
However, if the computers sense that the engines have all started correctly, the fuel flow is nominal, no leaks, no anomalies in any of the systems, then the computer releases launch clamps holding the Eagle 9 to the pad, and the rocket will take off, triggering thousands of near instant actions in the dozen computers in various places in the rocket and capsule.
Kingsley watches his panel as the clock ticks through to zero. Time slows down, yet the clock marches forward, giving little hint of the massive number of calculations being made, the number of steps followed in that split second. Kingsley feels the fuel starting to flow, then the deep rumble of combustion starting, followed quickly by the rippling roar of the Eagle's exhaust. Then the over two-hundred-foot-tall rocket lurches upward, feeling almost like an earthquake, or a skyscraper swaying in the wind.
It's that instant when the computers either decide to go forward with launch and the rocket pushes the men in their seats as they take to the sky, or it shuts the engines down and they go nowhere at all. Kingsley knows this sequence so well on an intellectual level that he seems to think the split second will be decipherable. But it isn't. There's no sense that millions of calculations and checks are being made. The clock hits zero and they're forced down in their seats in an instant without any time to think about all the things that just happened. The acceleration on the Eagle 9 is like being in a car that's going zero-to-70 mph in 2.2 seconds...for three straight minutes. Add to that the vibrations that come from being attached to nine rocket engines, and you've got quite an intense experience.
(T+0:01) Guidance: Flight Computer is in first stage.
(T+0:01) Launch Control: Liftoff!
(T+0:02) Payload Control: Griffin has sensed first stage acceleration. Nominal.
(T+0:08) Rocket Control: Eagle 9 has cleared the tower.
(T+0:13) Guidance: Starting pitch.
(T+0:31) Pilot, Commander Tim Bower: Starting gravity turn.
(T+0:35) First Stage Control: First stage at full power.
Between T-plus-50 and T-plus-52, the rocket's velocity through the dense lower atmosphere causes a shock wave to create a cloud of condensation that follows the rocket. It looks a bit like the rocket is creating a cloud. The phenomenon is called a Prandtl-Glauert singularity and can be see on fighter planes nearing the speed of sound.
(T+0:56) First Stage Control: First stage propellant utilization active.
Until this point, the first stage's nine engines have been burning the liquid oxygen and RP-1 kerosene on a fixed mixture ratio, meaning that the propellants are being used in a set proportion to each other. An internal combustion engine, like in your car (unless you're reading this in the near-future, in which case your Tezla electric car will have no such thing, so go look up what an internal combustion engine was), carries fuel, but not oxidizer, as there is oxygen in the air. Combustion engines can run lean or rich, using more or less fuel. Rocket engines can run lean or rich also, except that they are providing both fuel and oxidizer. So it's possible for a rocket to run out of oxidizer, while it still has fuel, which means that the fuel can't be burned, or it could run out of fuel first, and be left with useless oxidizer. Theoretically the tanks should be filled in precisely the right proportions and that both propellants will run out at the same moment. However, in practice, this isn't always the case. For the first 56 seconds, the engines are happily burning through their propellants at their most efficient mixture. But when propellant utilization is activated, the computers look at the levels of fuel and oxidizer and adjust the mixture so that both propellants will run out simultaneously. It's just another reminder that a rocket is not a simple piece of hardware.
(T+1:00) Guidance: Vehicle is 6 kilometers in altitude, velocity of 241 meters per second, downrange distance 1 kilometer.
If you're not up on your metric conversions, a meter-per-second, m/s, is equal to about 2.237 miles-per-hour. And a kilometer, km, is 0.6214 miles. So a minute after this twenty-two story high building was sitting on the launch pad, it's 3.7 miles high, or nearly 20,000 feet. It's traveling at 539 mph. And it's covered a horizontal ground distance of just over 3000 feet.
(T+1:14) Rocket Control: Vehicle is supersonic
(T+1:26) Guidance: Max-Q. Vehicle has reached maximum aerodynamic pressure.
(T+1:38) Second Stage Control: Second stage has started engine chill.
(T+2:00) Guidance: Vehicle remains on nominal trajectory, vehicle is 30 kilometers in altitude, velocity of 1 kilometer per second, and downrange distance of 23 kilometers.
Getting to orbit is not about going up, it's about going sideways very very fast. Imagine if we took a cannonball up to 200 miles high, in space, just holding still, not moving, and let it go. What would happen? If you say it would float in space, you would be wrong. Gravity still works, in fact, gravity is only slightly lower at that altitude, around 10% weaker, but that's still a significant force pulling that cannonball straight down. In a short time, that cannonball would be falling extremely fast, hitting the upper atmosphere, until plummeting all the way back to Earth.
Instead of letting go of the cannonball from a stationary position 200 miles high. Let's give it a little push. We'll blast it out of a cannon, horizontally, at a 1000 mph. Gravity still acts on it, pulling it down. But the cannonball is traveling sideways at 1000 mph. At that speed, the curvature of the Earth starts to matter, because in the few minutes it takes for the stationary cannonball to hit the ground, the fired cannonball will travel far enough sideways that the curved surface of the Earth will seem to have fallen away. 1000 mph is nowhere close to orbital speed, so this cannonball will still hit the ground, but it will take longer. If we fire a cannonball to a horizontal speed of 17,500 mph, then as the Earth pulls down on it, the cannonball will free-fall toward the planet. However, the rate that the curvature of the Earth makes the ground fall away will be the same speed that the cannonball is falling. After the cannonball has gone one fourth of the way around the planet, it will still be going at the same speed, but it will have taken a 90 degree turn, and so will the Earth's surface. The cannonball will continuously fall around the Earth, and the curvature of the Earth will follow right with it. This is a circular orbit.
Getting to orbit is first about gaining altitude, getting out of the dense atmosphere. Then it's about getting up to an immense speed of around 17,500 mph, totally horizontally. Once a rocket climbs out of the atmosphere and there is no air resistance to slow it down, it can spend several minutes accelerating toward orbital speed without impediment.
So launch is a balancing act of gaining altitude and horizontal speed. The first minute is almost entirely devoted to gaining altitude, and after that, horizontal velocity becomes more and more important.
At two minutes after liftoff, the rocket is nearly 100,000 feet high, traveling at over 2,200 mph.
(T+2:15) Flight Engineer, Travis Clayton: Griffin power systems nominal.
(T+2:30) Guidance: Vehicle remains on nominal trajectory, vehicle is 51 kilometers in altitude, velocity of 1.8 kilometers per second, and downrange distance of 59 kilometers.
As the rocket continues to pitch over, the rate of acceleration increases. A rocket burning horizontally will pick up speed faster than a rocket burning vertically, since vertical acceleration has to fight gravity. Notice that the first full minute of flight went from 0 to 241 m/s. Whi
le the 30 seconds between T+2:00 and T+2:30 saw the rocket accelerate from 1000 m/s to 1800 m/s. That's partially because the rocket has pitched over, more horizontal, partially because the atmosphere at that altitude is less dense, thus there is far less air resistance, but mostly the difference is due to the ever-decreasing mass of the rocket. Remember that most of the weight of the rocket is the fuel and oxidizer, and as the first stage tanks quickly empty themselves, the rocket gets much lighter, while the same 9 engines are still burning.
If the amount of force generated by those engines stays the same, but the mass of the rocket is much lower, that translates into higher acceleration. Thus to avoid too much acceleration the engines are throttled down to limit the structural loads, as well as to keep the g-forces on the crew down. At lift-off the whole rocket weighs over a million pounds. When the tanks of the first stage run out, the engines will have used over 700,000 pounds of fuel. So if the engines were left at full power, they would still be producing the same thrust, while the rocket would be a quarter of the weight.
So as the rocket loses weight rapidly, the engines throttle down to maintain a safe structural load and rate of acceleration.
(T+2:42) Rocket Control: Approaching MECO-1.
(T+2:50) Stage One Control: MECO-1.
MECO stands for Main-Engine-Cut-Off. The Arthur engines cannot be throttled down smoothly from 100% to 1%. At a certain point, lowering the throttle causes the engines to burn much less efficiently or to even flame out, not producing enough combustion pressure to maintain stable thrust. So rather than throttle all 9 engines down, at MECO-1, they shut down two of the nine engines to limit the acceleration of the rocket. The engines on the rocket are numbered like the buttons on a phone; engines 1 and 9, on opposite corners, are shut down while engines 2-8 keep running at a lower thrust level. So from MECO-1 to MECO-2 a mere 10 seconds later, the Eagle 9 is more like an Eagle 7. Theoretically they could fly from liftoff with only 8 engines running. The good engines would just be left at higher power levels a little longer than usual and the rocket's performance would be only marginally degraded. The ability for a rocket to lose an engine and still accomplish its mission is called “engine-out capability.” The Eagle 9 could sustain multiple engine losses, as long as they don't lose more than two engines early in flight. Most other rockets don't have this capability. For example, the ULA's Atlas rocket has only two engines in its first stage. If one those engines fail, the rocket is doomed. The Saturn V rocket had an engine out capability in both first and second stages, as each of those stages had five engines, and could continue on just four engines if an engine failed (which happened more than once in the Apollo program).