Beyond: Our Future in Space (15 page)

Space travel is indeed dangerous, though not quite as dangerous as you might think. Interestingly, given its smothering influence in other areas, the FAA has been very casual with vehicle certification. For now, they’ve agreed to license private spacecraft without certifying, as they do for aircraft, that they are safe to carry people. To quote the regulations: “The FAA has to wait for harm to occur or almost occur before it can impose restrictions, even against foreseeable harm.” So safety criteria will only be applied when specific problems arise, or there’s an actual fatality rate. Meanwhile, space tourists will have to waive any claims against the American government and the operator. Which begs the question: What are the risks?

As of late 2013, about 540 people have been in space, and twenty-one have died, a fatality rate of 3.9 percent. The result is similar if counting launch or reentry attempts that have killed their crew; for both Soyuz and the Space Shuttle, which account for the vast majority of launches, the fatality rate is 2 percent.
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The statistics are reassuring, but the particulars of the losses are chilling. It was soft-pedaled by the media, but both of the doomed Space Shuttle crews almost certainly survived the initial incident and were conscious as they plunged to Earth. Some of the Soviet losses were equally grim, when the details emerged from a veil of secrecy. When Soyuz 1 crashed in 1967, cosmonaut Vladimir Komarov knew he was going to die and raged against the engineers for ignoring prior warnings. Three cosmonauts died in 1971 returning from the Salyut 1 space station. Their ventilation valve ruptured 100 miles up, exposing them to the vacuum of space and asphyxiating them. There were also some close calls. The most memorable was Apollo 13, but in 1965 the Russian Voskhod 2 spacecraft missed its reentry site and the cosmonauts landed in a heavily forested wilderness at night. The two cosmonauts huddled in the cold, gripping pistols as wolves and bears roamed outside. The first Moon landing was so risky that President Richard Nixon had a speech prepared in case Neil Armstrong and Buzz Aldrin were stranded. It read: “Fate has ordained that the men who went to the Moon to explore in peace will stay on the Moon to rest in peace.”
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If that had happened, America’s space program might have played out very differently.

How do these fatality rates compare to more prosaic modes of travel and risks we take without thinking about them? Commercial aircraft are remarkably safe, with 1.3 deaths per hundred million miles flown in 2008. That converts to a lifetime probability of death in an airplane of one in 20,000, or 0.005 percent. In 1938, a more pioneering era in aviation, odds of death while flying were ten times higher. But the eye-popping number is the death rate from driving, giving a lifetime probability of death of one in 84, or 1.1 percent.

So, assuming it’s a once-in-a-lifetime joyride, traveling into space is four hundred times more dangerous than flying but only twice as risky as driving (
Figure 23
).

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In the early fifteenth century, the eunuch Chinese admiral Zheng He sent a fleet of 320 ships and 18,000 men on seven major voyages to India, Arabia, and Africa. Their goal: to seek out new curiosities and animals and make any civilizations they encountered submit and swear fealty to the Chinese emperor. But that vast effort was squashed. Nobody in China was allowed to own a ship and foreign trade was discouraged. Exploration simply ended. At the end of that century, Europeans began to explore in ships that were much smaller and less sophisticated than the ships of the Chinese fleet. They had some government seed money but the exploration was spurred mostly by trade and colonization. Some of these settlers embraced free enterprise and declared freedom from the smothering embrace of their former rulers, becoming the United States of America. Therein lies a lesson for the best way to go beyond the horizon into space—accept the risks and give the visionaries a free rein.

Rockets Redux

Bureaucracy is a human construct. An optimist might imagine that it can be reduced or even avoided in an ideal world. But physics is more obdurate. So the young Turks of the commercial space industry face something they can’t duck: the tyranny of the rocket equation.

As we’ve seen, rockets are machines for generating momentum. They spew gas out of a nozzle at high speed and the rocket attached to it goes in the opposite direction. Isaac Newton defined the physics and Tsiolkovsky codified it into an equation with three variables. Specify two of the variables and the third is cast in stone. No sleight of hand or cleverness can change that fact. One variable is the energy needed to work against gravity and get to the destination, which for low Earth orbit corresponds to accelerating from rest to eight kilometers per second. The other two variables relate to the fuel: how much energy or impulse it provides, and what fraction it is of the total rocket mass.

The energy for a rocket comes from rearranging atoms. So modern rockets work at the limit of what’s possible in chemistry. (One day we may be able to power rockets by rearranging atomic nuclei in a fusion reaction, but for now we’re stuck with chemistry.) The most efficient reaction uses combustion, or oxidation, of hydrogen. It’s clean burning, because the product is water, but it has the big complication that both molecules are gases at room temperature, so they both must be cooled and pressurized into liquid form. How does hydrogen-oxygen burning compare with other common fuels? It releases three times more energy per kilogram than gasoline or natural gas, five times more energy than coal, and ten times more energy than wood. The only thing that comes close is a highly refined and volatile kind of kerosene called RP-1.
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With the fuel specified, the final variable is locked into place. A solid or kerosene-powered rocket must be 95 percent fuel, and a hydrogen-oxygen–powered rocket must be 85 percent fuel. The latter number was the fraction of total mass in fuel when Saturn V and the Space Shuttle launched. Just compare the 85 percent fuel fraction to that of a cargo plane (40 percent), a diesel train (7 percent), a car (4 percent), or a container ship (3 percent). These spacecraft were both mostly just hauling fuel around; the actual payload was 4 percent for the Saturn V and 1 percent for the Space Shuttle (
Figure 24
).

A rocket has engines, nozzles, and fuel tanks. It has a lot of plumbing that has to deliver pressurized liquid propellant swiftly and accurately to the combustion site. It has a structure that must survive the stress, vibration, and g forces of launch. It has to be able to fly in air and in the vacuum of space. Unlike the Saturn V and Space Shuttle launch systems, it must be reusable. To achieve lightness and strength, it has to be made from a combination of aluminum, titanium, magnesium, and epoxy-graphite composites. The constraints of the rocket equation are so severe that the engineering margins are very small. Testing and modeling are only taken to 20 to 30 percent above the designed limit. Imagine driving a car at 60 mph and then drifting up to 75 mph, only to have your car blow up.

Despite the structural problems that led to the loss of two Space Shuttles, its engines were superb and had the best performance ever achieved in a rocket. The external tanks were as big as a family home. They held a combustible cryogenic fluid that was chilled to –250°C, pressurized to 60 pounds per square inch, and delivered to the engines at 1.5 tons per second. The Space Shuttle was like a Ferrari, but it was a project driven by performance, not cost. Thousands of man-hours were required to refurbish it between launches. The astronauts knew they were riding in an exquisite machine, where hundreds of thousands of parts had to work in perfect synchrony (
Figure 25
). They also were uncomfortably aware that it had been built by the lowest bidder. Rocket technology hasn’t improved much since the 1960s. But there’s a cheaper way to design rockets.

When Elon Musk thinks about rockets, he thinks like a physicist. Just as rocket fuel works by rearranging atoms, so does building a rocket. He observes that the cost of rocket materials represents about 2 percent of the cost of the final rocket. That compares to 20 to 25 percent for a car. SpaceX has innovated in ways to save on materials costs, such as making welds without riveting. They fabricate most of their components in-house, rather than pay nosebleed prices to subcontractors. They have simplified construction, with many common components among their launch systems. And they don’t file patents, since Musk says the Chinese would just use them as a recipe book.
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SpaceX is building a Toyota Corolla, not a Ferrari.

The other private space companies are following similar strategies. It’s too early to tell how far they’ll drive down costs, but the early results are promising.
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A benchmark for efficiency in space technology is the launch cost per kilogram delivered to low Earth orbit. Saturn V, the Space Shuttle, the American Delta 2, and the European Ariane 5 rocket each delivered payloads for about $10,000 per kilo. The prolific Russian Soyuz, with nearly 800 launches, costs roughly $5,300 per kilo. Its sturdy successor, the Proton-M, comes in at about $4,400 per kilo. The Chinese are tight-lipped about the economics of their Long March rocket, but they say they can’t beat the cost of the Soyuz. Virgin Galactic’s price tag of $250,000 per person works out to $3,000 per kilo for an average adult, but that’s only suborbital. SpaceX aims to go one better. It claims its new Falcon Heavy rocket will lower the cost to low Earth orbit to $2,200 per kilo (
Figure 26
).