Space Disasters and Public Opinion

Commercial space exploration and tourism were dealt a major double punch in the last two days.

First an Antares rocket by Orbital Science Corporation exploded at lift-off. It was an unmanned rocket with a payload destined for the International Space Station, contracted by NASA. The rocket and payload were worth $200 million, and there was additional damage to the launch pad.

Then, yesterday, there was a catastrophic failure of Space Ship Two, the Virgin Galactic vehicle designed to take tourists into space starting in 2015. In this case, the catastrophe occurred during a high altitude test flight. Two pilots were on board, one died, and the other is seriously injured. No details have been released. I am actually amazed that one pilot could have survived such an explosion. I am sure we will find out the details eventually.

Already there are voices claiming that the private sector does not have enough of the Right Stuff to be successful in space, and that we might want to leave space exploration to the expertise of NASA, or the Russians, or the Chinese, or the Indians. David B. Grinberg’s column here is such an example.

Have we really forgotten the famous “O-ring disaster” that destroyed the Space Shuttle Challenger in 1986? What about the heat shield failure in the Columbia catastrophe. What about the Apollo 1 fire on the launch pad?

The fact is, space travel and space exploration are very serious and very dangerous endeavors. With the technology we have today, to reach orbit, a space vehicle consists of more than 85% propellant when it sits on the launch pad. 85% is on the low side, as it was the case for the Space Shuttle. When a rocket with a capsule is launched, it’s more like 95%.

To visualize that, picture an aluminum can of Coca Cola. It contains 94% Coke and 6% packaging. A rocket, in comparison, usually has about 95% propellant and 5% packaging. A rocket is therefore more flimsy than a soda can. But it’s not benign soda that’s inside the package. In the case of the Space Shuttle external tank, it contains cryogenic fluids at 20 degrees above absolute zero (0 Kelvin), pressurized to 60 pounds per square inch and can withstand 3gs while pumping out propellant at 1.5 metric tons per second. On top of that, we put little capsules with tiny, soft and fragile human beings that need a constant temperature of 98.6 degrees F.

Space travel is dangerous. Rich and famous people like Justin Bieber, Ashton Kutcher, Leonardo DiCaprio and Stephen Hawking have signed up for $250,000 per flight on Virgin Galactic. Many will fly, and inevitably, some will die along the way, even though the risk with suborbital space travel, like it is in the case of Virgin Galactic, is far, far lower than it is with orbital flights.

This was a hard week for the space community. It was a formidable setback. But I am rooting for Branson and Musk and the many other visionaries who are building effective solutions that advance the human race and provide alternative ways for us soft and fleshy things to get off this planet.


Implications of the Rocket Equation

During this morning’s browsing session of the blogs I follow, I came across this post from Self Aware Patterns, which led me to a brilliant article about the realities of space travel titled The Tyranny of the Rocket Equation by Don Pettit, a NASA astronaut and flight engineer. I say brilliant, because his writing is simple and succinct, and he explains complex engineering challenges in everyday language for the likes of me to understand.

If you are not into science and engineering, you won’t want to read the NASA article. However, I know that a good portion of my readers are engineering and science buffs. Every one of you will enjoy Pettit’s article – unless you are a rocket scientist yourself, in which case this is Rockets 101.

The majority of the human race will never know what it’s like to launch – and then land – in a space shuttle. Fourteen humans died trying it. No human from here on forth will ever again experience the space shuttle. It’s now a historic vehicle. But the trusty old Soyuz capsule still flies and is currently the only human rated spacecraft available to reach the International Space Station (ISS) and return from it. I got a kick out of Pettit’s one sentence description of what it’s like to land in a Soyuz capsule:

The Soyuz goes thump, roll, roll, roll; aptly described by one of my colleagues as a series of explosions followed by a car wreck.

Most of the article deals with the complexities and the physics involved in rocket science, and its practical limitations based on today’s technology. He compares the shuttle’s external tank with a soda can:

The common soda can, a marvel of mass production, is 94% soda and 6% can by mass. Compare that to the external tank for the Space Shuttle at 96% propellant and thus, 4% structure. The external tank, big enough inside to hold a barn dance, contains cryogenic fluids at 20 degrees above absolute zero (0 Kelvin), pressurized to 60 pounds per square inch, (for a tank this size, such pressure represents a huge amount of stored energy) and can withstand 3gs while pumping out propellant at 1.5 metric tons per second. The level of engineering knowledge behind such a device in our time is every bit as amazing and cutting-edge as the construction of the pyramids was for their time.

The stunning revelation is that the external tank has proportionally less material than a soda can, yet it flies into space. No wonder things did not go so well when the Challenger O-rings failed.

This article was first written in May 2012, before SpaceX made its major headline and surfaced as a viable player in the rocket world. I appreciate all the more the successes of SpaceX after reading The Tyranny of  the Rocket Equation.