A Belated Christmas Present To My Kickstarter Supporters

An excerpt from my project that I just wrote:

I’ll conclude with a discussion on mission risk and reliability. SLS supporters make an argument like this:

The greater the number of flights it takes, the more the probability of successfully delivering the elements needed for a Mars mission is reduced, because that probability is a multiplication of the individual probabilities of success of each rocket flight. For instance, if it takes thirty flights of a vehicle with 98% reliability, the probability of mission success (POM) will be 0.98 to the thirtieth power, or only 55% or so. A rocket with the same reliability for which only six flights are required will have a much better POM: 0.98 to the sixth power, or 89%.

Moreover, because of NASA’s superior experience and processes developed over decades, SLS will probably be greater than 98% reliability, compared to those amateur commercial rockets. SpaceX just blew one up last summer, so their demonstrated reliability is only 20/21 (as of the end of 2015), or 95.2 percent. That means that a mission that required thirty successful Falcon flights would only have 0.952 to the thirtieth POM, or about 23%, less than a one in four chance. Why are you trying to sabotage our Mars plans by insisting on using these dinky, unreliable rockets?

I know that because I don’t have a specific quote, this sounds sort of strawmannish, but there have been arguments like this made by SLS proponents for years. And the logic and math seems indisputable, right?

Well, it’s a lot more complicated than that. In fact, a greater number of flights to accomplish a given job actually increases the chance of mission success. And also in fact, this would only be counterintuitive to someone in the warped space industry, stuck in the Apollo and general “mission” mindset. Let’s unpack the above “analysis,” to see why.

First, it assumes without basis that the loss of a single flight causes the loss of an entire Mars mission, ignoring the fact that the lost payload could be delivered on another flight. The only flight failure that could cause mission failure would be one carrying an irreplaceable mission element. But if we have irreplaceable mission elements, we’re clearly doing it wrong.

We could do a reductio ad absurdum, and assume that we are going to deliver everything for a human mission beyond earth orbit and back in a single launch.

Oh, wait! That’s what we did in Apollo!

For Apollo, the Saturn V carried all of the hardware elements described in the DRM, plus propellant. If the launch system failed, the mission failed. The reliability of the launcher put a ceiling on the POM; if the Saturn was 95% reliable, the POM could be no greater than that, and of course it would be less, because of the potential for failure of any of the other mission elements (as happened with Apollo 13, when the liquid-oxygen tank in the service module exploded). For the launch system, it was all or nothing.

Let’s go back to the truck analogy. Suppose we build the house in the factory, ready to live in, and then deliver it to its final destination on a giant truck. It’s a very expensive payload, because of all the value added in the factory where it was built.

Now the success of getting your house to your building site is totally dependent on the truck not crashing somewhere along the way. Would you really want to make that bet? Because trucks do crash with some regularity. And if it happens, you’ve lost a hundred-thousand-dollar (or more) house. Who would insure that?

That’s why we build houses on site from much smaller, less expensive parts, and we add value by assembling them there. That way, if you lose a shipment, it’s not that big a deal. You just send out another load of cheap cement or plywood or studs or drywall, or whatever.

This is the way we do things on earth. There is nothing magical about space that means we should do it any differently there, except that the one time we successfully did what we’d like to do again—send humans beyond earth orbit—we did it the crazy way, because we were in a hurry, and got away with it half a dozen times.

There will be more to come. BTW, I’ve been struggling to find a quote like that, but we all know that people have made that argument. Anything folks can come up with via crowdsourcing would be appreciated, particularly from NASA officials.

Space Exploration Delenda Est

Not really Christmas related, but I was working on a section of the report about this, and realized that I hadn’t blogged it at the time, a few days ago. Pew Research released an opinion poll, in which they asked “what role the US government should play in advancing space exploration,” in the context of a broader poll asking what the government role should be in a wide range of activities. For “space exploration,” the public was basically split according to Pew, with almost half favoring a government role, and almost half favoring little or none. But there was a crucial assumption in the question: That everyone agreed on what “space exploration” meant.

I think polls like this are meaningless, because the public is so ill informed, and the notion of “space exploration” so (no pun intended) nebulous. Planetary probes? Space mining? Space settlement? Astronomy? The answer is going to depend very much on what the individual thinks that space exploration is. That’s why I’ve declared warfare on the phrase.

Social Justice

…comes to Whoville:

I have been “othered.” I have been mocked and ignored. I have been forced to live in red-lined areas of the community. I have been slandered and slurred and libeled and smeared. I have been treated, quite simply, the way one might treat a “monster.”

The hate ends now. It ends today.

You want your Christmas back? Seriously? The colored lights and the jingtinglers and floobfloobers? The roast beast? The Who Whompers? Want to know what I want back? I want the land your people stole from me. I want an awareness of exactly how I’ve suffered for the past two centuries. I want an acknowledgment that your Who Privilege has perpetuated a system in which people like me have been kept down (ironically by being exiled above) and forced to accept and use the language of oppression.

Finally.

George W. Bush And Christmas

Why he never left the White House until the day after:

After a few years, curiosity finally got to the former Washington Times reporter and he asked a low-level administration official why.

“I still remember what she said,” Curl wrote. “’So all of us can be with our families on Christmas.’”

“Who was ‘us’? Hundreds and hundreds of people, that’s who. Sure, the reporters who covered the president, but also dozens and dozens on his staff, 100 Secret Service agents, maybe more, and all of those city cops required whenever the president’s on the move in D.C.,” Curl added in his column.

However, things seemingly changed when Obama took office.

“[T]his president would never delay his trip to his island getaway. He’s off every year well before Christmas. Hundreds and hundreds head off with him, leaving family behind,” Curl wrote.

Some people have class, others are narcissists and leaches on the wealth of the taxpayer.

[Update a couple minutes later]

Barack Obama’s top ten violations of the Constitution this year. Note that this implies that there were many more.

Troops Die In Afghanistan

..and the Washington Post decides it’s all about Obama:

He’s dead now but the thing you have to worry about is how this might spoil Obama’s 600th round of golf.

Don’t think about these minor characters.

Think only of this Hero, the Star of Our Movie, in a difficult moment on his Hero’s Journey. The deaths of these walk-ons with no lines aren’t important, except to the extent they cause him to reflect, or feel a moment of triumph in…. golf.

At least when he’s golfing it minimizes the damage he’s doing to the country.

[Update a few minutes later]

Speaking of the WaPo, here are the ten stupidest things about it portraying Ted Cruz’s kids as monkeys.

The Food Fight Over Government Nutrition

No, the Republicans aren’t “politicizing it”:

For decades, the government has advised Americans on what they should eat. The advice isn’t just advisory; it drives everything from school lunches and agricultural subsidies to marketing for those bowls of candy we call breakfast cereal. But the science behind this enterprise has always been shaky.

Yes. And Michelle’s lunch program continues to constitute literal, physical child abuse.

Biting Commentary about Infinity…and Beyond!