Wednesday, May 6, 2009

Editorial: 'NASA should abandon Ares 1'

Henry Spencer, computer programmer, spacecraft engineer and amateur space historian
New Scientist Blog

It looks like Ares I, the rocket being designed to carry NASA astronauts into orbit when the space shuttle retires, is in trouble. Actually, Ares I has been in trouble for a long time, but now the chickens (or are they vultures?) are coming home to roost: the Orlando Sentinel says that as early as Thursday, the White House may announce a review to look into whether to proceed with the rocket's development or switch gears and pursue other options.

As I wrote last summer, it's been clear almost from the start that Ares I was a very marginal, optimistic design, just barely adequate if everything went right. But there are always problems, and Ares I had no margin for problems.

As one underlying assumption after another has turned out to be wrong, requiring design change after design change, NASA has nevertheless clung to the same basic approach, unwilling to admit its mistake and hoping that sheer persistence would see the project through. Perhaps it could, but the price for such bullheadedness can be very high, and the budget projections are now starting to reflect that - the Sentinel says that its estimated costs through 2015 have swelled from $28 billion in 2006 to $44 billion today.

Some of us thought from the start that this was blatant empire-building. At first glance, the US's existing big rockets - Atlas V and Delta IV - seemed quite adequate for launching people and supplies into Earth orbit. (They wouldn't suffice for launching to the moon and beyond, but then, Ares I couldn't do that either - that job was assigned to its big brother, Ares V.)

NASA studied this option at some length, and decided that Atlas and Delta just weren't good enough. In particular, NASA thought it would be very expensive to modify them to meet NASA's official "human-rating" standard, which specified what a rocket had to do to be safe for launching people.

Even at the time, some of us had doubts about this. It's unlikely that there was any actual rigging of the analysis, but all too often, the devil is not in the details but in the assumptions.

The "human-rating" standard was very demanding - indeed, far more demanding than any previous specification of its kind. The shuttle couldn't possibly meet it; neither could Apollo or Soyuz. But since then, the standard has been revised, and the new one is a lot less specific and demanding (a cynic would suggest it was changed because Ares I couldn't meet the original standard - but some cynicism might be in order here).

Could NASA make do with Atlas V or Delta IV rockets if they really wanted to? Yes, I think so. Compared to the original hypothetical Ares I, these launchers can't carry as heavy a load and they do need some work on details . . . but compared to the real Ares I, their problems look a lot less serious.

It's true that the Orion crew capsule designed to sit on top of the Ares I rocket has turned out to be very heavy, but part of that weight growth is actually Ares I's fault! An escape rocket to pull an Orion away from a malfunctioning Ares I has to be very powerful, because Ares I's first stage can't be shut down. With a liquid-fuelled launcher like Atlas or Delta, the main engines would be shut down as the escape rocket fired. I'm told that this alone could cut as much as 3.6 tonnes (8000 pounds) off an Orion built to fly on an Atlas or Delta launcher.

NASA, predictably, is not happy about being forced to change. NASA's ex-administrator, Mike Griffin, has been a particularly vocal opponent of the idea, claiming that outsiders shouldn't try to second-guess NASA on technical decisions, and that it's cheaper to stay on course after four years of effort than to start over from scratch. Sorry, but that's not the way it looks to me.

I'd agree that it would be cheaper, if I thought NASA had made four years of progress. But Ares I is the International Space Station of rockets: redesigned again and again, justified using assumptions that no longer apply, and already escalating mightily in cost (and already well behind schedule). There comes a time when it really is cheaper to start over in some more sensible way, because banging your head against the wall harder and harder isn't getting you through it.

Back before Ares I had a name, it was sometimes known as "the Stick" because it was unusually long and thin (especially before its second stage started gaining weight). About three years ago, in an online discussion group, I coined a name that I thought suited it better: the White Cane.

It's time the folks at NASA opened their eyes