Thursday, February 21, 2008
Life, the universe, everything space-y
Carnival of space number 42 is up over at Chris Lintott's place.
Tuesday, February 19, 2008
Wishing Their Problems Away
This New York Times article inadvertently suggests that some of the top level people in NASA are using hope rather than sound engineering practice when it comes to designing the Ares-1 rocket, which will be the US government's replacement for the Space Shuttle.
It is not trivial to change the Ares rocket to eliminate the resonance caused by the natural operating frequency of the solid rocket booster. The shuttle gets away with it because its 4-stage solid rockets are attached at top and bottom to the side of the external fuel tank, which acts as a strongback for the shuttle stack and dampens the vibrations from the SRBs due both to the strength of the materials of the tank and the dual connection points. On the Ares, the second stage is balanced atop a brand new 5-stage solid rocket booster; there really is only one attachment point, a ring at the top of the solid rocket. To damp out the oscillation "by adding a shock absorber" means adding a lot of mass between the SRB and the second stage or (worse) an even larger mass between the second stage and the Orion crew module.
The Ares-1 is overweight as it is; NASA still has to cut a ton from the mass of Orion in order to get the Ares off the pad, even though most of the weight of the safety systems has already been stripped from the design. In some cases the safety systems are single-string. That's brittle design - a single failure equals disaster.
The other option is to modify the design of the rocket to change the resonant frequency. The problem is that such a resonance is inherent to the design of any solid rocket booster. As the New York Times article points out, an SRB is like a pipe in a pipe organ. As the fuel burns, what remains behind is a hollow tube with a lot of air moving through it. No matter what solid rocket booster design NASA goes with, they still have the same issue of a resonant frequency. If they change the booster significantly (and many engineers would argue that adding a fifth segment to the booster is already a huge change), then they end up with completely different hardware than was used on the space shuttle; in other words, an entirely new, untested rocket, with no commonality to the existing shuttle system.
When Wernher von Braun put astronauts atop the Saturn V rockets, he wasn't guessing that the system would work. Every component and subsystem was thoroughly tested beforehand. With the Ares-1, they have eliminated much of the testing under budget pressure and the assumption that it is all legacy hardware from the shuttle system. Any redesigns to change the resonant frequency of the "Stick" will mean that they basically have to start over with a clean sheet (negating the efforts of the past three years and pushing back the first launch of Ares by that much) and test all components of the system as well as all subsystems (adding more dollars and years to the project). This is the very "full-scale redesign" that Garry Lyles of NASA's Marshall Space Flight Center dismisses out of hand.
There are other solutions, of course. For the upcoming moon missions, there will be two launches per mission: one Ares-V to launch the bulk of the hardware and fuel, and one Ares-1 for the crew. If instead the mass of the launches are divided up into two nearly-identical rockets midway in size between Ares-1 and Ares-V, then NASA can avoid the resonance issue by having two SRBs attached top-and-bottom to the sides of the strongback of the rocket and develop one rocket instead of two, using far more legacy (spaceflight tested) hardware. This is the essence of the DIRECT 2.0 proposal.
Another approach is to ensure and even expand the funding for the Commercial Orbital Transportation System teams. In comparison to the vaporware produced so far by NASA on the Ares, SpaceX has actually produced - from a standing start - two new rocket engines, and already started doing test flights. They have spent over the last five years about what NASA spends every eleven days. That's cost effective. Assuming NASA does not choke off COTS, then at the very least SpaceX will beat the Ares to orbit - and they may do so even if NASA kills COTS in the cradle. If that happens, then there will be no need whatsoever for Ares, and NASA will have wasted billions of dollars and years of effort for no actual results at all. And, if NASA assures funding for or even expands COTS, then there will be more than just SpaceX ready to provide rides to orbit for NASA astronauts.
Yet another approach is for NASA to actually do what it is supposed to do as a government agency - develop technologies that are not yet commercially viable but which lead to infrastructure improvements that make space access easier and more economical for everyone. Jon Goff has already written a lot about that, particularly about orbital propellant transfer and other technologies necessary for a spacefaring society.
And finally, NASA can go with existing launch systems like the Delta or Atlas. So what if they are not "man rated"? As Rand Simberg has pointed out many times, that qualification is artificial and not one of the rockets that NASA has ever used to fly men into space has ever met that qualification - "man rating" is simply a cudgel used by NASA as part of the not invented here syndrome.
For NASA, relying on hope that the system will work simply isn't good enough. Wishful thinking is no substitute for good engineering practice.
It is time for NASA to realize that the definition of "hindsight" does not include "inserting one's head in a very uncomfortable place". The Ares-1 "Stick" may be Mike Griffin's pet project, but that doesn't mean that its obvious shortcomings can be ignored any longer.
Still, Mr. Lyles said there would be no need for a full-scale redesign. Additional analysis has indicated the problem is not as severe as first thought, and the two vibrational frequencies may turn out to be far enough apart, more than 10 percent, that nothing needs to be changed at all.Why is this a problem, you ask? Observe this video of the Tacoma Narrows Bridge. Since 1940 this bridge has been an object lesson to engineers of all stripes. It is inconceivable that the engineers at NASA are not aware of this bridge and the issue of resonant frequency. It is further inconceivable that they would assume that a ten percent difference in the resonant frequencies of the solid rocket booster and the second stage would be enough to save them from the same fate as Galloping Gertie.
If fixes are necessary, rocket scientists know what to do. A shock absorber could be added between the first and second stages, or the structure could be modified to change the resonance frequency.
It is not trivial to change the Ares rocket to eliminate the resonance caused by the natural operating frequency of the solid rocket booster. The shuttle gets away with it because its 4-stage solid rockets are attached at top and bottom to the side of the external fuel tank, which acts as a strongback for the shuttle stack and dampens the vibrations from the SRBs due both to the strength of the materials of the tank and the dual connection points. On the Ares, the second stage is balanced atop a brand new 5-stage solid rocket booster; there really is only one attachment point, a ring at the top of the solid rocket. To damp out the oscillation "by adding a shock absorber" means adding a lot of mass between the SRB and the second stage or (worse) an even larger mass between the second stage and the Orion crew module.
The Ares-1 is overweight as it is; NASA still has to cut a ton from the mass of Orion in order to get the Ares off the pad, even though most of the weight of the safety systems has already been stripped from the design. In some cases the safety systems are single-string. That's brittle design - a single failure equals disaster.
The other option is to modify the design of the rocket to change the resonant frequency. The problem is that such a resonance is inherent to the design of any solid rocket booster. As the New York Times article points out, an SRB is like a pipe in a pipe organ. As the fuel burns, what remains behind is a hollow tube with a lot of air moving through it. No matter what solid rocket booster design NASA goes with, they still have the same issue of a resonant frequency. If they change the booster significantly (and many engineers would argue that adding a fifth segment to the booster is already a huge change), then they end up with completely different hardware than was used on the space shuttle; in other words, an entirely new, untested rocket, with no commonality to the existing shuttle system.
When Wernher von Braun put astronauts atop the Saturn V rockets, he wasn't guessing that the system would work. Every component and subsystem was thoroughly tested beforehand. With the Ares-1, they have eliminated much of the testing under budget pressure and the assumption that it is all legacy hardware from the shuttle system. Any redesigns to change the resonant frequency of the "Stick" will mean that they basically have to start over with a clean sheet (negating the efforts of the past three years and pushing back the first launch of Ares by that much) and test all components of the system as well as all subsystems (adding more dollars and years to the project). This is the very "full-scale redesign" that Garry Lyles of NASA's Marshall Space Flight Center dismisses out of hand.
There are other solutions, of course. For the upcoming moon missions, there will be two launches per mission: one Ares-V to launch the bulk of the hardware and fuel, and one Ares-1 for the crew. If instead the mass of the launches are divided up into two nearly-identical rockets midway in size between Ares-1 and Ares-V, then NASA can avoid the resonance issue by having two SRBs attached top-and-bottom to the sides of the strongback of the rocket and develop one rocket instead of two, using far more legacy (spaceflight tested) hardware. This is the essence of the DIRECT 2.0 proposal.
Another approach is to ensure and even expand the funding for the Commercial Orbital Transportation System teams. In comparison to the vaporware produced so far by NASA on the Ares, SpaceX has actually produced - from a standing start - two new rocket engines, and already started doing test flights. They have spent over the last five years about what NASA spends every eleven days. That's cost effective. Assuming NASA does not choke off COTS, then at the very least SpaceX will beat the Ares to orbit - and they may do so even if NASA kills COTS in the cradle. If that happens, then there will be no need whatsoever for Ares, and NASA will have wasted billions of dollars and years of effort for no actual results at all. And, if NASA assures funding for or even expands COTS, then there will be more than just SpaceX ready to provide rides to orbit for NASA astronauts.
Yet another approach is for NASA to actually do what it is supposed to do as a government agency - develop technologies that are not yet commercially viable but which lead to infrastructure improvements that make space access easier and more economical for everyone. Jon Goff has already written a lot about that, particularly about orbital propellant transfer and other technologies necessary for a spacefaring society.
And finally, NASA can go with existing launch systems like the Delta or Atlas. So what if they are not "man rated"? As Rand Simberg has pointed out many times, that qualification is artificial and not one of the rockets that NASA has ever used to fly men into space has ever met that qualification - "man rating" is simply a cudgel used by NASA as part of the not invented here syndrome.
For NASA, relying on hope that the system will work simply isn't good enough. Wishful thinking is no substitute for good engineering practice.
It is time for NASA to realize that the definition of "hindsight" does not include "inserting one's head in a very uncomfortable place". The Ares-1 "Stick" may be Mike Griffin's pet project, but that doesn't mean that its obvious shortcomings can be ignored any longer.
Monday, February 11, 2008
blood on their hands
Click on these two images for background information. Is there any substantive difference between these two cases?
Wednesday, February 06, 2008
Scrolling Blogroll, redux
A while back I posted the code necessary for the scrolling blogrolls in my sidebar. Recently Rob Singleton had some questions about how to implement these scrolling blogrolls himself. The problem is that he is using different blogging software than I am, and my previous instructions didn't make sense with his type of template. So, I have come up with a simplified version of the scrolling blogroll code, which can be implemented in pretty much any web page at all. To add a scrolling blogroll to your own blog or website, just copy the code in the text area below and paste it into your website or blog template code. In the case of a blog, that would likely be somewhere in your sidebar code, anywhere you like. Then, make changes to the code to customize it for your own site; the comments within the code should help guide you with the necessary changes.
Monday, February 04, 2008
Moving the Goalposts
A few days ago, I wrote a blog post directed at Mark Whittington that said:
So yes, by all means, let us hold SpaceX to the same standard as NASA - or rather, let us hold NASA to the same standard as SpaceX. Let NASA pay for its mistakes out of its own pocket without dinging the taxpayers for its failures... what's that? NASA doesn't have money of its own? Then perhaps we should hold NASA to the same standards to which NASA holds Rocketplane/Kistler.
Whittington goes on to say:
There is no double standard at work here. SpaceX used its own money for the Falcon-1 tests. NASA is using taxpayers' money for the obviously flawed-from-before-starting Ares. The difference is not subtle.Mark Whittington replied that
Technically, he is correct that SpaceX used private money for Falcon 1 tests. But it also is using public money to develop the Falcon 9/Dragon launch system. So, using Robot Guy's logic, one ought to gove SpaceX the same benefit of a doubt--or lack there of--as NASA.Perhaps I ought to have included more of Mark Whittington's original statement, as based on his reply one might think I was making an apples-to-oranges comparison. Here's the full paragraph from Whittington's original post:
Even in the commercial area, technical problems crop up. SpaceX's Falcon 1 have had two launch failures, for example. SpaceX's engineers have ascertained the causes of these failures and are fixing them. It is noted that no one who is having Internet vapors over the Ares is having the same over the Falcon. There seems to be, perhaps because of a double standard, more of an understanding that problems will occur in rocket development in the private sector than at NASA.Clearly Mark was comparing SpaceX's (self funded) Falcon 1 launches to NASA's (taxpayer funded) work on Ares. He was not referring to the Falcon 9/Dragon launch system (and thus, neither was I), which admittedly is being partially funded by NASA and thus by taxpayers. He was referring to Falcon 1.
So yes, by all means, let us hold SpaceX to the same standard as NASA - or rather, let us hold NASA to the same standard as SpaceX. Let NASA pay for its mistakes out of its own pocket without dinging the taxpayers for its failures... what's that? NASA doesn't have money of its own? Then perhaps we should hold NASA to the same standards to which NASA holds Rocketplane/Kistler.
Whittington goes on to say:
...the bald, unsupported statement "obviously flawed from the start Ares" (I wish someone would offer some actual evidence to support that)I had left the support for that statement out of my original post because I thought it was so obvious that further explanation was unnecessary. One could look at the Aviation Week article discussing the thrust oscillation problems, which are going to happen with any solid rocket motor first stage. One could point to the weight problems and schedule slippage. One could keep going, but I suspect that anyone who has been following NASA closely over the last four years would have to know about the problems with Ares/Orion. Any other assumption beggars belief.
Friday, February 01, 2008
what's in it for me?
A few weeks ago Leonard David pointed out a National Science Board report which among other things stated that
Well, it might be a kick in the head for NASA, but the U.S. space agency is not synonymous with "space", and the lack of enthusiasm for increased funding for NASA is not synonymous with a lack of enthusiasm for space projects.
At one time, Americans could be convinced that NASA == space, but that time is long past. When the Collier's articles by Wernher von Braun, Willy Ley, Fred Whipple, and others were published in 1952-54, people paid attention. When the Russians launched Sputnik, people sat up and took notice. And then came Kennedy's speech:
Well, that got people excited. And that race to the moon gave people more than the impression that NASA == space. It gave them hope - hope that one day they too could go to space. How many kids went into science and engineering because of the work that NASA did in the eight years following the Kennedy speech at Rice university? I can't quantify that, but I bet it was a lot. And, in the years during and immediately following the Apollo missions, people were excited about the apparent progress, the seemingly inexorable movement of man into space.
2001: a Space Odyssey showed routine flights into space to a gigantic wheel-shaped space station, multiple bases on the moon, and a manned voyage to Jupiter. In 1968 these seemed plausible enough, certainly not laughable. There were proposals to build enormous space colonies ("L5 by 95!"), and it seemed as though nothing could stop us. We were going to be a spacefaring civilization, and in a hurry. In the 1960s and 1970s kids could realistically dream of a career as an astronaut.
Thirty-five years after the last man set foot on the moon, it seems that we are further than ever from becoming a spacefaring civilization - that is, at least with NASA as a driving force. NASA is in fact going backwards, struggling to recover ground that was won nearly four decades ago after having wasted the intervening period going around in circles. A kid today has a greater chance of winning the Powerball lottery than of being a NASA astronaut. Why bother doing something as hard as science or engineering if the chance of a payoff is so remote?
Why is support for NASA so low? Perhaps it is because one can only rest on one's laurels for so long. One needs to actually do something in order to engage the public and convince them that you are doing something worth their tax dollars. And, if all you are doing is putting a handful of government employees into low earth orbit a few times a year, then convincing people that you are indeed doing something worthwhile is a pretty tough sell.
I have to feel sorry for Damaris B. Sarria. She writes a blog entitled How I Am Becoming An Astronaut - and she's doing it by working for NASA. She's not in the astronaut corps yet, and it is sad to say but if NASA's present course is continued then she will never become an astronaut. The agency already has far more astronauts than it will need for the shuttle program, some of whom will never be launched into space. By the time that the Ares series of boosters is finally developed - the schedule slips by more than a year every year - NASA will have had to defend its funding and indeed the entire raison d'etre of US Space Exploration Policy through several presidential administrations and congresses. At the current rate of schedule slippage, budget woes, and obvious problems with the Ares it is a crapshoot whether NASA will even exist in 2020, never mind be sending anyone to the moon.
But, as I said, NASA is not "space". Robert Bigelow has already done something that no government space agency has ever done: he has two space stations in orbit simultaneously, right now. Elon Musk of SpaceX has developed two completely new rocket engines and begun launching rockets, from a standing start five years ago, using the amount of money that NASA consumes in about eleven days. Burt Rutan has put two people into space (only spending about what NASA spends every 14 hours), and is developing a bigger craft capable of carrying paying passengers into space as early as next summer. Google has put up a $30 million prize for a lunar robotic rover, and private companies are lining up around the block to compete for that prize. There are over 80 private space companies at my last count. And even in the realm of government space activity, the cool cutting-edge stuff isn't being done by NASA; it is being done by the Pentagon in partnership with the Space Frontier Foundation.
Support for space hasn't died; it has shifted from an increasingly irrelevant NASA to the private sector. There is a good reason for that. People can see that the private sector work in space has potential to offer them. There's something in it for them - they once again have the possibility of going to space themselves. They have the possibility of making money on space. And, they don't need to go through an ossified government space agency whose glory days were over before most people alive today were even born. It is no wonder that support for increasing NASA's budget is so low.
Scientific research ranks about on a par with mass transit (38%) and well ahead of space exploration (14%) and assistance to foreign countries (10%) in the proportion of the U.S. population favoring increased spending.Leonard David called this a "kick in the head for space fans".
Well, it might be a kick in the head for NASA, but the U.S. space agency is not synonymous with "space", and the lack of enthusiasm for increased funding for NASA is not synonymous with a lack of enthusiasm for space projects.
At one time, Americans could be convinced that NASA == space, but that time is long past. When the Collier's articles by Wernher von Braun, Willy Ley, Fred Whipple, and others were published in 1952-54, people paid attention. When the Russians launched Sputnik, people sat up and took notice. And then came Kennedy's speech:
Well, that got people excited. And that race to the moon gave people more than the impression that NASA == space. It gave them hope - hope that one day they too could go to space. How many kids went into science and engineering because of the work that NASA did in the eight years following the Kennedy speech at Rice university? I can't quantify that, but I bet it was a lot. And, in the years during and immediately following the Apollo missions, people were excited about the apparent progress, the seemingly inexorable movement of man into space.
2001: a Space Odyssey showed routine flights into space to a gigantic wheel-shaped space station, multiple bases on the moon, and a manned voyage to Jupiter. In 1968 these seemed plausible enough, certainly not laughable. There were proposals to build enormous space colonies ("L5 by 95!"), and it seemed as though nothing could stop us. We were going to be a spacefaring civilization, and in a hurry. In the 1960s and 1970s kids could realistically dream of a career as an astronaut.
Thirty-five years after the last man set foot on the moon, it seems that we are further than ever from becoming a spacefaring civilization - that is, at least with NASA as a driving force. NASA is in fact going backwards, struggling to recover ground that was won nearly four decades ago after having wasted the intervening period going around in circles. A kid today has a greater chance of winning the Powerball lottery than of being a NASA astronaut. Why bother doing something as hard as science or engineering if the chance of a payoff is so remote?
Why is support for NASA so low? Perhaps it is because one can only rest on one's laurels for so long. One needs to actually do something in order to engage the public and convince them that you are doing something worth their tax dollars. And, if all you are doing is putting a handful of government employees into low earth orbit a few times a year, then convincing people that you are indeed doing something worthwhile is a pretty tough sell.
I have to feel sorry for Damaris B. Sarria. She writes a blog entitled How I Am Becoming An Astronaut - and she's doing it by working for NASA. She's not in the astronaut corps yet, and it is sad to say but if NASA's present course is continued then she will never become an astronaut. The agency already has far more astronauts than it will need for the shuttle program, some of whom will never be launched into space. By the time that the Ares series of boosters is finally developed - the schedule slips by more than a year every year - NASA will have had to defend its funding and indeed the entire raison d'etre of US Space Exploration Policy through several presidential administrations and congresses. At the current rate of schedule slippage, budget woes, and obvious problems with the Ares it is a crapshoot whether NASA will even exist in 2020, never mind be sending anyone to the moon.
But, as I said, NASA is not "space". Robert Bigelow has already done something that no government space agency has ever done: he has two space stations in orbit simultaneously, right now. Elon Musk of SpaceX has developed two completely new rocket engines and begun launching rockets, from a standing start five years ago, using the amount of money that NASA consumes in about eleven days. Burt Rutan has put two people into space (only spending about what NASA spends every 14 hours), and is developing a bigger craft capable of carrying paying passengers into space as early as next summer. Google has put up a $30 million prize for a lunar robotic rover, and private companies are lining up around the block to compete for that prize. There are over 80 private space companies at my last count. And even in the realm of government space activity, the cool cutting-edge stuff isn't being done by NASA; it is being done by the Pentagon in partnership with the Space Frontier Foundation.
Support for space hasn't died; it has shifted from an increasingly irrelevant NASA to the private sector. There is a good reason for that. People can see that the private sector work in space has potential to offer them. There's something in it for them - they once again have the possibility of going to space themselves. They have the possibility of making money on space. And, they don't need to go through an ossified government space agency whose glory days were over before most people alive today were even born. It is no wonder that support for increasing NASA's budget is so low.
Whittington swings and misses
It was so predictable. Rand writes something that points out some of the shortcomings of NASA's implentation of the Vision for Space Exploration U.S. Space Exploration Policy and Mark Whittington, in his usual rebuttal, gets something completely wrong:
Update: An anonymous commenter (whom I am certain I have met before on Rand Simberg's blog) saw fit to use a scatological rhyme for Whittington's name in a comment on this post. The rest of the comment had some good points, but I simply will not tolerate such juvenile name-calling on my blog. Anonymous, if you choose to re-post your comment without the ad hominem, then I will allow it through moderation. Otherwise, not.
It is noted that no one who is having Internet vapors over the Ares is having the same over the Falcon. There seems to be, perhaps because of a double standard, more of an understanding that problems will occur in rocket development in the private sector than at NASA.There is no double standard at work here. SpaceX used its own money for the Falcon-1 tests. NASA is using taxpayers' money for the obviously flawed-from-before-starting Ares. The difference is not subtle.
Update: An anonymous commenter (whom I am certain I have met before on Rand Simberg's blog) saw fit to use a scatological rhyme for Whittington's name in a comment on this post. The rest of the comment had some good points, but I simply will not tolerate such juvenile name-calling on my blog. Anonymous, if you choose to re-post your comment without the ad hominem, then I will allow it through moderation. Otherwise, not.
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