Before becoming the current NASA administrator, Griffin had been part of a group sponsored by The Planetary Society to study how to extend human presence into the solar system. In the report that group put together, one of the things discussed was a potential alternative to the Boeing and Lockheed operated EELVs for launching NASA’s planned Crew Exploration Vehicle. This idea, referred to rather affectionately as “The Stick” by it’s promoters at ATK and NASA, consists of basically stacking a large LOX/LH2 stage on top of one of the solid rocket boosters that currently are used on the Space Shuttle, with a capsule on top. The picture on the right is from ATK’s glitzy new propaganda site, SafeSimpleSoon.
When it first came out, I thought this was a rather silly idea, but figured it wouldn’t get very far anyway. After all, who in their right mind would want to fly on what is little more than the worlds biggest firecracker? Unfortunately, with ATK’s bigtime marketing effort, and with Griffin’s being selected as the new NASA administrator, this idea has been getting a lot of attention lately. In fact, if recent rumors have any connection with reality, it looks like Griffin has more or less made up his mind that he wants to do both “The Stick” and a massive, 120-ton to LEO “In-Line” Shuttle Derived Booster.
I have several problems with “The Stick”, and with the apparent decision to go with it, and I want to spend the rest of this article looking at a few of them.
- One of the biggest things that bugs me about The Stick is the fact that NASA appears to be changing the CEV requirements specifically to favor The Stick over its currently existing rivals. When the request for proposals on the CEV originally came out, the plan was for the CEV to be able to deliver 4 people to orbit, and the spacecraft mass was supposed to be limited to about 20 tons or less. Since ATK started it’s marketing blitz, all of the sudden NASA needs 6 astronauts per flight and the CEV has crept up to 30-35 tons. Since the CEV is now this big, we are told that it can’t possibly fly on the EELVs without extensive upgrades, but The Stick can do it! How convenient.
But does it really need to be this big? I mean, for comparison, the Big Gemini spacecraft proposed by McDonnell-Douglas as a follow-on for their succesful Gemini program would have weighed in one version 15,600kg carrying 9 people to orbit and 2500kg of cargo. The vehicle would have had about the same volume envelope as the Apollo Command Module, with a 3.9 meter diameter at its base. It included a reentry module with both a crew section and a passenger section, a launch escape system, a retrograde module for delivering the reentry burn, and a Manuevering/Cargo module with a docking adapter, cargo space, and a pressurized pass-through door that could allow for shirt-sleeves transfer of cargo to other vehicles or a space station. A 6-man version of this, with no cargo would probably weigh in around 8-tons, which would make it small enough to launch on one of the Atlas V or Delta IV versions that have no solid strapon boosters. And that is with 1960’s era technology!
As a more recent data point, a good friend of mine out here in the Bay Area, George Herbert, is starting up a company, Venturer Space that is trying to develop a 5-6 man capsule for the America’s Space Prize that he is designing to be flyable on a Falcon V. That’s only 6 tons. One can handwave him away relatively easily so far, since he hasn’t built or flown any hardware yet, but from what I’ve seen of his work, it appears valid. More importantly, the guys who were pushing for the Big Gemini had built and flown manned orbital spacecraft only shortly before making this proposal, and had a very good feel for what was reasonably possible and what wasn’t.
Now, this may not seem related, but follow with me for a second. The proposed inflatable Nautilus module that Bigelow Aerospace is developing, is expected to weigh in at 23,000kg. It provides about 330 cubic meters of useable volume, a docking adapter, and enough life support equipment to function as a self-supporting space station, if I’m understanding the articles correctly. The reason why I bring this up is that when you add the 23 tons to the 15.6 tons of the 9-passenger Big Gemini, you come out with about craft that weighs 39 tons, and can support 9 people with luxurious accomadations for long durations with 2500kg of cargo to boot. If you scaled it down to a 6-man version, you could likely keep the mass of the whole system to less than that of the proposed NASA launcher, in spite of the fact that you’d be flying both a capsule and a space station every single time you fly to orbit!
The thing that gets me about this is that one of the reasons why they are pushing for the big in-line booster is so that all the translunar equipment and long-duration facilities can be launched in a single-shot without having to do on-orbit assembly. So if The Stick is only launching a 6-person earth-to-orbit capsule, with minimal cargo, and only short-duration life support facilities, why does it need to weigh so much? The only reason I can possibly see for making the capsule so heavy is if they are including long-duration habitation facilities, but the fact is that they don’t need such for just launching people or cargo to the station or to a waiting translunar stack. If you already have a flying space station for a CEV, why do you need such a big heavy lifter to put up a lander and a transfer stage? Something doesn’t add up.
Now NASA may have a perfectly good reason for why they need it to weigh so much, but it looks to me at least like someone is trying to get the numbers fudged to match their predetermined conclusions. I’m not saying that to accuse Griffin of any sort of malfeseance, but merely saying that as nerds it’s easy to get so excited about a given technical solution that its easy to start ignoring contrary evidence or start making unwarranted assumptions or unneccessary requirements that lead to your preferred solution.
- The next major issue I have with The Stick is the bait-and-switch that appears to be going on. In making their clam that The Stick would be Simple and Soon, ATK made their original case using a standard, 4-segment SRM like what is used on the Shuttle, with no real modifications, and then stack a modern version of the S1C stage on top of it. Supposedly that means that almost everything is right off-the-shelf, and would be quick and easy to put together. The problem is that in NASA’s attempts to grow the CEV big enough to justify the solution they want to push, they’ve outgrown the capacity of that setup. Now they’re talking about a 5-segment SRM with an SSME driven upper stage. I think I’ve even heard from someone that the SSME used would have a nozzle extension. While the 5-segment SRM has been ground fired I think, it hasn’t to my knowledge been ever flown on the shuttle. I could be wrong on that, but I don’t know. I also don’t know if the SSME has ever been tested with a nozzle extension like that. Not to mention that throwing away an SSME with every crew launch is likely to get spendy.
- Another issue I have that is related to the first two is the glossing over of the development work that would need to be done in order to actually bring The Stick into operation.
In order to adapt the SRM for use as a first stage, the burn profile for the booster will likely need to be changed. While this isn’t too rediculously tough, it will require redesign of a lot of tooling, and a lot of validation testing and possibly some flight testing to develop. More importantly, as several people have noted on usenet, the Shuttle SRMs can provide some pitch and yaw control, but no roll control. Roll control would thus need to be provided either by adding some sort of roll control package to the booster itself, or as part of the upper stage. Once again a straighforward piece of engineering, but a piece of engineering nonetheless.
Additionally, they talk about resurrecting the J-2 as though it wouldn’t take much work at all. The reality though is that many, if not most, of the original subcontractors for the J-2 no longer exist. Some of the fabrication techniques are obsolete, inferior, or much more expensive than modern techniques. Many of the sensors would need to be replaced, and should be replaced, by lighter, cheaper, and more reliable modern sensors. New tooling would need to be made, the pumps and engine would need requalification. Even if you stuck faithfully to the old J-2 system and only update those parts that were absolutely obsolete and require updating, it would still take a lot of time and money to requalify those systems and get them up to flight worthiness. If an SSME is modified, that may be quicker, but would likely still require some additional testing work if they do a nozzle extension. And though the SSME is available on the shelf, it’s a really expensive, and not really designed for in-space use. You really don’t need a 3000psi chamber pressure for an upper stage engine. There are other possible engines that could be used like the RS-68, that might not actually require as much development, but the engines suggested so far would require a lot of work.
Lastly redesigning a huge LOX/LH2 stage again from scratch is also a time-consuming, non-trivial, and expensive process. This stage would be much larger than most LOX/LH2 upper stages that have flown in recent history. You’re basically redesigning half of a Delta IV.
Lastly, you’d have to make substantial modifications to the launch facilities there at the Cape. The Stick is much taller than the current shuttle stack, and a very different form factor. Redesigning the launch pad and mobile transporters is definitely doable, but will cost money and take time.
Lastly, the whole thing would need at least a few flight tests to prove itself out before it could be pressed into service.
The only way that ATK can get away with trying to claim that this is Simple and Soon is if they can get NASA to force the CEV mass to be so heavy that it can’t be flown on Delta IV or Atlas V without them doing a bunch of redesign. But as I’ve already discussed, their reasoning on the mass requirements doth stink.
- Notice that they don’t mention anything about the cost on their site. They will need to start up a new assembly line for a very big LOX/LH2 upper stage that will be making at most 6 stages per year. If they go with a J-2 derivative, those will also be made in small quantities and require a new plant. The SRMs aren’t horrendously expensive themselves, but they aren’t phenominally cheap either. The ATK site claims that they can deliver $3000/lb prices, but doesn’t say if that includes any amortization on the development costs, or capital costs for these new facilities. It also doesn’t mention if that includes their share of the old Shuttle infrastructure that will have to be maintained for use with The Stick and the In-Line Booster. Even if it does include all that, $3000/lb is nothing to brag about. It only looks tolerable when compared to current EELV prices, and only if you assume that you have to fly some bloated CEV that requires you to fly the most expensive EELV versions. One of the reasons why EELV prices are so high is that their flight rate is much lower than they designed their pads and factories for. I don’t have the numbers on-hand, but I recall that they could produce a total of about 50 cores between the two of them per year without expanding their factories. They’re flying less than 5-6 each out of a capacity nearly 4 times that. If NASA went with a reasonable sized CEV that could fly on the Delta IV Medium, or the Atlas V 401, they could probably get much more reasonable prices. Adding another 6-10 flights per year would make a big difference for the prices the EELV companies would need to charge to actually make a profit.
Now, being a libertarian, I can’t stand the big government contractors, but at least their vehicles exist! It’s fairly obvious that they could give better prices if there were more flights. There is already a glut of launch providers in this weight class and general price range. Why does Griffin feel that we need to add a NASA operated competitor to make things even worse? While I’d rather that the US government just leave space launch alone, I’d rather they at least not try to compete with the market and develop their own redundant system when adequate capabilities already exist.
- As I mentioned in my previous post, NASA wants to offer non-traditional providers a chance at some of the action by buying ISS cargo delivery services. These could definitely be done on existing US boosters, or could reasonably be done with startups like SpaceX or t/Space. However, in spite of the bloated CEV mass requirements no longer being a reasonable excuse, ATK still wants to develop a cargo version of The Stick too. There’s just no valid reason why this needs to be done. ISS cargo delivery can be done using existing or commercially developed boosters. I guess that if you’re already fixated on developing the crew version, making a cargo version doesn’t seem like that big of a deal, but it is an entirely different spacecraft that should be designed to be flyable on other boosters. Making a government funded cargo delivery vehicle that can only be flown on a government operated booster is a recipe for waste and innefficiency.
- Lastly, I can’t understand why so many people are so concerned with trying to maintain jobs from the Space Shuttle program. The main reason why the Shuttle program costs so much is because so many people are on the payroll. Even if the Shuttle doesn’t fly in a given year, you still have to pay the salaries of nearly 10,000 employees. Sure if you get rid of the orbiter, you can get rid of about half of those people, but now you need to add people back for processing the CEV, and soon you’ll find that what little savings could have been had from retiring the Shuttle have been completely been squandered. Sure, it’s politically easier to try and bribe congresscritters by maintaining useless jobs performed in their districs, but haven’t we learned how much of an inefficient, bureaucratic mess that is?
We have to chose whether we’re trying to open up the solar system for human development, or if we’re trying to run welfare for aerospace nerds. NASA can’t afford both.
I think there are other points that could be made, but these are the key ones that have been bothering me.
Some people wonder why I care. I work for a commercial space company that is making suborbital vehicles. We aren’t involved with any of the contractors, and really aren’t looking for NASA money. I’d like to see us do stuff related to lunar landers or orbital launch vehicles sometime in the future, but we’re still on babysteps ourselves. Some argue that NASA’s irrelavent, that we should just let them make stupid decisions that waste money, because at least that will keep them spinning their wheels and not actively impeding the alt.space community.
The problem is that NASA’s decisions to try and do an Apollo redux does hurt the rest of us. It makes it more difficult for commercial companies to raise money, it perpetuates the myth that space needs to be hard, needs to be expensive, or requires big government agencies to do correctly.
Anyhow, it’s getting late, and I’m running out of things to say, so I’ll leave it at that for now. Comments are open and always appreciated.
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