http://www.spacedaily.com/news/rocketscience-03zj1.html The End Of US Manned Spaceflight Looms Ever Closer The US manned space program has at best only a few more years of missions left in it, until its cost, complexity and design flaws results in another failure that grounds all US manned launches until a new transport system is designed and built. by Jeffrey F. Bell Honolulu - Jul 10, 2003 Once again, NASA has proposed to develop a replacement for the troubled Space Shuttle. This year's project goes by the ungrammatical moniker "Orbital Space Plane". An interim version of OSP called the CRV (Crew Rescue Vehicle) to be developed by 2010 will take over the International Space Station lifeboat task now done by Soyuz. An improved OSP called the CTV (Crew Transfer Vehicle) will assume the ISS crew exchange task now done by Shuttle in 2012. To minimize development costs, the OSP will be launched on one of the new EELV family of expendable boosters, Delta 4 or Atlas V. Sound familiar? It should. The OSP is only the latest of many "Shuttle replacement" programs that have all failed dismally. A close look at OSP shows that this program is also doomed to failure due to fundamental technical defects. It's no surprise that such usually reliable NASA boosters as "Space Coast" Congressman Dave Weldon and aerospace lobbyist Lori Garver have publicly attacked OSP. Most critics have focused on the suspiciously low development costs, or the embarrassing gap between 2006 and 2010 in which no ISS lifeboat is planned. In fact, the basic concept of the program is so stupid that every knowledgeable person involved in it must be perfectly aware that it will never fly. The basic problem is that the OSP, as currently defined, must carry such heavy mass penalties in the form of wings, wheels, and various escape systems that its performance will not be much better than the Dyna-Soar design of 40 years ago. Because it cannot carry any of the supplies needed to sustain its passengers once they arrive at the ISS, it will not reduce the number or expense of Shuttle missions needed to support the International Space Station, and will not provide "assured access to space" as NASA claims. Instead OSP will force NASA to simultaneously fly two very expensive man-rated vehicles at a time when it is financially unable to support even one, and will double the risk of long stand-downs in ISS operations due to lack of either replacement crewmen or the supplies needed to keep them alive. The Shrinking Spaceplane Mystery: The original OSP concept envisioned a 7-seat vehicle which could rescue or exchange the entire ISS crew in one sortie. (NASA's proposed Budget Amendment of 14 November '02 said "as many as 10".) The Level I requirement document reduced this to "at least 4" persons. This major decline in the OSP's basic performance measure was widely criticized. Although I have not seen an official justification for the 4-seat requirement, it appears to be based on an agreement among ISS users that NASA will be responsible for escape and exchange only of the non-Russian ISS crew members, with the RSA continuing to support 2 or 3 Russian crewpersons with 2-3 Soyuz TMA flights per year. However, a later NASA document "interpreting" the Level I requirements (online reference) has gone mostly unnoticed. In this 'interpretation" the requirement for "at least 4" seats in OSP has been changed to a "system requirement" that can be reached using multiple spacecraft instead of only one! Presumably, proposals for 2-seat or even 1-seat spacecraft would be now considered acceptable under this bizarre "interpretation" of the "at least 4" requirement. I know of no other aerospace program in which the basic performance goal has been lowered by a factor of FOUR in the first few months! This isn't just a question of being "a step backward from Shuttle" (or even from Soyuz), but fundamentally wrecks the economics of the program. Even in the CRV mode, a 2-seat OSP is an extremely dubious proposition. The normal configuration of the station would then be one in which two OSPs and a Soyuz would occupy three docking ports, oriented in such a way that all three lifeboats could be manned and pull away from the Station in any desired order, while leaving other ports free for CTV or supply vehicle docking. In the CTV mode, the 2-seat OSP would be heavily burdened by the irreducible overhead of basic nav, comm, and docking equipment that cannot be scaled down. So by cutting the seating in half, NASA has much more than doubled the annual cost of rotating ISS crews. NASA has not given any reasons for this extraordinary lowering of the bar that the three competing contractor teams have to reach. The most likely explanation is that preliminary studies have revealed a 7-seat or 4-seat spaceplane turns out too heavy to be launched on Delta 4 or Atlas V, when all necessary requirements are met. [Table 1 and many other figures and justification deleted] Another lesson from the dreary history of orbital spaceplanes is that the R&D costs are usually underestimated. The Hermes Euro-OSP quadrupled in cost over seven years, and X-38 tripled in six. The idea that one can design and test a new manned vehicle roughly half as complex as Shuttle with a budget only %2-5 as big is clearly a fantasy. The tyranny of wings: Several semi-ballistic orbital ferry designs are included in Table I to show just how much we are paying for the dubious benefits of wings and runway landing. One of the main reasons X-20 Dyna-Soar was cancelled in 1964 was that Gemini provided the same capabilities on about one-third the total launch weight. The Soviet designs OK-M and Zarya, 2-seat winged and 6-seat ballistic CTVs designed to fit the same mass limit, show the same factor of three. A modified Apollo CM was proposed to meet the 6-seat CRV requirement on about half the weight of X-38. Given today's huge launch costs, what possible reasons exist to justify launching two or three times the necessary mass? Many years of Shuttle flights have give some people the idea that reusable spacecraft must have wings, but in fact the only reason the Shuttle has wings is a long-forgotten USAF requirement. It is perfectly feasible to put a new ablative heat shield on a semi-ballistic vehicle and reuse it. The Gemini 2 capsule was actually refurbished and reflown in 1967 as part of the Air Force MOL program. The Chelomei Design Bureau in the USSR also reflew several examples of a fully reusable 3-man ballistic space station CRV called "TKS-VA" or "Merkur" in 1977-83. Another myth is that a water landing would require borrowing a carrier battle group from the Navy. For regular scheduled CTV landings near KSC, NASA could use its two dedicated recovery tugs which lie idle at Port Canaveral between the occasional Shuttle SRB recovery missions. Apollo missions regularly landed within 2nm of the predicted point, so it should take less than an hour to hoist the spacecraft aboard and hose it off with fresh water. For emergency CRV landings, existing search and rescue organizations would be adequate. The feasibility of a ballistic design for OSP was demonstrated by ESA in 1998, when they flew and recovered a prototype Station CTV called "ARD", which was an %80-scale Apollo CM with modern avionics and recovery gear. Curiously, NASA recently completed a study (online reference) of an Apollo-based OSP design, which does not mention either Gemini 2R, Merkur, or ARD, but instead repeats all the standard anti-ballistic myths. This is another example of the fact that airplane pilots, who all have a gut feeling that the ballistic spacecraft concept was an unfortunate diversion from the "correct path" of gradually developing airplanes into spaceships, dominate NASA's manned program. (Actually, Table I suggests that this approach makes as much sense as gradually developing steam locomotives into airplanes.) Although Sean O'Keefe has said that ballistic designs are acceptable in the OSP competition, it is unlikely that any of the three industry teams will propose one. They have received plenty of hints from lower-level NASA pilot-officials, pilot-astronauts, and even some pilot-Congressmen that only a winged, streamlined, Shuttle-like design with sticks and rudder pedals will satisfy them. The Space-Tech Vacuum. "But surely all the technological advances made since Dyna-Soar/Shuttle/ Hermes will allow OSP to be much faster/better/cheaper," some of you are saying. Whenever anyone says this, I demand that they name those technological advances. Nobody is ever able to, since there haven't been any since about 1964, when NASA's narrow focus on the Moon Race caused them to stop funding basic rocketry research. What little progress has been made is the gradual reduction in the cost and failure rate of expendable boosters, demanded by and funded by the comsat industry and the DoD. If you look at the current technological shelf that the OSP design teams can pull components off of, it has pretty much the same stuff on it that the Dyna-Soar team had in 1964. (The X-38 did employ the most advanced technology now available, and one can see from Table I that no major improvement in performance resulted.) And it is just not possible to propose to develop anything new within the cost and budget constraints of the program. Of all the Shuttle replacement programs, it was the ones that tried to develop new technology (X-30 and X-33) that failed most spectacularly, and the one that stuck with low tech (DC-X) that actually flew. New technology in an area as specialized as space flight just doesn't appear; it requires years of sustained effort by large numbers of scientists and engineers at a cost of billions of dollars. And NASA has not been willing to spend billions of dollars on anything except the "operational" programs, Shuttle and Station. This is the reason our astronauts are flying in Russian capsules and Atlas V will be launching our satellites with a Russian engine. Until NASA makes a major shift in its priorities from current operations to long-term research, don't expect any new technology like aerospike or tri-propellant engines to arrive. [Table 2 and much other stuff deleted] Launch safety issues: A simple way to make OSP bigger would be to launch it on the "heavy-lift or "triple-barreled" versions of Delta 4 and Atlas 5 which can lift about 24000kg. In fact, many NASA graphics do show the OSP mounted on these much more capable boosters. But this option would raise both the cost and the launch failure rate. The OSP Level I Requirements includes an "increased safety" requirement for the survival of crews, but this is irrelevant. The basic limitation on the operational lifetime of Shuttle, OSP, or any reusable spacecraft is not the loss rate of crews, it is the loss rate of spacecraft. Astronauts, after all, are easily replaceable. The number of overqualified applicants vastly exceeds the demand. But the OSP vehicles will be expensive, hand-built national treasures that simply can't be thrown away. Just imagine what would have happened if the Shuttle fleet had actually flown the advertised 50 times a year -- at a loss rate of 1 in 60 flights, we would have run out of Orbiters long ago. The same logic applies to OSP, only more so because Delta 4 and Atlas 5 are cheap, non-man-rated commercial boosters whose reliability goal is only 98%. Furthermore, Delta 4H and Atlas V HLV are both likely to have launch failure rates about double those of their medium-lift versions. Experience has shown that reliability of boosters scales directly with the number of stages and the number of non-redundant engines on each stage. Both heavy-lift boosters have bad configurations from this perspective. The 1st stage is made up of three engines fed from independent tanks, so even a non-catastrophic shutdown of any engine is non-survivable. Both EELV-Hs are effectively 4-stage boosters from a reliability perspective. Now the old 2-stage versions of Delta and Atlas have a combined recent failure rate of ~%1.6, consistent with the rule of thumb that any individual stage fails a little less than %1 of the time. This implies that the Delta 4H and Atlas 5H will fail on about %3 of launches, three times the rate of Shuttle. Even if the LES rockets the OSP away from the booster blast, it is left gliding down toward the Atlantic ocean with approximately the subsonic L/D of a brick. Many studies of spaceplanes have shown that they can't survive high-speed high-AOA water landings. Clearly we can save the crews with ejection seats (more weight and volume lost!), but probably not the vehicles. Now the baseline requirement for the CTV is to relieve the 4 non-Russians on the ISS every four months. So, we have a choice of launching 6 times a year with 2-seat CTVs and splashing one every 10 years, or launching 3 times a year with 4-seaters and... splashing one every ten years. Apparently, NASA has decided to minimize its losses by choosing the 2-seat option. This is consistent with the announced plan to fly Shuttles with 2-man "kamikaze" crews. There has already been discussion of reducing the failure rate by developing a special "man-rated" version of the EELVs. This is unlikely to work. A vast amount of effort was put into "man-rating" the shuttle, and the overall failure rate is still %2. And the whole basis of using an expendable booster is that they are cheap. The basic Atlas V costs only a little more than the $60M Shuttle external tank! Introducing special safety requirements for the OSP boosters will run up the expense and introduce many operational complications. [remainder of article deleted; the author concludes that NASA's prescription of staying the course and trying to do everything with Shuttle means an end to the US manned space program after the next inevitable loss, while our allies and competitors fly cheap borscht and sushi cans to orbit and back and actually get things done.]3 responses total.
This article reads easier on the web. Why not post the url?
Grex has a Web-interface, dearie.
He did post the url... ;)
You have several choices: