The primary negative criticisms of the Space Shuttle program are: Shortcut: WP:CU Marking articles for cleanup This page is undergoing a transition to an easier-to-maintain format. ... This Manual of Style has the simple purpose of making things easy to read by following a consistent format — it is a style guide. ...

• It failed in the goal of greatly reducing the cost of space access (e.g. a 'Space Truck'). Space shuttle incremental per-pound launch costs are not appreciably cheaper than other expendable launchers.^[1]
• It failed in the goal of achieving reliable access to space, partly due to multi-year interruptions in launches following Shuttle failures.
• NASA budget pressures caused by the chronically high NASA Space Shuttle program costs have eliminated NASA manned space flight beyond low earth orbit since Apollo, and severely curtailed more productive space science using un-manned probes.
• NASA's promotion of and reliance on the Shuttle retarded domestic commercial ELV programs until after the 1986 Challenger disaster.
• The mundane shuttle flights have failed to inspire, excite, or motivate the American public as the previous Mercury, Gemini, and Apollo projects did.
• It has proven to be a technological "dead-end," as the next generation of NASA manned spacecraft are primarily enhancements of the Apollo-Saturn launch system of 1966 - 1975, making the Shuttle program a "30-year detour."

An expendable launch system or expendable launch vehicle, ELV, is a single-use launch vehicle usually used to launch a payload into space. ...

Published criticism of the Space Shuttle program

James Van Allen, the father of physics in space and a longtime critic of the space shuttle program, described the program as "too expensive and dangerous". "It's a vastly difficult effort with almost no significant purpose," Van Allen told The Associated Press."^[2]

Louis Friedman, director of the space interest group known as The Planetary Society, said, "...the shuttle is enormously expensive. It's a risky vehicle. It's an old technology,"^[3]

"By any measure of 'safe,' this [program] is not safe... It remains dangerous. We have got to replace this vehicle as soon as possible." -- CAIB Chairman Harold Gehman^[4]

"The Shuttle is fundamentally flawed." --NASA Administrator Mike Griffin^[4]

The NASA Chief Administrator Michael Griffin has recently suggested the decision to develop the Space Shuttle and International Space Station was a mistake by saying, "It is now commonly accepted that was not the right path. We are now trying to change the path while doing as little damage as we can." [1][2] Dr. Michael D. Griffin Dr. Michael Douglas Griffin (born November 1, 1949 in Aberdeen, Maryland) has been the Administrator of NASA since April 13, 2005. ... ISS redirects here. ...

"The only thing we can get in return for the $25-30B now budgeted for Shuttle operations between now and 2010 is more heartache and more delays in the new space initiative. Every day that Shuttle cancellation is put off, another $15,000,000 is wasted and the return of humans to the moon is delayed by another day." "The only reason left to fly the Shuttle is to finish the International Space Station. But simple arithmetic tells you that it is not capable of doing this task." Jeffrey Bell, retired space scientist^[4]

"The shuttle is an unsafe, expensive way for humans to explore space just a few hundred miles above Earth. The problem with the shuttle isn't chunks of foam, it's the shuttle itself. NASA should mothball the program and put the nation's scientific and technological expertise to better use." LA Times Editorial, June 29, 2006 [3]

News release from The Planetary Science group, about the NASA 2007 budget: "The NASA (FY2007) Budget released today shortchanges space science in order to fund 17 projected space shuttle flights. Despite recent spectacular results from NASA's science programs, this budget puts the brakes on their growth within the agency. It seriously damages the hugely productive and successful robotic exploration of our solar system and beyond. "According to this budget, flight projects that were already underway, such as the Space Interferometry Mission, will be delayed. Others, such as the Terrestrial Planet Finder and a mission to Jupiter's moon Europa, will be deferred indefinitely. Furthermore, the new budget slashes funding for the fundamental space science that makes such missions possible and turns raw data into discoveries. "Using money intended for science programs to fund continued operation of the shuttle is a serious setback to the U.S. space program, NASA is essentially transferring funds from a popular and highly productive program into one scheduled for termination." The Planetary Society Board of Directors points out that the very first goal stated in the original Vision for Space Exploration announced by President Bush was to "implement a sustained and affordable human and robotic program to explore the solar system and beyond." [4]

Theodore Postol, professor of science, technology and national-security policy at the Massachusetts Institute of Technology: "I think the science argument is very weak. The only argument that I would accept as science-based is the argument that you're learning about peoples' biological response to being in zero gravity," "You don't need a reusable vehicle to do those experiments. In fact the Russians have shown that you can do it very well without a reusable vehicle." [5]

More than 20 years after its first flight, the shuttle has essentially become a space truck that gets terrible gas mileage. It totes cargo at a cost of roughly $20,000 a pound. [6]

Former astronaut Joe Allen, who also served as the agency's assistant administrator for legislative affairs in the late 1970s: "I've become exasperated, I am so proud of what NASA did in the halcyon days, and appalled at the cul-de-sacs it's gotten into. We have an extraordinarily expensive asset in space and an extraordinarily expensive transportation system to service it. That takes all the money. There is nothing left over for something new." [7]

Neal Lane, science adviser to former President Clinton and former director of the National Science Foundation: "Unless we can get a clear, stated mission, we should step back and not risk further lives, If we don't go somewhere, the current program is unsustainable." [8]

Louis Friedman, executive director of the Planetary Society: "As long as we are wed to the shuttle architecture, we can't go anywhere else," [9]

The shuttle does not work as first envisioned. It does not fly every other week, but five or six times a year. It hoists people and cargo into orbit not for $100 a pound, but for 200 times that. It relies not on a lean ground support crew, but a vast engineering bureaucracy with an annual budget in the billions. [10]

"The Shuttle was the result of NASA's desire to continue as a separate entity." "While the DOD and HUD are critical components of government, the same is not the case with NASA and space exploration. It is a luxury that can be expended when economic pressures require it." "The agency has lived on public relations, and that Congress has enjoyed this glitter as well." --Les Aspin, a Democratic Congressman from Wisconsin "The Space Shuttle: Who Needs It?" The Washington Monthly. September 1972, pp. 18-22.[11] He is skeptical of the necessity of the Shuttle and chalks its support up not to legitimate requirements but to NASA "puffery."

Mr. Robert F. Thompson, shuttle program manager from 1970 to 1981, in CAIB testimony: "Operating costs. (Laughter) I had a better answer for development costs.

"At the time we were selling the program at the start of Phase B, the people in Washington, Charlie Donlan, some of them got a company called Mathematica to come in and do an analysis of operating costs. Mathematica sat down and attempted to do some work on operating costs, and they discovered something. They discovered the more you flew, the cheaper it got per flight. (Laughter) Fabulous.

"So they added as many flights as they could. They got up to 40 to 50 flights a year. Hell, anyone reasonably knew you weren't going to fly 50 times a year. The most capability we ever put in the program is when we built the facilities for the tank at Michoud, we left growth capability to where you could get up to 24 flights a year by producing tanks, if you really wanted to get that high. We never thought you'd ever get above 10 or 12 flights a year. So when you want to say could you fly it for X million dollars, some of the charts of the document I sent you last night look ridiculous in today's world. Go back 30 years to purchasing power of the '71 dollar and those costs per flight were not the cost of ownership, they were only the costs between vehicle design that were critical to the design, because that's what we were trying to make a decision on. If they didn't matter -- you have to have a control center over here whether you've got a two-stage fully-reusable vehicle or a stage-and-a-half vehicle. So we didn't try to throw the cost of ownership into that. It would have made it look much bigger. So that's where those very low cost-per-flight numbers came from. They were never real." [12]

"NASA received about 110% of the total money it estimated would be necessary for development of the shuttle at the program's outset." "A close examination of the historical record allows for no conclusion other than that claims of a weak commitment to the (shuttle) program are completely unfounded. Responsibility for this false view becoming part of conventional wisdom must be shared by NASA, which unjustified the program, and then claimed the program was underfunded." "The problem of poor performance in the civil space program is more a matter of inefficiency in use of the resources being provided than a lack of resources required." --Roger A. Pielke, Center for Public Policy Research, University of Colorado "A reappraisal of the Space Shuttle Program" [13]

NASA initially touted the shuttle as a reusable launch vehicle that would provide a cheap way to place satellites into orbit. The proposed and actual numbers have proved quite different. "The [original] numbers that NASA gave to the White House were that shuttle would cost about $5.5 million per launch and the launch rate would be anywhere between 50 and 60 launches a year," said John Logsdon, director of the Space Policy Institute at George Washington University. Shuttles have instead averaged about five launches a year, and NASA was way off on the cost. "Most people use a figure like $400 [million] or $500 million [per launch]," Logsdon said. "Anyway you look at it, it's a lot of money." After Columbia became the first shuttle in space in 1981, shuttle crews became, in effect, human couriers to do deliveries that unmanned rockets could do at the same or lower cost, and without human risks. [14]

"Is the shuttle well-suited for manned space flight and is it technically well-suited for science exploration? It seems to me, it's not technically suited for either," the physics professor said. Expendable launch vehicles with simple return capsules would be safer and cheaper to fly in the long run, Postol suggests. "We're spending a lot of money to return 150,000 pounds of shuttle home and make it safe for another human sojourn into space," "On re-entry, a vehicle should simply bring the crew back. It shouldn't be an enormous plane-like vehicle with all these tiles." Postol argues against sending humans into space at all, saying we should be leaving the inhospitable void to unmanned craft. "I could do an enormous amount of science with robotics. That is much safer and doesn't risk lives." --Theodore Postol of the Massachusetts Institute of Technology [15]

"The international space station, like the shuttle, is an instrument in search of a purpose." "[We] are doing a variety of piddley experiments with little larger application to anything." --Wesley Ward, chief space geologist for the U.S. Geological Survey. [16]

More serious criticism of the space program comes from those who believe the new exploration architecture should make more room for private enterprise and competition. Those in this camp were hoping the space agency would reinvent itself radically, questioning its basic assumptions and rebuilding itself from the ground up. They want massive layoffs, commercial bidding, and several major technical changes to the exploration architecture.[17]

Through the 1990s and into the new century, America’s manned spaceflight program would remain consigned to low earth orbit, flying up and down in the space shuttle, building a space station that never fulfilled its promise.[18]

"After writing the (1985) piece for Discover, I concluded that the shuttle program was unsustainable--that is, it was based on an economic model that simply could not work. I said we shouldn't send people into space unless we have something that's worth the cost and the risk of putting them there. So I got labeled as being opposed to manned space flight, and that isn't quite my argument. My argument with NASA has always been: The shuttle was a good idea that just didn't work. What you really need to do if you want to open up space for human exploitation, whether you're sending people or machines, is to have a better launch vehicle. Then, all kinds of things will be possible in space that are impractical now. ... So it's been the same program ever since the late 1960s. They started to build the shuttle and they made some rather optimistic projections. They said it was going to reduce launch costs by 95 percent. One of their own engineers told them that was impossible, because half of launch cost is not in the vehicle itself, it's the overhead, it's maintaining the Kennedy Space Center and all the other infrastructure. So, even if you reduced the cost of the shuttle to zero, you could only bring the total costs down by 50 percent. Nonetheless, that was the promise that they made to Congress. ... Then they started flying it and, as it turns out, it's more expensive to send a pound into space on the space shuttle than it was on the old rockets. And that was my argument to NASA: The shuttle wasn't an unreasonable program. It probably could have reduced launch costs, but when you find out that isn't true, then you've got to stop and face reality. They didn't. ... NASA faces serious budget problems, consistently, ever since the shuttle started flying, because it is so much more expensive to fly than they had predicted. To compound the problem, they decided to bowl ahead with what I call "summit shuttle," the space station. If you did a realistic economic model, Congress would never buy it. So they promised them this bargain-basement thing, and, of course, it's late and over-cost and under-specification. They just kept hoping that things would get better. Instead, it's not one but two albatrosses surrounding them, and it's strangling the program. NASA's got a satellite that's essentially taking a picture of the whole universe. It's measured the whole universe to the very end. It's an enormous scientific achievement, and, to boot, you can go to a website now and see a picture of the whole universe. It's just staggering. All NASA has to do is advertise that stuff, but they have consistently downplayed their space science and built all of their public relations around the astronauts. They think that the astronaut sells, so that's what they market. In fact, the astronauts, what they're doing, what NASA's doing, is pretty dull stuff. For twenty years we send people up, and they fly around in orbit, and they do these silly experiments. They're not pioneering. They're not doing new scientific research. They're not expanding the bounds of exploration or anything. But NASA's perception is that people really like to see people in space. And my argument with them is, if you really want people in space, then build a launch vehicle that makes it practical for them to get there. ... the astronauts in the Columbia died for nothing; they were not doing anything worth the cost and the risk. The Israeli astronaut, Colonel Ilan Ramon, was up there to push a button on a camera, to take pictures of the desert. We have satellites that do that all the time and do it much better than he could. That was just make-work. To the extent that people want to pay just for the romance of having people in space, sure, that's worth something. I just don't think it's worth the enormous cost that we are investing." --NASA historian Alex Roland[19]

"President Bush's 2006 budget recommends $16.5 billion in budget authority for the nation's space program and roughly half of that will be devoted directly and indirectly to manned space activities. Most of the remainder will go toward supporting the NASA scientific program, which chiefly carried out with unmanned space vehicles. NASA's unmanned space probes and satellites have helped create a 'golden age of astronomy' and given humankind a vastly improved understanding of the universe and their place in it. The scientific community widely views the manned space flight program as a large waste of resources." --Charles L. Schultze, Senior Fellow, Economic Studies[20]

The scientific projects that are suitable for and carried out in the space shuttle are widely considered by scientists as low priority. "Any specific mission you can identify to do in space, you can design and build an unmanned space craft to do it more effectively, more economically, and more safely." Historian Alex Roland [21]

"The problem from the start has been the Shuttle. Mankind's greatest scientific instrument was built under a NASA decree that anything that goes into space must go there by way of the shuttle. That meant Hubble had to be put in low-Earth orbit, which is far from ideal for observations. Moreover, Hubble was designed for routine shuttle maintenance visits. NASA said shuttle launches would be weekly, but five or six times a year was the best they could do. After Columbia, O'Keefe decided it's too dangerous for astronauts to service Hubble, we'll have to use robots. But if astronauts can't go to Hubble, how they gonna go to Mars? This week, the National Research Council said it's not likely that NASA could complete development of a robotic mission before Hubble breaks down, and called for a mission of the rebuilt shuttle to repair Hubble. Could we be seeing the influence of the astronaut lobby? Like who needs astronauts if a robot can fix Hubble?" Robert L. Park is a professor of physics and former chair of the Department of Physics at the University of Maryland[22]

Comments from Legendary Aerospace designer Burt Rutan: NASA's space shuttle is complex and generically dangerous. Still, not flying the shuttle to the Hubble Space Telescope is symbolic of a larger issue. "The budget forecast [for NASA] is to go out and spend hundreds of billions of dollar to go to Mars and yet you don't have the courage to go back to the Hubble … it looks like you got the wrong guys doing it," [23] Now we're flying the space shuttle, in my opinion the most expensive and dangerous system ever developed. "NASA abandoned affordability in favor of the shuttle, and now it's spending hundreds of millions to study frog legs. I want to fly in space, and I'm tired of waiting for NASA. [24] Space entrepreneur Burt Rutan, whose company Scaled Composites sent the first private astronauts into space last year, opened the International Space Development Conference with a blistering critique of NASA. He said the agency is wasting taxpayers' money on a deeply flawed space shuttle and paper spaceships that never get beyond the planning stage. According to Rutan, NASA should get out of the human spaceflight business and leave the flying to the emerging commercial spaceflight industry. At stake is whether ordinary citizens will have a role to play on the high frontier. [25] "NASA basically failed with the space shuttle program in the late 1970s before the first launch because it couldn't deliver on the low-cost-to-orbit promise, and it can't deliver on the safety,"[26] "Look at the progress in 25 years of trying to replace the mistake of the shuttle. It's more expensive…not less…a horrible mistake," Rutan said. "They knew it right away. And they've spent billions…arguably nearly $100 billion over all these years trying to sort out how to correct that mistake…trying to solve the problem of access to space. The problem is…it’s the government trying to do it." [27]

Scott Hubbard, a former member of the Columbia Accident Investigation Board (CAIB) and past director of NASA's Ames Research Center: "I think the concern by many members of the CAIB, myself included, is that there are other failure mechanisms … other types of aging going on that may appear at any time," "You have this uneasy feeling of what else might show up in such an incredibly complex vehicle … any vehicle that is that complex has failure modes that are difficult to predict or anticipate." Every shuttle launch "is a holding of the breath". [28]

Joseph Pelton, a research professor with the Institute for Applied Space Research at George Washington University: "In truth, the problems that NASA continues to experience with its shuttle and the International Space Station program—really the only reason the shuttle is still flying—goes back at least to the Challenger disaster in 1986," ... "Two major national space commissions back then—one looking into the Challenger accident, the other delving into the future of the American space program—noted that the shuttle was indeed becoming "obsolescent" and that it had to be replaced by another vehicle within at least 15 years, or 2001" "Instead of developing alternative plans for the launch of International Space Station components in smaller and more modular parts at that time, NASA pushed ahead without developing a new vehicle, nor developing a back-up plan." "Now, not only is NASA's credibility and space funding at risk, Pelton continued, but also at risk are the agency's international partners that are engaged in the $100 billion station program. "The now 'tar baby-like tandem' of the ISS and the space shuttle has done great harm to space programs around the world." "NASA has over-invested in both the shuttle and station initiatives taking away money from programs that truly matter to the United States and indeed the world." "The truth of the matter is that the shuttle program—an experimental program when designed in the 1970s—should have been grounded years ago. It should be replaced by better, safer, and more cost efficient programs. The development of private space vehicles that are human-rated, something that NASA is currently actively supporting, is clearly the right step forward," [29]

Roger Launius, Chair, Division of Space History at the Smithsonian Institution’s National Air and Space Museum in Washington, D.C.: "A sustained and underlying depression seems present among those working in the program, some of them for their entire careers," Launius explained. "There is a sense of ending—as well as an ever-present perception of loss and failure—present among many members of the space shuttle team." "As the space shuttle enters its home stretch, it should be remembered with both praises for its many accomplishments and criticisms for its shortcomings," Launius suggested. "I am in favor of giving the shuttle an honorable retirement and to give a full measure of respect and thanks to those charged with its operations over the years for their efforts."

Design issues

All systems as complex as the space shuttle inevitably have design issues:

• Positioning of the orbiter on the side of the launch stack - instead of atop it as on all other U.S. multi-stage launch systems - leaves it, the astronauts, and the payload vulnerable to certain in-launch failures and events. For example, the orbiter's heat shield is currently exposed to damage by foam, ice, or other debris falling off the external tank.
• With the orbiter exposed on the side of the fuel tank during launch, the decision to use ceramic tiles as the primary heat shield could appear questionable, as such tiles are fragile, expensive, and time-consuming to replace. However metallic shielding similar to that developed during the Dyna-Soar program was examined extensively during shuttle development, but would have been too heavy.[30]
• The original O-ring/joint on the SRB was inadequately designed; this in combination with the low ambient temperatures at the time of its final launch led to the loss of Challenger.
• Designers originally contemplated that in the event of a problem, SRBs thrust could be terminated. However, later study showed the resultant thrust termination forces would have either destroyed the vehicle or entailed a prohibitive weight penalty for structural reinforcement.
• The Space Shuttle Main Engines SSMEs, while powerful and reusable are also very maintenance intensive. An extensive inspection is required after every launch to ensure their operational condition.
• The first iteration of the SSMEs did not use hydrostatic bearings, adding to the maintenance issues.

Artists conception of the X-20 during re-entry The X-20 Dyna-Soar was a USAF program to develop an orbital spaceplane that could be used for a variety of military missions including reconnaissance, bombing, space rescue, satellite maintenance, and sabotage of enemy satellites. ... NASA Image of the final solid rocket booster (right) being mated to a Delta II rocket (blue). ... Space Shuttle Main Engine block The Space Shuttle orbiter has three main engines. ... Space Shuttle Main Engine block The Space Shuttle orbiter has three main engines. ... Fluid bearings, also called fluid dynamic bearings or hydrostatic or gas bearings, are bearings which support load on a thin layer of liquid or gas. ...

Costs

Some reasons for the higher-than-expected operational costs are:

• The final design differs from the original concept
• Maintenance of thermal protection tiles turned out to be very labor-intensive, averaging about a week's work for one person to replace a tile, with hundreds damaged with each launch. ^{[citation needed]}
• The Space Shuttle main engines were highly complex and maintenance-intensive, needing removal and extensive inspection after each flight. Before the current "Block II" engines, the turbopumps (a primary engine component) had to be removed, dissembled, and totally overhauled after each flight. ^{[citation needed]}
• The launch rate has been significantly lower than initially expected. While this does not reduce actual operating costs, more launches per year gives a lower cost per launch. Some early hypothetical studies examined 55 launches per year, (see above) but the maximum possible launch rate was limited to 24 per year based on manufacturing capacity of the Michoud facility that constructs the external tank. Early in the shuttle development, the expected launch rate was about 12 per year. ^[5] Launch rates reached a peak of 9 per year in 1985 but averaged less thereafter.
• During the 1970s, the U.S. suffered from severe inflation. Between when the program began in 1972 and first flight in April 1981, inflation increased prices over 200%. When evaluating shuttle development costs in later-year dollars, this gives rise to a superficial large cost overrun in the program. In fact, discounting inflation, the shuttle development program was within the initial cost estimate given to President Richard M. Nixon in 1971. ^[5]
• The shuttles originally had an anticipated 10-year lifespan of each Shuttle. This has since been increased to around 25 years.
• When the decision was made on the main shuttle contractors in 1972, work was spread among companies to make the program more attractive to Congress and the Senate, such as the contract for the Solid Rocket Boosters to Morton Thiokol in Utah. Over the course of the program, this raised operational costs, though the consolidation of the US aerospace industry in the 1990s means the majority of the Shuttle is now with one company: Boeing.

Space Shuttle Main Engine cluster The Space Shuttle Main Engines (SSMEs) are the three main engines on the Space Shuttle orbiter. ... A turbopump can refer to either of two types of pump. ... A Trident C-4 FBM launches and fires its Thiokol solid rocket first stage Thiokol (variously Thiokol Chemical Company, Morton-Thiokol Inc. ...

Cultural issues and problems

Some researchers have identified a cultural issue in the design and maintenance of the Space Shuttle in particular and in overall NASA operations in general. Anthropologist Diane Vaughan ("The Challenger Launch Decision: Risky Technology, Culture and Deviance at NASA", University of Chicago press, 1997) examined in detail the engineering and managerial processes used in launching the shuttle. The National Aeronautics and Space Administration (NASA) is an agency of the United States Government, responsible for that nations public space program. ...

She found that in recommendations such as "think like a manager and not an engineer", aired at a videoconference before the 1986 launch of Challenger, a "normalized deviance", which can be best described as a decrease in s/r, where s is the amount of resources given to safety and r is the emphasis on ontime launches. That is, s/r's values in the 1980s started to decrease, with full buy-in from NASA upper level managers but some resistance from engineers, relative to their values in the first decade of the Shuttle. Management (from Old French ménagement the art of conducting, directing, from Latin manu agere to lead by the hand) characterises the process of leading and directing all or part of an organization, often a business, through the deployment and manipulation of resources (human, financial, material, intellectual or intangible). ... Look up engineer in Wiktionary, the free dictionary. ... 1986 (MCMLXXXVI) was a common year starting on Wednesday of the Gregorian calendar. ... The 1980s refers to the years of 1980 to 1989. ...

In addition, the late physicist Richard Feynman, appointed to the official enquiry on Challenger, published a personal statement as an appendix to the official report in which Feynman said that in some ways, NASA was trying to repeal the laws of nature in its aggressive launch schedules. [31] Richard Phillips Feynman (May 11, 1918 – February 15, 1988; surname pronounced FINE-man; ) was an American physicist known for expanding the theory of quantum electrodynamics, the physics of the superfluidity of supercooled liquid helium, and particle theory. ...

Aggressive launch schedules, according to Vaughan, started in the Reagan years as attention turned to the space program in general and the shuttle in particular (as America's only manned spaceflight after the final Apollo missions) not so much for scientific reasons but instead as a way to enhance America's prestige post-Vietnam. Famous people with the family name Reagan include: Ronald Reagan, 40th President of The United States Nancy Reagan, the wife of Ronald Reagan and influential First Lady Ron Reagan, President Reagans son and liberal journalist Michael Reagan, President Reagans son and conservative talk show host John Henninger Reagan...

Despite Feynman's warnings, and despite the fact that Vaughan served on safety boards and committees at NASA, follow-ups in the general and technical press have found that the NASA culture, described charitably as aggressive, mathematically as smaller s/r, and uncharitably as normalized deviance, persists to this day. Evidence for these claims exists in the disregard of small foam chunk breakage and the assumption that the lack of damage from past breakages made a larger and more serious incident less rather than more probable.

Shuttle operations

The Shuttle was originally conceived to operate somewhat like an airliner. After landing, the orbiter would be checked out and start "mating" to the rest of the system (the ET and SRBs), and be ready for launch in as little as two weeks. Instead, this turnaround process usually takes months; Columbia was once launched twice within 56 days. Because loss of crew is unacceptable, the primary focus of the Shuttle program is to return the crew to Earth safely, which can conflict with other goals, namely to launch payloads cheaply. Furthermore, because in many cases there are no survivable abort modes, many pieces of hardware simply must function perfectly and so must be carefully inspected before each flight. The result is high labor cost, with around 25,000 workers in Shuttle operations and labor costs of about $1 billion per year.^{[citation needed]} A Space Shuttle abort is an emergency procedure due to equipment failure on NASAs Space Shuttle, most commonly during ascent. ...

Some shuttle features initially presented as important to Space Station support have proved superfluous:

• As the Russians demonstrated, capsules and unmanned supply rockets are sufficient to supply a space station
• NASA's initial policy of using the Shuttle to launch all unmanned payloads declined in practice, and eventually was discontinued. Expendable Launch Vehicles (ELVs) proved much cheaper and more flexible.
• Following the Challenger disaster, use of the Shuttle to carry the powerful liquid fueled Centaur upper stages planned for interplanetary probes was ruled out for Shuttle safety reasons.^{[citation needed]}
• The Shuttle's history of unexpected delays also makes it liable to miss narrow launch windows.
• Advances in technology over the last decade have made probes smaller and lighter. As a result, unmanned probes and communications satellites now can use cheaper and more reliable expendable rockets, including Delta launcher, and Atlas V.

Liquid fuels are those combustible or energy-generating molecules which can be harnessed to create mechanical energy, which in turn usually produces kinetic energy, and which also must take the shape of their container. ... Model of Centaur with Surveyor as payload. ... Delta EELV family of launch vehicles (US Govt) Delta rocket (sometimes retroactively called Delta I) Delta II rocket Delta III rocket Delta IV rocket The Delta family of expendable launch vehicles has been a mainstay of the United States space launch capability since 1960. ... Launch of the Mars Reconnaissance Orbiter, 7:43:00 a. ...

Accidents

An SRB O-ring "blow by" is what caused the Challenger Accident

While the technical details of the accidents are different, the organizational problems show similarities. In both cases events happened which were not planned for or anticipated. In both cases, engineers were greatly concerned about possible problems but these concerns were not properly communicated to or understood by senior NASA managers. The vehicle gave ample warning beforehand of abnormal problems. A heavily layered, procedure-oriented bureaucratic structure inhibited necessary communication and action. A mind set among senior managers developed that concerns had to be objectively proven rather than simply suspected.^{[citation needed]} Image File history File links Download high resolution version (550x750, 9 KB) Summary Camera E-207 show a plume near the aft struct that attaches the right solid rocket booster to the external tank. ... Image File history File links Download high resolution version (550x750, 9 KB) Summary Camera E-207 show a plume near the aft struct that attaches the right solid rocket booster to the external tank. ... For further information about Challengers mission and crew, see STS-51-L. An iconic image of the accident. ...

With Challenger an O-ring which should not have eroded at all did erode on earlier shuttle launches. Yet managers felt because it had not previously eroded by more than 30%, that this was not a hazard as there was "a factor of three safety margin". Morton Thiokol designed and manufactured the SRBs, and during a pre-launch conference call with NASA, the Thiokol engineer most experienced with the O-rings pleaded with management repeatedly to cancel or reschedule the launch. He raised concerns that the unusually cold temperatures would stiffen the O-rings, preventing a complete seal, which was exactly what happened on the fatal flight. However, Thiokol's senior managers overruled him, dismissing his safety concerns and allowed the launch to proceed. Challenger's O-rings eroded completely through as predicted, resulting in the complete destruction of the spacecraft and the loss of all seven astronauts on board. Factor of safety (FoS), also known as Safety Factor, is a multiplier applied to the calculated maximum load (force, torque, bending moment or a combination) to which a component or assembly will be subjected. ...

Columbia was destroyed because of damaged thermal protection from foam debris that broke off the external tank during ascent. The foam had not been designed or expected to break off, but had been observed in the past to do so without incident. The original shuttle operational specification said the orbiter thermal protection tiles were designed to withstand virtually no debris hits at all. Over time NASA managers gradually accepted more tile damage, similar to how O-ring damage was accepted. The Columbia Accident Investigation Board called this tendency the "normalization of deviance" — a gradual acceptance of events outside the design tolerances of the craft simply because they had not been catastrophic to date.^{[citation needed]} The Thermal Protection System (TPS) is the overall name for a collection of systems that protect the Space Shuttle from heat generated during reentry. ... Memorial emblem for the three U.S. human space flight accidents. ...

The subject of missing or damaged thermal tiles on the Shuttle fleet only became an issue following the loss of Columbia in 2003 as it broke up on re-entry. In fact Shuttles had previously come back missing as many as 20 tiles without any problem. STS-1, STS-16 and STS-41 have all flown with missing thermal tiles from the orbital maneuvering system pods (visible to the crew). This image from the NASA archives shows many missing tiles on the STS-1 OMS pods : [32] The problem on Columbia was that the damage was sustained to the carbon-carbon leading edge panel of the wing, not the heat tiles. On the same subject, a little-publicized detail about the first Shuttle mission, STS-1, was that it had a protruding gapfiller that ducted hot gas into the right wheel well on re-entry, resulting in a buckling of the wheel well door.[33]

Looking back

The neutrality of this section is disputed. Please see the discussion on the talk page.

Opinions differ on the lessons of the Shuttle. While it was developed within the original cost and time estimates given to President Richard M. Nixon in 1971 [34], the operational costs, flight rate, payload capacity, and reliability have been much worse than anticipated. In order to get the shuttle approved, NASA over-promised its economies and utilty. To justify its very large fixed operational program cost, NASA first forced all domestic, internal, and DOD payloads to the shuttle. When that proved impossible (after the Challenger disaster), NASA used the space station as a justification for the shuttle. Some speculate had NASA avoided the shuttle program and instead continued to use Saturn and commercially available boosters that costs might have been lower, freeing funds for manned exploration and more un-manned space science. The domestic commercial booster industry could have been stimulated, with more resources directed towards lowering the cost of space access. Image File history File links Unbalanced_scales. ...

It can be argued that the general concept of a reusable manned launch vehicle was good, but the shuttle's implementation was flawed. To achieve a reusable vehicle with early 1970s technology entailed several design decisions that compromised operational reliability and safety. For example, an early point in the design phase, reusable main engines became a priority. This necessitated that they not burn up upon atmospheric reentry, which in turn made mounting them on the orbiter itself (the one part of the shuttle system where reuse was paramount) a seemingly logical decision. However, this had the following knock on effects;

• a more expensive 'clean sheet' engine design was needed, using more expensive materials, as opposed to existing and proven off-the-shelf alternatives (such as the Saturn V mains),
• increased ongoing maintenance costs related to keeping the reusable SSMEs in flying condition after each launch, costs which in total may have exceeded that of building disposable main engines for each launch,
• less absolute tonnage available to be lifted into space, since the mass of the SSMEs attached to the orbiter necessarily cut into the craft's 'payload budget' (more payload launched at any one time, by definition, reduces launch costs per pound), and
• having the orbiter mounted on the side of the launch stack makes it more vulnerable to debris shed from the external tank and solid rocket boosters. In the Columbia disaster, the vehicle and crew were lost because of shed debris damaging the orbiter heat shield.

Some maintain that the Shuttle program advanced the State of the Art, while others say the shuttle program only made incremental advances and pushed the early 1970s technology excessively to build a new capability. Some argue the high costs of the Shuttle program caused the cancellation of worthy manned (X-38, DC-X, X-33, X-34, etc.) and un-manned programs, however some of these such as the X-33 had troubled development histories. The shuttle program also caused all other US boosters (ELVs) to be discontinued until the Challenger accident thereby costing the US initiative in ELV technology. The X-33 was a technology demonstrator for NASAs next-generation of space launch vehicle. ...

Looking ahead

Future designers look to more economical and reliable launch systems with lower maintenance and operational costs. One approach is Single Stage To Orbit (SSTO), which would be 100% reusable and use a single stage. NASA evaluated several concepts in the 1990s, and selected the X-33, which would eventually have been the VentureStar. During design that program increased in complexity and development cost, encountered problems and was finally canceled. A single-stage to orbit (or SSTO) vehicle could reach orbital velocity without using multiple stages. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... VentureStar VentureStar was Lockheed-Martins proposed design for a SSTO RLV. The programs primary goal was to develop a reusable unmanned space plane for launching satellites into orbit at about 1/10 the cost of other systems that would completely replace the space shuttle. ...

Another variant of SSTO is a hypersonic, scramjet-powered, airbreathing vehicle. This would be launched and landed horizontally like an airliner. It would achieve much of orbital velocity while still within the upper atmosphere. It was originally investigated by the U.S. Department of Defense, but passenger-carrying civilian versions were planned, sometimes called the "New Orient Express". The official name was the Rockwell X-30. Like the X-33, the X-30 encountered major technical difficulties, primarily due to the system complexity and materials required for hypersonic flight, and was also canceled. A single-stage to orbit (or SSTO) launcher describes an as-yet theoretical class of spacecraft designed to place a load into orbit as a self-contained vehicle without the use of multiple stages. ... Boeing X-43 at Mach 7 In aerodynamics, hypersonic speeds are speeds that are highly supersonic. ... X-43A with scramjet attached to the underside at Mach 7 A scramjet (supersonic combustion ramjet) is a variation of a ramjet where the flow of the air and combustion of the fuel air mixture through the engine happen at supersonic speeds. ... The United States Department of Defense, abbreviated DoD or DOD and sometimes called the Defense Department, is a civilian Cabinet organization of the United States government. ... 1986 artists concept of X-30 on liftoff. ...

Another approach is lower cost expendable launch vehicles. NASA currently uses commercial ELVs for unmanned launches, and could use commercial ELVs for future manned launches. This would fit with NASA's mandate to promote commercial access to and use of space. However, NASA plans on rejecting the low-cost commercially available boosters, and instead, designing their own similar but competing boosters using modified shuttle components to build an expendable Shuttle Derived Launch Vehicle. This technology would be used to develop two separate launchers, one for manned missions and the other for unmanned heavy cargo. This contrasts with the current shuttle where astronauts and heavy cargo are launched in a single vehicle. Unlike the shuttle, this future launcher and associated crew exploration vehicle will have a launch escape system to greatly improve the chances that the crew can be saved in the event of a disaster. Comparison of the Saturn V, Space Shuttle and the two Shuttle Derived Launch Vehicles proposed to replace the Shuttle. ... CEV with lunar lander CEV during a landing on earth CEV rocket, the Crew Launch Vehicle (CLV) (right) along side the heavy-lift Cargo Launch Vehicle (CaLV) rocket. ... Apollo LES Pad Abort test A Launch Escape System (LES) is a top-mounted rocket connected to the crew module of a crewed spacecraft and used to quickly separate and launch the crew module away from the rest of the rocket in the case of an emergency. ...

The proposed CEV and CaLV bear a strong resemblance to the Saturn I & V rockets respectively - even to the point of the proposed launchers being numbered in honor of their predecessors; Ares I & V. In terms of flight profile, hardware design concept, and mission capabilities, there is actually little to choose between Ares and Saturn - though the proposed CEV is larger than the Apollo CM. Some critics have seized upon this as a serious indictment of the shuttle program. They argue that if a Saturn-type mission architecture is technically and economically viable for missions currently performed by the shuttle, then the Saturn launchers should never have been abandoned in the first place, and that the shuttle has been a massive waste of time and money.

The reversion of NASA to the capsule/booster technology of Ares/CEV/CaLV must be viewed as a clear rejection of the shuttle concept. Burt Rutan of Scaled Composites, the company that successfully designed, built, and flew the world's only privately funded reusable spaceplane, SpaceShip One, has had harsh words for NASA’s Shuttle and CEV programs. Likening the agency's new Moon-shot efforts to "archeology", Rutan contends that the space program must encourage some risk in technological development in order to continue to innovate. He says of NASA's current strategy:

"They are forcing the [Ares/CEV] program to be done with technology that we already know works. They are not creating an environment where it is possible to have a breakthrough ... It doesn’t make sense." [35] This echoes other arguments that NASA should utilize commercially available boosters where possible, and concentrate on space exploration, space science, and research and development to reduce the cost of space access. These arguments assume that the Shuttle program has run its course, and needs to be retired to make way for a new generation of cost effective and efficient vehicles.

Many feel that the decision by NASA to spurn commercially available Delta IV and Atlas V boosters, and instead, design and develop their own versions, is unwise. They think government should use commercially available products where available, rather than develop their own, and thereby reduce the cost of access to space. Many feel that NASA should instead promote private enterprise, and devote national resources to meaningful technology advancements rather than replicating existing ELVs.

References

Futron Corporation, founded in 1986, is a minority-owned technology consulting firm based in Bethesda, Maryland. ... September 6 is the 249th day of the year (250th in leap years). ... For album titles with the same name, see 2002 (album). ... 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... November 2 is the 306th day of the year (307th in leap years) in the Gregorian Calendar, with 59 days remaining. ... August 10 is the 222nd day of the year (223rd in leap years) in the Gregorian Calendar. ... 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... November 2 is the 306th day of the year (307th in leap years) in the Gregorian Calendar, with 59 days remaining. ... July 28 is the 209th day (210th in leap years) of the year in the Gregorian Calendar, with 156 days remaining. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... November 2 is the 306th day of the year (307th in leap years) in the Gregorian Calendar, with 59 days remaining. ... July 29 is the 210th day (211th in leap years) of the year in the Gregorian Calendar, with 155 days remaining. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... November 2 is the 306th day of the year (307th in leap years) in the Gregorian Calendar, with 59 days remaining. ... The National Aeronautics and Space Administration (NASA) is an agency of the United States Government, responsible for that nations public space program. ... April 23 is the 113th day of the year in the Gregorian Calendar (114th in leap years). ... 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... August 6 is the 218th day of the year in the Gregorian Calendar (219th in leap years), with 147 days remaining. ...

External links

• When Physics, Economics, and Reality Collide: The Challenge of Cheap Orbital Access
• Review of ELV cost-to-orbit per pound
• Space Transportation Costs: Trends in Price Per Pound to Orbit