Space Shuttle Replacement

[spacefanagain]

If a new generation space shuttle was to be designed, what improvements would be made?

 

[KosmicHero]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>If a new generation space shuttle was to be designed, what improvements would be made? <br />Posted by spacefanagain</DIV><br /><br />We would make it a capsule and call it Orion.</p><p>&nbsp;I think that we've come to the realization that a shuttle which could carry large masses to space and flown to locations by humans is not really viable right now.&nbsp; There isn't enough of a manifest to warrant it.&nbsp; Also, the advances in automated docking and computer guidance methods are superior to human docking techniques.&nbsp; So it makes sense to separate those two capabilities in the same way that Orion and Ares V do.</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> kosmichero.wordpress.com </div>

 

[qso1]

<p>NASA tried this several times since the 1980s. They were called NASP, Orient Express, Delta Clipper, Venture Star, Shuttle II, and all met the cost barrier.</p><p><font color="#800080">KosmicHero</font> commented <font color="#800080">"I think that we've come to the realization that a shuttle which could carry large masses to space and flown to locations by humans is not really viable right now."</font> And I would largely agree with that. The only hope I can see now is that private industry/enterprise will find a viable economic solution to the problem of economical access to low orbit. </p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[JimL]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>he only hope I can see now is that private industry/enterprise will find a viable economic solution to the problem of economical access to low orbit. <br /> Posted by qso1</DIV></p><p>I would agree, but how would you get private industry to include the thousands of unnecessary design complications required for government approval?&nbsp;</p>

 

[qso1]

<p><font color="#800080">I would agree, but how would you get private industry to include the thousands of unnecessary design complications required for government approval? Posted by JimL</font></p><p>The lack of these design complications is what would likely greatly aid private industry in pulling this off. I think even the government is ready for change because they can see funding NASA beyond bandaid funding and placebic budget increases is never going to be reality anytime soon.</p><p>Anyone in government working with government financing (OMB) surely knows NASAs budget history. NASA went from 2 to 4% of GDP in the 1960s early 70s to 1 to .6% GDP since the 1970s. If private industry cannot get economic access to space to become reality, then human spaceflight is probably over for the United States in the foreseeable future.&nbsp;</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[JimL]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I think even the government is ready for change&nbsp; <br /> Posted by qso1</DIV><br /><br />Your optimism leads me to wonder if you are new to this part of space or only new to this country.<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" /> </p>

 

[Cygnus_2112]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I would agree, but how would you get private industry to include the thousands of unnecessary design complications required for government approval?&nbsp; <br /> Posted by JimL</DIV></p><p>That is an outdated sterotype.&nbsp; Typical of someone not in the know. </p><p>&nbsp;Government approval is not required.&nbsp; NASA doesn't buy hardware, it buys launch services from ELV contractors for its unmanned spacecraft .&nbsp; Basically, take this satellite and put it into orbit. &nbsp;</p><p>&nbsp;</p><p>Also why does it have to be a "shuttle"&nbsp;</p>

 

[Swampcat]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That is an outdated sterotype.&nbsp; Typical of someone not in the know. Posted by Cygnus_2112</DIV><br /><br />Careful, Jim. Yor're gonna blow your cover and get banned again.<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" /> <div class="Discussion_UserSignature"> <font size="3" color="#ff9900"><p><font size="1" color="#993300"><strong><em>------------------------------------------------------------------- </em></strong></font></p><p><font size="1" color="#993300"><strong><em>"I hold it that a little rebellion now and then is a good thing, and as necessary in the political world as storms in the physical. Unsuccessful rebellions, indeed, generally establish the encroachments on the rights of the people which have produced them. An observation of this truth should render honest republican governors so mild in their punishment of rebellions as not to discourage them too much. It is a medicine necessary for the sound health of government."</em></strong></font></p><p><font size="1" color="#993300"><strong>Thomas Jefferson</strong></font></p></font> </div>

 

[MeteorWayne]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Careful, Jim. Yor're gonna blow your cover and get banned again. <br />Posted by Swampcat</DIV><br /><br /><img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-yell.gif" border="0" alt="Yell" title="Yell" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[crazyeddie]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Careful, Jim. Yor're gonna blow your cover and get banned again. <br /> Posted by Swampcat</DIV></p><p>"Jim" ?? &nbsp;who is/was Jim?&nbsp;</p> <div class="Discussion_UserSignature"> </div>

 

[kyle_baron]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Careful, Jim. Yor're gonna blow your cover and get banned again. <br />Posted by Swampcat</DIV></p><p>&nbsp;</p><p>I believe in 2nd chances.&nbsp; A little pessimism&nbsp;now and then, won't&nbsp;hurt anyone.<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" /><br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>

 

[MeteorWayne]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;I believe in 2nd chances.&nbsp; A little pessimism&nbsp;now and then, won't&nbsp;hurt anyone. <br />Posted by kyle_baron</DIV><br /><br />Except it's the 4th chance <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[qso1]

<p><font color="#800080">Your optimism leads me to wonder if you are new to this part of space or only new to this country. Posted by JimL</font></p><p>Optimism has little to do with it. The number of private enterprise upstarts that are actually doing things has jumped in the last decade, especially since the "X" prize was won by Burt Rutan and Scaled Composites. NASA itself has just awarded a contract to Space "X", one of the upstart companies to which I'm referring.</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That is an outdated sterotype.&nbsp; Typical of someone not in the know. &nbsp;Government approval is not required.&nbsp; NASA doesn't buy hardware, it buys launch services from ELV contractors for its unmanned spacecraft .&nbsp; Basically, take this satellite and put it into orbit. &nbsp;&nbsp;Also why does it have to be a "shuttle"&nbsp; <br />Posted by Cygnus_2112</DIV></p><p>NASA does in fact get involved in the details of the hardware for the "launch services" that they buy.&nbsp; For the modifications made to the Pegasus launch vehicle&nbsp;for the Hyper-X vehicle, doe instance, &nbsp;NASA not only got involved with the launch provider but with the make of the solid rocket motors.&nbsp; They did not provide design, but did participate in technical reviews of the design modifications, the manufacturing processes, and the as-built configuration and quality paper.&nbsp; In fact the number of NASA people involved in the reviews greatly outnumbered the number of contractor people (the NASA program manager referred to throng of NASA employees as "strap hangers").</p><p>Maybe the gentleman that you insulted is more in the know that you think, and perhaps you are less so.<br /></p> <div class="Discussion_UserSignature"> </div>

 

[Cygnus_2112]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>NASA does in fact get involved in the details of the hardware for the "launch services" that they buy.&nbsp; For the modifications made to the Pegasus launch vehicle&nbsp;for the Hyper-X vehicle, doe instance, &nbsp;NASA not only got involved with the launch provider but with the make of the solid rocket motors.&nbsp; They did not provide design, but did participate in technical reviews of the design modifications, the manufacturing processes, and the as-built configuration and quality paper.&nbsp; In fact the number of NASA people involved in the reviews greatly outnumbered the number of contractor people (the NASA program manager referred to throng of NASA employees as "strap hangers").Maybe the gentleman that you insulted is more in the know that you think, and perhaps you are less so. <br /> Posted by DrRocket</DIV></p><p>&nbsp;</p><p>You are mistaken on many counts. </p><p>Hyper-X was not a launch service.&nbsp; Nor was it a orbital launch vehicle.&nbsp; Hyper-X is a case were NASA bought the hardware and is nothing like other launches.&nbsp; Additionally, the extra insight was in response to the failure. </p><p>And the gentleman couldn't be more in the know</p><p>&nbsp;Additionally, I take his comment as an insult&nbsp; </p>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;You are mistaken on many counts. Hyper-X was not a launch service.&nbsp; Nor was it a orbital launch vehicle.&nbsp; Hyper-X is a case were NASA bought the hardware and is nothing like other launches.&nbsp; Additionally, the extra insight was in response to the failure. And the gentleman couldn't be more in the know&nbsp;Additionally, I take his comment as an insult&nbsp; <br />Posted by Cygnus_2112</DIV></p><p>Sorry, I was there.<br /></p> <div class="Discussion_UserSignature"> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I would agree, but how would you get private industry to include the thousands of unnecessary design complications required for government approval? Posted by JimLThe lack of these design complications is what would likely greatly aid private industry in pulling this off. I think even the government is ready for change because they can see funding NASA beyond bandaid funding and placebic budget increases is never going to be reality anytime soon.Anyone in government working with government financing (OMB) surely knows NASAs budget history. NASA went from 2 to 4% of GDP in the 1960s early 70s to 1 to .6% GDP since the 1970s. If private industry cannot get economic access to space to become reality, then human spaceflight is probably over for the United States in the foreseeable future.&nbsp; <br />Posted by qso1</DIV></p><p>Design complications are really not the issue.&nbsp; Rocket designs are actually about as simple as it is possible to make them.&nbsp; The cost of the hardware involved in a launch is actually a relatively small part of the cost of the launch itself.&nbsp; What tends to drive the cost is the cost of preparation of the vehicle, particularly payload work and integration of the payload with the propulsion system.&nbsp; Even with respect to the hardware itself, a good deal of the cost is associated with inspection, quality control, ongoing engineering work and documentation.</p><p>Let's take a solid rocket motor as an example.&nbsp; The design of a solid involves relatively few parts, and in that regard is "simple".&nbsp; There is a good deal more sophistication involved in the materials and design nuances than meets the eye however.&nbsp; We'll consider one typical of that used to launch a big satellite.</p><p>Start with the case.&nbsp; Most large solids of recent manufacture, the shuttle motors are an exception, use a graphite composite case.&nbsp; That case is wound using a specific fiber and a specific resin on a mandrel on top of a piece of rubber that insulates the case structure from hot gasses.&nbsp; The rubber is compounded from specific raw stock including and elastomer and typically an&nbsp;aramid fiber (like Kevlar) that is added to make the charred rubber adhere to the virgin rubber more tenaciously during the burn.&nbsp; The material lots are tested and come with "written certifications" that are recorded an put into a log book that documents the condition of the case after it built.&nbsp; The rubber is mixed to specification and each step in the manufacturing process is witnessed and stamped off.&nbsp; Then the rubber is used to manufacture the insulator, either by winding raw rubber directly onto the mandrel or by modeling and curing it beforehand.&nbsp; Again each step in the process is noted, entered into a log book and stamped off.&nbsp; Once the insulator is put on the mandrel, and again the process is inspected and stamped off, the case winding process begins.&nbsp; The materials for the case have been manufactured, each lot of fiber has been tested and the data verified and certified.&nbsp; Resin chemistry has been verified and certified.&nbsp; For wet wound cases the resin is mixed to specification and the mix parameters recorded and stamped off.&nbsp; The case is wound, winding parameters, most importantly band tensions&nbsp;and time for each layer are recorded and stamped off.&nbsp; The case is taken to the cure oven.&nbsp; The temperature-time curves for the cure are measured, recorded and stamped off.&nbsp; The case is removed from cure and inspected using a variety of inspection techniques, most prominently checks of all dimensions and ultrasound inspection of the quality of the composite itself in a set-up customized to the particular rocket motor case.&nbsp; Any discrepancies are written up and sent to engineering for disposition.&nbsp; In fact, any item found at any time to be outside of tight specification limits is referred to engineering for disposition -- use, rework or scrap.&nbsp; Each disposition requires documentation and a signature by an engineer with specific authority over that aspect of the case.&nbsp; The case is then taken to hydroproof, instrumented with strain gauges and sometimes more sonic sensors and taken up to a proof pressure, typically 1.1 times the maximum expected operating pressure MEOP (MEOP typically assumes a statistically high propellant burn rate at high temperature and is never actually achieved in a launch).&nbsp; The data from the hydroproof receives engineering evaluation and a go/no go decision is made.&nbsp;If all is well, the case is accepted and is sent to the propellant cast facility.</p><p>In parallel, a nozzle is manufactured.&nbsp; The care in that component is similar.&nbsp; Materials are tested and certified.&nbsp; Manufacturing parameters are stamped off.&nbsp; Components are tested via w-ray, ultra-sound and sometimes with CT.</p><p>Ordnance components are manufactured, certified, and inspected, often with N-ray.</p><p>Propellant is prepared.&nbsp; Components are evaluated for chemistry.&nbsp; Ammonium perchlorate is ground to specified particle size distributions and particle size checked.&nbsp; Aluminum particle size is verified.&nbsp; Binder lots are checked for molecular weight and strength.&nbsp; Small trial batches are mixed, burn rate checked and mechanical strength verified.&nbsp; Full scale mixes are made, and mix parameters verified and stamped off.&nbsp; Uncured propellant is sampled and tested for burn rate and mechanical properties.&nbsp; Cure catalyst is added to the mix the mix completed, samples taken and the propellant poured into a waiting case over a core mandrel.&nbsp; Cure is monitored, parameters recorded and verified.&nbsp; In the meantime the sampled propellant is checked for burn rate and mechanical properties and the results recorded and evaluated by engineering.&nbsp; The mandrel is removed, and extraction forces measured and recorded.&nbsp; The loaded case is weighed and the CG determined.&nbsp; All data is recorded an put in the log book.</p><p>The loaded case is taken to finishing and final assembly.&nbsp; Stand-offs and brackets are bonded onto the case.&nbsp; The epoxy used has been verified for chemistry, the mix parameters stamped off and each step in the manufacturing instructions verified with key points stamped off.&nbsp; Each bracket is subjected to a pull test, and the results recorded.&nbsp; Location is likewise inspected and stamped off.&nbsp; Any discrepancy is dispositioned by engineering.&nbsp; The nozzle is installed,&nbsp; All o-rings have been inspected and verified.&nbsp; The igniter is installed, and thru-bulkhead-initiators installed in the igniter closure.&nbsp; All o-rings in those components have also been inspected and verified.&nbsp; A closure is placed in the nozzle throat, and the motor is pressurized with a gas that contains a small amount of helium.&nbsp; Pressure is held and measured to verify that there are no leaks.&nbsp; In addition a helium detector is used to sniff for helium&nbsp;leaks near all joints.&nbsp; Once the leak check is passed, the nozzle, igniter and TBIs cannot be removed without repeating the test.&nbsp; Finally the thrust vector activation system may be installed and function verified and certified.&nbsp; The rocket motor is now ready for shipment on equipment specifically designed and build for that particular design.</p><p>With all of that, the rocket motor is a small part of the cost of the launch.&nbsp; Similar care is taken with other components and with the assembly at the launch site.&nbsp; And with all of that, the rocket and launch are much less expensive than a typical unmanned launch payload.&nbsp; It is the value of the payload that justifies&nbsp;the extreme care and cost of the launch and the components of the launch.</p><p>The payload people want this level of check and verification.&nbsp; They want it because the payloads cost billions and return much more in revenue. or in military intelligence.&nbsp; Failure of a rocket will destroy that very expensive payload and delay the revenue stream from a commercial satellite or, worse, might deny needed intelligence to a soldier on the front line.</p><p>And why is such inspection and care needed for reliability?&nbsp; Gravity is worthy opponent.&nbsp; Launch systems are high performance items.&nbsp; They are closer to a Ferrari than to a Peterbilt.&nbsp; To get the needed performance systems and subsystems are designed to be a light in weight as possible consistent with high reliability.&nbsp; There are few backup systems, everything must work or the mission fails.&nbsp; In terms of a reliability engineer, a rocket is a string of single-point failure modes.&nbsp; So they are built to minimize the potential for anything to fail.&nbsp; If you were to be a passenger would you expect anything less ?&nbsp; This care is driven by the commercial customer as much as by the government customer.</p><p>There is one area where, no matter whether the payload is government or commercial, the government requirements rule.&nbsp;&nbsp;That is in the area of range safety and particularly with the destruct system&nbsp; The eastern and western test ranges have jurisdiction over the destruct system and determine whether or not it is used.&nbsp; Destruct system designs and manufacture must meet their requirements.&nbsp; They know what they want, and they get it.&nbsp; Other government agencies must meet their requirements, period.&nbsp; They are not unreasonable.&nbsp; They are very strict.&nbsp; What they demand is that the destruct system absolutely do its job when called upon to do so and the when it is used no debris leaves the launch corridor.&nbsp; Nobody launches until range safety is satisfied. And when the launch, it is range safety who has their finger on the destruct button.&nbsp; I personally have nothing but respect for these guys.</p><p>There are arenas in which costs can be reduced safely.&nbsp; Chiefly in the area of bureaucratic paperwork and in the size of the crew used at the launch site for preparation of the rocket and payload.&nbsp; There is also money to saved by use of common components across a family of launchers, and that is being done with EELV systems.&nbsp; But there are really no major design shortcuts in the rocket itself that would be available to a commercial launch provider that are consistent with the high reliability that is needed.</p> <div class="Discussion_UserSignature"> </div>

 

[Cygnus_2112]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Sorry, I was there. <br /> Posted by DrRocket</DIV></p><p>Still doesn't change the facts that I stated.&nbsp; Hyper-X was not a spacecraft nor was the launch vehicle procured through the standard procument for launch services </p>

 

[Cygnus_2112]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Chiefly in the area of bureaucratic paperwork and in the size of the crew used at the launch site for preparation of the rocket and payload.&nbsp; </DIV></p><p>What&nbsp; bureaucratic paperwork?&nbsp; There isn't any except for the processes you mentioned.</p><p>How is the size of the crew reduced when it has to do all the processes you listed&nbsp;</p>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Still doesn't change the facts that I stated.&nbsp; Hyper-X was not a spacecraft nor was the launch vehicle procured through the standard procument for launch services <br />Posted by Cygnus_2112</DIV></p><p>Hyper-X was not a spacecraft.&nbsp; It was a verhicle for an air-breathing propulsion test, a scramjet.&nbsp; However, the vehicle on which it was carried was a modification of the Pegasus launch vehicle which is a space laucher, and one that NASA also uses for other purposes.&nbsp; I cited that particular mission because I have detailed knowledge of NASA's participation.&nbsp; They also participate in the decision making of other un-manned missions.&nbsp; They even sometimes are invited to participate with the Air Force.&nbsp; Their participation varies, but it is not a totally hands-off proposition.</p><p>I don't know quite what you mean my the "standard procurement for launch services".&nbsp; It certainly was procured in compliance with the FAR.&nbsp; </p><p>Not sure what makes you so over-confident of your opinion.&nbsp; Do you have some expertise that is not evident ?</p> <div class="Discussion_UserSignature"> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>What&nbsp; bureaucratic paperwork?&nbsp; There isn't any except for the processes you mentioned.How is the size of the crew reduced when it has to do all the processes you listed&nbsp; <br />Posted by Cygnus_2112</DIV></p><p>The crew is quite large and not 100% utilized at all times.&nbsp; There is room for significant increase in efficiency.&nbsp; That was one of the reasons for the EELV program.&nbsp; It is also possible to make some of the processes more efficient, and allow more of them to proceed in parallel rather than in series.&nbsp; Payload preparation is one example where some of that can be accomplished.&nbsp; In some cases the preparation of the propulsion piece is shut down while classified work is carried on the payload which is mounted on the launch vehicle at the time.&nbsp; When that can be done in parallel and off-line efficiencies are obtained.</p><p>There is a tremendous amount of reporting and communication between engineering groups, often through rather inefficient contractual channels that can be siimplified.&nbsp; Time is money and speeding up communication and resolution of issues can save a ton of it.&nbsp; There are also often a myriad of formal reports that are required by specification and many times not used for any constructive purpose.&nbsp; That is one reason that when the EELV RFP went out, the Air Force imposed only one specification.&nbsp; Contractors then had the flexibility to propose alternate means of doing business for consideration by the customer.</p><p>Reduction in the size of the launch crew was one of the significant cost reduction steps taken in the EELV program.&nbsp; The benchmark for reduction was the Titan IV program, and a major rationale for EELV was to provide an alternate and less expensive heavy lift capability to replace Titan IV.</p><p>Small launch vehicle providers have tried, with some success, to reduce costs by simplifying launch site operations.&nbsp; Pegasus is a case in point.&nbsp; It is relatively inexpensive on a per launch basis, at about $20 million give or take.&nbsp;&nbsp; But it still is expensive on a per pound to orbit basis, and the individual launch costa are nearly double the original goal.&nbsp; Still it has a substantially lower launch site cost, both because of&nbsp;preparation procedures and because of the use of an aircraft as the "zero stage".</p> <div class="Discussion_UserSignature"> </div>

 

[aphh]

<p>Why shuttle type winged spacecraft?</p><p>A small shuttle with good cross-range could land on any runway thus enabling rapid deorbit in case of emergency. </p>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Why shuttle type winged spacecraft?A small shuttle with good cross-range could land on any runway thus enabling rapid deorbit in case of emergency. <br />Posted by aphh</DIV></p><p>Could you expand on your question.&nbsp; I don't think I understand the total issue.<br /></p> <div class="Discussion_UserSignature"> </div>

 

[aphh]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Could you expand on your question.&nbsp; I don't think I understand the total issue. <br /> Posted by DrRocket</DIV></p><p>Somebody asked earlier why the spacecraft should be shuttle type with wings. With wings you could glide and change the landing trajectory. This would give a lot more entry opportunities for rapid deorbit.</p><p>The NASA concept was HL-20, a lifting body design originally developed by the Russians, which has been further developed by Spacedev and called DreamChaser. I have no knowledge whether DreamChaser project has made progress recently.&nbsp;</p>

 

[wubblie]

I think the next generation shuttle was already produced in the Energia/ Buran system. The main engines would be located on the external tank, not the orbiter. This would allow a corgo-only configuration. If the shuttle had been designed this way, we would not need the Aries IV, so it would have been very easy to go back to the moon by simply producing a stick-capsule medium lift rocket for the crew. There would not be any pause in the manned mission, because we could send modules to the moon using Energia-like rocket while we were waiting for the manned capsule to be produced. Yes, the decision to use the "piggy back" configuration was a mistake, but the much more crucial mistake was the decision to mount the engines on the shuttle. It may even be that we would continue to use the shuttle system to ferry people to the ISS. Even though it is probably more dangerous than using a stick-capsule, we have yet to see if a stick-capsule design is feasible for ferrying 6 people into space (we'll soon find out). Also, one has to wonder if the Ares I will be any safer than the shuttle. The shuttle 1s 118-120 *overall*, but as with any system, after every mistake, it actually becomes more safe, because the things that can break are fixed, reducing the number of failure modes. So, I think it is safe to say that the shuttle is probably 99% safe today. We'll see if any stick-capsule design lifting 6 people can reach this level of safety. I know that I would rather fly on STS-134 than Area-1-1. Of course, the fact that the shuttle cannot do heavy-lift duty *combined* with the fact that using a capsule is more efficient is what doomed the shuttle program. If we had used a Buran-like shuttle, the program would not be cut, and we could have a space station and moon base.