What would have saved Challenger was the first "all-the-way-down" human decision turtle: 15% higher cost for one-piece SRBs instead of the 4-piece propellant sections.
If only the decision was that simple... Sadly, it wasn't.
First there were performance issues; The solid motors need to match to within 5% of each other - which proved essentially impossible to achieve with a monolithic grain as the propellant tended to stratify during the extended pour and the extended curing time. The solid motors needed to have consistent and predictable performance during the burn - which was almost impossible to achieve due to the aforementioned stratification problems. Both problems were also made worse because they couldn't figure out how to safely mix and pour the grains for both boosters in a single batch. Segmented grains, which could be poured in LH and RH segments from a single (smaller) batch suffered from none of these problems.
Next, there's storage and handling problems. The larger the grain, the heavier it is, and the harder it is to prevent it from flowing and deforming under it's own weight. Equally, since the large grains have to be cast upside down they have to be rotated rightside up - and nobody knew how to do that with large monolithic grains. A flex of as little as a couple of millimeters could crack the grain or lead to delamination. Also, segments could be stored individually, reducing fire and explosion risk.
Inspecting the grains with the technology of the time was also several orders of magnitude harder for a large monolithic grain.
Lastly, while there was a only a limited base of flight experience with large segmented grains (via the Titan IIIC)... there was no flight experience with large monolithic grains.
tl;dr version - there were a lot fewer known unknowns with segmented solids than with monolithic solids. A number of the known unknowns for monolithic grains were either outright show stoppers or could result in ruinously expensive R&D programs to discover if a solution was even possible. The known unknowns for segmented grains were all issues of scaling from existing experience.
Why on earth or space would you design an escape system like this?
Because it's solid fueled and thus much more reliable than liquids and, depending on design details, much faster to react. Also, it's pretty easy to build in a passive attitude control system that arcs the capsule out of the booster's path while the Draco will require active differential throttling. (Which in the case of Orion also increases reliability, as the launch abort system doesn't depend on guidance being available.)
I believe that this must be disposed of on every flight
Which also means it isn't carried to orbit and poses no further risk to the crew or mission. It also reduces total landed weight, reducing the size of the parachutes required and/or reducing landing shock for the same size parachutes.
and the separation is not without risk
Nothing is without risk - and Draco has a number of risks inherent in it's higher parts count and more complex operation that the Orion launch abort system does not have.
There are advantages and disadvantages to both approaches. Neither NASA nor Musk has the absolute One Best Design - because there isn't any such thing. (And both of them are leaps and bounds above the complex horror that is Soyuz's launch abort system. Sure, it worked when called on... but that doesn't change the nature of the beast.)
Provided, off course, that they hadn't mounted the payload NEXT to the exploding external fuel tank... yes, I know doing it that way let you have lighter structure, but it introduced a whole range of problems and failure modes you wouldn't have had if the orbiter had been mounted on top.
Mounting the orbiter on top has it's drawbacks too... The orbiter's wings now act a lot more like fins, making it harder to maneuver during the early part of the ascent and inducing (very) high structural loads on the stack. And of course the wings are generating lift... right at the part of the stack where they have a nice long lever arm. In addition, if you screw up the stack's angle of attack, you can end up with the wings at an undesirable angle to the apparent wind. (Undesirable in this case means "the wings are trying to turn the vehicle but not the stack", I.E. tearing the vehicle off the top of the stack.)
Second, the boosters cannot be shut off. That's the big safety drawback of solid rockets - you light them, and they aren't going out until they're out of fuel.
*sigh* This is one of the biggest pieces of misinformation about solid rockets floating about out there, spread and repeated by shuttle detractors in a cargo cult like fashion until it's now regarded as a law of nature. What most people (including engineers who should know better) don't realize is that you don't need to shut them down in the first place- you just need them to produce net zero thrust. This is done via blowout panels in the front dome, and sometimes by blowing off the nozzle as well. And it's not like this is a new fangled technique either... It was used on the Polaris A-1 and A-2, Poseidon C-3, SUBROC, ASROC, Minuteman I and -II, and Peacekeeper missiles. It would have been used of the SRB's of the Titan IIIC booster for manned Dyna-Soar and MOL launches. It's used by Minuteman III missiles...
It wasn't used by the Shuttle because during the SRB burn, the SRB's are essentially 'dragging' the ET behind it... and thrust termination would have resulted in them 'hanging' from the ET or having to be jettisoned and the resulting changes in structural loads would have shredded the ET and tossed the Orbiter into the airstream where it would be broken up. (Which is essentially what happened to Challenger.) A normal SRB jettison doesn't shred the ET, because the loads come off gradually as SRB thrust decays and they're jettisoned as the T/W ratio passes through 1.
NASA looked at using an Orbiter mounted solid rocket to power it away from the stack, but even if the motor was used on a normal flight for orbital insertion after ET jettison it was too heavy.
Third, the Main engines are nearly useless in-atmosphere. They're lit mainly because they sometimes fail to light, and having that failure occur halfway to orbit would suck. The "boosters" provide about 80% of the thrust, if memory serves. The SSMEs aren't even at full throttle for much of the flight - Challenger had just set them to full when the stack exploded.
A friend of mine, an aerospace engineer by trade, once explained it thusly - "during first stage flight, the SRB's lift the ET and the SSME's lift the orbiter". This isn't entirely true, but it's a useful first approximation. And that being said, other than a brief time right around Max-Q (when the throttles are backed off to control aerodynamic loads) and as MECO approaches (when the throttles are backed off to control G loads) the engines are in fact run at full throttle during powered flight.
Step 1: research on the ISS focused on biosphere components and food production.
Those aren't baby steps - your step 1 is no lower than about step 5 in any rational plan. We don't even know how to build a biosphere _on the ground_. Baby steps start with the basics, not three quarters of the way up the curve in the most expensive place to perform research.
At the same time, work on high efficiency, low reaction mass propulsion systems.
We already have those. The problem is, they absolutely suck because high efficiency and low reaction mass means absurdly low thrust. (F=MA after all.) Absent new physics, that's not going to change and such drives are going to be useless for manned expansion.
And this isn't old news either - that a Presidential candidate (JFK) was Catholic was a divisive issue within living memory.
The problem with knowing the truth of US history is, starting in the 60's the black civil rights movement co-opted the idea of discrimination and painted in simple black-and-white terms. Steadily since then, except for things like the internment of the Japanese that simply couldn't be overwritten, the story of discrimination and persecution in the US has been told solely in terms of antisemitism and Jim Crow.
I believe the differences between the two is mostly to the "no nonsense" approach to the Russians, and the fact that they like re-using designs and equipment that work instead of constantly re-inventing the wheel.
Except... they don't re-use designs and equipment. The current mark of the Soyuz (capsule) has almost nothing in common with the early ones other than a reasonably similar moldline. Soyuz has been modified and updated multiple times, not the least as it evolved from a general purpose Earth orbiter into a very specialized station taxi.
Sure, their spacecraft may look "ugly" (or at least, "uglier") than western or American ones, but they get the job done and they are reliable workhorses.
Reliable... is a very shaky claim given the number of near failures and almost disasters suffered by Soyuz over the years. It hasn't killed anyone in a long time, but it's come uncomfortably close an uncomfortably significant percentage of it's flights.[1] And speaking of flights and workhorses... even though it started flying over a decade earlier, it won't match the number of Shuttle flights until somewhere around the end of this decade at the current flight rate. (Last time I looked, I haven't calculated in a while.) In the same vein, while Shuttle suffered two LOCV accidents, it had zero complete mission failures and only one partial mission failure due to an abort-to-orbit placing it in too low of an orbit. Meanwhile, Soyuz had one pad abort, one failure to orbit, and at least two complete mission failures due to an inability to dock with a space station. (As well as several instances of either the orbital module or the re-entry module failing to separate properly.)
All of which is a roundabout way of saying the comparison isn't really as black-and-white as people would like it to be once you compare the actual Shuttle against the actual Soyuz (as opposed the largely fictional Soyuz the actual Shuttle is commonly compared to) and look at the actual numbers.
The point is that Boeing has nothing but mockups, powerpoints, and disastrous wind tunnel tests, so Sierra Nevada doesn't have to do much to have more technical merit.
When it comes to the most important part of it's flight regime, all Sierra Nevada has is "mockups, powerpoints, and wind tunnel tests". Worse yet, that regime is actually an area in which we have very little actual experience (essentially limited to Space Shuttle re-entries).
But go ahead and keep pretending that Boeing won based on the "technical merit" of a less tested, less developed, less capable, and more expensive system.
"Less tested and lest developed" is a relative matter... Boeing has a "less tested and less developed" craft that operates in a (relatively) simple and well understood flight regime. Sierra Nevada has an all but completely untested and undeveloped craft that operates in an extremely complex and little understood flight regime. Their flight tests to date, all low altitude ad subsonic, have nowhere approached the regime where the questions reside, not even close.
That you have to have this pointed out to you *twice*... well, further proof that you're a clueless fool.
I really doubt SpaceX is going to stop work on a vehicle they were developing before they were awarded the contract.
If they don't, then the costs of work they perform cannot be reimbursed under the contract. Further, not doing so may also result in significant penalties being levied for breaking the terms of the contract.
So SpaceX may or may not stop work entirely, but they *will* stop any NASA specific work and may have to stop work that's not necessarily NASA specific but is being paid for under the contract. (It can actually get pretty complicated at this level.) Your faith in SpaceX is touching and charming, but it utterly at odds with the real world.
I interpreted Firethorn's first point to be that the shuttle was designed to retrieve and bring back to Earth a large object, but none of the objects it actually did return to Earth were that large.
The Shuttle was generally limited more by CG than by weight or physical size. That being said, STS-32 did return the LDEF, which pretty much filled the payload (but was actually pretty light for it's size). Any number of ISS flights returned a Spacehab or MLPM at pretty much the maximum weight the Shuttle was capable of boosting to the that orbit.
I'm not sure why that capability was included in the original design; if it was included in case a bad but still reasonably possible scenario happened then retroactively removing it from the design seems like a bit of 20/20 hindsight.
If you take off with a payload - then you need to be able to land with that payload in an abort scenario, whether it's as (relatively) benign as an ATO or the screaming horror of the RTLS. Once you've certified the design to return with a full payload under the worst case abort scenario, that you now have the capability to do so in normal operations is pretty much axiomatic.
That being said, there were actually three payload return weight limits;
Normal processing - the loads were below that which would damage the shuttle.
Special processing - the loads could damage the shuttle and would require a mandatory OMDP on return in order to conduct an inspection and analysis of the structure.
One time - the loads would almost certainly damage the Shuttle and while it could land safely and intact there would be a significant chance of the vehicle subsequently being written off. This option was actually exercised once, for the Chandra X-Ray Observatory, which was the heaviest payload ever boosted by the Shuttle.
I agree that it's not as obviously gamed as everyone says.
Very few people actually discussing this issue (here on Slashdot and other geek/fanboy fora) have the knowledge to actually evaluate these proposals. Add in a strong anti-corporate bias, a strong anti-NASA bias, and the geek cool factor of having a space plane that avoid the "obvious" flaw of the Shuttle's parallel mounting... and you have people essentially making judgements on the process on what amounts to religious grounds.
I'm as cynical as the next guy when it comes to politics, but there is certainly more to it here.
Which is pretty much my point... the answer lies in the technical issues, which are *MUCH* thornier than most people grasp.
One some planet where the aerodynamics of a winged craft are in any way comparable to a ballistic re-entry... your comment would make sense. In the real world, where the Dream Chaser hasn't been flight tested in anything even remotely close to the most difficult portion of it's flight regime... you just come off as clueless.
Seriously, you have no clue what you're talking about if you think the equivalent of turning the engine over "proves" that a car will be the fastest and best performing in the Indianapolis 500.
A space plane isn't inherently unreliable. Placing said space plane below the level of cryogenic fuel tank insulation, with ice subject to crashing into it at hundreds of miles an hour is, in retrospect, pretty silly. Dream Chaser (DC) sits at the top of the rocket stack - it's smaller than the space shuttle, so this is feasible.
Putting the space plane on top of the stack isn't without it's own problems though... mainly in the form of huge aerodynamic issues because the wings are now where they can exert the greatest leverage. (Read among other things: in the exact right spot to cause the most control problems and to tear the stack to shreds if there's only a small problem with the angle of attack.) That's why the Dyansoar's Titan booster had suchhuge fins, simply gimbaling the engines did not provide sufficient control authority to offset the resistance of the wings.
For the record, as a huge fan of Spacex, I don't think the DC needs to be trashed on - it was a good (not great) proposal stuck between the big PR darling and the politically best-connected contractor in the business.
You forgot: "and was the most technically difficult proposal and submitted by the contractor with the least experience of any kind". Sierra Nevada has no substantial grounds for complaint, their solution may have been competitive on price, but contrary to popular belief these types of contracts are NOT awarded solely on the basis of costs. Technical factors also play a huge role. Which also explains the award to Boeing, it wasn't political connections, it was because SpaceX has a damm poor track record when it comes to delivering on time.
Logsdon and Callahan, for reasons best known to themselves and like so many others, continue to mythologize the space program... to the detriment of the facts.
They forget, as so many do, there's a third President (Johnson) and a number of years between President's Kennedy and Nixon. Nixon's policy decisions were shaped largely by decisions made by and during the Johnson Administration by the President and Congress. Most notably, in the budget battles of '65-'67 Apollo's budget was sharply cut, capping hardware production (and thus limiting the number of landings) and all but cancelling the follow on Apollo Applications program. During the same period, both NASA management and the Administration began to concentrate on the Shuttle as an Apollo follow on as cheaper access to space began to loom as a more important national priority than flags-and-footprints stunts. Nixon was thus caught between a rock and a hard place - inheriting (as every President after him has) a rudderless, directionless mess that would take far more money to fix than the public would stand for and far more political capital than the returns could possibly justify.
And really, Apollo has screwed us up in space pretty much for all time... Because it's lead too many people to believe that progress is only made by Great Leaps Forward. Because it stuck us (as a nation) with a bloated and inefficient NASA bureaucracy. Because it's blinded too many people to the fact that it was an accident of history and a detour from any rational path of space development.
First, I would hope that the avionics themselves were shielded and tested before deployment and use. I mean, we don't want the altimeter interfering with the artificial horizon, do we? (stupid, simple, but real example)
They are shielded and tested before deployment. But no testing is 100% effective, ever. And EMI is a tricksy thing to test and shield against.
Second, the whole cockpit and supporting avionics and other fight critical systems are in an enclosed conductive vessel, ie the cockpit and support area. It's a Faraday cage within a larger Faraday cage (the aircraft)
First off, the cockpit and other systems are not in an enclosed conductive vessel - they're part of the main fuselage, just like the passenger cabin. Second... the aircraft is not a Faraday cage, or at least not a very effective one as a broad range of frequencies can be received in the passenger cabin.
Polite language: you haven't a clue what you're talking about.
The utility company already has a lot of the hardware anyway.
Um, no. They have precisely none of the hardware.
I'm not talking about what it would cost me to build my own battery buffer - I'm talking about the incremental cost to the power company to include me in their power buffer.
Well, no. The power company has all the other costs I mentioned as well. Failing to include them is misleading.
That I'm doing so with consumer-oriented prices should be taken as evidence that I haven't a clue what I'm talking about
So: 30kWh * $0.02/kWh/day = $0.60 per day just for the power buffering, or $18 per month. Not nothing, but an eminently survivable expense.
Plus the cost of the converters (most houses run on AC, not DC). Plus any associated remodeling/installation costs (ventilation, additional wiring, structural changes). Plus the square footage costs (batteries occupy physical space after all).
So no, your numbers aren't a good estimate. They're based on numbers from the producer and leave out the installation costs.
The companies need to be evolving to be that backup power supply. They need to be shifting generation strategy and bringing online storage so they can displace the gaps so customers don't do it themselves.
That sounds simple in theory. In reality? You're just blowing smoke - because online storage in the capacities required simply doesn't exist. Pumped storage in a few places, maybe, in a decade or two when the utilities finally convince the regulatory bodies to let them sell the bonds... and after four rounds of court challenges for non environmental reasons and three for, not to mention the environmental impact statements themselves.
The cost of launching from earth is much higher than from space because we have to break Earth's gravity and pass through the atmosphere.
Build the next space station already. Build it big and ship it people and supplies and do it there. If we cat accomplish that, we don belong in space.
The funny part is.. you don't seem to grasp that you aren't actually saving anything by "building a big station and doing it there" - as all that material comes from Earth in the first place, the station is merely a temporary way station. You aren't saving any money by launching from the station, just "cooking the books".
For what, all of thirty seconds? A minute? People get excited about space all the time, it doesn't last. (And no, this isn't a new thing. It runs at least as far back as the sixties.)
Nonetheless, after the Cold War fueled space race fizzled out.. and it has been a couple of decades now, hardly anyone is doing anything worthwhile as far as space exploration is concerned. You will probably admit that we have regressed more than we have made progress.
Only if you only consider "manned and boldly going" to constitute the whole of space exploration. Otherwise, especially on the unmanned side, we're in something of a golden era. Especially with regards to planetary science.
For sure, this is only a "proof of concept" kind of a launch, but the thing is - it now sets some new benchmarks in terms of cost, capability, scale of ambition, and execution. You can push something to Mars in 75 mil. That is pretty frickin sweet.
Only is you consider a subcompact econobox to be "pretty frickin sweet". While Mangalyaan is indeed cheap, it's neither particularly capable, nor particularly ambitious. Even though it's impressive that they managed to do it all - as always, you get what you pay for.
Why begrudge ISRO their moment in the spotlight?
Nobody is begrudging them their moment in the spotlight - only attempting to counterbalance and correct the hype and hyperbole that so many people (like you) are spinning.
The reason is that "a single source for services" wasn't their plan. Their plan was "to greatly boost their numbers to make it look like they were winning versus Facebook, by cooking the books and padding the numbers by going absolutely nuts pushing G+".
TFTFY.
Seriously, Google was very late to the party, screwed up their implementation, screwed up the launch, and was desperate to make it look like G+ was *huge* and growing exponentially. Pretty much their only even remotely legitimate option was to force everyone who used a Google service (or later an Android product) to sign up for Facebook. Sadly, pretty numbers didn't equate to user engagement and G+ was soon a dying wasteland.
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If only the decision was that simple... Sadly, it wasn't.
First there were performance issues; The solid motors need to match to within 5% of each other - which proved essentially impossible to achieve with a monolithic grain as the propellant tended to stratify during the extended pour and the extended curing time. The solid motors needed to have consistent and predictable performance during the burn - which was almost impossible to achieve due to the aforementioned stratification problems. Both problems were also made worse because they couldn't figure out how to safely mix and pour the grains for both boosters in a single batch. Segmented grains, which could be poured in LH and RH segments from a single (smaller) batch suffered from none of these problems.
Next, there's storage and handling problems. The larger the grain, the heavier it is, and the harder it is to prevent it from flowing and deforming under it's own weight. Equally, since the large grains have to be cast upside down they have to be rotated rightside up - and nobody knew how to do that with large monolithic grains. A flex of as little as a couple of millimeters could crack the grain or lead to delamination. Also, segments could be stored individually, reducing fire and explosion risk.
Inspecting the grains with the technology of the time was also several orders of magnitude harder for a large monolithic grain.
Lastly, while there was a only a limited base of flight experience with large segmented grains (via the Titan IIIC)... there was no flight experience with large monolithic grains.
tl;dr version - there were a lot fewer known unknowns with segmented solids than with monolithic solids. A number of the known unknowns for monolithic grains were either outright show stoppers or could result in ruinously expensive R&D programs to discover if a solution was even possible. The known unknowns for segmented grains were all issues of scaling from existing experience.
Because it's solid fueled and thus much more reliable than liquids and, depending on design details, much faster to react. Also, it's pretty easy to build in a passive attitude control system that arcs the capsule out of the booster's path while the Draco will require active differential throttling. (Which in the case of Orion also increases reliability, as the launch abort system doesn't depend on guidance being available.)
Which also means it isn't carried to orbit and poses no further risk to the crew or mission. It also reduces total landed weight, reducing the size of the parachutes required and/or reducing landing shock for the same size parachutes.
Nothing is without risk - and Draco has a number of risks inherent in it's higher parts count and more complex operation that the Orion launch abort system does not have.
There are advantages and disadvantages to both approaches. Neither NASA nor Musk has the absolute One Best Design - because there isn't any such thing. (And both of them are leaps and bounds above the complex horror that is Soyuz's launch abort system. Sure, it worked when called on... but that doesn't change the nature of the beast.)
Mounting the orbiter on top has it's drawbacks too... The orbiter's wings now act a lot more like fins, making it harder to maneuver during the early part of the ascent and inducing (very) high structural loads on the stack. And of course the wings are generating lift... right at the part of the stack where they have a nice long lever arm. In addition, if you screw up the stack's angle of attack, you can end up with the wings at an undesirable angle to the apparent wind. (Undesirable in this case means "the wings are trying to turn the vehicle but not the stack", I.E. tearing the vehicle off the top of the stack.)
*sigh* This is one of the biggest pieces of misinformation about solid rockets floating about out there, spread and repeated by shuttle detractors in a cargo cult like fashion until it's now regarded as a law of nature. What most people (including engineers who should know better) don't realize is that you don't need to shut them down in the first place- you just need them to produce net zero thrust. This is done via blowout panels in the front dome, and sometimes by blowing off the nozzle as well. And it's not like this is a new fangled technique either... It was used on the Polaris A-1 and A-2, Poseidon C-3, SUBROC, ASROC, Minuteman I and -II, and Peacekeeper missiles. It would have been used of the SRB's of the Titan IIIC booster for manned Dyna-Soar and MOL launches. It's used by Minuteman III missiles...
It wasn't used by the Shuttle because during the SRB burn, the SRB's are essentially 'dragging' the ET behind it... and thrust termination would have resulted in them 'hanging' from the ET or having to be jettisoned and the resulting changes in structural loads would have shredded the ET and tossed the Orbiter into the airstream where it would be broken up. (Which is essentially what happened to Challenger.) A normal SRB jettison doesn't shred the ET, because the loads come off gradually as SRB thrust decays and they're jettisoned as the T/W ratio passes through 1.
NASA looked at using an Orbiter mounted solid rocket to power it away from the stack, but even if the motor was used on a normal flight for orbital insertion after ET jettison it was too heavy.
A friend of mine, an aerospace engineer by trade, once explained it thusly - "during first stage flight, the SRB's lift the ET and the SSME's lift the orbiter". This isn't entirely true, but it's a useful first approximation. And that being said, other than a brief time right around Max-Q (when the throttles are backed off to control aerodynamic loads) and as MECO approaches (when the throttles are backed off to control G loads) the engines are in fact run at full throttle during powered flight.
Those aren't baby steps - your step 1 is no lower than about step 5 in any rational plan. We don't even know how to build a biosphere _on the ground_. Baby steps start with the basics, not three quarters of the way up the curve in the most expensive place to perform research.
We already have those. The problem is, they absolutely suck because high efficiency and low reaction mass means absurdly low thrust. (F=MA after all.) Absent new physics, that's not going to change and such drives are going to be useless for manned expansion.
Looking at the list, that was my thought too...
And this isn't old news either - that a Presidential candidate (JFK) was Catholic was a divisive issue within living memory.
The problem with knowing the truth of US history is, starting in the 60's the black civil rights movement co-opted the idea of discrimination and painted in simple black-and-white terms. Steadily since then, except for things like the internment of the Japanese that simply couldn't be overwritten, the story of discrimination and persecution in the US has been told solely in terms of antisemitism and Jim Crow.
Except... they don't re-use designs and equipment. The current mark of the Soyuz (capsule) has almost nothing in common with the early ones other than a reasonably similar moldline. Soyuz has been modified and updated multiple times, not the least as it evolved from a general purpose Earth orbiter into a very specialized station taxi.
Reliable... is a very shaky claim given the number of near failures and almost disasters suffered by Soyuz over the years. It hasn't killed anyone in a long time, but it's come uncomfortably close an uncomfortably significant percentage of it's flights.[1] And speaking of flights and workhorses... even though it started flying over a decade earlier, it won't match the number of Shuttle flights until somewhere around the end of this decade at the current flight rate. (Last time I looked, I haven't calculated in a while.) In the same vein, while Shuttle suffered two LOCV accidents, it had zero complete mission failures and only one partial mission failure due to an abort-to-orbit placing it in too low of an orbit. Meanwhile, Soyuz had one pad abort, one failure to orbit, and at least two complete mission failures due to an inability to dock with a space station. (As well as several instances of either the orbital module or the re-entry module failing to separate properly.)
All of which is a roundabout way of saying the comparison isn't really as black-and-white as people would like it to be once you compare the actual Shuttle against the actual Soyuz (as opposed the largely fictional Soyuz the actual Shuttle is commonly compared to) and look at the actual numbers.
[1] Here's three accounts just covering reentry and landing failures.
When it comes to the most important part of it's flight regime, all Sierra Nevada has is "mockups, powerpoints, and wind tunnel tests". Worse yet, that regime is actually an area in which we have very little actual experience (essentially limited to Space Shuttle re-entries).
"Less tested and lest developed" is a relative matter... Boeing has a "less tested and less developed" craft that operates in a (relatively) simple and well understood flight regime. Sierra Nevada has an all but completely untested and undeveloped craft that operates in an extremely complex and little understood flight regime. Their flight tests to date, all low altitude ad subsonic, have nowhere approached the regime where the questions reside, not even close.
That you have to have this pointed out to you *twice*... well, further proof that you're a clueless fool.
If they don't, then the costs of work they perform cannot be reimbursed under the contract. Further, not doing so may also result in significant penalties being levied for breaking the terms of the contract.
So SpaceX may or may not stop work entirely, but they *will* stop any NASA specific work and may have to stop work that's not necessarily NASA specific but is being paid for under the contract. (It can actually get pretty complicated at this level.) Your faith in SpaceX is touching and charming, but it utterly at odds with the real world.
The Shuttle was generally limited more by CG than by weight or physical size. That being said, STS-32 did return the LDEF, which pretty much filled the payload (but was actually pretty light for it's size). Any number of ISS flights returned a Spacehab or MLPM at pretty much the maximum weight the Shuttle was capable of boosting to the that orbit.
If you take off with a payload - then you need to be able to land with that payload in an abort scenario, whether it's as (relatively) benign as an ATO or the screaming horror of the RTLS. Once you've certified the design to return with a full payload under the worst case abort scenario, that you now have the capability to do so in normal operations is pretty much axiomatic.
That being said, there were actually three payload return weight limits;
Very few people actually discussing this issue (here on Slashdot and other geek/fanboy fora) have the knowledge to actually evaluate these proposals. Add in a strong anti-corporate bias, a strong anti-NASA bias, and the geek cool factor of having a space plane that avoid the "obvious" flaw of the Shuttle's parallel mounting... and you have people essentially making judgements on the process on what amounts to religious grounds.
Which is pretty much my point... the answer lies in the technical issues, which are *MUCH* thornier than most people grasp.
One some planet where the aerodynamics of a winged craft are in any way comparable to a ballistic re-entry... your comment would make sense. In the real world, where the Dream Chaser hasn't been flight tested in anything even remotely close to the most difficult portion of it's flight regime... you just come off as clueless.
Seriously, you have no clue what you're talking about if you think the equivalent of turning the engine over "proves" that a car will be the fastest and best performing in the Indianapolis 500.
Putting the space plane on top of the stack isn't without it's own problems though... mainly in the form of huge aerodynamic issues because the wings are now where they can exert the greatest leverage. (Read among other things: in the exact right spot to cause the most control problems and to tear the stack to shreds if there's only a small problem with the angle of attack.) That's why the Dyansoar's Titan booster had suchhuge fins, simply gimbaling the engines did not provide sufficient control authority to offset the resistance of the wings.
You forgot: "and was the most technically difficult proposal and submitted by the contractor with the least experience of any kind". Sierra Nevada has no substantial grounds for complaint, their solution may have been competitive on price, but contrary to popular belief these types of contracts are NOT awarded solely on the basis of costs. Technical factors also play a huge role. Which also explains the award to Boeing, it wasn't political connections, it was because SpaceX has a damm poor track record when it comes to delivering on time.
Dog is a pretty popular meat in some parts of the world. So are guinea pigs. Don't mistake your cultural biases for global truths.
Logsdon and Callahan, for reasons best known to themselves and like so many others, continue to mythologize the space program... to the detriment of the facts.
They forget, as so many do, there's a third President (Johnson) and a number of years between President's Kennedy and Nixon. Nixon's policy decisions were shaped largely by decisions made by and during the Johnson Administration by the President and Congress. Most notably, in the budget battles of '65-'67 Apollo's budget was sharply cut, capping hardware production (and thus limiting the number of landings) and all but cancelling the follow on Apollo Applications program. During the same period, both NASA management and the Administration began to concentrate on the Shuttle as an Apollo follow on as cheaper access to space began to loom as a more important national priority than flags-and-footprints stunts. Nixon was thus caught between a rock and a hard place - inheriting (as every President after him has) a rudderless, directionless mess that would take far more money to fix than the public would stand for and far more political capital than the returns could possibly justify.
And really, Apollo has screwed us up in space pretty much for all time... Because it's lead too many people to believe that progress is only made by Great Leaps Forward. Because it stuck us (as a nation) with a bloated and inefficient NASA bureaucracy. Because it's blinded too many people to the fact that it was an accident of history and a detour from any rational path of space development.
They are shielded and tested before deployment. But no testing is 100% effective, ever. And EMI is a tricksy thing to test and shield against.
First off, the cockpit and other systems are not in an enclosed conductive vessel - they're part of the main fuselage, just like the passenger cabin. Second... the aircraft is not a Faraday cage, or at least not a very effective one as a broad range of frequencies can be received in the passenger cabin.
Polite language: you haven't a clue what you're talking about.
Yes, I know basic power generation. I also know the difference between reality and pie-in-the-sky someday maybe schemes.
You don't.
Um, no. They have precisely none of the hardware.
Well, no. The power company has all the other costs I mentioned as well. Failing to include them is misleading.
There, fixed that for you.
Plus the cost of the converters (most houses run on AC, not DC). Plus any associated remodeling/installation costs (ventilation, additional wiring, structural changes). Plus the square footage costs (batteries occupy physical space after all).
So no, your numbers aren't a good estimate. They're based on numbers from the producer and leave out the installation costs.
That sounds simple in theory. In reality? You're just blowing smoke - because online storage in the capacities required simply doesn't exist. Pumped storage in a few places, maybe, in a decade or two when the utilities finally convince the regulatory bodies to let them sell the bonds... and after four rounds of court challenges for non environmental reasons and three for, not to mention the environmental impact statements themselves.
The funny part is.. you don't seem to grasp that you aren't actually saving anything by "building a big station and doing it there" - as all that material comes from Earth in the first place, the station is merely a temporary way station. You aren't saving any money by launching from the station, just "cooking the books".
For what, all of thirty seconds? A minute? People get excited about space all the time, it doesn't last. (And no, this isn't a new thing. It runs at least as far back as the sixties.)
Only if you only consider "manned and boldly going" to constitute the whole of space exploration. Otherwise, especially on the unmanned side, we're in something of a golden era. Especially with regards to planetary science.
Only is you consider a subcompact econobox to be "pretty frickin sweet". While Mangalyaan is indeed cheap, it's neither particularly capable, nor particularly ambitious. Even though it's impressive that they managed to do it all - as always, you get what you pay for.
Nobody is begrudging them their moment in the spotlight - only attempting to counterbalance and correct the hype and hyperbole that so many people (like you) are spinning.
TFTFY.
Seriously, Google was very late to the party, screwed up their implementation, screwed up the launch, and was desperate to make it look like G+ was *huge* and growing exponentially. Pretty much their only even remotely legitimate option was to force everyone who used a Google service (or later an Android product) to sign up for Facebook. Sadly, pretty numbers didn't equate to user engagement and G+ was soon a dying wasteland.