[HN Gopher] SLS vs. Starship
___________________________________________________________________
SLS vs. Starship
Author : willvarfar
Score : 191 points
Date : 2020-11-13 13:02 UTC (9 hours ago)
(HTM) web link (everydayastronaut.com)
(TXT) w3m dump (everydayastronaut.com)
| generalizations wrote:
| > If you love SpaceX, you can thank NASA for that.
|
| > If it were not for NASA's initial investment of nearly $400
| million for the Falcon 9 and Dragon spacecraft, SpaceX would not
| be here.
|
| Is this true? I thought SpaceX was well under way before they
| figured out Falcon 9 or the dragon module.
| gbear605 wrote:
| SpaceX was well underway, but they would have gone bankrupt
| without investment from NASA.
| HPsquared wrote:
| Suetonius quotes the Roman emperor Vespasian: "You must allow my
| poor hauliers to earn their bread."
| m0zg wrote:
| > "Why do both programs exist".
|
| For the same reason why we still manufacture tanks, only to then
| park them in the desert: pork.
| ruph123 wrote:
| One is for science, the other to realize one person's megalomanic
| phantasies.
| horseRad wrote:
| wow
| atonalfreerider wrote:
| This is a very broad claim. Here is a factual refutation:
|
| https://spacenews.com/nasa-certifies-falcon-9-for-highest-pr...
|
| From the article lead: >NASA has certified SpaceX's Falcon 9 to
| launch the agency's most important science missions, giving the
| agency new options that could result in lower costs.
|
| NASA sees reducing launch cost as a top scientific priority.
| The mission of Starship is to do the same.
| kanox wrote:
| SLS is not "for science", it's a jobs program for Shuttle
| contractors.
| ppur wrote:
| Especially with the way innovation works now, one person's
| "megalomaniacal fantasies" can easily lead to scientific
| progress.
| bryanlarsen wrote:
| Who is the megalomaniac? Elon Musk or Richard Shelby?
| boomskats wrote:
| The title made me think the post was something to do with
| starship.rs, comparing it with a newer, potentially even better
| shell prompt that I had yet to hear about. I feel weirdly
| disappointed.
| hwc wrote:
| From May, 2020. Seems like 50 years ago.
| _Microft wrote:
| Yeah, in 2020, we actually might want to add the month to the
| submission title. ;)
| _Microft wrote:
| Pah, the feeling when your shallow post gets all the upvotes
| but the link to a Covid-risk calculator of a renowned
| research institute that you submitted earlier gets none.
| _Priorities, folks, pri-or-i-ties..._ ><
| agsacct wrote:
| SLS is the last major gasp of a military industrial complex that
| has completely taken over congress. The fact that we're paying
| $146M for each engine on the SLS (takes 4 to launch) and SpaceX
| is promising an entire launch for Starship at <100M is obscene.
| (Oh, and SLS ends up at the bottom of the ocean...Starship you
| can just refuel).
|
| While I don't agree with all thing Musk, he's revolutionized the
| global spacelaunch industry by reducing costs 10x. Now, totally
| dominant in an industry, he's making that rocket obsolete in
| favor of a better one (Spaceship).
| CraftThatBlock wrote:
| Starship launch price should only be a couple millions (see the
| article).
|
| <100M is _technically_ right, but very far off. Since Starship
| will be fully reusable, it's upfront building investment (the
| ~100M price-tag you are referring to), spread over the lifetime
| of the vehicle, plus staff/maintenance/fuel for launches.
|
| Falcon 9 was already a +10x reduction (~~1.5B per launch ->
| ~70M, likely cheaper for reused boosters), and Starship will be
| another +10x cheaper than F9. This means Starship will be >100x
| cheaper than competitors (excluding small-sat rockets like the
| Electron)
| fabian2k wrote:
| Where is that 10x reduction and the ~1.5B per launch from for
| the Falcon 9 comparison? I mean Falcon 9 certainly was
| cheaper than the competition even without reuse, but I'm
| quite sure the difference wasn't as large as you're stating
| there.
|
| The Falcon 9 did disrupt the industry for sure, but you don't
| need a 10x price reduction for that.
| CraftThatBlock wrote:
| You're right, I was using incorrect numbers. An Atlas V's
| sticker price is 110M~160M, so about 2-3x cheaper
| vikramkr wrote:
| If you think it's the _last_ major gasp, you 're gonna find
| yourself awful disappointed. One does not simply kill a jobs
| program. There'll be SLS, and then some other 2 trillion dollar
| airplane, then some satellite system, and again and again
| forever. Nobody votes to kill these projects because of the
| jobs they maintain. There will always be more
| kevin_thibedeau wrote:
| Rumsfeld put a lot of people out of work with his cancel
| stamp.
| mtgx wrote:
| > _Nobody votes to kill these projects because of the jobs
| they maintain._
|
| Sounds like dirty communism to me. Surely market freedom
| politicians wouldn't support such programs, would they?
| NortySpock wrote:
| If we can redirect from SLS to building Moonbase Alpha (with
| SpaceX presumably doing most of the shipping), I'll consider
| that a success.
| vikramkr wrote:
| Find a way to do it keeping the same contractors and adding
| a couple in some states with senators and representatives
| who are simultaneously members of the majority party and
| vulnerable, then maybe you've got a bill, though it might
| still get filibustered. NASA is a political work of art
| binarycodedhex wrote:
| The MIC will find a way to make a flying car/moon rocket that
| fires Hellfires and a gatling railgun. Let's call it a multi-
| program total cost of $40 terabucks that could've given every
| American a nice home (household assets are $130T but this
| counts both impoverished and wealthy persons) and UBI; but
| no: self-serving, subsidized wealth transfer to the Cheney's
| and the Erik Prince's comes first.
| rch wrote:
| There's also a strategic capabilities argument that never
| goes away.
|
| I'm anticipating a significant investment in synthetic
| biology facilities in the next few years. Ideally these would
| be 99% automated, remotely operated via secure dedicated
| networks, and maintained by small on-site skeleton crews.
| They'd be geographically distributed, with a majority in 'red
| states', but not because of any jobs they might create.
| vikramkr wrote:
| I'm not understanding what you're suggesting. What is a
| "synthetic biology facility" (research center?
| Manufacturing plant?), who is paying for them, why are
| there no jobs, why are they in red states, and since when
| did synbio become a low labor field? If its private sector
| investing in synbio manufacturing, they'll do that wherever
| the tax credits are. If it's the government, they aren't
| going to be doing any manufacturing, and research needs
| people.
| wongarsu wrote:
| I have no clue what GP is proposing, but "strategic
| capability" projects tend to be in red states because
| those are the low-population states where you can spread
| things out enough to be somewhat resistant to nuclear
| attacks. Being far from the coast is preferable for
| similar reasons (more time to intercept missile attacks).
| p_l wrote:
| Some of the low population states have had certain
| facilities allocated specifically because the facilities
| would be high priority target for ICBMs, thus making them
| "nuclear bomb sponges".
| wongarsu wrote:
| Yes, if you put your facility in the middle of San
| Francisco you give the enemy two targets for one bomb.
| Better make them work for it (and have a slightly higher
| chance that either your facility or part of San Francisco
| survives)
| vikramkr wrote:
| The problem with synthetic bio is that it's going to be
| pretty hard to drag synbio people away from boston, and I
| don't think the NIH is leaving bethesda any time soon.
|
| I guess my comment is pretty scattered rereading it now -
| I guess that's because as you mentioned we don't know
| what exactly was being proposed - synthetic bio is wide
| enough it could refer to a million different wildly
| divergent things.
| rch wrote:
| Sorry my comments are so vague. I'm thinking along the
| lines of the existing CIADM centers, but with different
| capabilities.
|
| https://www.medicalcountermeasures.gov/barda/core-
| services/c...
| skykooler wrote:
| Of course, a large part of the cost of those engines is that
| they're designed to be reusable (a difficult task with
| hydrogen/oxygen engines due to thermal shocks and hydrogen
| embrittlement). This made sense when they were being built for
| the Space Shuttle. It no longer makes sense now that they are
| using the same engines for an expendable first stage.
| kanox wrote:
| The $146 million figure is specifically for new engines that
| are no longer designed to be reusable.
| agsacct wrote:
| Which makes the plans to throw them away with each launch
| even more silly. They are cobbling together jobs programs
| from space shuttle components with no real strategy except
| "worked before" and "we can charge a lot of money for this".
| SiempreViernes wrote:
| "last major gasp [...] that has completely taken" Uh, does
| anyone else see a contradiction there?
| bigbubba wrote:
| Yes, that's a botched idiom. If the MIC has consumed
| Congress, it would be Congress doing the last gasping, not
| the MIC. The MIC is alive and well.
| ClumsyPilot wrote:
| The plans for Starship are haisy, not scrutinised and it has
| not been delivered. So far design has changed massively, it was
| scaled down a lot, and it's stil a vehicle looking for a
| purpose.
|
| I have significant doubts that we will see it launch at that
| price-point withing the next 10 years.
|
| All the best luck to spaceX, but you can't base the entire
| national space programm on something that flaky.
|
| SLS solidly gets you to the moon, and you van make real plans
| on it. If it turns out to be redundant, that's ok
| nickik wrote:
| I remember when people said that about Falcon Heavy and
| people were defending SLS by saying 'Falcon Heavy is not
| real, SLS is real and exists'. 2017 was a simpler time.
|
| You don't need SLS for a moon program, Starship or not. Its a
| major waste of money and only needed because the whole
| architecture was designed to need it. It makes neither
| economic, nor infrastructural sense considering the rest of
| the infrastructure and American space industry.
|
| Starship will very likely fly, even at 100x over its target
| price, its a bargain. Putting in 30+ billion into a project,
| even if we assume complete 100% success from now on, will not
| succeed in the mission 'going to the moon and staying'. At a
| same-time invest basically 0 in a system that could literally
| revolutionize human space travel, is beyond nonsensical.
|
| I would bet a fair amount of money on Starship transporting
| humans before SLS. SLS Core stage just spent almost a year
| preparing for a single static fire test, and has already
| fallen behind again.
| orangecat wrote:
| _SLS solidly gets you to the moon_
|
| Speaking of things that have not been delivered...
| kanox wrote:
| > vehicle looking for a purpose
|
| While I agree that Starship is very much an early-stage
| project it has a clear commercial utilization: Starlink.
|
| Assuming demand for Starlink is strong and SpaceX will be
| able to scale it up like crazy since Starship will give them
| far more LEO capability than anyone else.
| AlanSE wrote:
| Starlink doesn't need Starship. It works right now and the
| current SpaceX vehicles are sufficient for what it does.
| Maybe you could talk about Starship as a means to increase
| the total receiving area, number of satellites, and thus
| total bandwidth, users, etc. Maybe it could reduce the
| necessary size of the terrestrial receiver.
|
| But... this is both speculative and marginal. If Starlink
| needs more hardware, they can ramp up Falcon 9 rocket use,
| which is already partially reusable, and will continue to
| increase reuse. Starship could drive down launch costs, but
| it can't reduce the cost of the satellites themselves.
| You'll hit a floor where it could reduce costs, but not
| remotely enough to justify it.
|
| Starship is on a completely different playing field. It
| strives for a VERY large payload with a VERY large fraction
| of reuse. This makes no sense unless actual people are
| riding on it at some point. The demand for orbital
| transport is not enough otherwise. It only makes business
| sense by assuming some future activities will happen which
| will bring in a massive amount of funding. This is beyond
| conventional business risk, this is a leap of faith.
| nickik wrote:
| Elon has already said that Falcon 9 is the largest and
| most expensive part of Starlink, for Starlink to be fully
| successful it needs Starship.
|
| Falcon 9 is limited by Falcon 9 second stage product.
|
| > This makes no sense unless actual people are riding on
| it at some point.
|
| It actually makes a lot of sense, if that performance
| gets you a cheaper vehicle.
|
| > This is beyond conventional business risk, this is a
| leap of faith.
|
| Starlink, the NASA Moon program, commercial sat
| buissness, SpaceX Mars Plans, SpaceX Space tourism and so
| on. A cheaper vehicle always has more usage.
| kanox wrote:
| > Starship could drive down launch costs, but it can't
| reduce the cost of the satellites themselves. You'll hit
| a floor where it could reduce costs, but not remotely
| enough to justify it.
|
| You're assuming that satellites are so expensive that the
| difference between Falcon 9 and Starship is not relevant
| but we don't know this. Satellite hardware is usually
| very expensive but SpaceX is building them internally as
| a series product so they might be able to drive the
| marginal cost/unit much lower.
|
| It's safe to assume constellation bandwidth (and
| potential revenue) scales linearly with total payload
| mass, meaning it is proportional to
| ($satellite_cost_per_keg + $launch_cost_per_kg). Unless
| satellite cost is much higher than launch cost there are
| benefits from switching to a cheaper launcher.
|
| Since Falcon 9 design is mostly frozen and still requires
| throwing away an upper stage for every launch it has a
| price floor of its own. I honestly wouldn't be surprised
| if launch is already more expensive than satellites.
| m4rtink wrote:
| With Falcon 9 you always throw away the second stage,
| even if you reuse the rest - that adds up. Also even
| though 60 says per launch and the many hundred in orbit
| are a monumental achievement already, it pales in
| comparison with their plans. Also the stats have finite
| lifespan, so with many thousand in orbit even a weekly 60
| sat launch migh not be enough to replenish & add more
| sats over time.
| hwc wrote:
| > I have significant doubts that we will see it launch at
| that price-point within the next 10 years.
|
| But what if it is only half as expensive per ton to low-Earth
| orbit as Falcon-9/Heavy? And if it can only deliver 100 tons
| at a time, not 150?
|
| That's still going to dominate the launch market for some
| time.
|
| If they eventually prove it to be safe for human passengers
| and can demonstrate in-orbit refueling? It then replaces SLS,
| and is still a fraction of the cost.
| jvanderbot wrote:
| Who would have known the SpaceX experiment would work? There is
| some case to be made that US Gov was overly conservative and not
| willing to innovate, but I suspect that's safer than using
| taxpayer money on a SpaceX-like iniative that suffers as many
| failures as SpaceX did initially. __Can you imagine the political
| fallout? __We don 't have an appetite for that from the Gov any
| more, not like we did in decades past.
|
| NASA and the US Gov made the decision to fill a strategic gap the
| only way they knew how (and the way that had worked in the past).
| Now, other options are _emerging_ , but not _available_ and
| certainly not _certified_.
| andromeduck wrote:
| Literally anyone familiar with politics and economics.
|
| At a fundamental level, industry responds to price incentives
| and government responds to political incentives.
| bryanlarsen wrote:
| The non-governmental market size for conventional super-heavy
| launch vehicles is zero.
| jvanderbot wrote:
| I think this is a textbook example of hindsight being 2020.
| Of course it's obvious _now_.
| Beached wrote:
| everyone and their grandma, including some of SpaceX's
| biggest supporters thought spacex would fail. your statement
| is hyperbole
| gbear605 wrote:
| Ten years ago, it was unknown if the technology behind SpaceX
| would pan out. No one doubted that the economics would work
| if the technology also did.
| jjoonathan wrote:
| I didn't think the early SpaceX rockets did much that was
| technologically novel.
|
| The real reason why everyone expected the commercial crew
| program to turn into big contractor grift is because they
| saw the same story play out 100 times before and 100 of
| those times the big contractors found a way to capture the
| money and send the project into development hell. The 101st
| time was different.
| mempko wrote:
| Governments create markets. They create the games. People
| like Musk just plays them.
| kanox wrote:
| There are space companies other than SpaceX which
| participated in the same contracts and were nowhere nearly as
| successful.
|
| * Boeing did not yet deliver commercial crew. * Antares
| rocket did not expand beyond ISS delivery. * Blue Origin is
| not yet flying, despite immense funding. * Virgin Galactic
| did not yet fly any customers.
|
| The other great space launch success in the last decade was
| RocketLab but they're far too small to be relevant to SLS.
| LeifCarrotson wrote:
| Scott Manley's video today talks about the political machines
| behind SLS:
|
| https://youtu.be/WVKC54H3v78
| samizdis wrote:
| Related to this, I found this article [1] interesting, from
| Arstechnica in September: _Charlie Bolden_ [former NASA
| administrator] _says the quiet part out loud: SLS rocket will go
| away_
|
| [1] https://arstechnica.com/science/2020/09/former-nasa-
| administ...
| nn3 wrote:
| I find the point that SpaceX has no plans beyond the next step
| hard to believe. I could imagine they perhaps have no firmly
| officially approved plans like a full waterfall project, but
| surely there must be already a lot of trade studies on the next
| steps, and at least some rough plans.
|
| Or maybe the even have approved plans, but with the understanding
| that they could change quickly as new data comes in.
|
| Otherwise a project like StarShip is likely not feasible. For
| example for a Mars project you must at least have some idea that
| long term live support is feasible with the chosen size. They
| likely have that idea based on data from ISS, but I bet there
| were some preliminary studies on this at least.
| kanox wrote:
| > surely there must be already a lot of trade studies on the
| next steps, and at least some rough plans.
|
| Starship was always designed to refuel in Earth orbit, land on
| Mars, refuel on Mars and fly back to Earth in a single stage.
| This kind of architecture has never been attempted before and
| it has a lot of long-term implications for the design, for
| example the same reentry maneuver must work on two planets and
| orbital refueling is mandatory.
|
| All other rocket designs consider "planetary landing" as
| something for the payload to worry about.
| rbanffy wrote:
| Long duration projects face the risk of looking silly when
| something radically changes the landscape. SLS took the safe
| route back to mostly expendable launchers from a "reusable"
| system that was the result of extensive feature creep and left
| the agency with some psychological scars (and some extremely cool
| and inspiring museum pieces).
|
| As the author says, some things are impossible until they aren't.
| Starship may still hit a development wall, but, at this point,
| it's doubtful. If it works, it changes the landscape completely.
| Diederich wrote:
| I can't recommend Tim's channel enough:
| https://www.youtube.com/c/EverydayAstronaut/videos?view=0&so...
| (sorted here by most popular, where his most informationally rich
| material shows up on top.)
|
| His material is SpaceX heavy but far from exclusive, and he works
| very hard to recognize and compensate for any biases he might
| have when doing deep dives and analysis.
|
| There's quite a lot of technical material in many of his videos,
| presented in an organized, pleasant and approachable fashion.
| BadThink6655321 wrote:
| While I see a lot of discussion about the contents of the article
| (politics, engineering, etc...) I want to comment on the article
| itself. Very well done. A delightful read during lunch. Bravo!
| walrus01 wrote:
| It's not really fair to put the N1 in the category of successful
| giant rockets that have flown. Yes it flew, it exploded every
| time. No third stage of an N1 ever made it to low earth orbit.
| bryanlarsen wrote:
| The reasoning behind SLS sort of made sense 10 years ago. We
| didn't know that Starship, New Glenn and Falcon Heavy were coming
| down the pipe. We decided that the US & NASA needed super-heavy
| lift capability. Previous attempts to design a heavy lift vehicle
| were lost to political regime change and congress in-fighting.
| Previous attempts to design a single-stage-to-orbit vehicle were
| cancelled due to its virtual impossibility.
|
| So NASA & Congress designed a program that was unkillable. It
| greased too many wheels and lined too many pockets to make it
| easy to kill. It was also designed ultra-conservatively using
| mostly existing designs so there was no technical risk.
|
| So now when we complain that it's a pork-filled boondoggle that's
| impossible to kill, that was the plan, and there was a certain
| logic behind it. It makes no sense in a world with Falcon Heavy,
| Starship & New Glenn, but who would have predicted that with
| confidence in 2010?
| bnralt wrote:
| Perhaps the problem was deciding that the U.S. needed to have a
| super-heavy lift capability in the first place. A lot of the
| U.S. space program seems to be rather aimless, doing things
| because they seem cool rather than practical. We shouldn't
| really be surprised when situations like this occur.
| Nbox9 wrote:
| I strongly disagree with this opinion. The US space program
| is incredibly practical, particularly in the last 3 decades.
|
| * An unbelievable amount of scientific data about biology and
| microgravity comes from the ISS. To say this is "aimless"
| only is true if you believe humans will always live on Earth
| and only Earth.
|
| * A wealth of fundamental knowledge about the universe comes
| from spaced based telescopes. These are helping us understand
| the laws of nature, some of the most raw R&D.
|
| * There are significant military applications to our space
| program. These range from GPS, surveillance, communications,
| and potentially weapons. There are some government space
| launches that we know very little about their mission because
| it is highly classified. The Space Shuttle had a use case for
| rapid troop deployment. There is significant military
| applications to the engineering knowledge of rockets. The
| difference between a rocket and a missile is mostly the
| application.
|
| * Our exploration of our solar system provides possible
| future avenue for economic development. There is more fresh
| water, raw minerals, and energy inside our solar system but
| outside of Earth than there is water, mineral wealth, and
| energy on Earth. Certain things we consume are non-renewable,
| and we will need to find sources for them outside of Earth.
|
| * It gives hope, inspires young people to become engineers
| and scientists, and gives us a feeling of awe as we go
| through the process of understanding our existence in the
| context of the cosmos.
|
| EDIT: This isn't to say there is major bloat inside the space
| program, and that NASA is not in need of a significant
| culture change.
| bnralt wrote:
| > There are significant military applications to our space
| program.
|
| It's interesting looking at the military and space, since
| the military seems to be more objective focused than NASA.
| Early on (1960's), the military was planning on a manned
| station (MOL), but ended up going with automated satellites
| in the end because they made more sense. Likewise the Space
| Force believes it might eventually send up astronauts, but
| doesn't think that will happen for decades. They're
| interested in sending people up when it's useful to do so,
| not just sending them up for the sake of sending them up.
| ufmace wrote:
| I mostly agree, but what in the world do you mean by "The
| Space Shuttle had a use case for rapid troop deployment"? I
| can't picture that being anything but the worst way
| imaginable to get like 2 or 3 guys somewhere.
| Nbox9 wrote:
| I'm having a hard time finding the source, but a mission
| requirement of the Space Shuttle was something along the
| lines of "Deploy a dozen marines to Moscow in less than 1
| hour."
| ufmace wrote:
| Maybe somebody wrote a requirement about that once, but
| it doesn't sound very practical. I know they were
| dreaming up a lot of fanciful things when they were
| setting the requirements though.
|
| I think the actual shuttle had a life support capability
| for like 7 people. Not sure of the actual flight crew
| requirement, there's probably room for like 3-4 other
| guys. It can land on a runway, but it's gotta be really
| long, and there's only one shot, and it'll be really
| obvious and has no ability to evade defenses. No chance
| of it landing in Moscow unless the Russians let it. And
| then you'd be in the middle of a huge military base or
| something, and what are 4 guys going to do except be
| killed or captured immediately.
|
| Maybe they could get there in an hour. From a specific
| launch pad in Florida, and if the shuttle is all set up
| to launch, which takes months. And it'll be blindingly
| obvious to everyone in the world that something just
| launched heading straight at Moscow.
| jasonwatkinspdx wrote:
| Yeah, that's just mythology. The concept doesn't work
| out.
|
| The shuttle did have a military requirement: the air
| force wanted to be able to launch into an orbit over the
| south pole, then up across Russia from the south, to
| return and land after that single orbit. That pretty much
| forced the use of wings that could glide, vs capsule
| style re-entry, and opened the path to most of the
| shuttle's design flaws.
| TeMPOraL wrote:
| The key word here is likely _rapid_. Doing a suborbital
| hop is much faster than going through atmosphere, because
| you get to accelerate to _much_ higher velocities. Even
| supersonic planes take forever to get anywhere, while a
| suborbital hop would let you get to any place on the
| planet in under 2 hours.
| khuey wrote:
| There never was a space shuttle sitting around ready to
| launch on-demand though. A 2 hour travel time is
| irrelevant if it takes weeks to prep for the mission.
|
| The space shuttle could also only land at a handful of
| runways on the planet.
| Already__Taken wrote:
| And everyone on the planet would know you're doing it via
| national television or every inter-continental ballistic
| warning system?
| nickik wrote:
| > The Space Shuttle had a use case for rapid troop
| deployment.
|
| No it didn't. The DoD didn't even want it before it even
| flew.
|
| Very little of the things you talk about has much to do
| with the NASA Human Directorate and that is the many part
| of NASA that people dislike, and this is not just from the
| outside, even inside NASA this is well known.
|
| Watch the talks by Dan Rasky.
| BurningFrog wrote:
| Yeah, I wonder how much of the real US space program is
| secret military projects.
|
| Keeping much of it secret distorts the public impression of
| it, when we don't know of a substantial portion of the
| accomplishments.
| Gravityloss wrote:
| SLS never made sense.
|
| Too big, too expensive, too low flight rate. These all problems
| contribute to each other.
|
| Also, large solid rockets are very troublesome. They can not be
| fueled on the pad, so they are heavy and dangerous from casting
| to stacking to launch. There will never be a high launch rate
| reusable rocket with solids.
| pfdietz wrote:
| Right. I will go further: if SLS is the best that could be
| done, then human space activities themselves would make no
| sense. SLS is a solution to no real problem beyond "how do we
| deliver $$$ to the appropriate pork consumers?"
|
| If you believe humanity has a future in space, then you must
| believe it's possible to do much better than SLS. So do that,
| not waste time on a pointless and hideously expensive
| diversion.
| bryanlarsen wrote:
| Big was the whole point, people decided we needed the
| capability to send large masses beyond Earth orbit in a
| single launch. Anything smaller would mean "giving up" on
| human spaceflight to the moon or Mars. Doing it in a single
| launch is silly, but that thinking was widespread at the
| time.
|
| And a low flight rate was also a given. Delta IV Heavy only
| files about once every 18 months, there's insignificant
| demand for anything even bigger. That was why NASA decided
| they had to do this themselves, because it would be insane
| for any commercial company to build a rocket without a
| market.
|
| And expensive was also part of the plan, you can't spread
| enough pork to make it unkillable if it isn't expensive.
|
| Big, expensive, low flight rate. Those weren't problems, they
| were requirements.
| Gravityloss wrote:
| I think you misunderstood what I said. I understand that
| NASA _thought_ it needed the vehicle. However I 'm saying
| it did not in fact need it for any missions. (The idea for
| docking in earth orbit at the start of a mission is not
| new.)
|
| Very different thing, and you actually demonstrate those
| points.
|
| Everything starts with the misplaced thought that it needs
| to be so big. Not actually required.
|
| Probably correct thought that it needs to be NASA-made
| since it wouldn't make sense commercially, but this is a
| consequence of misplaced thought 1.
|
| Expensive to spend pork. Again, not needed for the mission,
| if something more sensible was chosen in the first place.
|
| There could have been a capsule flying on Atlas V for many
| years already. The ESAS study just had all kind of really
| bad assumptions that made Ares happen instead.
| bryanlarsen wrote:
| Yes, bad assumptions led to a bad result. Some of those
| bad assumptions made sense 10 years ago. Some of them
| didn't. I was far too generous to Congress by only
| talking about the former and not mentioning the latter.
| Multi-launch for large beyond-Earth missions made much
| more sense 10 years ago than a big rocket. Heck, multi-
| launch probably made more sense in the 60's than Apollo,
| if it wouldn't have been for that 1969 hard deadline.
| wongarsu wrote:
| Multi-launch was considered for the Apollo program, but
| was ruled out because it had higher technical risk than
| just scaling up the rocket and making the payload extra
| light. If we didn't have the hard 1969 deadline we would
| likely have gone with the multi-launch option back then.
|
| It's an interesting alternate reality to imagine: we
| might have had a more interesting moon program that had
| the ability to naturally scale to larger and larger
| missions, instead of repeating basically the same thing
| until the public gets bored and cancels it.
| garaetjjte wrote:
| There were plans for more interesting moon missions under
| Apollo Applications Program, cancelled because of budget
| cuts. (and what was left was botched as Skylab)
| Gravityloss wrote:
| Yeah, first orbital docking was done 1966 on Gemini 8.
| The architecture for Apollo was decided much earlier
| already (it did include the lunar orbit rendezvous and
| docking which was indeed risky).
|
| We now have 54 years of repeated low earth orbit dockings
| so maybe the architecture designs could start taking that
| into account.
|
| Even SpaceX is planning on doing orbital refueling.
| nickik wrote:
| > using mostly existing designs so there was no technical risk.
|
| If only that was so. Using a bunch of old tech in a new way
| does not actually lead to great success. The re-qualification
| of the RS-25 alone took years and cost 100s of millions. And
| that is without producing new ones.
| mlindner wrote:
| I think you're misrepresenting the past.
|
| > It was also designed ultra-conservatively using mostly
| existing designs so there was no technical risk.
|
| Politicians can't design a rocket and cannot get what is
| "ultra-conservative". Rockets are not Lego blocks that you can
| just mix and match. They're explicitly designed a certain way
| to support a certain load profile. Even if the parts of the SLS
| _look_ like they have low risk, they do not and that's why the
| vehicle has taken so long to develop.
|
| One example, if the shuttle boosters were could actually have
| been used directly they wouldn't have needed to extend the
| number of segments from 4 to 5, redesign the liner between the
| segments, and completely redesign the nozzle. It's a new
| booster.
|
| Second example, even though the shuttle external tank looks
| like it's being used, in previous iterations the shuttle
| external tank did not support any axial loads, it was simply
| held on to the bottom of the Orbiter. Now the external tank has
| to withstand the entire axial load of the rocket so it's
| basically redesigned from scratch.
| bryanlarsen wrote:
| Yes, it's still rocket engineering. It's never trivial.
|
| What would have been a more conservative design? Reusing the
| Apollo design was considered and discarded because so much
| knowledge and tooling had been lost that it was considered to
| be less conservative than the SLS design.
| giantrobot wrote:
| I love the whole "lost Saturn V engineering" trope. It
| sounds so good despite being bullshit. Rocket dune and NASA
| did an extensive knowledge retention project for the F-1
| and J-2 engines. NASA also maintains several copies of
| extant F-1 _and_ F-1A engines. If we approached Rocketdyne
| tomorrow with a billion dollars they could restart F-1A
| production. The J-2X is in fact the second stage engine for
| the SLS stack.
|
| The SSME was selected for the SLS (and Ares V before it)
| because it had twice the burn hours of the F-1 and the SRBs
| existed and were a known quantity. The SLS (and Ares V) can
| reuse more of the Shuttle's infrastructure than an F-1
| based design. The SRBs allow for use of smaller first stage
| tankage and the less powerful SSMEs which allow for reusing
| Shuttle launchpads which replaced the Saturn launchpads at
| LC-39.
|
| While the SLS _is_ moving into boondoggle territory the
| Ares V and SLS designs made economic sense to reuse Shuttle
| designs and infrastructure. It didn 't have anything to do
| with the myth of lost engineering knowledge.
| nickik wrote:
| Ares V was actually designed with the RS-68, not the
| RS-25. That why it was not human rated.
|
| > Ares V and SLS designs made economic sense to reuse
| Shuttle designs and infrastructure
|
| Theoretically made economic sense.
| Robotbeat wrote:
| Probably EELV Phase II.
| OnlyOneCannolo wrote:
| It made sense as an institutional flywheel.
|
| The Constellation Program [1] that preceded SLS had two
| vehicles - Ares I for ISS crew and supplies after Shuttle was
| retired, and Ares V for occupying the moon. The missions gave
| some justification for needing vehicles. Their design was
| primarily a means to preserve existing contracts and jobs.
| Additional wheel greasing made it happen.
|
| That stuff about re-using parts to reduce risk is just what
| people say because it sounds good, but isn't inherently true.
| Kind of like how "drug delivery" and "machine learning
| application" are go-to pseudo-justifications for many research
| proposals.
|
| Constellation was eventually canceled when ISS resupply went to
| the Commercial Crew Program [2]. Ares V was stripped down and
| reimagined as the mission-less SLS. SLS is not really intended
| to do much more than exist for the time being.
|
| There are a lot of factors that will go into canceling SLS -
| infighting between NASA centers, preserving jobs and contracts
| with Old Space companies, even more wheel greasing. I'm
| interested to see how it plays out.
|
| [1] https://en.wikipedia.org/wiki/Constellation_program
|
| [2] https://en.wikipedia.org/wiki/Commercial_Crew_Program
| tobmlt wrote:
| I was going to mention the issue with reuse of old designs
| "being conservative" but you got there first. Mandated reuse
| of some component of a prior vehicle is, by definition, an
| extra constraint on the new design. Extra constraints make
| design harder, not necessarily safer, and the use of old
| stuff in the new vehicle to some extent kills the "flight
| proven-ness" of the old thing.
|
| (Generally speaking. Maybe some of this is less of a factor
| or more depending on the system... point is you can't say up
| front that old hardware is a good idea)
| Someone wrote:
| Makes me think "Boeing 737 MAX".
| OnlyOneCannolo wrote:
| Thank you for elaborating on that point. From some of the
| other comments, it seems that it's maybe a contentious
| issue.
|
| There's a lot of pressure to include hand-wavy references
| to "heritage hardware" in the risk assessments for various
| reasons, but it's not well-substantiated where it exists.
| lumost wrote:
| I'd imagine it's partly due to the view of the public
| that NASA's launch tech has regressed since the Apollo
| program. The Saturn V had crew escape, could deliver 110
| tons to leo, and was cheaper per launch than the shuttle.
| The F1 engine is still considered superior to the shuttle
| main engines. Pitching new tech when you haven't matched
| capabilities from 60 years ago is hard.
|
| Combine this with incumbents looking to keep new entrants
| out of the market and heritage, and reuse become the
| operative words
| OnlyOneCannolo wrote:
| Shuttle was canceled because its bay wasn't needed, it
| was overly expensive, and its service record was pretty
| accurately tracking the projected 1 shuttle loss for
| every ~50 flights. There wasn't a strong commitment to
| the missions at the time, so making something completely
| new was out of the question. But there was a lot
| politically and strategically riding on Shuttle, so they
| had to find some way of keeping some lights on. Those
| points can be elaborated, but the decision really wasn't
| much more complicated than that.
|
| The F1 and SSME are apples and oranges. They have
| separate uses and achievements for their times. I haven't
| heard of either being widely considered objectively
| superior to the other.
| avmich wrote:
| So ironic Saturn-V is drawn as carrying 140 tons, while Apollo
| CSM is 30 tons and Lunar Module is 15 tons, yet Space Shuttle is
| drawn carrying just 27 tons. Definitely a case of apples and
| oranges.
| jccooper wrote:
| The chart is tons to LEO. Saturn V wasn't designed for LEO, but
| it certainly could have dropped that much there. (Skylab used a
| pretty fair fraction of that capability.)
|
| When you're comparing launchers you have to pick some baseline
| target orbit. LEO is a good lowest common denominator, but
| isn't quite fair as launch systems optimized for higher energy
| orbits (like the Saturn V) lose some of their advantage. But a
| higher orbit is even less fair to systems designed for LEO;
| choose anything else, like GEO or lunar insertion, STS would
| have a big fat 0.
| avmich wrote:
| Yeah, I know, but the point is Saturn V is shown as carrying
| to LEO 140 tons - and 140 tons was actual translunar payload
| (Apollo CSM + LEM, ~45 tons) plus dry 3rd stage (~15 tons)
| plus unspent fuel in the 3rd stage (about 2/3 of initial load
| of 105 tons of fuel). At the same time Space Shuttle doesn't
| show the empty mass (a lot) and unspent fuel (very little) of
| Space Shuttle "second stage", which is Orbiter, and mentions
| only payload in the bay of that Orbiter.
|
| We could arbitrarily say Energia brings 0 tons on orbit -
| because it's, strictly speaking, a suborbital rocket, the
| payload needs to add some ~100 m/s of velocity to get to
| orbit, this was done to avoid getting empty stage to orbit
| (so no littering, no necessary maneuver to deorbit). Or,
| alternatively, we could say Energia brings 170 (!) tons to
| LEO - indeed, if one pays no attention to factual suborbital
| speed and adds mass of empty 2nd stage of Energia, which is
| 78-86 tons (http://buran.ru/htm/rocket.htm), one gets this
| number.
|
| So it's important to carefully compare similar things. 140
| tons for Saturn V is too different from 27 tons of Space
| Shuttle by method, not by result.
| Tuna-Fish wrote:
| They are listed with numbers about payload to (quite low) LEO.
| Apollo CSM and the Lunar Module were launched into a much
| higher-energy trajectory. The Saturn V _could_ have launched
| 140 tons to LEO, it just never did. IIRC the most massive thing
| it ever launched was ~90 tons of Skylab.
| avmich wrote:
| > They are listed with numbers about payload to (quite low)
| LEO.
|
| Then one should include the mass of Shuttle Orbiter. That the
| orbiter is used as a second stage... Saturn-V lists mass of
| third stage alright.
|
| > The Saturn V could have launched 140 tons to LEO, it just
| never did.
|
| No, it _never could_. It 's a popular illusion. The only way
| to reach 140 was to count parts of Saturn V reaching orbit as
| payload. When you count payload only, that number falls. It's
| like counting the mass of Sputnik 1 adding the weight of the
| second stage of R-7. Or, in other words, a satellite with
| mass 140 tons couldn't be brought to LEO by Saturn V.
|
| To get Saturn V realistic number for LEO in similar sense to
| Shuttle's 27 tons (did Shuttle ever got 27 tons to orbit?
| Could it even be launched safely with 27 tons payload, given
| that it could only land with about 15 tons in the bay?), you
| should look at ~77 tons of Skylab. There is at least a hint
| that LEO payload is not all which gets to LEO.
| bobthebuild123 wrote:
| I think you're confusing mass of the payload with something
| else. Mass of the payload to LEO is just how much mass is
| brought to LEO. According to "Alternatives for Future U.S.
| Space-Launch Capabilities" [0], the Saturn V did in fact
| bring 140 tons to LEO...
|
| [0] https://www.cbo.gov/publication/18196
| [deleted]
| DannyB2 wrote:
| Idea: Let's take an expensive re-usable engine (left over from
| the Shuttle) and put it on an expendable launch vehicle!
| danpalmer wrote:
| I believe engine re-use is on their roadmap. Not for the first
| launch, or the second, but I think the aim is to have it soon.
|
| That said, it's "re-use" by ejecting them and parachuting them
| down to a safe landing, so who knows if that will work.
| bbatsell wrote:
| You are thinking of ULA's Vulcan rocket, and there are
| indications that their engine reuse plan has been entirely
| abandoned. Aerojet has modified the Shuttle's RS-25 engine
| design to make it explicitly non-reusable (in the hopes of
| reducing costs).
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