Eric Berger was there last night.
And if you have the time, a good explanation of the Raptor engine design.
61 thoughts on “Hopper Hopped”
Comments are closed.
Eric Berger was there last night.
And if you have the time, a good explanation of the Raptor engine design.
Comments are closed.
I’ve watched a live feed for two nights to see the flight. Since the sight I was at sells SpaceX stuff like T-shirts, I mentioned that a scaled down Starhopper, powered by propane and with a removable top and a grate, would make the perfect patio grill.
Can we make the burners look like little inverted Raptors? Then I’d be in. I’m in the market for a new gas grill!
Once they get Raptor production smoothed out, they should think about upgrading the Merlin with an oxygen rich preburner and staged-combustion, which would basically make it an RD-180 analogue with a single combustion chamber.
With respect George, why should they spend a nickel making the Merlin into a copy of a decades old Russian motor?
Because the decades old Russian motor has a much higher ISP (311 SL, 338 vac) than the Merlin (282 SL, 311 vac). Now that SpaceX knows how to make an oxygen rich pre-burner, they could probably build one for the Merlin without too much difficulty, which would give them better performance and more LEO cargo capacity in essentially the same rocket with the same amount of fuel.
The engine would likely cost more to produce, but they’re re-using them multiple times so that might not be much of a factor.
Crunching a bunch of numbers on both stages in a spreadsheet, and assuming a vacuum optimized upper stage with the same ISP as the RD-58 (359 sec as opposed to Merlin 1D vac’s 348 sec), and not allowing for any increase in engine weight, and slightly increasing the fuel capacity of the upper stage, I roughly predict a 40% increase in LEO payload.
Whether that’s worth it is a question for marketing.
All of SpaceX’s development resources appear to be directed now to Starship development,though.
Musk has said on more than once occasion that they’re pretty much done with Falcon, and the sooner they can simply switch over to Starship/SuperHeavy for all their launch operations, the better.
Spot-on about the roughly 10% increase in Isp going from gas-generator to staged combustion.
Only problem is, staged combustion engines tend to be significantly heavier than g-g. So “not allowing for any increase in engine weight” may not fly.
Bottom line is, SpaceX probably doesn’t want to mess with the F9 block 5 any further anyway, lest they create new problems with NASA Crew cert.
I would agree, although a methalox upper stage with a single Raptor might be a very easy way to boost their GTO payload capability, once they’ve got Raptors coming out their ears and the liquid methane infrastructure at the pad.
If BFR is anywhere near as capable and cheap as it’s planned to be, it’ll make Falcon 9 (upgraded engines or not) and every other rocket instantly and hilariously obsolete.
That depends quite a bit on the nature of the satellite market, how well a few BFR launches can handle a much larger number of individual payloads going to different orbits, etc. If the market is mostly pizza delivery, a semi truck isn’t the right vehicle even though it’s highly capable and highly efficient at hauling lots of pies.
For small missions like delivering three or four crewmen and a couple thousand pounds of supplies to the ISS, BFR would be overkill.
Currently the Falcon 9 can’t reuse the upper stage because it would eat too far into the payload capability, but if higher-ISP engines upped the payload capacity by 40%, a “mini Starship” upper stage might be both feasible and practical.
And if nothing else, he needs to hold on to his current niche or New Glenn will take it over.
“For small missions like delivering three or four crewmen and a couple thousand pounds of supplies to the ISS, BFR would be overkill.”
Doesn’t matter.
If Musk is right about how cheap they can make it, Starship will cost less to launch than a Falcon 9. So even a single satellite will be cheaper to launch that way and Falcon will be retired.
Plus, if NASA have the option of delivering a hundred tons of stuff to ISS rather than a couple of tons, I’m sure they’ll think of something they can stuff in there.
I think it all depends on reading the market as the market continues to develop.
He’s got the smaller Falcon 9, but BFR ups the technology in almost every aspect. However, much of the tech he’s switched to can also be applied to a Falcon-size vehicle, such as just using several Raptor engines instead of 17 for a first stage. Parts of rockets scale up well, but at some point the natural head pressure in really tall tanks starts pushing the mass ratio back down (expanding sideways instead of upward alleviates that trend). So a lot depends on how much BFR’s cost advantage depends on size, and how much depends on technology that can be easily scaled up or down. BFR itself is a smaller version of their earlier Mars transporter concepts.
There are all kinds of ways they could make a smaller version of BFR, if there’s a surviving market for it. They could possibly run Raptors on LOX/ethanol with almost no modification (possibly just software changes), which would give them a dense non-cryo fuel similar to RP-1 (but oddly cheaper), while retaining most of Raptor’s ISP advantages. Or they could make a LOX/methane Falcon-sized rocket. Given his teams very fast development times, SpaceX should be quite nimble at filling any niche they want.
Most transport markets are segmented. Trucks, planes, and ships all span a wide range of sizes, and I don’t see anything on the market or mission side that would make rocketry uniquely favor one particular size of vehicle. A few weeks ago I also mentioned my surprising finding that a Falcon 9 could deliver more payload to GTO than BFR, due to Starship’s low mass ratio in LEO. Starship could certainly launch smaller tugs that head to GTO to beat a Falcon 9, but as a do-everything vehicle, it can’t make those deliveries itself. So that gets into having the cheapest LEO to GTO expendable stage in $/lb, or coming up with a smaller returnable stage or refuelable tug.
BFR has a tremendous cost advantage now, but so would an Airbus A-380 if it was introduced back in the 1950’s or 60’s. Airbus would look at the speed/range/$ per seat mile numbers and assert that everything is going to fly on A-380’s, but its competitors would look at the A-380 and think “Scale down those high bypass turbofans and we could make twins to fill every market niche from 50 to 300 seats.”
A well-developed, high-volume orbital refueling market would do the most to play to BFR’s advantages, since any unsold payload capacity could be trivially filled with bulk fuel delivery, so no mission would have wasted capacity. Musk of course wants to develop orbital refueling in a big way to enable his lunar and Mars missions, but it may take a while for the commercial markets to catch up.
Where all of this might come into play is competition with Blue Origin. SpaceX brought new thinking into play against legacy aerospace manufacturers, but what Blue Origin, or rather Amazon, has in spades is expertise at marketing and running highly efficient shipping and delivery systems. They are ruthless, versatile, innovative, and will go to extreme lengths to cut costs on things like bubble wrap, box tape, and delivery fleet utilization.
Both are nimble competitors with different strengths and weaknesses, so it will be fascinating to watch things play out. It will also be extremely refreshing after watching NASA and legacy aerospace flying around in circles for forty years. It makes me look at the SLS and scratch my head, like they’re trying to compete in the expanding commercial transport business with an ark or a giant hot-air balloon.
Once Starship/SH are in service outcompeting in carrying medium-to-heavy payloads, it might make sense for come back to F9 and build a reusable upper stage. I understand it’d mean giving up roughly half F9’s current payload, but that might make more sense in the context of having F9 as a fully reusable “pickup truck” to Starship/SH’s “18-wheeler”.
If NASA wants to have 100 tonnes of stuff at a time delivered to ISS, it’s going to need to add a new docking module with a really big door and pack all that stuff in order of intended use into a swappable warehouse module that would stay with ISS until empty.
Right now, it takes the ISS crew about a week to unpack three or four tonnes of stuff from a Dragon or Cygnus and get it stowed around ISS. The station hasn’t got remotely enough spare space to stash 100 tonnes of stuff and the crew has neither the time nor, I would strongly guess, the inclination to be zero-G warehousemen for most of their duty tours. So the stuff needs to stay in the delivery can and only be fetched out a bit at a time as used.
Another non-trivial problem is where to accumulate 100 tonnes of trash as things like once-worn clothing and food scraps accumulate. I can’t think of any particularly sanitary way to keep all that stuff from becoming a zero-G compost pile over the months or years it would take to fill a second “warehouse module” with the used contents of the other.
Trash could still be incrementally sent way in Progress, Cygnus, Cargo Dragon 2, Dream Chaser Cargo and HTV vehicles, because, even with the consumables covered for years at a whack by Starship, the smaller cargo vehicles would still need to visit a few times a year strictly to bring up new science-y stuff and take science-y result stuff back down.
Progress, Cygnus and HTV would retain their roles as strictly trashcans after science-y payload was removed. The really nasty trash would be reserved for these, one presumes, while the reusable Cargo Dragon 2 and Dream Chaser Cargo would remove stuff like broken station equipment needing Earthside repairs and anything else that wouldn’t start to smell PDQ.
My guess is that there would be a lot fewer such missions unless it was decided that purely science payloads – which now account for less than half the payload mass of a typical cargo run – would be valuable enough to justify the still considerable expense of operating these smaller craft.
Delivering 100 tonnes of consumables at one whack would probably only happen a maximum of twice even if ISS stays in commission thru 2030 as some in Congress want. More probably, only once, covering the needs of a seven-person crew for as long as ISS remains in commission.
I’m not sure the whole idea makes much sense at this relatively late date in ISS’s history.
Massive Starship-sized cargo deliveries to an orbiting space platform would make more sense if the destination was something like the 2001 double wheel. Even then, with a much bigger crew to feed, the trips probably wouldn’t be especially frequent as, with artificial gravity due to spin, ordinary Earthside laundry appliances could be used to largely eliminate the need to haul mass quantities of one-time-use clothing items to orbit.
Of course Starship could just act as a straight substitute for Cargo Dragon 2 by taking up two or three tonnes of the same sorts of stuff at a time with most of its considerable LEO payload capacity given over to propellant destined for a LEO propellant depot that – for safety reasons – would almost certainly need to be visited before going on the ISS with the small, dry cargo payload.
I must say I’m really looking forward to how all this is going to work out over the next few years after Starship flies, NASA is presented with a fait accompli and, no longer able to pretend SHS is just some half-mad traveler’s tale, actually have to grapple with how to make effective use of the thing. Especially after such pointless distractions as SLS, Orion and Gateway have been killed and buried.
Yeah, if BFR is as designed everything else is boxed in. It’s not perfectly efficient at delivering small payloads, but it’s good enough that no likely estimate for R&D on a better design could achieve payback.
If small payloads have a high launch rate BFR can batch them and SFR loses. If small payloads have a low launch rate SFR can never get payback on its R&D. I douby there’s a joke in the middle where it makes sense, unless you’re say China and want to subsidize one anyway for strategic reasons.
“New Glenn will take it over.”
*snort* Sure, “Sorry, NASA, your satellite was late. As a result we’ll give you a 1% discount on your next launch.”
I had an Amazon delivery to my apartment last week. For context, I live in a gated building with 200+ apartments in a metro suburb of Dallas. There are trucks from Amazon, UPS, and Fedex every single day, but they “couldn’t figure out” how to get into my building, so had to reschedule a redelivery attempt for the next day. I assume the driver was new and just didn’t have the building access code, because I called Amazon and told them to call me to let the driver in, but the next morning when I took my dog out for a walk, when I got back, the package was on my doormat at 8:30 AM.
The issue is, could they scale down the upper stage–the Starship itself–to F9 size? The whole scheme is based on 100% reuse of hardware (including the fairings), and originally began from SpaceX’s attempts to design a reusable second stage for F9. It may be that you need a certain minimum size in order to bring back the upper stage, and that size is closer to Starship than F9.
Elon *did* make the claim, in his original presentation, that BFR would be cheaper to fly than even F1, and it’s all because nothing has to be refurbished or replaced.
Seems like a waste of money given the state obsolesce of the Falcon 9 family.
Methane certainly seems like a good rocket fuel if going to Mars.
Methane good rocket fuel to leave and travel around the Martian surface.
But if going to transport rocket fuel to Mars- ie Case for Mars, it seems LH2 is better to ship, because you can convert CO2 into Methane and oxygen. It’s lower mass and bringing energy to Mars.
The Moon might have methane. What more valuable on the Moon, 1 kg of H2 or 1 kg of CH4?
Or in term term of mining lunar water, I guess O2 is worth less than H2. LOX is cheaper to liquefy than Hydrogen and I claimed LOX is worth about $1000 per kg and LH2 worth about 4000 kg [or at least $4000 per kg, if LOX is $1000 per kg].
And it seems to me at some point, you mine H2 and maybe just CH4.
Or it’s said that the Moon has 2 billion tonnes of H2 within top meter of entire surface of the Moon. And it seem likely that is some region one have lower and higher concentration of H2 in the top 1 meter of lunar surface. And it has guessed that Lunar polar region might have higher concentration of H2 {or detecting lunar water, it might be more H2 being detected rather than higher level of H2O}
And when the stage was crashed in lunar surface, Methane was detected.
So when it becomes cheaper to mine larger amounts of lunar regolith, instead mining spots where have highest amount of lunar water, one might focus higher concentration of H2 and/or CH4 and other types of volatiles].
Or simply as mine more lunar water, you also getting more of these other volatiles.
So which worth more H2 or CH4 per lb.
Obviously on Earth H2 is more expensive and you make H2 from CH4.
One can ask would ever make H2 from CH4 at any time and any place in space. And/or is CH4 ever cheaper than H2 in space or specifically on the Moon is CH4 ever cheaper than H2.
Let’s just say liquid methane and Hydrogen is same price, $4000 per kg when LOX is $1000 per kg.
In terms of rocket fuel: $6000 of LOX per $4000 of LH2
$10,000 / 7 = $1,428. 57 per kg of rocket fuel.
And methane is 3.5 times O2 so
2 kg of CH4 per 7 kg of LOX:
7000 + 8000 is 15,000 divided by 9 =
$1666.67 per kg of rocket fuel.
It doesn’t seem you pay more Methalox as compared to LH2.
If methane was $3000 per kg:
7000 + 6000 is 13000 divided by 9 =
$1444.44 per kg of rocket fuel
Or say, LH2 is $8000 per kg
6000 + 8000 = $14,000
14000 / 7 = $2000 per kg of rocket fuel.
Let’s say lunar Methalox is being sold for $3000 per kg
LOX is $1000
How much would the price of LH2 need to be, before would decide
that $3000 per kg for Methalox is better price to pay for lunar rocket fuel?
Like Earth, the Moon surface is 40% oxygen.
So when lunar LOX is $500 per kg
And say LH2 was $4000
3000 + 4000 = 7000 is rocket fuel at $1000 per kg
Methalox at $3000 per kg:
3500 + 6000 = 9500 divided 9 =
$1055.55 per kg of rocket fuel
700 + 6000 =
And when lunar LOX is $100 per kg.
LH2
600 + 4000 is 4600 / 7 =
$657.14 per kg of rocket fuel
Methalox:
700 + 6000 = 6700 / 9 =
744.44 per kg of rocket fuel
BUT if LOX tenths in price, H2 and CH4 probably half in price
LH2:
600 + 2000 is 2600 / 7 =
$371.42 per kg of rocket fuel
Methalox:
700 + 3000 = 3700 / 9 =
$411.11 per kg of rocket fuel
So, I say that within 10 years one has to mine 10,000 tons of water or about 2000 tons of water within 5 years.
And 9000 tons of water is 8000 tons of O2 and 1000 tons of H2 from the lunar water.
In this time period how much CH4 and H2 would be mined without including amount from splitting water.
As wild guess one might have 100 tons of both CH4 and H2 totaling 200 tons. Or 100 tons of either.
If mining water and making rocket fuel you get surplus of O2 and would want to export LOX. But you “don’t have enough” H2 or don’t have the “natural surplus” of hydrogen.
But as said, later, one might focus on mining Hydrogen {and other volatiles} by finding a site which richer in them. Or mining site richer something [other than lunar water] and these other volatiles are by product of whatever mining is- a common example is if you mining He3. But it could be iron or glass or whatever.
Anyhow you get in short time period, 100 tons each or either of H2 and CH4 in order to get say 10 kg of He3. And with that amount of helium [about world consumption in a year] you ship it to Earth. And you have rocket fuel somewhere around $1000 per kg, so cheap rocket fuel and cheap to send to Earth.
Or making glass or whatever.
But point is would you want to export hydrogen or CH4.
With Mars, it seems to me you don’t want Methalox sent to Mars surface, but could send to Mars orbit. But you want to send LH2 to Mars surface.
Given that Mars has plenty of water that can be split into hydrogen, and CO2 that you can split into carbon, would you really want to deliver any kind of fuel to Mars? Once ISRU is up and running, I’d try to make sure the rockets land almost empty and fuel them back up while on the surface.
–George Turner
July 26, 2019 At 4:57 PM
Given that Mars has plenty of water that can be split into hydrogen, and CO2 that you can split into carbon, would you really want to deliver any kind of fuel to Mars?–
In terms commercial lunar mining, the first priority is sending rocket fuel to Low lunar orbit. So send LOX to lunar orbit, and get LH2 sent from Earth to low lunar orbit.
Sending Lunar LOX to low lunar orbit, because there extra LOX, and assume LOX is cheaper. So idea is can deliver cheaper LOX from Moon, than can send LOX from Earth.
And since water is cheaper than LOX or LH2, and someone values water in Low Lunar orbit, then can sell water for $500 less than can sell LOX, ie: water $500 per kg, LOX $1000 and Hydrogen about $4000 per kg. And if anyone want lunar dirt in lunar low orbit, about $500 less than the water.
Or LH2 would cost $4000 per kg more than lunar dirt.
So in sequence, at lunar low orbit, lunar dirt about $3000 per kg, lunar water $3500 per kg, LOX: $4000, and LH2 about $7000 to $8000 per kg {LH2 has high percent of weight in terms tank weight, but since travel time might be 10 mins, and low gees, it might be less of issue}.
As said:
“BUT if LOX tenths in price, H2 and CH4 probably half in price
LH2:
600 + 2000 is 2600 / 7 =
$371.42 per kg of rocket fuel
Methalox:
700 + 3000 = 3700 / 9 =
$411.11 per kg of rocket fuel”
So then maybe sent LH2 to low lunar orbit for
less than $3000 per kg
And Mars high orbit for less than $3500 per kg
Mars Low orbit for about $4000 per kg
And getting to Mars surface depends of cost or have much
they will pay for the container. So say $4500 per kg plus cost of container.
Or prior to going down gravity well, one might imagine some means of recycling the container. And container needed to travel thru atmosphere might be expensive.
But this is more or less when still largely about mining lunar water, rather than when thousands of tons of H2 per year is happening {small fraction per year of the 2 billion tons of H2 in top 1 meter of entire surface of Moon which if sold at average value of $5 per kg or 5000 per ton, totals 10 trillion dollars, though first 1% might average at about $50 per kg, and 99% is never mined because there are cheaper ways to get hydrogen- maybe, on Mercury, space rocks, gas giants, or whatever]\
Also space has far more water than both Earth and Mars.
And open space has far more solar energy than Earth, Mars, or the Moon- one can certain Hydrogen will imported to Mars, and you certain water will imported to the Moon.
But when?
Could be less than 100 years, assuming there is mineable water on the Moon- and someone finds it, soon.
Quite right. Mars has potential to become the OPEC of the inner solar system – maybe of the outer as well, though Titan would certainly be in the mix too.
Compared to the Moon, Mars is known to be sopping wet. With atmospheric CO2 and groundwater/ice, both hydrolox and methalox are readily doable. Even synthetic RP-1 isn’t out of the question, though I’m not sure why anyone would want to do that. The Martian atmosphere also contains a lot of argon usable for electric propulsion and nitrogen usable for agriculture.
All could be major future exports for a nascent Martian colony.
You just want to ship small nuclear power plants to Mars. The rest is there.
Any updates on TeraPower in the last couple years?
They are still in pre-application talks with DOE. I work in the medical device field now and the FDA approval process looks like the road runner next to DOE glacial speeds.
https://www.facebook.com/nrcgov/photos/a.730738480322948/2481808021882643/?type=3&theater
According to Wiki, Trump also cancelled their development deal with China due to issues of technology transfer.
I have no objections; the technology is easily scalable into wet navy ships, and possibly even aircraft.
Preferably thorium-powered so more fuel can be obtained from local deposits.
It would make more sense to build a Falcon 4 or 5-R if there was a advantage rather than divert resources to develop what would be a new engine. That may have gone into the choice to make Raptor sort of medium sized.
What makes even more sense is to continue to profit from a very successful Falcon design as they move on to the next stage.
I also wanted to say that that was a very good video. Very much on point and well worth the time.
The first thought that occurred to me was that it’s been a long time since I’ve seen anything 10% as good on major media. Those that suggest that the laid off media learn to code should probably lower their expectations. Learn to push a broom is probably more in line with reality.
The second is: How many billions of dollars have we spent and how many billions more will we spend to use up the remaining R-25 engines? Maybe someone should raise the money to get this dubbed onto VHS so it would be available for our elected representatives.
Third: It’s going to be a while before I’m used to the wrinkly skin.
To make a massive profit using Starship to launch individual Falcon-sized satellites: Sell rides to tourists and let them throw it out the hatch.
Well, that brings up a question about its launch abort system. On a ship that large, are they even go to try and have any kind of escape or abort system?
Is large ship trying reduce cost of long transit time and launch windows to Mars, or mostly the launch cost to leave Earth?
Think 707…no parachute for the passengers, non expected either. Hopefully the safety record reaches and surpasses that of air travel of the 50’s
Yes, but a 707 can glide. Propulsive landing has no margin for error. If the ship is low on fuel, all the control system does is pick where to put the crater.
Starship has multiple engines.
Yes, but sadly, every one of them requires fuel to run. ^_^
During one of the Space Shuttle missions someone uploaded a state update that told the Shuttle it was off in the Andromeda galaxy somewhere, and it started madly firing its low-rate maneuvering thrusters until the crew woke up and intervened. If the controls had been left on high-rate thrusters, the mistake would have consumed so much fuel that it wouldn’t have been able to deorbit.
With Starship, the risk is that a slight mistake in CG or some kind of minor flight deviations requires it to use too much of its landing fuel to maintain its re-entry attitude, so that it comes up short for for powered landing. We saw quite a few such errors during the early attempts at landing Falcon 9’s, where they would either miss entirely or slam into the drone ship and explode.
The speed at which it comes down leaves little or no margin for error, and it requires 100% reliable restarts of pump fed cryogenic engines that have just re-entered from orbit. I would rate the landing as the highest risk of the whole mission profile, far more so than their early attempts at using pressure-fed hypergolic Super Dracos.
All good points and all, I suspect, already considered by SpaceX. Starship, for instance, isn’t going to have to rely on a ground station to tell it where it is. It will have GPS and, soon, Starlink to refer to.
And I don’t recall that any of the F9/FH stage recovery failures was due to lack of propellant. One was due to lack of hydraulic fluid for the grid fins, another was due to lack of sufficient TEA-TEB to relight the intended three engines and a third was due to lack of redundancy in the grid fin hydraulics. Starship won’t have a total loss hydraulic system, will have backup components in its hydraulic system and I don’t think it will rely on TEA-TEB for engine relights.
Will it still be possible to lose one on re-entry. Sure. But I don’t think that’s going to be anything remotely resembling a common occurrence. And when and if it happens, it will probably wind up being caused by something that isn’t on our “usual suspects” list. That has certainly been the pattern with SpaceX’s infrequent failures to-date.
Personally, I think Elon should put back the currently deleted seventh center engine on Starship for extra oomph in a launch abort situation anent a failed Super Heavy booster. Seven Raptors yields a bit over 3 million lbf of thrust at sea level and well over that at altitude. That’s enough to lift Starship from a dead stop on the pad – albeit at very low G – even with a 150 tonne payload aboard. With a 100 tonne payload, Starship could be fairly lively on seven engines.
But a Starship configured to carry people isn’t going to have a total payload mass anywhere near even 100 tonnes so I think a passenger-carrying Starship could step out quite briskly in the event of a booster explosion.
I also think just chilling in all the Starship engines on the pad instead of waiting to do it during ascent as is now done with F9 and FH would allow a quick enough escape burn initiation and RTLS or abort-to-orbit and go around at any altitude from pad to orbit.
With the newly-planned complement of 35 Raptors on Super Heavy, putting seven back on Starship would also raise the stack total to 42 as Elon joked about being so close to in a recent tweet.
Probably every thread about SperHeavy/Starship should begin my noting it is cheaper to build and operate than Falcon 9, with at least six tumes as much payload.
I don’t know what Musk plans, but there’s no reason it couldn’t have an ejection cabin, with plenty of margin to waste. Look at it this way: you could stuff 15 people in a Dragon 2 (minus trunk), put three Dragons under a frangible nose cone, and there are 45 people riding in ejectable lifeboats that would cover all missions in cislunar space, including landings and takeoffs from the the Earth, the Moon, and in transit between. That would include zero-zero abort from the launch pad or the surface of the Moon (with 1/6th g, the abort could include a propulsive landing), would include abort to LEO or LLO for some parts of flights, and could be equipped to support those 15 people for a very uncomfortable but survivable free return. There’s even a possibilty the Dragons could eject successfully from a sudden landing crash. Of course, during successful flight, they’d get out and use the rest of the ship.
Mars is another matter. Go in a fleet (so ships can rescue one another), and if you happen to die on Mars “at the point of impact,” you died doing about the coolest thing ever. Your name will be on a monument somewhere. People are going to die colonizing Mars. I’ll be dead within 20 years. I’d rather it be on Mars, instead of mowing my lawn, or worse, in a hospital.
If you had ejectable Dragons in the nose, or a larger separable cabin with pressure-fed Super Dracos, the abort problem is basically solved. If anything like Dragon 2, it will be capable of acceleration at 6 or 7 G’s, which is far higher than the G’s Starship is going to use for liftoff, breaking, and touchdown.
You could program their flight controller with a minimum deceleration profile, such that the crew cabin is going to try and make a soft touchdown at about the height of the Starship. If the Starship fails to decel properly, it would simply fall away from the now separately decelerating crew cabin, which is insistent on making a softer style of landing than the malfunctioning Starship that just made a splash or dent somewhere.
The second part of the abort is for the crew cabin to hover and translate sideways a couple of Starship lengths, in case the big rocket tipped over, and then make a controlled touchdown. The same system also covers all launch aborts.
About the only thing the system couldn’t handle is an exploding check valve, but they got rid of those.
Launch 100 tons of water to high earth orbit with +90% sunlight.
Assume 20,000 Kg water costs 100 million dollar to put in the orbit.
Or water cost $5000 per kg. Total: 500 million
Change that, let’s mix Ethanol with water:
“if you mix 50 mL of water and 50 mL of ethanol you get approximately 96 mL of liquid, not 100 mL. ”
So mostly bring Ethanol rather than water.
Or realized I don’t want oxygen, or don’t want to ship oxygen from Earth. I was thinking Propane or LPG
Density of Propane: 493 kg/m
LPG about 550 kg/m3
And wonder if make could H2 from them, finally ask how do H2 normally, apparently can make from Ethanol {though not normally}.
Ethanol Density 0.7893 g/cm [789.3 kg per cubic meter]
And need water also and they can be mixed.
“Steam reforming reaction (ethanol)
C2H5OH + H2O (+ heat) → 2CO + 4H2
Water-gas shift reaction
CO + H2O → CO2 + H2 (+ small amount of heat)”
https://www.energy.gov/eere/fuelcells/hydrogen-production-biomass-derived-liquid-reforming
Other than CO2, it’s resulting in H2
So could get Methane or H2
And should take less energy than splitting water.
Though perhaps will also split water, because a point wanted
look at was idea splitting lunar water in orbit.
So anyhow just splitting water gives too much Oxygen.
As wild guess say 2/5th is just water and 3/5th 1/2 Ethanol
and water.
Then need power, let’s assume costs is $20 per Kw hour
And amount power will depend of storage and amount rocket fuel needed per year.
In terms of selling, say LOX is $5000 per kg and LH2 is $9000
and Methalox is $8000.
Or not very profitable. But based idea that moon has mineable water and need cheap lunar water shipped to it, for any hope of making profit.
And roughly assumed one can get lunar water at $3500 and lunar LOX at $4000 and might still paying $5000 for the Ethanol shipped from Earth.
Now if it was in Low lunar orbit, one would only get 50 to 60% sunlight. And perhaps not wanted thermal effects. More station keeping. Roughly due lack of constant power, 1/2 production ability.
I would say want lowest delta-v to get to it from Earth, have most sunlight time, and use space tug to transfer from it to Low lunar orbit.
Another thing is you probably want lunar dirt shipped to it.
Also, could have gas {say, CO2} in tanks and pressurized allowing transfer in Microgravity. And/or does having water mixed with Ethanol have any effect in terms of micro-gravity environment.
Or do need to spin it. Or what tidal gravity gradient effect in term being in Earth/Moon L-1 [or L-2].
Anyhow, simple stuff. How big is 20,000 Kg container.
First water only. 3.7 meter diameter, 1 meter length: 10.75 cubic meter. So 2 meters tall
Ethanol – Water density: 894.65 kg per cubic meter is
9617.4875 kg per 1 meter length if 3.7 meters in diameter.
100 tons about 20 meter long.
Would be any advantage to having smaller diameter and taller?
Wouldn’t need a fairing but could designed to function better or more shaped like fairing.
Can’t say I have a plan, yet. I did more digging- large pile:
” Forecourt production is used for facilities that produce approximately 1,500 kg H2/day, while central production is
used for facilities that produce 50,000 kg H2/day.”
Forecourt is high production rate in terms space application
Or 1,500 kg H2 per week is a lot.
1500 times 52 is 78,000 kg per year and for LH2 & LOX rocket fuel is times 7 = 560 tons per year of rocket fuel
to be used. Or if only used to land payload of Moon, about 500 tons of payload landed per year.
Or in terms cost lifting payload form earth and if 1/2 billion per 100 tons: 2.5 billion dollars of Earth
launch costs per year.
Or in terms LOX exported from Moon: 500 tons LH2 & LOX is 428.6 tons of Lunar LOX.
Which about +1000 tons of lunar water and +1000 tons of rocket fuel made each year
Or production level of about 5 year level of lunar rocket yearly production.
Though if consider +10 year lifetime of production capability, it would need to be increased.
But as said Forecourt is production rate is 7 times greater than this, so it should not needed within 10 years.
Further down:
“All system designs were optimized to the best knowledge of the SA/NREL/ANL team and the subject
matter experts consulted. Optimization efforts specifically targeted meeting DOE’s MYPP goal of H2
production costs of less than $2/kg H2.”
So both low production {1,500 kg H2/day} and higher 50,000 kg H2/day. And interested in the 1,500 kg H2/day
and we can assume the $2/kg is largely cost of energy.
Earth cheap electical power of 10 cents per kw hour and/or cheap cost methane gas to make heat.
In terms of space cost, the electical cost is about 100 times greater, so $2/kg is
roughly $200/kg, but probably closer to about $500/kg
Though this is about converting methane to H2, I wondering about ethanal, as it is densier and easer to store.
1.2. Summary of the H2 Production Technologies Analyzed
1.2.1. Proton Exchange Membrane (PEM) Electrolysis
{so splitting water}
1.2.2. Solid Oxide Electrolysis Cell (SOEC)
{water spliting}
1.2.3. Dark Fermentation of Biomass
[nope}
1.2.4. Reformation of Bio-oil in Monolithic Piston-Type Reactors
“The Monolithic Piston Type Reactor process consists of a pair of reactors, each containing a catalyst
coated TiO2 monolith filled with a CO2 sorbent. The reactors operate temporally out of sync, switching
between steam reforming of pyrolysis oil and regeneration of the CO2 sorbent. During reformation,
steam and pyrolysis oil are fed to one of the reactors at ~600°C”
{Maybe related, other than using meathane}
1.2.5. Reformation of Natural Gas in a Reformer-Electrolyzer-Purifier (REP)
“The Reformer-Electrolyzer-Purifier (REP) technology is a product of Fuel Cell Energy, Inc. and derives
from the company’s existing Molten Carbonate Fuel Cell (MCFC) technology, which normally generates
electricity for large applications. The REP is essentially a MCFC stack operated in reverse (i.e.
electrolysis). In short, natural gas (NG) first undergoes steam methane reforming (SMR) in a separate
SMR reactor and the reformed gas is then fed into the REP unit, where the CO2 is effectively transported
across the electrolyte, splitting a water molecule as part of the reaction. Thus H2 is generated both from
reforming of methane and also from water electrolysis. ”
{ditto}
1.3. Results Summary
…
“It is worth noting that the Projected Current fermentation hydrogen cost ($51.02/kg H2) represents a significant
outlier within the data due to its low level of commercial readiness: without this particular data point, the
range of costs for hydrogen production from the Projected Current cases narrows to $2.58 – $5.14/kg H2.”
https://www.osti.gov/servlets/purl/1346418
{fermentation was a nope, anyhow}
And so roughly on earth, about $4/kg H2, for methane. Move on:
“2.1 Reforming of Bio-Derived Liquids
Status
Hydrogen can be produced by distributed or semi-central facilities that
employ gas-phase or aqueous-phase reforming of bio-liquids such as sugars,
cellulose slurries, ethanol, or bio-oils, which can be extracted from primary
biomass feedstocks. Bio-liquid reforming is similar to NG reforming but is
usually challenged by limited catalyst activity and durability.”
https://www.energy.gov/sites/prod/files/2017/11/f46/HPTT%20Roadmap%20FY17%20Final_Nov%202017.pdf
So, problem with catalysts? Hmm well: “…has been
primarily proposed for reforming of biomass or the aqueous phase of the pyrolysis oil”
and not interested in using “pyrolysis oil” {“Natural” crude oil}. though could get ethanal from it
Here is something:
Abstract
In this study, the hydrogen selling price from ethanol steam reforming has been estimated for two different production scenarios
in the United States, i.e. central production (150,000 kg H2/day) and distributed (forecourt) production (1500 kg H2/day), based on
a process flowchart generated by Aspen Plus® including downstream purification steps and economic analysis model template published by
the U.S Department of Energy (DOE). The effect of several processing parameters as well as catalyst properties on the hydrogen selling price
has been evaluated. $2.69/kg is estimated as the selling price for a central production process of 150,000 kg H2/day and $4.27/kg for a
distributed hydrogen production process at a scale of 1500 kg H2/day.
https://www.sciencedirect.com/science/article/pii/S0360319909016152
So apparently, ethanol is somewhere is ballpark as compared to Methane.
More on catalyst with ethanol:
https://www.ripublication.com/ijerd_spl/ijerdv4n3spl_02.pdf
there seems to be some problems. But in other news:
Until recently steam reforming ethanol for hydrogen was a topic discussed only in scientific papers. Most have dismissed this alternative for renewable hydrogen as not commercially viable.
In November 2014, a group of researchers in Singapore at the A*Star Institute of Chemical and Engineering Sciences disclosed an important breakthrough in hydrogen production through
steam reforming of ethanol. They have developed a novel rhodium catalyst that enables hydrogen production with low temperatures and without producing a harmful carbon monoxide by-product.
The rhodium is iron-promoted and the iron oxide converts the carbon monoxide to carbon dioxide and hydrogen. ”
http://www.altenergystocks.com/archives/2015/01/making_hydrogen_from_ethanol/
{though I might want that “harmful” carbon monoxide by-product”, but if lower temperature that is good}
So, let’s try something planish:
So: 20 tons of water, 80 tons of water and ethanol
And not throwing away booster that got the payloads
to say somewhere in Earth/Moon L-1
Need some kind of space tug lifted to same spot.
A space tug which had solar panels and ion engine
could dual use it’s electrical power capability.
But also ship up more solar solar panels which generate electrical
power, plus need solar power for heating rather electrical power.
They would cheaper and more efficient as compared using electrical power from PV panels for heating.
The Ion engine probably need to 2 to 4 times more powerful than the ones Europe is using to go to Mercury, or just more of them[2 to 4 times] of these engines. Or 2 to 4 tugs which work as unit- can dock and undock with each other and with a payload. And in terms tugs carrying payload, it could limited to carry lots ion engine propellant [and cheaper type could much better].
Plan is to make some LOX and LH2, but mostly it;s making a lot LH2 and maybe some Methanlox.
It’s always going to import ethanol from Earth, but some point it will import water from the Moon.
The Moon might have surplus of LOX, but with ethanol shipped to depot, depot can have surplus of H2 and Methane {or CO2}.
One could say this similar to Gateway, but I don’t think NASA should be running it. Or it’s part of commerical lunar mining, though could part of supply chain of providing Lunar water and LH2 [for Mars surface} and rocket fuel to get to Mars.
As far as I can see, it’s just a single piece with no separable crew/passenger section. Any escape system would have to be as powerful as the engines. I doubt that they could be started quickly enough and they might be what you were trying to run away from anyway.
Building a separate capsule would look possible. It would still be big and you’d have the added weight of a parachute and the weight and risk of a large power source. Just the parachute would be a major, possibly impossible, undertaking for something that big. We’ve just seen how the escape engines add a significant risk.
Well, it’s kind of a mystery. It can’t be a single piece or they couldn’t deliver 100 tons of payload, plus return a very significant fraction of that, so there has to be a big cargo bay in there somewhere.
Given the bring-back capability, keeping the CG near the CP during re-entry implies that the big cargo bay is centrally located, or they’re doing some really creative fuel transfers, and they’re not going to have a whole lot of fuel left to transfer on re-entry.
We naturally expect the passengers to be up front, but Starship isn’t a capsule on a rocket, it’s just one big ship, so the crew cabin could be almost anywhere. Logically, the landing mode kind of argues that the crew cabin should be just above the engines, so when it lands a ramp can come out and the captain can walk down and say “Take me to your leader”.
But all I can say with confidence is that the cargo bay and crew cabin are almost certainly internal.
I suspect chilling in Starship’s engines on the pad instead of waiting to do so at altitude on ascent would allow a fast enough startup to push Starship briskly away from a stricken Super Heavy.
As you note, there are certainly scenarios where survivability is not possible. The TWA 800 disaster, for example, would have chalked up pretty much the same fatality total even if every passenger and crewperson had had a full pressure suit and an ejection seat.
In terms of strictly the engines of the SHS stack, a Super Heavy with 35 engines has almost a six times greater probability of an engine failure than the – at least for now – six-engine Starship. But engine failure is not always explosive. Nor does it always require an abort.
CRS-1’s Falcon 9 v.1.0 booster had a Merlin 1-C engine fail non-exposively on ascent and still completed its mission. Apollo 12 suffered not only its famous pair of lightning strikes on ascent but also a non-explosive failure of the center J-2 engine on its S-II second stage. Again, the mission continued to success.
Based on the evidence of SpaceX flight ops and the D2 that exploded during a test, it isn’t SpaceX’s engines that should really be the central concern anent in-flight RUD’s. Further, SpaceX’s one in-flight and one on-ground loss of mission and payload accidents would have been survivable to human crew on either vehicle had there been functioning LAS systems in place. The D2 explosion simply underlines the fact that escape systems can, themselves, be sources of potential new hazards and, thus, require particularly aggressive testing to vet – as SpaceX has done and is doing.
That said, there will inevitably be more fatalities incurred as human spaceflight becomes more frequent. But staying home, like perfect safety, is simply not an option.
Well, the good thing about Starship is that stainless is very easy to work with (cutting and welding don’t present the huge difficulties of modifying an existing welded aluminum structure), and the large size means they could get quite creative when they need to make changes.
In a thread a few weeks ago I calculated that for the weight of Orion’s LAS, they could have put in a circular steel plate with the same thickness as the frontal armor on a Sherman tank. On a vehicle as big as Starship, a tough, armored crew cabin that can survive an explosion, separate, stabilize its attitude, and parachute down is certainly an option for much of the flight envelope.
There’s also the trivially simple concept of flying cargoes on Starship and crews on Dragon 2 until they come up with something they’re happy with. As NASA eventually concluded with the Shuttle, crew and cargo together might not be the ideal way to do things.
All good points. We shall have to see what SpaceX comes up with by the time a passenger-carrying Starship is built.
Mea culpa, I misremembered my Apollo history. It was Apollo 13, not Apollo 12, that had that center J-2 failure on ascent.
That must’ve been pretty tense, considering S-II was a LOX/LH2 stage. I don’t think NASA was designing for catastrophic engine failures like SpaceX has, so that was one lucky crew.
Luckier on ascent than they were even anent the later SM oxy tank explosion. From Wikipedia’s Apollo 13 page:
The engine shutdown was determined to be caused by severe pogo oscillations measured at a strength of 68 g and a frequency of 16 hertz, flexing the thrust frame by 3 inches (76 mm). The vehicle’s guidance system shut the engine down in response to sensed thrust chamber pressure fluctuations. Pogo oscillations had been seen on previous Titan rockets, and also on the Saturn V during the uncrewed Apollo 6 mission, but on Apollo 13, they were amplified by an unexpected interaction with turbopump cavitation. Later missions implemented anti-pogo modifications that had been under development. These included addition of a helium-gas reservoir to the center engine liquid oxygen line to damp pressure oscillations, an automatic cutoff as a backup, and simplification of the propellant valves of all five second-stage engines.
While that was going on I suspect the ride was even rougher than Shuttle while the SRB’s were firing.
So their vehicle made two nearly successful attempts on their lives and failed each time by a hairsbreadth.
The entire nose of the passenger Starship is that big window and observation deck. That’s largely empty space that could be replaced by the frangible nose cone and Dragon-based lifeboats (or some more advanced ejection cabit) without losing anything but aesthetics. (and some cargo mass; three stripped-down dragons might weigh 30 tons of so).
How much testing is enough? The valve that failed must have been tested numerous time as was the whole system. If it had held through this test, the design wouldn’t have been changed. It might have ridden through a hundred launches. What other bombs are there just waiting for the right set of conditions?
Adding “safety” by multiplying complexity is how the nuclear power industry has gotten to where it is. The real joke is that while we wait for all of the t’s to be crossed, we’re paying through the nose to use the Russian hardware. About the only thing that can be said of it is that it hasn’t killed a crew lately. Does anyone think that the Russian could pass the same sort of quality audit that SpaceX has? The inspectors that didn’t run screaming for the door in the first 20 minutes would probably be found curled up on the floor in a catatonic state of shock.
Well, pretty obviously all the previous testing of D2 hadn’t been enough.
That “paint-shaker” D2 test must have been brutal. It’s a good thing SpaceX doesn’t flinch from being aggressively cruel to its creations in testing. One reason the Merlin has been nearly bulletproof is the acceptance criterion, established early on, that its turbomachinery had to be able to swallow and spit out a 3/8″ stainless nut without failure. I’m sure the Raptor is similarly rugged.
The real question is not how much testing is enough but how much is too much. That, one can only know with certitude after “too much” testing has already been done and no anomalies in service have shown up for some extended period – or ever. At that point, one can say, with some assurance, that the most severe tests applied that nonetheless revealed no weaknesses were, perhaps, superfluous. But since “torture” testing is pretty much a one-time up-front activity, it’s worth doing even if it turns out, in the long run, to have been overkill.
So how much testing is enough as opposed to too much? As a practical matter, the same amount for both cases.
SpaceX seems to agree.
As to the “What other bombs are there?” question, that is never possible to establish with certainty up-front. Unknown unknowns are always potentially waiting to leap out and get you when you least expect them. SpaceX’s public failures with F9 and D2 have all had rather exotic and recondite causes.
The fact that the D2’s failure occurred in testing and not in service, as did the CRS-7 and Amos-6 failures, suggests that the SpaceX trend line for such things is headed in the correct direction. And, in the case of D2, it was mechanically sadistic testing that surfaced the problem. I expect SpaceX’s newer creations to be subjected to the same medieval treatments or worse.
As to your most apt and amusing scenario anent NASA ASAP encountering the Soyuz – good show and spot on. Carriage of copious spare underwear strongly encouraged.
Maybe that’s why they drink all that vodka. I imagine the quality banners in their production factories are quite different from US practice.
“Keep Your Mouth Shut!”
“Pretend You Didn’t See That.”
“Achieve the Goal: Plausible Deniability.”
“It only needs to work once.”
“When you drop a wrench, the wrench store sells more wrenches.”
“We’re not paying you for perfection, we’re giving you a little cut of what the American fools are paying to ride this thing.”
I expect the Russian posters say about what ours do. My observation is that the number of posters is in inverse proportion to the actual effort expended in the same direction.
When I used to do work in cotton gins, I would always have to walk past a long line of the most gruesome “safety” posters you will ever see. Cotton gins were then and remain one of the most dangerous places to work anywhere.
The escape towers on Mercury, Gemini and Apollo were pretty simple. A solid rocket motor mounted to a lever arm long enough that it didn’t need any sort of active guidance system. The Dragon is a lot more complicated. Especially with two modes, normal and !!!
All of the renderings I’ve seen of the Starship show a lot of windows on the pointy end. Not definitive for sure. The same renderings don’t seem to show any way for the cargo on the inside to get outside.
Most of the renderings I’ve seen would clearly imply that the crew and cargo beam in and out on transporter pads. Once they decide that doors and hatches are more practical, I think we’ll start to see more evidence as to what they’re thinking.
Given that reconfiguring the Shuttle’s cargo bay for different payloads actually added a lot to the turn-around time, which wasn’t anticipated during development, I think the idea of a modular Starship has some merit. What if the top front section was simply bolted down and plugged in?
Any sort of large cargo bay adds a lot of weight and complexity. The Shuttle bay doors are an example. Maintaining structural integrity and air tightness on something that big will always be a problem. When payloads start being counted in many tons, just moving it in small pieces through a hatch takes a lot of time and is probably pretty dangerous in 0g. The exception would be liquids that could be pumped.
I think it makes more sense to configure large masses on Earth and transport them in big pieces for assembly in orbit. Those wouldn’t need any crew on board. As you say, a small crew compartment could be bolted on top, or even better below the cargo area so it could be covered with just a fairing when that made sense. They don’t really need to see where they’re going.
I figured on top would be a good location just from thermal and mechanical considerations regarding the tiles. I’d want big removable equipment to stay as far away from those things as possible! ^_^
However, the Space Shuttle didn’t seem to have any problems with the landing gear doors, so perhaps it’s not a cause for concern.
Another simple cut point might be the nose versus the body, treating the main vehicle like a second stage that stays attached during flight, to make re-entry and re-usability work, but is still just a payload on top of a booster from a process standpoint.
But that would likely come down to costs. If it’s cheap and easy to make a new Starship, they’ll just make more models of Starship. It most of the cost is in the tanks and engines, they might make fewer of those and relay on a variety of attachable modules that swap in and out based on mission requirements.
Either way, we’ll get to find out a whole lot more soon enough because they’ll be flying it.
It should be pretty clear, looking out to the next ten years (or whatever, in Elontime) that the most prevelent upper stages for SuperHeavy will be Startankers and Starkickers (which is basically a space tug). Crewed Starships and cargo haulers are going to be less common for a long time to come. My guess is, there will be ten tankers and five kickers for every Starship, and that two-thirds of the Starships will be crewless. That adds up to one out of every 18 launches being crewed.