totm nov 2023 SpaceX Discussion Thread

[ChrisSpace]

17 hours ago, Rakaydos said:

The website Atomic Rockets suggests that methane as an NTR fuel is sooty. The heat breaks the methane down into elemental hydrogen (awesome NTR fuel) and elemental carbon. (which cakes the reactor walls)

So at the very best, a methane NTR will require frequent cleanings, very close to/inside the reactor, which will drive up the service costs. this could make "just use more chemical methane rockets" the better choice over the long run.

Would it really cost much to clean the soot out of a nozzle?

16 hours ago, MatterBeam said:

Also, when orbital refuelling is in play and the deltaVs are under 10km/s, the benefits of NTRs are quite limited. They only produce high exhaust velocities using liquid hydrogen. Using denser fuels such as ammonia or methane only increases Isp by about a 100 to 200 seconds over Methalox. You'd be investing massively in a very strictly regulated technology, developing it to modern standards, testing it to higher rigor than manned spaceflight (no-one wants a rocket launch accident spraying nuclear dust over all of Europe... again) and mounting it on the ITS for a drastic thrust reduction just to save on propellant, arguably the cheapest part of a spaceship refuelled in orbit. 

DeltaV to Mars is about 5km/s, down to 4km/s using aerobraking. Mass ratio using 375s Isp methalox (Raptor) is 2.96. An 85 ton rocket will need 167 tons of propellant. A methane NTR might achieve 644s Isp. Mass ratio for 4km/s is 1.88, so that 85 ton rocket will need 75 tons of propellant.

All in all, you'd save about 92 tons of propellant.

I actually did my math the other way around. The current BFR plan uses 240 metric tons of Liquid Methane and 860 metric tons of Liquid Oxygen, giving a total propellant tank volume of 566.3 + 750.2 = 1316.5 m^3. If all that was filled with Liquid Methane you'd have a wet mass of 793 metric tons (assuming a dry mass of 235 metric tons). With an Isp of 644s that gives a total Dv of 7681 m/s. That's over a kilometer per second more than the current design, plus the lowered mass means the launch vehicle wouldn't need to be as large and expensive. But that doesn't even matter since SpaceX wouldn't be able to aquire the assets to mass-produce NTR thrusters anyway.

[Elthy]

1km/s of DeltaV is extremly low compared to the hassle with NTRs, especially if you want to reuse them multiple times including landings near settlements...

[ChrisSpace]

24 minutes ago, Elthy said:

1km/s of DeltaV is extremly low compared to the hassle with NTRs, especially if you want to reuse them multiple times including landings near settlements...

I suppose in most situations it would be, but I can still see a few advantages:

- larger payloads can be delivered to the moon and Mars

- travel times to Mars can be shorter, reducing radiation exposure for the passengers

- much more of the solar system can be opened up for... something. Surely the moons of the outer planets must have something profitable?

- using one type of propellant instead of 2 might make stuff easier, I think

- rescue/damage control vehicles can arrive at emergency situations faster

- aforementioned stuff about the launch vehicle

[MatterBeam]

3 hours ago, ChrisSpace said:

Would it really cost much to clean the soot out of a nozzle?

I actually did my math the other way around. The current BFR plan uses 240 metric tons of Liquid Methane and 860 metric tons of Liquid Oxygen, giving a total propellant tank volume of 566.3 + 750.2 = 1316.5 m^3. If all that was filled with Liquid Methane you'd have a wet mass of 793 metric tons (assuming a dry mass of 235 metric tons). With an Isp of 644s that gives a total Dv of 7681 m/s. That's over a kilometer per second more than the current design, plus the lowered mass means the launch vehicle wouldn't need to be as large and expensive. But that doesn't even matter since SpaceX wouldn't be able to aquire the assets to mass-produce NTR thrusters anyway.

That deltaV advantage doesn't sound very useful if the BFR is only supposed to go to LEO in the short term, and translates into a few extra tons on a Mars trajectory...

3 hours ago, Elthy said:

1km/s of DeltaV is extremly low compared to the hassle with NTRs, especially if you want to reuse them multiple times including landings near settlements...

Exactly this. There might be methods to increase the deltaV advantage, but I am thinking mostly about two things:
-TWR. Nuclear rockets have low TWR compared to something like the Raptor. This will mean that for the same acceleration, nuclear rockets will be quite a bit heavier and will cut into the mass ratio advantage they provide.
-Refurbishment. Nuclear reactor cores running at high temperature, with sooting from methane and poisoning from radioactive products, will need constant upkeep. When your entire assembly needs to be taken to a special closed environment and worked on by specialized engineers using special precautions, you will have a much harder time keeping up with  the rate of launches of a conventional chemical rocket system.

2 hours ago, ChrisSpace said:

I suppose in most situations it would be, but I can still see a few advantages:

- larger payloads can be delivered to the moon and Mars

- travel times to Mars can be shorter, reducing radiation exposure for the passengers

- much more of the solar system can be opened up for... something. Surely the moons of the outer planets must have something profitable?

- using one type of propellant instead of 2 might make stuff easier, I think

- rescue/damage control vehicles can arrive at emergency situations faster

- aforementioned stuff about the launch vehicle

Instead of a nuclear thermal rocket, what about a nuclear electric rocket? Double down on the deltaV advantage without covering your entire propulsion unit in radioactive waste particles. 

[tater]

Commercial crew just got bumped 2 months.

SpaceX crew Dragon uncrewed in April (was Feb)

Boeing uncrewed test flight in August

SpaceX crew flight August

Boeing crew flight Nov.

[wumpus]

1 hour ago, MatterBeam said:

Instead of a nuclear thermal rocket, what about a nuclear electric rocket? Double down on the deltaV advantage without covering your entire propulsion unit in radioactive waste particles. 

Downsides include needing radiators for both producing and consuming electricity.  For sufficiently small values of RTG and ion drives, such is already feasible (and might even be done for a "Voyager III" probe that needs a bit of help for the grand tour), but only if you really need "burns" beyond Mars (otherwise you would simply bounce around the inner planets while gaining delta-v from solar panels).

From the sound of it, VASIMIR might be able to consume more power than an RTG can supply.  But the real problem is that unlike nuclear plants, you don't have a river or ocean nearby.  You have to provide both cooling to the reactor and a "cold side" to your heat engine in vacuum.  This is how you get radiators the size of aircraft carriers... 

 

[MatterBeam]

39 minutes ago, wumpus said:

Downsides include needing radiators for both producing and consuming electricity.  For sufficiently small values of RTG and ion drives, such is already feasible (and might even be done for a "Voyager III" probe that needs a bit of help for the grand tour), but only if you really need "burns" beyond Mars (otherwise you would simply bounce around the inner planets while gaining delta-v from solar panels).

From the sound of it, VASIMIR might be able to consume more power than an RTG can supply.  But the real problem is that unlike nuclear plants, you don't have a river or ocean nearby.  You have to provide both cooling to the reactor and a "cold side" to your heat engine in vacuum.  This is how you get radiators the size of aircraft carriers... 

 

I seriously doubt that anyone needs radiators the size of aircraft carriers unless you want to radiate at very low temperatures for safety or endurance reasons. The FFRE's design specifically needs to remove megawatts of heat from components running at 140K and 590K! That's extremely low! Because waste heat rejection scales with temperature to the power 4 (!), the low temp radiators are massive.

Now, how will electricity be made from a modern spacegoing nuclear reactor? There's two options - thermoelectric, and gas turbine. Thermoelectric allows for very high operating temperatures (rejecting even in 2000K range, but 1500 seems more likely) and no moving parts. It can work even when cells are damaged and requires no maintenance for years on end... but they have terrible efficiency and even worse W/kg ratings. Compact gas turbines do exist, and using something inert like nitrogen or CO2 as a working fluid allows for decently high temperatures at the radiator's entrance - 800 to 1200K. They have high W/kg ratings, so you can compensate for their complexity by just installing several redundant turbines and using probability of failure to your advantage. If failure rate after one mission is 10%, then having three turbines reduces means you'll have a 24% chance of at least one turbine failing, but a 0.1% chance of all turbines failing.

If we use electric engines with an Isp of 2000, the mass ratio for a Mars mission of 6km/s is 1.35. An 85 ton craft with 150 tons of payload will need only 82 tons of propellant. If SpaceX uses 1kW/kg reactors and engines, then it can 'invest' 10 tons into propulsion and produce 1kN of thrust... the ship would start accelerating at a measly 0.327 milligees... terrible!

This isn't a very accurate calculation however. 1kW/kg is an assumption that even NASA research into powering the VASIMR engines hasn't achieved. A rocket would still need a high thrust chemical engine to make a retro-propulsive landing on Mars, so some of that mass budget will be used for landing. Also, Musk wants to do a rapid transit, so 6km/s isn't enough. 

Overall, I think I answered my own question. Unless the power density of nuclear electric craft is massively improved (10x or more), then rapid interplanetary travel is best solved by piling on the chemical propellants.

[NSEP]

8 hours ago, rudi1291 said:

Would a F9 upper stage fit into BFR?

Yes, probably the F9 upper stage weighs 73 tons with fuel inside. And is only 14.6 meters tall, I don't know if a 15 m long payload can fit inside the BFR, i doubt it can not fit a 15 meter long payload inside the cargo bay. And if it can, it can send 2 second stages into space.

[Racescort666]

So I did some math and you would need 13 (o_O) SNRE engines to match the thrust of an MVac engine. Improved performance is something that people always talk about when discussing NTRs but the cost (that's rarely quantified) is the mass penalty. So here we go:

• Payload 10 886 kg (constant for this analysis)
• dV: 7205 m/s (based off of F9 upper stage with the above payload) The goal of this exercise is to concept an NTR upper stage to replace the current F9 upper stage so it has to have roughly the same performance.
• M1D mass: 490 kg
• SNRE cluster: 31 200 kg (over 63X the mass)
• MVac ISP: 348 s
• SNRE ISP: 900 s  

The thing that doesn't get talked about is how much tank and fuel you would need to match this dV. All else being equal (including rocket diameter), you get:

• Fuel mass: 87 646 kg, Not bad considering the F9's 107 990 kg mass but you need to store it.
• Tank mass: 27 376 kg, If you're following along at home... 
• Total mass: 157 108 kg, way more than the F9's 122 876 kg
• Also of note, tank length: 117.7 m, more than double the F9 first stage. There's no way this is practical.

The easy way to fix this is to increase the tank diameter. Arbitrarily, I chose the same diameter as the F9 payload fairing:

• Fuel mass: 74 529 kg, still better but lets see how the rest of it stacks up
• Tank mass: 19 820 kg, still a lot
• Total mass: 136 435 kg, still more than the current F9 upper stage but possibly in the realm of what the booster can handle
• Tank length: 49.6 m, longer than the F9 first stage, it might look a little goofy. 

The last diameter that I calculated was the same diameter as the Space Shuttle ET 8.4 m. I used the ET as my benchmark for tankage mass by area and simplified everything to cylinders. I figured this was a good approximation of how to get a stage mass. There will be other components that factor into the mass but in general, the larger the tank, the more that stuff comes out in the wash.

• Fuel mass: 67 264 kg
• Tank mass: 13 954 kg
• Total mass: 123 304 kg
• Tank length: 17.1 m

Finally something that's reasonable in terms of size and mass but now we have a weird egg shaped tank below the fairing. NTRs are cool and awesome but I don't think they are practical for Falcon 9 unless you wanted to do some sort of NTR kicker stage for an interplanetary mission. Even then, it may be worth considering alternate options.

Sorry if this wasn't really relevant to the thread but I had crunched the numbers and decided to share.

[Spaceception]

7 hours ago, tater said:

Commercial crew just got bumped 2 months.

SpaceX crew Dragon uncrewed in April (was Feb)

Boeing uncrewed test flight in August

SpaceX crew flight August

Boeing crew flight Nov.

I hope the delays for SpaceX were from increased prioritization on BFR, and not a problem with the capsule.

[tater]

I'm sure it has nothing at all to do with BFR. Their existing customer, NASA, comes first.

I'd imagine it has to do with 39a. The October 30 launch still shows 39a, which means they can't start working on it until November. That means FH is January earliest. Crew Dragon demo was February, with a few months after FH. Maybe the crew stuff to pad happens after FH.

[ChrisSpace]

14 hours ago, MatterBeam said:

That deltaV advantage doesn't sound very useful if the BFR is only supposed to go to LEO in the short term

Nothing about my idea is short-term. Or even realistic.

14 hours ago, MatterBeam said:

-TWR. Nuclear rockets have low TWR compared to something like the Raptor. This will mean that for the same acceleration, nuclear rockets will be quite a bit heavier and will cut into the mass ratio advantage they provide.

Atomic Rockets has an NTR weighing 5 metric tons that has a thrust of 3500kN. For a full NTR vessel that's 0.45g of acceleration per engine. So this isn't as much of a problem as you might expect.

14 hours ago, MatterBeam said:

Instead of a nuclear thermal rocket, what about a nuclear electric rocket? Double down on the deltaV advantage without covering your entire propulsion unit in radioactive waste particles. 

If by "nuclear electric" you mean "Ion/Magnetoplasma/VASMIR powered by a nuclear reactor", like Hermes in The Martian, the main problem there is acceleration. You'd basically need two propulsion systems, one for travel in deep space and one for high-thrust manuvers such as liftoff and landing on Mars.

[tater]

1 hour ago, ChrisSpace said:

If by "nuclear electric" you mean "Ion/Magnetoplasma/VASMIR powered by a nuclear reactor", like Hermes in The Martian, the main problem there is acceleration. You'd basically need two propulsion systems, one for travel in deep space and one for high-thrust manuvers such as liftoff and landing on Mars.

OT for SpaceX, but the VA in VASIMR is for Variable. The reason to change the Specific Impulse (the SI part) downwards is to trade it for thrust. Throw more mass out the back, lowering the I_sp considerably, but gaining higher thrust. That's the idea, anyway. It needs loads of power, though. 

[Northstar1989]

On 10/4/2017 at 2:38 AM, Nibb31 said:

Musk claimed that the reusable price of a Falcon 9 launch could go down to $10 million. He also claimed that FH would fly by 2015. Seriously, you can talk about Musk's vision and plans all you want, but when it comes to schedules and numbers, nobody takes him seriously.

Internal prices and the price SpaceX charges consumers are two entirely different things.  By most accounts, SpaceX makes a very considerable (more than $10 million) profit on each launch.  A lot of that is plowed back into the company to make further upgrades to the design and work on future projects, which is why company profits don't well reflect this.  But make no mistake, SpaceX *is* inching towards the cost/kg that $10 million price would represent (capacity upgrades mean the Falcon 9 is now a larger rocket with higher payload capacity than it had when that promise was made- so $10 million wouldn't be a fair bar to set) and could have eventually achieved it if they didn't decide to discontinue the Falcon 9 to rededicate resources to the Big Falcon Rocket...

As for timelines- yes, Musk does tend to give very optimistic timelines (which is why I think SpaceX won't send humans to Mars until 2032, not 2024), but his company does achieve remarkably well.  You've clearly got a chip on your shoulder against SpaceX and Musk though- I've never seen you give this kind of treatment to companies like Boeing or people lime Jeff Bezos, no matter how obscenely unrealistic their projected timelines are (if the established players made accurate projections, Constellation and the Area program would have been a roaring success and not deemed "financially infeasible" with NASA's budget and cancelled by Congress after numerous development delays...  Mind you I think that was a bad idea- but my point is made.)

[Northstar1989]

On 10/4/2017 at 11:56 AM, kerbiloid said:

30.10.1968. NASA (MSC and MSFC departments) has booked a post-Saturn reusable LV. According to calculations, its reusability would decrease costs 10 times.

1969. Four companies got technical specifications. In 1970 two of them still were in the contest.

09.1969. Two variants of further spacecraft development were proposed: "flight to Mars, lunar orbital station, heavy LEO station" or "LEO station and shuttle".
Any variant cost at least 5 bln USD, both were rejected by the government due to financial reasons.

NASA had to decide: either to finish manned flights, or create a shuttle, but not just as a build-and-support vehicle for an orbital station, but also as a self-financing launch vehicle for common use.

1970. NASA estimated that if the shuttle will fly at least 30 times per year _{(that famous "once per two weeks")}, and if give up other single-use LVs, the shuttle can be self-sustaining.
In its turn, this meant that the shuttle should perform all military launches, too.

NASA had to negotiate with military office, which changed initial requirements:
greater than originally planned, payload;
side maneuver up to 2000 km - so additional lifting force at hypersonic speed (which resulted into double swept (?) wing, enforced heat protection).

1971. NASA won't receive requred 9-10 bln USD and has to cut off something.
03.1972. The draft (MSC-040C) is adopted. The shuttle receives its "classic" shape; turbojets gone; boosters solid rather than liquid; external tank - expendable; payload was decreased for several tonnes. Estimated cost of the system development - 5.15 bln.

07.1972. Developers have received money.

Originally orbiter hull was to be made of titanium, it would be 15% lighter and didn't require such heavy heat protection.
But as an aluminium hull was 80 mln USD cheaper, titanium was rejected, the orbiter was made of aluminium with thick heat tiles.

1988. New, optimized boosters were under development. They should increase payload up to the project 29.5 t value.
1993. Funds are cut, boosters gone.

That entire history was one of cancelled half-finished projects, political interference in the R&D process, and skimping on upfront R&D costs and paying for it in much higher flight costs.

When you constantly get partway through projects and the cancel them, those sunk costs don't go away.  They may not be important to future decision-making on how to finish the overall program, but they are inevitably tallied up by bean-counters who then claim them as part of the final cost of the program.

In truth the Shuttle Program was not one continuous set of projects but 16-20 *DIFFERENT* projects, most of which were cancelled after some money had already been sunk into them.a more honest accounting of the Shuttle's R&D costs for the purpose of appetizing them over the flight schedule would only look at the line of development that was followed and not cancelled- all the other costs were not really the cost of developing the Shuttles, but of political contractor nepotism and interference in tbe design process by power-mad politicians who don't know the limits of their own scientific knowledge...

So, the Shuttle wasn't really as expensive as most people give it credit for being- It's not really fair to plough all the projects thst were cancelled for reasons having nothing to do with technical feasibility into the program costs...

And the actual Shuttle flight costs, ignoring amortized R&D, were MUCH higher than they could have been- because the politicians, in all their power-plays over whose favorite contractors would or would not get rich off the Shuttle's sweetheart contracts, forgot that NASA was supposed to be trying to design an actual feasible, affordable spacecraft- and thus they did not allow many critical projects (such as the improved boosters) to become a reality.  Shortsightedness also played a major role- politicians often only think ahead to the next election, and were unwilling to suffer some pain now for a substantially larger payoff down the line (most likely after they had already left office).  So R&D into design improvements and better designs thst could have paid for themselves many times over were never funded through to completion, because politicians couldn't bear to raise taxes a little (or rather not LOWER taxes) in the short term on their wealthy constituents for large cost-savings down the limr...

 

The Shuttle was a political (and consequently, economic) cluster I-won't-say-what, and a lesson in why politicians should keep their grubby paws out of certain matters and just let the scientists and engineers do their bloody jobs.

But SpaceX doesn't have to deal with nearly as much political interference, and will instead hopefully prove a lesson in the strengths and weaknesses of a more independent private space industry (technically the Shuttle was built by private firms as well- but on government contract and under NASA leadership) that proves a SUCCESS rather than miserable failure like did the Shuttle Program and ultimately could the Space Launch System...

 

[Northstar1989]

14 hours ago, MatterBeam said:

If we use electric engines with an Isp of 2000, the mass ratio for a Mars mission of 6km/s is 1.35. An 85 ton craft with 150 tons of payload will need only 82 tons of propellant. If SpaceX uses 1kW/kg reactors and engines, then it can 'invest' 10 tons into propulsion and produce 1kN of thrust... the ship would start accelerating at a measly 0.327 milligees... terrible!

You need to adjust your thinking.  0.000327 g's equates to 1 m/s of velocity change ever 312 seconds (a little more than 5 minutes), and the capability to accelerate 6 km/s in a little more than 21.67 days of acceleration.  That's not bad at all, when you're talking about a journey that already takes 6-9 months! (for that Delta-V cost)

Not to mention you don't have to perform all that acceleration with crew onboard.  It's entirely possible to place your mission vehicle into a Mars free-return trajectory and just accelerate the crew in a smaller and more lightweight vessel to meet up with the main spacecraft on its next journey by Earth...

If what I just described sounds familiar, That's because what I just described is a Mars Cycler, with the most practical free-return trajectory being an Aldrin (named after Buzz Aldrin, who postulated its existence) Cycler Orbit.

Place your spacecraft in that trajectory (the Delta-V requirements for which are nearly IDENTICAL to a normal 4-5 month "fast" transfer to Mars) with electric thrusters and gravity-assists over YEARS if you want- it doesn't matter, as long as you eventually get it into an orbit that makes a cycle between Earth and Mars.

Then just take your crew capsule you already needed to get people to Low Earth Orbit, stick an oversized upper stage on the back (the requirements for Cycler intercept are highly similar to those for the upper stage of a rocket going to GTO), and intercept with the main mission vehicle in a Cycler Orbit instead of in LEO (time from leaving LEO to intercept should only be a week tops- so similar space and life support requirements to the Apollo Command Module are all that is needed).  Ta Da!  You now have a practical way to use electric thrusters to get to Mars without having to worry about how many weeks, months, or years it takes to accelerate to Mars with electric thrusters...

Edited October 7, 2017 by Northstar1989

[Northstar1989]

15 hours ago, MatterBeam said:

This isn't a very accurate calculation however. 1kW/kg is an assumption that even NASA research into powering the VASIMR engines hasn't achieved. A rocket would still need a high thrust chemical engine to make a retro-propulsive landing on Mars, so some of that mass budget will be used for landing.

Landing is a different problem, with different challenges than getting to Mars in the first place.  So if your mission costs are at all sensitive to the mass you need to launch to Low Earth Orbit, you DON'T use the same spacecraft to reach Mars as to land on it.  The BFR only gets away with thos because Musk thinks rapid reusability will make costs to launch a bigger rocket to LEO a joke compared to the R&D of designing multiple spacecraft for different roles, but under ANY other set of conditions (or even with Musk's miracle launch-costs if you want to bring down marginal mission-costs even further, at the expense of large additional R&D costs you have to amortize and pay interest on over future missions) you go for the specialized approach.  Certainly if it costs you $10,000/kg to get payload to Low Earth Orbit...

Really, you only have one practical option if you're going to specialize to bring down overall launch-mass: you must design a capsule to reach LEO (and act as your ship for reaching the main vessel in a Cycler Orbit under that kind of plan), an orbit-to-orbit specialized vessel to reach Mars (if It's a Cycler, you definitely want to give it electric thrusters, as they help with extremely small/efficient course-corrections, but otherwise the minimum design requirements are much the same), and a specialized lander/ascent vehicle to carry your crew to the Martian surface and back...  It's possible to combine your capsule/interceptor and lander into one vessel, but you don't perform either role quite as efficiently then, as the requirements for EDL (Entry, Descent, and Landing) on Earth and Mars are quite different (you face much more re-entry heating on Earth, but a higher terminal velocity and a more difficult propulsive landing on Mars)

Some missions even call for SEPARATE landers and ascent vehicles- but this isn't as mass-efficient, unless you have no ISRU or reusability and need to carry ALL your propellant with you in single-use spacecraft...  Even refueling a 1-man lander (remote-controlled by one of the mission's pilots) 5 times in orbit from propellant brought from Earth, for 6 trips to carry a 6-man crew to the surface of Mars and back is many times more mass-efficient than a pair of disposable 6-man ascent/descent vehicles...

 

Anyways, Capsule, OTOTV (Orbit-To-Orbit Transfer Vehicle), and lander- basically you have the mission architecture the Mars branch of Constellation was going to use before it was cancelled.  Also, the inspiration for one of the raddest KSP videos ever made based on that mission architecture:

 

https://youtu.be/Tp6yj2k0Fpc

 

Simply put, unless your launch-costs to Low Earth Orbit are obscenely low (like Elon Musk hopes for with the fully-reusable BFR) having a specialized lander simply makes sense for the mass-savings provided by not having to carry your Mars return-fuel all the way to the Martian surface with you.  Also, It's actually much less aerodynamically and structurally challenging than an all-in-one rocket like the BFR, and enables more specialized OTOTV designs- like those relying on an inflatable rotating habitat or a counterweight-and-tether system to create certipetal force based "artificial gravity" on the way to Mars...

So, given the need to design a separate lander anyways, using chemical propulsion for landing, and electric thrusters and atmospheric drag for orbital maneuvers (including your Mars transfer and aerocapture) really isn't that big a deal.  Each vessel ends up specialized for a different type of propulsion- neither needs to be capable of BOTH propulsion methods (even propulsive Earth or Mars capture can be managed with electric thrusters, at higher Delta-V cost, if you start your maneuver 3-4 weeks ahead of reaching the planet and design your transfer trajectory with this type of capture in mind to begin with...)

Edited October 7, 2017 by Northstar1989

[Nibb31]

6 hours ago, Northstar1989 said:

You've clearly got a chip on your shoulder against SpaceX and Musk though- I've never seen you give this kind of treatment to companies like Boeing or people lime Jeff Bezos, no matter how obscenely unrealistic their projected timelines are (if the established players made accurate projections, Constellation and the Area program would have been a roaring success and not deemed "financially infeasible" with NASA's budget and cancelled by Congress after numerous development delays...  Mind you I think that was a bad idea- but my point is made.)

My chip is with blind followers who take everything that Musk says at face value. Musk says a lot of things. A lot of his vision of the future is wishful thinking. Some of his ideas come to fruition, some of them take the long road, and some turn out to be not so good ideas when confronted with reality. The same is true for Bezos, Boeing, and Airbus to some extent, although for some reason, Musk has a fanboy audience that always gives him a free pass and seems to lose all critical thought for anything that he says.

In my book, skepticism is healthy. The loss of critical thought is a mark of cultism.

There is no good or bad or right or wrong in nature. Stuff happens because of reasons. I believe in chaos (theory) and causality more than in sci-fi-dream-driven fanboism. If we become a spacefaring civilization one day, it won't be because a bunch of followers believe in Musk's personal vision, but because the cultural, economical, and social reasons for our civilization to branch out into space will be reunited.

Edited October 7, 2017 by Nibb31

[tater]

It's possible to be a fan, and even to want to see the aspirational milestones achieved, and not be irrational about the likelihood of those goals being hit in a timely fashion.

While I don't see multiple BFS craft heading to Mars in 2020/2022, I actually think we will see them flying in some form in that timeframe (this prediction includes "grasshopper" style testing). I think it is important to realize that both SpaceX and Blue Origin operate outside the normal rules in many ways. Both have a goal being worked for that is counter to economics. There is not good reason for many humans to be in space, but that's what both companies were created to do. Making money along the way, while necessary for SpaceX, less so for BO, is incidental. This separation from the usual politics of spaceflight gives hope to many people who have seen how the sausage is made over the decades, and are tired of not seeing the progress we had hoped for, I think that's where the fanboism comes from, honestly.

I try to be as realistic as possible, so I'm not surprised when things take longer than claimed, but the visible progress over short time frames is nice to see (expendable LV to nailing landings in a short period). Bottom line in that the next few years will be telling.

[magnemoe]

10 hours ago, Northstar1989 said:

That entire history was one of cancelled half-finished projects, political interference in the R&D process, and skimping on upfront R&D costs and paying for it in much higher flight costs.

When you constantly get partway through projects and the cancel them, those sunk costs don't go away.  They may not be important to future decision-making on how to finish the overall program, but they are inevitably tallied up by bean-counters who then claim them as part of the final cost of the program.

In truth the Shuttle Program was not one continuous set of projects but 16-20 *DIFFERENT* projects, most of which were cancelled after some money had already been sunk into them.a more honest accounting of the Shuttle's R&D costs for the purpose of appetizing them over the flight schedule would only look at the line of development that was followed and not cancelled- all the other costs were not really the cost of developing the Shuttles, but of political contractor nepotism and interference in tbe design process by power-mad politicians who don't know the limits of their own scientific knowledge...

So, the Shuttle wasn't really as expensive as most people give it credit for being- It's not really fair to plough all the projects thst were cancelled for reasons having nothing to do with technical feasibility into the program costs...

And the actual Shuttle flight costs, ignoring amortized R&D, were MUCH higher than they could have been- because the politicians, in all their power-plays over whose favorite contractors would or would not get rich off the Shuttle's sweetheart contracts, forgot that NASA was supposed to be trying to design an actual feasible, affordable spacecraft- and thus they did not allow many critical projects (such as the improved boosters) to become a reality.  Shortsightedness also played a major role- politicians often only think ahead to the next election, and were unwilling to suffer some pain now for a substantially larger payoff down the line (most likely after they had already left office).  So R&D into design improvements and better designs thst could have paid for themselves many times over were never funded through to completion, because politicians couldn't bear to raise taxes a little (or rather not LOWER taxes) in the short term on their wealthy constituents for large cost-savings down the limr...

 

The Shuttle was a political (and consequently, economic) cluster I-won't-say-what, and a lesson in why politicians should keep their grubby paws out of certain matters and just let the scientists and engineers do their bloody jobs.

But SpaceX doesn't have to deal with nearly as much political interference, and will instead hopefully prove a lesson in the strengths and weaknesses of a more independent private space industry (technically the Shuttle was built by private firms as well- but on government contract and under NASA leadership) that proves a SUCCESS rather than miserable failure like did the Shuttle Program and ultimately could the Space Launch System...

 

This, and its seen an lot in large projects like road construction too, in the military far more, B1 bomber used parts from 45 states or something, hardly economical but an way to spread the pork around. Wonder if this is how pulled port was invented

On the other hand military is not ruled by purely economical needs, the US keeps the M1 tank production line alive, not because they need more M1 but because if they shut if down  they lose the ability to make tanks. Recreating it because they need an M1 replacement in 2029 would be harder. 
 

[CatastrophicFailure]

Tho sadly I do believe I'll be sleeping thru this one, 530 am on Monday morning... 

[Exploro]

On 10/7/2017 at 1:50 PM, magnemoe said:

On the other hand military is not ruled by purely economical needs, the US keeps the M1 tank production line alive, not because they need more M1 but because if they shut if down  they lose the ability to make tanks. Recreating it because they need an M1 replacement in 2029 would be harder. 
 

Foreign sales would be enough to keep production lines open and that would be sufficient to maintain capability; look at the F-16 for instance. The USAF bought it's last F-16 just after the turn of the century. However it has been foreign sales that have kept the F-16 production lines open. Therefore the claim that Congressional intervention of the Army halting production of tanks as a measure to retain capability is dubious. For example it's no secret that General Dynamics; a company that operates an M1 factory in Ohio, spent millions lobbying Congress (and the sitting Senator of Ohio Mike Turner). GD would be impacted by the Army halting M1 production and thus not surprising they spent millions to successfully lobby Congress to overrule the Army each and everytime the Service sought to halt production of the tanks.

[Ultimate Steve]

4:30 in the morning? Ugh... I'd love to, but I don't think my parents are going to like that with me being late to school basically all of last week (even if it was only by about ten seconds).

[StrandedonEarth]

5:37 Pacific, my time zone, cool. I'll be 37 minutes into my shift. So I'll be able to catch up on my break, if not sooner

[tater]

Oops, missed same post (on my phone).

Edited October 9, 2017 by tater