totm nov 2023 SpaceX Discussion Thread

[YNM]

1 hour ago, Northstar1989 said:

The ESA is apparently feeling kind of left behind by all this (...)

Well, they don't have as much development money, and they have even more bureaucracies.

[tseitsei89]

2 hours ago, Bill Phil said:

NASA doesn't build rockets. They engineer rockets, but they don't build them.

And I would not say that SpaceX is any better, since they would have almost nothing without NASA's assistance. Sure, they can land rockets, but that's not a very unique thing. If NASA was told to do that by congress they would do it. Not necessarily for cheap, but it'd be done.

But comparing the two isn't really useful. SpaceX is a launch service provider. NASA is a government organization that does many things, including buying launches.

If Musk has the money to do it then we can't stop him. The biggest obstacle to landing large payloads on Mars is getting large payloads in orbit of Mars. 

Okay then. Let me correct myself:

SpaceX has already shown that they are WAY superior at engineering rockets compared to NASA (and really currently, compared to anyone else). Just see SLS vs Falcon

And speaking of landing rockets. Currently that is exactly what you say it isn't. It is unique. Literally no one else does that. That is THE DEFINITION of unique...

1 hour ago, YNM said:

So, can I go back in time ? Can I fall from the edge of the Earth ?

No you can't. Because earth is round. 

You do not have to misundetstand/ be a smartass deliberately.

[YNM]

1 hour ago, tseitsei89 said:

You do not have to misundetstand/ be a smartass deliberately.

Well, what faces SpaceX is Physics as well.

I do have to admit though, it is possible that over a certain treshold, you don't need any parachute and just go in by TPS/heatshield and retrorockets.

The big question is the fact that without refueling, they'll have to make something on or more than the capabilities of an Earth SSTO. And the fact it's years of journey in deep space.

This is what we're more skeptical on.

 

EDIT :

If you suggest one-way travels ...

 

then courtesy of that same Science! , 

enjoy dying.

 

Edited February 18, 2018 by YNM

[Kerbal7]

1 hour ago, tseitsei89 said:

Okay then. Let me correct myself:

SpaceX has already shown that they are WAY superior at engineering rockets compared to NASA (and really currently, compared to anyone else). Just see SLS vs Falcon

 

Well to be honest, NASA has assisted SpaceX with technical expertise from the very beginning. NASA continues to work with SpaceX on engineering its rockets and spacecraft even today. Where SpaceX beats NASA and everyone else hands down is being able to bring down the development and launch cost to low earth orbit. That's where SpaceX has been far superior. But NASA is working with other private companies to develop their capabilities too, so in some time SpaceX will have competition.

NASA did a very smart thing here. It knew being a big bloated government bureaucracy it couldn't compete in the financial aspect of the low earth orbit space business. So it is aggressively commercializing access to low earth orbit to vastly bring down the cost. But I still believe NASA does and will continue to lead on the missions to the frontier of space exploration. Moon, Mars, asteroids, etc.     

[Delay]

9 hours ago, CatastrophicFailure said:

Looks like they’re serious this time.

When were they not serious with something?

[Starman4308]

2 hours ago, tseitsei89 said:

SpaceX has already shown that they are WAY superior at engineering rockets compared to NASA (and really currently, compared to anyone else). Just see SLS vs Falcon

Payload capacity: very heavily in favor of the SLS.

Fairing size: very heavily in favor of the SLS.

Main engine specific impulse: very heavily in favor of the SLS.

Per-engine thrust: RS-25 has twice the thrust of a Merlin.

Reuseability: in favor of the Falcon, with heavy assistance from NASA. Don't forget, though, that NASA reused rockets 128 times before SpaceX even attempted the feat.

Cost: In favor of the Falcon and Falcon Heavy.

 

Personally, despite being a fan of what Elon Musk has done with the Falcon 9/Heavy, I'm getting really tired of people misrepresenting what NASA does and the general disrespect for them. NASA can engineer a pretty good rocket, but, hobbled down by political considerations, they cannot produce it cheaply.

NASA is not made of incompetent fools. A lot of America's finest scientists and engineers work there. If let loose to perform their secondary mission of exploring space, they might be a competitive launch provider. Unfortunately, their primary mission of being a glorified jobs program and political tool gets in the way of their secondary mission.

Seriously, have some respect for the organization that helped pave the way for SpaceX's success, including a CRS contract that helped keep the company afloat as it just barely started.

EDIT: I'm reminded of the situation with Japan circa World War 2. Japan had some excellent engineers; they just had issues mass-producing their best designs because of mediocre industrial practice. America, on the other hand, had management and industrial practice down to an art form, and was actually able to mass-produce a lot of the best designs made by their engineers. The M4 Sherman was a good example of the difference between engineering and industrial practice: while the heavier Panther and Tiger tanks it faced were in many ways superior, the M4 Sherman could be built in large numbers, and more importantly, still transported on regular railcars and ships.

Edited February 18, 2018 by Starman4308

[PB666]

5 hours ago, Bill Phil said:

If Musk has the money to do it then we can't stop him. The biggest obstacle to landing large payloads on Mars is getting large payloads in orbit of Mars. 

In principle I agree, this will have to be apart of the process, but I should point out with a 'theoretical' reentry system obtaining a circular orbit is not neccesary to get large payloads on Mars if at least part of the PL is some fuel and a rocket engine with a TWR >> 0.39.

[PB666]

4 hours ago, Northstar1989 said:

dbreakers like SpaceX if my suspicions are correct.  Government space agencies have proven far too unwilling to gamble on risky new launch technologies in recent decades- which is why SpaceX beat them all to the next big breakthrough with reusable launch stages.

If spaceX can get their fuel costs down there is nothing any of these systems will add. I would be looking at things like this

1. A dedicated launch zone (say in the mid pacific) that has virtually no range restriction.
2. Potentially, a fuel generation system (Solar-seawater ----> H2 or Methane).
3. Automated, largely human-less launch control system.
4. Roboticized launch recycling.

Get these things in place, and there is pretty much nothing the ESA could do other than copy SpaceX. There is one advantage that SX has over BO, and that is experience and momentum. In this respect BO is behind SX by 5 years. Of course they both have a long way to go before public sector is forced to knock on their door for business.

[DAL59]

13 hours ago, Kerbal7 said:

No way. That thing has got to weigh at least 200 tons loaded. NASA pulls every trick in the book to land just 1 metric ton on Mars right now. So for Elon Musk to be landing giant 200 ton spaceships in 5 years is, it's not happening bro.

Spacex isn't NASA, and NASA hasn't tried to land more on Mars.

56 minutes ago, Starman4308 said:

Don't forget, though, that NASA reused rockets 128 times before SpaceX even attempted the feat.

Requiring millions in refurbishing.  Reusing the crew capsule and sometimes SRBs is not comparable with landing the first stage and engines upright.

[Starman4308]

19 minutes ago, DAL59 said:

Spacex isn't NASA, and NASA hasn't tried to land more on Mars.

Requiring millions in refurbishing.  Reusing the crew capsule and sometimes SRBs is not comparable with landing the first stage and engines upright.

First, I think you missed the point about political shackles. In the case of the Space Shuttle, to satisfy all the overlapping mission requirements, they had to engineer the RS-25 into being one of the most complicated, expensive engines ever built.

I think you're also conveniently ignoring the fact that the "crew cabin" also had all of the liquid-fueled engines onboard: 3 RS-25 and 2 AJ-10 engines, plus miscellaneous RCS thrusters. Unlike the Falcon 9, which has a 10% engine loss rate from the expendable upper stage, the Space Shuttle brought them all home: the only piece of equipment totally expended was the external tank.

 

[PB666]

30 minutes ago, Starman4308 said:

Payload capacity: very heavily in favor of the SLS.

Fairing size: very heavily in favor of the SLS.

Main engine specific impulse: very heavily in favor of the SLS.

Per-engine thrust: RS-25 has twice the thrust of a Merlin.

Reuseability: in favor of the Falcon, with heavy assistance from NASA. Don't forget, though, that NASA reused rockets 128 times before SpaceX even attempted the feat.

Cost: In favor of the Falcon and Falcon Heavy.

Let the cosmic disentangler disentangle your fact structures.

Add. Already exists: Falcon Heavy. You could launch in Sept if you ordered today. . . . .Proposed first launch of SLS is Dec 15, 2019
Add. Does not require a 2 billion $/year government subsidy: Falcon Heavy.
Add. Second stage engines for SLS (heavy) that significantly exceeds FH LEO to orbit (130T) do not exist: Falcon Heavy. 

[Note: Fairing on SX can probably be increased]
[Note: Singling out main engine ISP on heaviest payloads is cherry picking. . .you have to look at aggregate exhaust velocities for the entire stage, not just the most mass efficient engine]
[Note: And NASA ended that system without a fully functional replacement(s)]

SLS Engines. (remember that Falcon heavy uses side boosters that are just as efficient as the core)

16,000 kN x 2 boosters = 32,000 kN @ 124 seconds = 3968000000 N*sec @ 269 ISP
1862  kN x 4 engines = 7449 kN @ 62 seconds = 461863000 N * sec
2279  kN x 4 engines =  9116 kN @ 62 seconds =  565192000 N * sec [+461863000 = 1,027,055,000 N * sec]

The aggregate total of force * time is 4,995,000,000 during the first 124 seconds of flight.

Of that 79.3% was provided at 2600 Ve
and 20.7% provided at 4000 Ve therefore
0.79 x 2600 + 0.21 x 4000 = 2894 [/9.8] = 295.3 sec for first 124 seconds of flight (less is main engines throttle down for MaxQ).

This compares with Falcon Heavies average ISP during the same period of  . . . .of Average(280, 310) = 295

IOW during the first 124 seconds of flight the Falcon Heavy either had the same ISP or better ISP than the SLS would have (if it existed).

The expense however is enourmously different, the SLS has non-recyclable boosters and the core is a bulky fuel with added mass.

The gross Mass is 979,452 kg and empty mass is 85,270 = delta mass is 894192 kg. At a starting thrust of 7,449,000 and ISP of 3590 m/s = 2074 kg/sec
894192/2074 = 431 seconds. Of which 124 seconds of fuel are used in the initial flight. Thus 431 - 124 = 307 sec.

307 sec x 9116 kN = 2798600000 N*sec. So if we look at the entire first stage plus boosters. 

T = 8,738,600,000
B = 3,986,600,000
1 = 1,027,100,000
2 = 2,798,600,000

B% = 0.45
C% = 0.55 (0.05% provided at SL, .50 at vacuum roughly)
0.45 * 269 + 0.05 * 366 + 0.5 * 452 =  365.3 ISP

This is relative to an approximate 300 ISP for FH entire flight. The aggregate difference for the entire first stage is 18%. For that 18% difference you have traded recyclability of the core and 2 boosters.

I could compare the second stage SLS heavy (EUS) with FH second stage but, just like SLS, the engines for the Second stage are Vaporware.

 

 

 

 

 

 

[YNM]

34 minutes ago, Starman4308 said:

... the Space Shuttle brought them all home: the only piece of equipment totally expended was the external tank.

Don't forget the two thermite candles on the side, they don't return retropropulsively.

 

But yeah. BFR might be flying a bit soon, but sending a man on it to the far unknown and not causing a PR disaster ? Far cry.

[Bill Phil]

4 hours ago, tseitsei89 said:

Okay then. Let me correct myself:

SpaceX has already shown that they are WAY superior at engineering rockets compared to NASA (and really currently, compared to anyone else). Just see SLS vs Falcon

And speaking of landing rockets. Currently that is exactly what you say it isn't. It is unique. Literally no one else does that. That is THE DEFINITION of unique...

No, SpaceX is not superior at engineering rockets either. SLS was forced on NASA by the government, whereas Falcon 9 was something that only exists thanks to investments on the part of NASA, in the form of money and engineering. Heck, NASA basically developed the ancestor of the Merlin engine family.

Landing rockets isn't unique. SpaceX even did it after Blue Origin. And McDonnell Douglas even did it, just without going to space. Technically NASA did it with the Apollo LM. The only thing unique about SpaceX's achievement is the scale, and that was only doable thanks to NASA.

Edited February 18, 2018 by Bill Phil
Typo. I can't type on a phone for some reason

[Kerbal7]

1 hour ago, DAL59 said:

Spacex isn't NASA, and NASA hasn't tried to land more on Mars.

Requiring millions in refurbishing.  Reusing the crew capsule and sometimes SRBs is not comparable with landing the first stage and engines upright.

I don't think you understand the relationship between NASA and SpaceX. SpaceX is not some kind of threat or challenge to NASA's scientific or engineering capabilities. Have no doubt, NASA knows its stuff about spaceflight. It just can't do it cheap. NASA helped SpaceX develop its capabilities and continues to do so because it wants cost cutting. Not because it doesn't have the capabilities itself. And oh by the way, NASA is working with other private companies right now to develop their capabilities too to give SpaceX competition. For example, NASA is working with United Launch Alliance on a reusable booster program that might be cheaper than SpaceX's fly-back boosters. NASA is cost cutting to low earth orbit. Not seeking help because it forgot how to fly.

I know Elon Musk has this whole cult of personality thing going on and many will believe all his moonshine but it just aint so.

   

 

[StrandedonEarth]

3 hours ago, Kerbal7 said:

Well to be honest, NASA has assisted SpaceX with technical expertise from the very beginning. NASA continues to work with SpaceX on engineering its rockets and spacecraft even today. Where SpaceX beats NASA and everyone else hands down is being able to bring down the development and launch cost to low earth orbit.

 

4 minutes ago, Kerbal7 said:

Have no doubt, NASA knows its stuff about spaceflight. It just can't do it cheap. NASA helped SpaceX develop its capabilities and continues to do so because it wants cost cutting. Not because it doesn't have the capabilities itself. And oh by the way, NASA is working with other private companies right now to develop their capabilities too to give SpaceX competition.

 

53 minutes ago, Bill Phil said:

Falcon 9 was something that only exists thanks to investments on the part of NASA, in the form of money and engineering. Heck, NASA basically developed the ancestor of the Merlin engine family.

So, NASA has been and is doing what it and its predecessor, NACA, were chartered to do: research and develop aerospace technologies that private industry can't afford to, to be transferred to American commercial industry for the benefit of all. Meanwhile, they continue to break new ground with new vehicles as best they can, hobbled by the requirements of Congress.

Glad to hear it. Maybe I'll see boots on Mars in my lifetime after all!

[Bill Phil]

Even Musk has given credit to NASA:

" SpaceX has only come this far by building upon the incredible achievements of NASA, having NASA as an anchor tenant for launch, and receiving expert advice and mentorship throughout the development process. SpaceX would like to extend a special thanks to the NASA COTS office for their continued support and guidance throughout this process. The COTS program has demonstrated the power of a true private/public partnership and we look forward to the exciting endeavors our team will accomplish in the future."

[PB666]

But just to point out that One can look to both Russian and US engine designs (and going back to the V1) for contributors to Merlin 1 D design.
Social evolution does not occur in a vacuum and the Merlin 1 D is not a revolutionary engine.

[tater]

It's possible to take SpaceX plans at face value, and see that they are rational, and possible, without being a member of a cult of personality. The personality matters only to the extent that he's the guy writing the checks, and getting the investment, and he steers the company towards his goal (same applies to Bezos). SpaceX is going to build BFS right now. They will stop if they realize it is not plausible, but that will be a branching point once they get at least a "grasshopper," I think. This testbed will tease out possible fundamental problems which they certainly could discover. Composite tanks and frequent cycling, for example. The thing could work fine a few filling cycles, but not really work for multiple operational cycles. Once they have a grasshopper, they'll fly a bunch, and find out the, well, kerbal way, lol. If it blows up after a few hops since the tanks cannot cycle many times, then they might have to reevaluate the whole thing. If the grasshopper works as the F9 version did, then they have to cycle it including reentry profiles, same deal.

They could very well discover that the booster is easy (it's just a larger F9 stage 1), but the upper stage spacecraft is not reusable, or only reusable a couple times or something. We'll have to see how that works out.

Assuming they are right about it being doable, then I think the Moon in a 15 year timespan is absolutely possible. They need to test on that sort of terrain at some point anyway, should they want to send one to Mars. LZ-1 or Of Course I Still Love You is a far different landing than some spot on mars or the Moon that looks flat until you are 100m above the surface, and notice the boulder where your landing leg will soon be.

[sh1pman]

 

[PB666]

4 minutes ago, tater said:

Assuming they are right about it being doable, then I think the Moon in a 15 year timespan is absolutely possible. They need to test on that sort of terrain at some point anyway, should they want to send one to Mars. LZ-1 or Of Course I Still Love You is a far different landing than some spot on mars or the Moon that looks flat until you are 100m above the surface, and notice the boulder where your landing leg will soon be.

Its actually easier to land on the moon up until the point you actually land, then everything is more difficult.

Potentials.
If you have lO₂ and lH₂ (or Methane) the weight requirement goes way down. 
If you can launch a falcon heavy into Lunar orbit you can have a ton of mapping satellites that can (at an altitude of 10km map the moon to a centimeter if you so desire ....and this can be done in 3 dimensions with the proper  . . fourier type analysis . . .prepare however to have a huge database of information in space. Since the moon does not have an atmosphere you can use high energy active infrared lasers to map the moon to whatever level you want.
If you are willing to invest in a set of automated (something on earth like WGS markers) you can in real time adjust the surface of the moon in occurrence with the Earth and Suns tidal effects. If you know where your landing site is going to be, then just have 3 of these within a kilometer and can relay information

Then if these things are done you could virtually land on a dime on a stick sitting 10 meters off the group as a proof of function, with a single suicide burn.  Landing on Mars would be easier about the same as and RTLS.

The thing is that we don't land on dimes 10M off the ground. And so perfect landings for habitation ships would benefit from ground clearance, and there could be difficulty landing at the poles.

I would argue that if SpaceX can get a Mars ready vehicle in 5 years, then there will be moon-buyers within 10. It really depends on if they punch hard on solving some of the most difficult problems.

 

[Starman4308]

20 minutes ago, tater said:

It's possible to take SpaceX plans at face value, and see that they are rational, and possible, without being a member of a cult of personality.

Mostly, I agree with that, though I would say most of Elon Musk's publicly announced timelines have... loose relationships with the timelines that will actually happen.

[StrandedonEarth]

19 minutes ago, Starman4308 said:

Mostly, I agree with that, though I would say most of Elon Musk's publicly announced timelines have... loose relationships with the timelines that will actually happen.

He always says things like “Aspirational” timeline. Meaning if all goes according to plan. Everyone knows that no plan survives contact with reality. 

[tater]

27 minutes ago, Starman4308 said:

Mostly, I agree with that, though I would say most of Elon Musk's publicly announced timelines have... loose relationships with the timelines that will actually happen.

Yeah, if he was saying the sort of things that actually mattered, like "You'll get your Model 3 that you already paid for in 3 months." only to find out it's maybe 18 months, then that's a problem. When he says that their next gen LV will be BFR, and it will be testing as a grasshopper in ~2019, and hopefully flying in 2022, then I am far less concerned about the exact dates, he's spending SpaceX money, after all.

[Kerbal7]

41 minutes ago, Starman4308 said:

Mostly, I agree with that, though I would say most of Elon Musk's publicly announced timelines have... loose relationships with the timelines that will actually happen.

If they happen at all.

Elon Musk said he was planning to land a Dragon spacecraft on Mars in 2018, but that program was cancelled last July. Then he said he was going to fly two tourist around the moon in 2018 after being launched in a Falcon Heavy. But now that plan has recently been cancelled too. Except it is now going to be carried out by a BFR. Wait, what? If you can't fly 2 people around the moon in a little capsule what chance is there of you flying a 200 ton giant spaceship around the moon that holds 150 people? 

I'll be waiting for the announcement the BFR has been cancelled so he can focus on building the Death Star. 

Maybe you should start out small Elon and work your way up in this human spaceflight thing. Get your feet wet a little bit before you jump in the deep end.

[sh1pman]

9 minutes ago, Kerbal7 said:

If they happen at all.

Elon Musk said he was planning to land a Dragon spacecraft on Mars in 2018, but that program was cancelled last July. Then he said he was going to fly two tourist around the moon in 2018 after being launched in a Falcon Heavy. But now that plan has recently been cancelled too. Except it is now going to be carried out by a BFR. Wait, what? If you can't fly 2 people around the moon in a little capsule what chance is there of you flying a 200 ton giant spaceship around the moon that holds 150 people? 

I'll be waiting for the announcement the BFR has been cancelled so he can focus on building the Death Star. 

Maybe you should start out small Elon and work your way up in this human spaceflight thing. Get your feet wet a little bit before you jump in the deep end.

They can’t waste time and resources on human rating FH because New Glenn is coming, and they really need to have BFR soon in order to not get squashed by BO.

Edited February 18, 2018 by sh1pman