totm nov 2023 SpaceX Discussion Thread

[StrandedonEarth]

20 minutes ago, YNM said:

so perhaps every now and then you can ask for an expendable launch if it's really urgent.

"Sure, you can take 'Ol Sooty' at the back of the lot there. It probably won't survive another landing anyways!"

Edited February 9, 2018 by StrandedonEarth

[sevenperforce]

47 minutes ago, tater said:

Except of course that the analysis is largely BS. SLS uses Shuttle parts (some that actually failed), yet claims to be 1:500, vs shuttle's actual 1:72? Seems a stretch to magically make it safer than it actually was. Or does NASA calibrate safety with dollars burned? Or is it safer the more districts produce parts . RS-25s have been test fired many times, and 405 individual engine full duration firings during launches. 7 times engines failed on shuttle launches (6 resulted in last second holds, and engines replacements).

Merlins have fired 459 times during launches (9 per F9). Each was also static fired at least once (were all also fired in TX, first?) Meaning that Merlin is demonstrably more reliable than RS-25. That doesn't even count restarts for landings (of which we know of one engine related failure so far, the recent FH core landing burn restart).

What about VAFB SLC-4E (F9's 6th launch and first launch of v1.1), where the uncontrolled roll on descent flung propellant to the tank walls, starving the engine? That's not an engine failure. From what we know, the FH core landing burn failure was not an engine failure, but a failure of the engine to start due to consumables depletion, which is a different matter entirely.

The only Merlin 1D engine failure was CRS-1.

46 minutes ago, magnemoe said:

FH kind fall in an empty gap in an way, very nice for heavy payloads to LEO but not many customers, useful for heavy payloads to GTO however the fairly heavy second stage is an downside. Expendable its an heavy lift rocket with no missions, yes two missions could do an moon landing if you wanted it. 
BFR is another category, as in fully reusable heavy lift. You can do stuff like sending it to leo, have an 3rd stage who put an satellite into GTO, recover the 3rd stage and land. Most fun of all you can do this then taking tourist to a LEO cruise. 

BFR could take any commercial comsat ever launched direct to GEO (not just GTO), then come back and land, without any third stage at all.

With extended upper-stage loiter (2-3 weeks), Falcon Heavy could do a moon landing in 3-4 launches (if 3, then add a single-stick F9 RTLS), full core reuse, no orbital prop transfer required. Of course, it would need a lander.

38 minutes ago, tater said:

I somehow missed that SpaceX offered NASA a free ride on FH, and they refused.

I find it hard to believe that someone at NASA could not have cooked up some truly cheap yet interesting science to do with a free rocket launch with tons of excess capacity for them.

That's...just wrong.

[YNM]

9 hours ago, Aperture Science said:

Now that I think of it, it seems Elon's gone crazy

Well...

Spoiler

I know it's stereotypical stuff flung out at such times, but it's a good sum-up.

 

[Hesp]

53 minutes ago, tater said:

Except of course that the analysis is largely BS. SLS uses Shuttle parts (some that actually failed), yet claims to be 1:500, vs shuttle's actual 1:72? Seems a stretch to magically make it safer than it actually was.

Just having a Launch Escape System decreases dramatically the LOC probability.

Regarding Shuttle, risk assessment for STS-114 put a SSME catastrophic failure at 1:610

[YNM]

1 hour ago, tater said:

I somehow missed that SpaceX offered NASA a free ride on FH, and they refused.

Don't think they offered anything. NASA rarely gets to be "inaugural" customer for "commercial" launchers.

[tater]

9 minutes ago, YNM said:

Don't think they offered anything. NASA rarely gets to be "inaugural" customer for "commercial" launchers.

Lori Garver used to be the deputy administrator of NASA. If she says they were offered a free ride, they were offered a free ride.

I'd add that if things went differently a little over a year ago, she'd quite possibly be NASA Administrator already.

 

Edited February 9, 2018 by tater

[YNM]

8 minutes ago, tater said:

Lori Garver used to be the deputy administrator of NASA. If she says they were offered a free ride, they were offered a free ride.

... And they responded in one way.

After all, NASA's budget goes a very limited way, and they can't have a mid-life crisis along with operating their rockets or missions.

After all, they were offered at least 4 years ago. I call fair choice.

[Starman4308]

When it comes to that offered slot, as with most ridiculous things, I suspect there's something going on I don't know about that makes it non-ridiculous.

Anyways, while SpaceX is being held to a higher standard than ULA and the SLS, I don't think it's necessarily an outrageous standard. For all that I groan about continued complaints about the COPVs, I try to remember that many people at NASA were groaning about continued complaints about the SRB field joints... until they failed, and took seven astronauts with them.

The ULA standard is debatable. I'd like to see a few more 2-engine Centaur tests, but otherwise the Atlas V-Centaur combination has an almost ridiculous reliability record.

The SLS standard is absurd, but I suspect NASA is under political pressure to continue wasting their money on the rocket the Senate designed for them to waste money on. The only real bright side is it probably won't fly enough times to kill astronauts.

[zeta function]

What was the point of the first burn of the core stage (not launch burn)? Why didn't they just have the droneship farther east?

Edited February 9, 2018 by zeta function

[mikegarrison]

1 minute ago, zeta function said:

What was the point of the first burn of the core stage (not launch burn)? Why didn't they just have the droneship farther east?

They have to slow down enough to survive re-entry heating.

[Starman4308]

1 minute ago, zeta function said:

What was the point of the first burn of the core stage (not launch burn)? Why didn't they just have the droneship farther east?

My guess is because you really don't want an expensive and fragile rocket stage on top of an expensive and not terribly stable barge in the middle of the Atlantic Ocean very long. All it takes is one sudden storm to wreck your booster, your droneship, or both.

[tater]

29 minutes ago, YNM said:

... And they responded in one way.

After all, NASA's budget goes a very limited way, and they can't have a mid-life crisis along with operating their rockets or missions.

After all, they were offered at least 4 years ago. I call fair choice.

She gives a reason they didn't want a free ride. They are concerned about how SLS looks. SLS is a dead man walking. It WILL fly. It WILL continue to be funded. It also WILL be either grossly outclassed, or easily replaced with commercial vehicles in the timescale when it becomes routinely operational (mid 2020s).

Even with Musk's reality distortion field altering timelines, SpaceX has some FH follow on by the mid 2020s, and SpaceX realizes that bigger is better with rockets. BO already knows this as well. NG is big, and their next offering will be bigger still. BFR. NG, and even NA combined will cost less to develop than SLS and Orion, I'd wager.

[IncongruousGoat]

25 minutes ago, Starman4308 said:

When it comes to that offered slot, as with most ridiculous things, I suspect there's something going on I don't know about that makes it non-ridiculous.

Anyways, while SpaceX is being held to a higher standard than ULA and the SLS, I don't think it's necessarily an outrageous standard. For all that I groan about continued complaints about the COPVs, I try to remember that many people at NASA were groaning about continued complaints about the SRB field joints... until they failed, and took seven astronauts with them.

The ULA standard is debatable. I'd like to see a few more 2-engine Centaur tests, but otherwise the Atlas V-Centaur combination has an almost ridiculous reliability record.

The SLS standard is absurd, but I suspect NASA is under political pressure to continue wasting their money on the rocket the Senate designed for them to waste money on. The only real bright side is it probably won't fly enough times to kill astronauts.

I have to wonder how much testing is really required for DEC, since the stage in question was flown in that configuration as recently as 2002 on Atlas III.

[zeta function]

57 minutes ago, mikegarrison said:

They have to slow down enough to survive re-entry heating.

The re-entry burn does that, I am talking about the first one.

[GoSlash27]

55 minutes ago, zeta function said:

What was the point of the first burn of the core stage (not launch burn)? Why didn't they just have the droneship farther east?

The first burn is to place the booster on an intercept trajectory with the landing zone. Second burn is to mitigate the effects of reentry heating. Final burn is to cancel vertical velocity and lateral errors at touchdown.
 It's too much to ask to have the booster on a perfect landing trajectory at the moment of cutoff/ sep. Plus, the faster the core is travelling at the moment of separation, the more exponentially difficult it becomes to recover it intact.

Best,
-Slashy

[tater]

 

 

[DAL59]

1 hour ago, Starman4308 said:

 The only real bright side is it probably won't fly enough times to kill astronauts.

Or have astronauts to begin with.  Remember, EM-2 will take place after SpaceX lands humans on Mars.

Updated score:

1. Tesla

1. Apollo 15

2. Apollo 16

3. Apollo 17

5. [formerly] Reliant Robin 

[Starman4308]

1 minute ago, DAL59 said:

Or have astronauts to begin with.  Remember, EM-2 will take place after SpaceX lands humans on Mars.

Personally, I'll count SpaceX lucky if they manage a BFR launch by then, nevermind a Mars mission. Musk is no superman: just a charismatic man with some money to sink into reusable orbital rocketry right as compute hardware became powerful enough to support precision landings, and before the established companies had gotten over their conservatism enough to try it.

[Confused Scientist]

3 hours ago, tater said:

Likely we're talking well over 1000 firings of which at least 460 were full length burns.

 

That's understating the reliability, since the Falcon 9 is also the first rocket since the Saturn V to have a full engine-out capability on the first stage. That means that if one engine goes out on the first stage, they can still make the nominal orbit without any need for correction burns just by burning the other eight engines longer. The first stage almost certainly can't be recovered in that scenario, but the Falcon has repeatedly demonstrated its value even during failed landings. Compare that to the shuttle, where a single engine failure at any point prior to the "press to MECO" call is an abort. There's a lot of graphs about that here.

[YNM]

1 hour ago, zeta function said:

What was the point of the first burn of the core stage (not launch burn)? Why didn't they just have the droneship farther east?

Getting a steeper angle is good for a vertically-landing rocket. The other way for an "airplane" (or even a flying brick).

1 hour ago, tater said:

She gives a reason they didn't want a free ride. They are concerned about how SLS looks.

Rubbish. If they really want they can just get yet another TDRS or something.

But do they ever get a mission to full-up in 4 years ? Or would they will to extend launch-waiting for a mission by some time, up to 4 years ? They didn't even know when will Falcon Heavy flies.

Obviously now it's a different stuff, but history's a history. There are reasons.

Also, if you wonder "why four years", she resigns in 2013. I presume she lost any contact afterwards.

Edited February 9, 2018 by YNM

[DAL59]

5 minutes ago, Starman4308 said:

Personally, I'll count SpaceX lucky if they manage a BFR launch by then, nevermind a Mars mission. Musk is no superman: just a charismatic man with some money to sink into reusable orbital rocketry right as compute hardware became powerful enough to support precision landings, and before the established companies had gotten over their conservatism enough to try it.

Its not like NASA is doing anything though.  Have you looked at the SLS thread?  Literally no news except testing th pad water system.  

[mikegarrison]

4 minutes ago, DAL59 said:

Its not like NASA is doing anything though.  Have you looked at the SLS thread?  Literally no news except testing th pad water system.  

NASA is not supposed to be doing anything. The whole point of encouraging commercial launch services was to get NASA out of the launch service business. SLS is just a jobs program / slush fund for Congress.

[Starman4308]

1 minute ago, DAL59 said:

Its not like NASA is doing anything though.  Have you looked at the SLS thread?  Literally no news except testing th pad water system.  

Indeed. NASA is doing nothing whatsoever.

They're not, for example, managing:

Juno, Kepler,  ASTER, AIRS, ASE, Cloudsat, Dawn, DRS, DLRE, GRACE, Jason 2, Jason 3, the Opportunity and Curiosity rovers, Mars Odyssey, the Mars Reconnaissance Orbiter, MLS, the Spitzer space telescope, construction of JWST, the Space VLBI, WISE, and the Voyagers.

Absolutely. Nothing.

Once Musk actually delivers on a very-low-cost SHLV and the plethora of systems that would be needed for a Mars trip, plus extensive tests of that equipment, then I might believe him. Not before. Too many broken promises, and too many unrealistically optimistic plans.

[DAL59]

1 minute ago, Starman4308 said:

Absolutely. Nothing.

Manned.  

1 minute ago, Starman4308 said:

Once Musk actually delivers on a very-low-cost SHLV and the plethora of systems that would be needed for a Mars trip, plus extensive tests of that equipment, then I might believe him.

Thats understandable.  Well, we'll know by 2019!

[YNM]

2 minutes ago, DAL59 said:

Manned.  

There are some guys in a big space can.