totm nov 2023 SpaceX Discussion Thread

[tater]

 

[SOXBLOX]

Yay, DART!

[MKI]

I was able to see DART launch. Luckily my friend was over and told me about it, I thought it was another day and launching from the East coast.

Went outside and saw it among the clouds for only a few seconds before the marine layer hid it away. 

 

Looking forward to seeing the results of the mission

[JoeSchmuckatelli]

Was Dart SX's first paid extra-orbital mission?  (I know about the Tesla/Starman flying in a Solar orbit... but have they flown other NASA missions outside of Earth orbit?

[tater]

 

45 minutes ago, JoeSchmuckatelli said:

Was Dart SX's first paid extra-orbital mission?  (I know about the Tesla/Starman flying in a Solar orbit... but have they flown other NASA missions outside of Earth orbit?

Not that I remember.

[sevenperforce]

1 hour ago, JoeSchmuckatelli said:

Was Dart SX's first paid extra-orbital mission?  (I know about the Tesla/Starman flying in a Solar orbit... but have they flown other NASA missions outside of Earth orbit?

TESS went to a high eccentric orbit well beyond GTO (but slightly lower than TLI) and DSCOVR went to Earth-Sun L1 which is technically outside of Earth's SOI.

[Elro2k]

Is DART still attached to the second stage of F9? If so, how would it make smaller course corrections? Merlin can't throttle that precisely can it?

[RealKerbal3x]

1 hour ago, Elro2k said:

Is DART still attached to the second stage of F9? If so, how would it make smaller course corrections? Merlin can't throttle that precisely can it?

Dart separated from the second stage about an hour after liftoff.

[RCgothic]

2 hours ago, sevenperforce said:

TESS went to a high eccentric orbit well beyond GTO (but slightly lower than TLI) and DSCOVR went to Earth-Sun L1 which is technically outside of Earth's SOI.

I asked Jonathan McDowell about this. He disagreed.

 

DART is definitely F9's highest energy launch so far, beaten only by FH Demo which as pointed out they didn't get paid for.

[JoeSchmuckatelli]

10 hours ago, Elro2k said:

Merlin can't throttle that precisely can it?

Speaking of which - do we know if SX's future plans are for Vac Raptors (on F9 launches) or some upgraded Merlin / something else? 

I know they're pushing forward with SS - will F9 stay in the stable for small /LEO sats or be totally replaced  by the SS system (which doesn't seem to be the most efficient*)? 

 

 

 

 

*what would I know - I'm the resident knuckle-dagger... 

[cubinator]

1 minute ago, JoeSchmuckatelli said:

I know they're pushing forward with SS - will F9 stay in the stable for small /LEO sats or be totally replaced  by the SS system (which doesn't seem to be the most efficient*)? 

Starship is supposed to cost 1/25 of Falcon 9.

[RCgothic]

22 minutes ago, JoeSchmuckatelli said:

Speaking of which - do we know if SX's future plans are for Vac Raptors (on F9 launches) or some upgraded Merlin / something else? 

 

No new block upgrades are planned for F9 or Merlin to the best of my knowledge.

F9 will fly until it's no longer economical for SpaceX to maintain production. There'll come a critical point where enough of F9's customers fly on Starship and they'll shut F9 production down.

Yes, starship burns more fuel, but you also have to consider the energy and time expenses of always having to manufacture and throw away new upper stages. Starship should also be a lot easier to build and refurbish between flights.

[AtomicTech]

Maybe they'll keep it around or transfer its flight duties to another company or a spin-off of SpaceX and they'll recover the M-Vac with a modified Starship.

[sevenperforce]

9 hours ago, RCgothic said:

I asked Jonathan McDowell about this. He disagreed.

DART is definitely F9's highest energy launch so far, beaten only by FH Demo which as pointed out they didn't get paid for.

Oh, I wasn’t saying that DSCOVR was a higher-energy orbit than DART. DART is definitely the highest-energy mission that Falcon 9 has done. I was just giving the example of the two other Falcon 9 launches that went to “deep space” (although TESS doesn’t really count as deep space because it’s still sub-cislunar even if it’s well beyond GTO).

DSCOVR is in a heliocentric orbit, sitting at the very edge of Earth’s SOI. Technically it is in an oscillating halo orbit around L1, which means it is never actually inside Earth’s SOI. However, it’s still sort of accurate for McDowell to say it “did not leave the Earth-Moon system” because its heliocentric orbit is constrained by Earth’s gravity.

1 hour ago, RCgothic said:

1 hour ago, JoeSchmuckatelli said:

Speaking of which - do we know if SX's future plans are for Vac Raptors (on F9 launches) or some upgraded Merlin / something else? 

 

No new block upgrades are planned for F9 or Merlin to the best of my knowledge.

F9 will fly until it's no longer economical for SpaceX to maintain production. There'll come a critical point where enough of F9's customers fly on Starship and they'll shut F9 production down.

They would never put an RVac on Falcon 9. For one thing, it is very nearly too large. In addition, it would mean plumbing the same pad for both methane and RP-1, something SpaceX doesn’t want to do. Finally, because methane is less dense than RP-1, I believe that a Raptor-based swap-in for the Falcon 9 upper stage wouldn’t actually improve payload that much. 

[JoeSchmuckatelli]

15 minutes ago, sevenperforce said:

I believe that a Raptor-based swap-in for the Falcon 9 upper stage wouldn’t actually improve payload that much

That's what I'm wondering - if throttle response is important would they make changes... 

But if @cubinator is correct, cost more than anything dictates abandoning more expensive options 

[magnemoe]

On 11/24/2021 at 6:36 PM, tater said:

 

That an high attitude, way longer than the burn time for stage 2 is under 6 minutes unless mistaken. Was it an second burn, not an circulation but shaping the trajectory? 
I assume they want to check that trajectory is correct before releasing anyway in case some correction is needed. 

[cubinator]

2 minutes ago, magnemoe said:

That an high attitude, way longer than the burn time for stage 2 is under 6 minutes unless mistaken. Was it an second burn, not an circulation but shaping the trajectory? 
I assume they want to check that trajectory is correct before releasing anyway in case some correction is needed. 

Stage 2 entered a circular orbit, coasted until reaching a point near the southern tip of South America and Antarctica, then burned to escape the Earth. The satellite was released a while later, when the spacecraft was this far from the Earth.

[CatastrophicFailure]

It’s interesting that people seem to already have a “nostalgic” attachment to the Falcon 9 and want to see it keep flying once it’s no longer needed.  The paradigm shift that Starship could bring does take a real mental gearshift to grok. 

To put it another way, a brand new Cessna 172 costs about $300,000, and it can easily take your 50lb payload from, say, Seattle to San Francisco, then crash in the ocean. UPS can ship it there by jumbo jet for a measly $65 bucks, but they keep the airplane. Even if you wanted really personal service, chartering a whole 747 would still only cost around $70,000, but again, they get to keep the airplane. There’s just no economic justification to buy that Cessna and throw it away, no matter how classic is looks. 

Same deal with Starship (if it works), there’s just no economic justification to keep flying F9. Even your teeny, tiny cubesat all alone will be much cheaper on that reusable behemoth than the throwaway classic. No one else is gonna want to bother with it either, again because it makes no economic sense. 

[StrandedonEarth]

Yeah, the showstopper for keeping F9 flying is the expendable upper stage, which would need to stay in production.

Think of SS as a modern jetliner (I'd say jumbo jet but production is dwindling on those), and F9 as a DC-3. Sure, the DC-3 flew (and still flies!) for decades, serving niche markets long after production ceased and jetliners took over. They didn't have to keep a factory running to use the aircraft; spare parts could be handcrafted if necessary.

But to keep already-built F9 boosters flying requires development of a re-useable upper stage which would likely leave  it with about a cubesat's worth of payload. Or keeping a factory running, likely well under capacity. And there really is no niche market suitable for F9 that SS cannot also serve, probably at a lower marginal cost as well

Edited November 25, 2021 by StrandedonEarth

[magnemoe]

15 minutes ago, cubinator said:

Stage 2 entered a circular orbit, coasted until reaching a point near the southern tip of South America and Antarctica, then burned to escape the Earth. The satellite was released a while later, when the spacecraft was this far from the Earth.

They circulated before doing the ejection burn, I say this is pretty rare for interplanetary missions? Yes Apollo did but it was an manned mission 50 years ago. 
It very common in KSP as we don't have the NASA mission planning tools or want to spend more than 5 minutes planning an simple trajectory. 

Yes its other factors here like launch angles are restricted, still a bit cool that the second stage ended up in deep space. 

[magnemoe]

9 minutes ago, StrandedonEarth said:

Yeah, the showstopper for keeping F9 flying is the expendable upper stage, which would need to stay in production.

Think of SS as a modern jetliner (I'd say jumbo jet but production is dwindling on those), and F9 as a DC-3. Sure, the DC-3 flew (and still flies!) for decades, serving niche markets long after production ceased and jetliners took over. They didn't have to keep a factory running to use the aircraft; spare parts could be handcrafted if necessary.

But to keep already-built F9 boosters flying requires development of a re-useable upper stage which would likely leave  it with about a cubesat's worth of payload. Or keeping a factory running, likely well under capacity. And there really is no niche market suitable for F9 that SS cannot also serve, probably at a lower marginal cost as well

Now I see plenty of starship missions with rd stages for all sort of deep space missions, ride sharing an GTO burn would be nice.
Lots of use cases for simple pressure feed vacuum engines putting stuff places. One fun future option is to feed them LOX and methane before separation  

[sevenperforce]

9 hours ago, magnemoe said:

They circulated before doing the ejection burn, I say this is pretty rare for interplanetary missions? Yes Apollo did but it was an manned mission 50 years ago. 
It very common in KSP as we don't have the NASA mission planning tools or want to spend more than 5 minutes planning an simple trajectory. 

Yes its other factors here like launch angles are restricted, still a bit cool that the second stage ended up in deep space. 

Au contraire, most deep space missions circularize first. You launch from your designated launch site at an instantaneous launch window and then coast to the appropriate inclination, which is where you do your departure burn.

We don’t typically have this issue in KSP because the KSC is at Kerbin’s equator, so if you want to launch directly into a desired inclination at a desired instantaneous launch window then you can do so. But since the US does not have any launch sites at the equator, you need to perform a partial orbit first for phasing before you do your injection burn. 

[MKI]

Starship will take over for Falcon 9 launches in stages. Once Starship can get to orbit, and get back and do it faster/quicker than Falcon 9's, then Falcon 9's will become less needed for payload launches. However, they will still exist until Starship proves its reliable enough for all payloads. This will take time, and nevermind any Starship development to get beyond LEO.

The other area Falcon 9s would stick around for a while is manned space-flight for government agencies. Falcon 9s are rated for manned space flight, so they can keep servicing the ISS. I also can't see Starship bringing cargo to the ISS, but maybe just private stations in the near future. 

Its only once Starship is reliable enough for manned spaceflight into LEO with rapid re-usability does Falcon 9 more or less get 100% fully retired. 

 

Starship still needs to keep getting developed to get to Mars, but I can't see how it can't be improved in stages over time, as rapid re-usability will keep SpaceX far ahead of the competition.

[SunlitZelkova]

5 hours ago, MKI said:

I also can't see Starship bringing cargo to the ISS, but maybe just private stations in the near future.

Actually, wouldn't it be possible to launch Cargo Dragon inside of Cargo Starship? Which would be presumably cheaper than launching Cargo Dragon on Falcon 9.

[Beccab]

49 minutes ago, SunlitZelkova said:

Actually, wouldn't it be possible to launch Cargo Dragon inside of Cargo Starship? Which would be presumably cheaper than launching Cargo Dragon on Falcon 9.

You know what, that's not a bad idea. It doesn't need to abort after all