totm nov 2023 SpaceX Discussion Thread

[Beccab]

https://fcc.report/ELS/Space-Exploration-Holdings-LLC/0983-EX-ST-2021/277037 
New FCC report, mentioning an apogee of 250 km (should help with the math for the math people) and that the application begins on the 1st of August
Edit: it also mentions 1st of October as the finish date, so we have a window! It's August or September for the orbital flight

Edited June 29, 2021 by Beccab

[AVaughan]

17 hours ago, tater said:

Alternately make a SS that sheds the nose as a fairing, and what would be the payload adapter is just a match for the base. You now have a SS tug that has engines on the bottom, and a "bottom" for docking also on the top. Fill that. Fill LSS. Dock tug to LSS, give LSS 2.3 to 2.5km/s with tug. Tug propulsively returns to LEO. 80t LSS with normal 1200t props can fly to lunar surface and back to LEO using engines, no aerobraking.

The special sauce with SS is refilling. If they can land stage 2 just for uncrewed tankers and do the refilling ops... SS changes literally everything.

Why bother with a special tug variant.  You can achieve the same result by just using a fully fuelled LSS and tanker in low earth orbit.  Have both burn about 2.5 km/s into an elliptical orbit, rendezvous and refuel LSS.   

But if you are serious about wanting to return LSS to LEO, then you might as well take the cargo mass penalty and add flaps + heatshield and recover LSS to earth.  That gives the ability to do a through service, including repair/replace/upgrade things that are difficult and/or impractical in space, and removes issues of transferring/loading heavy cargo(s) in space.

If they want to work on a tug variant, then I would rather see a variant with one or two Vac raptor and 6+ of the LSS landing engines that is designed to

• Dock to a cargo module in space.   (From the tugs point of view even a crew habitation module is a cargo module).
• Dock to a cargo module that is inside a Starship's cargo bay, or attached to Lunar Gateway.  After the mission, be able to redock the cargo module to Starship/Lunar gateway.   
• Dock to the inside  of the Starship's cargo bay, and hence be not only launched by Starship, but be capable of being returned to Earth's surface for inspection/maintenance, if required.
• Able to be refuelled by Starship.
• Have Falcon 9 style retractable landing legs.  (Large legs, for a nice wide stable stance).
• Have enough dV to land on the Moon from Lunar gateway, then return to Lunar gateway, carrying a cargo module.  

That would give them a purpose designed,  reusable and flexible lunar landing architecture.  Crew modules and cargo modules, with the possibility of custom modules for special purpose needs.  Cargo modules might be able to reach 60+ tons.  No need to carry unnecessary atmospheric engines to/from the lunar surface, no need for an aerodynamic shape.   No problems with transferring heavy cargo between Starship and LSS in space. 

[RCgothic]

Trans-shipping of Cargo is going to be important if they're going to reuse LSS for lunar downmass. Got to restock it somehow.

[Rakaydos]

1 hour ago, RCgothic said:

Trans-shipping of Cargo is going to be important if they're going to reuse LSS for lunar downmass. Got to restock it somehow.

Imagining something like canadarm plucking a rover out of a Chomper and transferring it to LSS, in orbit.

[tater]

Sooty beast:

 

4 hours ago, AVaughan said:

But if you are serious about wanting to return LSS to LEO, then you might as well take the cargo mass penalty and add flaps + heatshield and recover LSS to earth.  That gives the ability to do a through service, including repair/replace/upgrade things that are difficult and/or impractical in space, and removes issues of transferring/loading heavy cargo(s) in space.

Doesn't work.

1. Can't have the landing engines.

2. Can't have the solar.

3. Can't have the wide stance legs.

All the above make recovering the LSS to Earth a non-starter.

 

But yeah, you could fully tank both, then have them burn to elliptical together, then dump remaining props from tanker to LSS, and burn from there, looks like it closes with margin.

Edited June 29, 2021 by tater

[Beccab]

17 minutes ago, tater said:

But yeah, you could fully tank both, then have them burn to elliptical together, then dump remaining props from tanker to LSS, and burn from there, looks like it closes with margin.

If anything, the presence of the solar panel makes it clear it is meant to be used for long periods of time, not just for a few days/weeks per LSS. SpaceX likely does want to keep using a LSS for as many times as possible

[tater]

If you did a stretched SS tanker optimized for orbit—50t dry mass, so that's no flaps, TPS, and shed the nose to reduce mass—it could deliver ~750t to a LSS in that 2.5km/s elliptical orbit, vs ~635t.

This easily closes for a LSS with a slightly stretched tank (80t LSS with 20t cargo, tank adding 200t additional props). In fact it could take more cargo.

Edited June 29, 2021 by tater

[tater]

 

[RCgothic]

 

 

 

 

[RealKerbal3x]

Transporter 2 stream is live

[cubinator]

Range not go

[RealKerbal3x]

Hold at 11 seconds to launch, apparently a range violation.

Aaand scrub

[tater]

Boo. Wayward boat/plane.

[insert_name]

said there was a plane in the range

[tater]

Friend at MCC said rain in area. Maybe that instead of plane/boat.

 

[ExtremeSquared]

Is a "failed range" a range violation or a sensor value out-of-range?

edit: In this case, it was a plane.

Ambiguous words in dynamic environments worry me. But I guess they have been chugging along with "LOS" having two different meanings relating to comms and understanding based on context for a while.

Edited June 29, 2021 by ExtremeSquared

[Beccab]

 

Edited June 29, 2021 by Beccab

[tater]

 

 

Edited June 29, 2021 by tater

[HvP]

"an aircraft entered the “keep out zone”, which is unreasonably gigantic. "

Maybe the no-fly zone is unreasonably large and maybe that's a topic that should be debated. But they are there for the safety and security of not just the community, and passengers of those flights, but also for national security concerns. Regardless, significantly increasing the pace of launches, as Musk wants to do, will only increase the chances of low probability encounters happening.

[Beccab]

4 minutes ago, HvP said:

Maybe the no-fly zone is unreasonably large and maybe that's a topic that should be debated.

...that was the topic of the post though, not the rest of your comment

[tater]

7 minutes ago, HvP said:

"an aircraft entered the “keep out zone”, which is unreasonably gigantic. "

Maybe the no-fly zone is unreasonably large and maybe that's a topic that should be debated. But they are there for the safety and security of not just the community, and passengers of those flights, but also for national security concerns. Regardless, significantly increasing the pace of launches, as Musk wants to do, will only increase the chances of low probability encounters happening.

Given that the FTS terminates the vehicle automatically if it slightly deviates form the flight path, the hazard area need only contain the actual volume where debris are possible. The areas are 10+ nm on the narrow sides, I doubt debris would be a problem past several hundred meters on either side of the flight path.

The launch hazard areas might still be the same as they were when range control had to decide "manually" to terminate a flight.

[RCgothic]

 

 

[RealKerbal3x]

(Note that plans could always change and this booster could be used for the orbital flight if it survives testing on pad A)

Edited June 29, 2021 by RealKerbal3x

[RCgothic]

 

 

 

[cubinator]

Wow, that's a whole Superheavy stage minus engines and grid fins? Very exciting.