RCgothic

There's no way Starship isn't going to be an economic success if it's also a technical success. If it succeeds technically it will be an order of magnitude cheaper per flight than Falcon 9 the current undisputed economic king. The excess capacity is irrelevant. If SpaceX get paid X per flight and the customer doesn't use the full capacity, SpaceX isn't any worse off. In fact a lighter flight means larger margins which means more propellant to mitigate re-entry and reduce wear. Light flights mean life extensions.

The idea that SLS is designed for anything optimal related to actual spaceflight is cute. It isn't remotely optimised for cost, cadence, or payload, which are the three things that matter for putting large amounts of mass into space. Orbital tethers require hundreds of thousands of tons of upmass. Cheap rapidly reusable superheavy launchers are essential. They're a prerequisite. Nobody will EVER build a space tether without first building something like starship. So instead of complaining that there's no use for a superheavy launcher like that, be glad that there are people willing to put their own money into making uses and actually advancing the things we can do in spaceflight, because I am NOT content to spend another 30 years going at a snail's pace because NASA is contractually prevented from breaking things and learning fast.

I'm almost a little sad - these modifications sound like they'll be effective enough to prevent casual Starlink spotting altogether.

Static Fire now Friday.

He isn't, so he will.

I think they're trying to imply SpaceX gets unfair subsidy for its other activities because NASA pays for their new rockets. But whoever designed those infographics is definitely not spacex material. They're awful.

Also wow, that is a seriously hot Falcon Heavy flight! Two payloads direct to GEO.

I think - firstly, very little propellant is used to de-orbit. The shuttle OMS had a capability for just 300m/s DV, and that was used for orbital insertion as well as de-orbit. The vast majority is scrubbed off through atmospheric drag. Increasing the drag just increases the g-loading. Secondly, I don't think any such flimsy structure has even a slight hope of withstanding re-entry conditions.

Mine isn't optimised packing. I just worked in giving each ring of engines a full diameter clearance, rounding down the number that would fit around that circumference. It's definitely restricted gimballing.

I think your #of engines logic may need another visit. Or at least explaining. I can fit 174 Merlin 1Ds under a 12m diameter. 38 in a 11.1m ring. 32 in a 9.3m ring. 26 in a 7.5m ring. 19 in a 5.7m ring. 13 in a 3.9m ring. 7 in a 2.1m ring 1 in the centre.

I used some of your numbers as a reference. ;-)

Centaur has rubbish mass fraction due to its tank insulation. About 9% dry. Taking F9 US (4t), removing the MVac gives a tank structure of 3.5t. Scale up 111t propellant to 148t means 32% more tank. Methalox 900kg/m3 vs kerolox 1085kg/m3 means 20% extra tank. So 5.6t for tanks, plus 1.2t for Raptor is 6.8t. 4.6% dry. Actually I'd forgotten to remove the Merlin before factoring earlier. So that pops the Raptor stage ahead to 11km/s with a 1t payload vs 10.7km/s for Super-Centaur. Much shorter burn time too due to higher TWR.

Interestingly - for a 150t kick stage with very low payload, there's almost nothing to choose between Centaur hydrolox and Raptor methalox. Centaurs's ISP advantage is almost exactly balanced by worse mass fraction. Both manage about 10.5km/s. But Raptor would be smaller, have a higher structural rigidity, and generally be less finicky. Plus no replumbing the pad for hydrolox!

Yup, sounds about right! That'd be the most recent batch of 60 Starlinks as the others will have spread out to their operational separation and not be clustered. Congrats on your satellite spotting!

I stated this a bit flippantly, but: Voyager 2 has ~15km/s. Escape velocity from its current position is ~4km/s. Velocity at infinity is therefore ~11km/s. Earth has 30km/s. In LEO you have roughly 8km/s. A 149t Raptor-powered kick stage with a similar tank fraction to Falcon9US could give ~11km/s to an 825kg Voyager replica. Solar escape velocity from earth orbit is ~42km/s, so you'd end up with 7km/s at infinity, just 4km/s short. You can easily pick up 4km/s with a single gas giant flyby. Pick up 6km/s and you can overhaul Voyager 1! And with orbital refuelling to get into an extreme elliptical you may not even need the flyby!

Digital image processing will soon catch up. It's not difficult to identify and remove high-brightness artifacts with high angular velocity from frames.

Indeed. Without refuelling and *expending* the second stage, Starship Superheavy is twice SLS's payload for less cost than a Falcon 9. With a reusable second stage you might as well call it Dreadnought because every other booster just became completely obsolete outside extremely niche applications. Even for those: Smallsat to weird orbit? Add more propellant to your sat and rideshare from somewhere more popular. Probe to high C3? Lift an entire fully fuelled Super-Centaur kick stage and watch your probe overtake Voyager2. With in-flight refuelling? There's nowhere in this solar system it can't go.

SN4's back down to 1 Raptor.

I love how this thread is basically a constant stream of updates these days!

"Ambient pressure test". Of course he means an ambient temperature pressure test. It would be a bit unfortunate if it failed a test at ambient pressure!

Sounds like they did a gaseous nitrogen proof test last night. There's a window for a cryo test again tonight.

Yeah, I agree. An SLS can't do Artemis by itself. Which leads to crazy things like the crew being sent on a gigantic crew-rated booster and the cargo being sent on smaller commercial vehicles. That's ass-backwards.

Once again the mission architecture trips over itself because SLS wasn't designed for sending a large lander to the moon as well as a large capsule.