RCgothic

It's not hard to add construction capability to a superheavy spacecraft. It takes what, a couple of robot arms and an airlock? Even Orion could do it if they'd given SLS an integral payload bay to carry a dockable construction module. Send one up on Falcon 9 and rendezvous. Job done.

NASA have really been letting the side down with rocket names since space shuttle/STS.

N1 was not a SpaceX rocket. The problems weren't just the number of engines, but the lack of testing. SpaceX has that thoroughly covered.

I wonder if the solution may involve robotic launch clamps that "catch" the booster by moving to engage target latches on the booster. With a system like that returning within 5-10m would be good enough.

There are people who'd do it.

So what? What useful tasks can it do with those numbers? Land on Mars? No. Land on the Moon? No. Put mass in orbit? Falcon 9 and Delta IV Heavy can do the same faster and cheaper. Put volume in orbit? Cool. But other launch providers will probably get there first. Launch flagship class payloads to faraway places? Perhaps. Occasionally. When NASA can afford to. Unless you're designing for a specific mission, your rocket needs to be good for a number of missions, which SLS patently isn't. So what do we want in a general purposee rocket? Firstly, there's no longer any good reason for it to be man rated. Orion's only a couple of tons too heavy to be put up on an expendable Falcon 9 (strongly suspect 22t will be exceeded by block 5) nevermind Delta IV Heavy or Falcon Heavy. So don't. Separate Crew and Cargo and rendezvous if necessary. Ares had this right. Secondly, it needs to put mass and volume in orbit cheaply. If you can't do that then you might as well go home because otherwise you're doing the equivalent of bringing a knife to a gunfight against the new space guys. Thirdly, if you want to go beyond Earth's sphere of influence you need to be able to support a rapid launch cadence. Yes, you can get to the moon by launching an enormous stack Apollo style. But if you want a moon base or a mission to Mars you have to be able to go to orbit much more often than a few times a year. You don't need 140t to orbit if you can do 25t every two weeks. IMO the best way to achieve 2 and 3 is reusability. Unless you rock those boxes there's really no point. SLS loses one of its only payloads. One step closer to cancellation.

Ares V wasn't even close to being in as hopeless a situation as SLS is now. ARES I was certainly a daft idea, but the idea of flying the capsule up separately was not.

Even without BFR or NG, sheer launch cadence and cost effectiveness allows Falcon Heavy (hell, even Falcon 9) to fill 90% of SLS's brief.

Better to take a chance on ripping up the current design and trying again than to continue to spend money on a design that certainly won't.

It's worth cancelling something when it's clear it's going to fail. The ongoing cash could be better spent on something else. The only mission for SLS that I highlighted that can't be done by another currently operational rocket is volume to LEO. That's a pretty niche requirement.

Guarantee SLS is not landing on the moon or Mars. Doesn't have cargo space for a lander or a lander designed for it even if it had the throw weight to include one, which it doesn't. Doesn't have life support capacity to reach Mars, or cargo space for a hab module or a hab designed for it even if it had the throw weight to include one, which it doesn't. Doesn't have the on-orbit it linger time to construct a mothership in leo, even if it had a design for one, which it doesn't. By the time the next SLS upper stage gets into orbit in a year's time the original second stage's dregs will have evaporated, leaving the newly arrived upper stage unable to throw the weight of the combined mothership anywhere useful. SLS has precisely 3 uses: 1) Large probes on high energy trajectories. But NASA can't afford to build any large probes whilst operating SLS, and other rockets becoming operational can throw multiple smaller probes to the same places for much less. 2) Large cargos to LEO. Gets spanked on a $/kg basis by currently operational rockets. It's a matter of time before a cheaper rocket with comparable volume comes along. 3) Orion to LLO. But currently operational rockets have a high enough launch cadence to support rendezvous missions and even a landing. And it's not cheap. The components it uses haven't flown in their current specification before. It's too expensive to do an all up test for. It will get cancelled the moment the public starts laughing at it, which will be round about the time Blue Origin or SpaceX demonstrate their next gen launchers.

So now you've got an engine specification that's never been flown before negating the safety argument and you've spent even more money on redesigning, stripping it down and rebuilding it. It was a Ferrari. Now it's a Koenigsegg. What would be appropriate is a Mercedes-Benz Actros.

It's certainly impressive that they got so much performance out of the RS25. But did they do so economically? Does the application depend on squeezing every last drop of usable performance out of the engine? Why won't a cheaper, less efficient engine with a denser fuel or slightly larger tank do? There's no point in building a Bugatti Veyron if a Ford Transit will do. Maybe the RS25 was the closest they could get to a solution for shuttle, but even then it didn't quite work. For an expendable first stage engine it's wholly unsuited. And then treating the test due of an engine that probably wasn't even built this century as a milestone. SMH. SLS certainly isn't going to Mars. It can't loft enough mass in one go for an Apollo-style mission to the red planet, and it can't be constructed fast enough to enable on-orbit construction of a mothership. The upper stage propellant would simply boil off before the next launch was ready, and it would take more than one launch worth of upper stage propellant to perform the TMI. For the same reason it's questionable it can even land us back on the moon. Even if NASA had the funding to develop the landers and habs it would require. It's sad to see NASA reduced to this. It's not even NASA's fault.

NASA test fired an RS 25 yesterday, and tried to dress it up as if it were an actual milestone achievement instead of an engine they've had in storage for over a decade based on even older technology and both hideously overcomplicated and expensive for a disposable stage.

I think they have enough recovered Blk3 boosters that if they have to expend a few before Blk5 comes online in April it's no big deal. They won't attempt to use a Blk3 a third time in any case.

April 15th, Iridium 51-55 according to Wikipedia. Date may vary.

Interferometer. Reassembly not required.

Poor dude. That wasn't footage of Falcon Heavy though.

Think I heard this too. The opposite engine would immediately shut down to balance the thrust I reckon, leading to two engines out.

After rewatching, the abruptness of the ASDS getting swamped and then cutting out fits with a nearby splashdown at 300mph. Nothing new beyond the outer engines ruining out of igniter.

Feedback is that the side cores are in good enough condition to fly again but they won't.

I believe I was there in July 2001 when it happened the time before. I recall because the guide said it was unusual. I also recall getting annoyed at her for not having heard of the Enterprise.

According to Wikipedia the first scheduled B5 launch is in April for Iridium Next 51-55

Assume that thrust decays to zero at 10s when Saturn V clears the tower from 100% at t=0 at constant acceleration. Distance s=ut+0.5at^2 condenses to s=0.5at^2 Rescaling y=0.5mt^2 with y between 0 and 1 allows us to find the constant m as 0.02/s^2 Area under that curve is A =1/6 * mt^3, or 3.33s out of a total area of 1*10s =10s. The area not under this curve is the weighted thrust fraction, 6.66s The average thrust fraction is therefore 0.66. So with a total fuel consumption of 13.6 te per second, Saturn's average thrust per second is 9.0 te per second. This beats Falcon Heavy over 10s (90te Vs 82te) but not if Falcon Heavy gets an extra 2s test (98.4te). Falcon Heavy hold down static fire is therefore a more extreme test for the flame trench than Saturn V in terms of total propellant. And with a higher ISP and exhaust velocity it's likely to be a harsher test in that regard too.

Falcon Heavy is something like 8.2 tonnes per second. Assuming Saturn V dumps negligible propellant into the flame trench after it clears the tower (exhaust slowed by distance, "aim" of exhaust wanders) then with a linear reduction it would need to take longer than 14.5s to exceed the Falcon Heavy's static fire. It doesn't take that long, so Falcon Heavy probably wins. But it's moving slowly to begin with. Assuming again zero as Saturn clears the tower and, 10s to clear the tower, and reduction proportional to distance ascended.... I'll do the maths later if nobody else beats me to it. I think it's close.