[rbanffy]

It can carry an Orion capsule to a suborbital trajectory and achieve the same reentry speeds the capsule experiences returning from the Moon. The trick is doing a second burn pointing down. If you don't use an actual Orion but just a mass simulator, you can even do some very off-nominal reentries to test limits.

There is ample delta-v for that.

[gaigalas]

Can you elaborate more on that?

I don't understand how the coupling between Orion and Falcon Heavy would be done (can't just put it inside the fairing).

I also don't understand how you plan to re-light the engines on the 3 falcon cores for a second burn (required for the delta-v you propose) and the fuel economics.

I also don't understand the trajectory you envision. Even if you could re-light the FH engines and couple Orion to it, I don't understand how you would get the re-entry angle correct.

Regarding the mass simulator, it's not clear by your description how the shields would be tested in that scenario.

Let's not leave it to the reader's imagination. If you're seeing something that I'm not, please, lay out the plan in more detail.

[rbanffy]

> I don't understand how the coupling between Orion and Falcon Heavy would be done (can't just put it inside the fairing).

A mechanical coupling is not that difficult to design. There needs to be no communication between FH and Orion for this use case. It could be mounted with the shield on top to simplify the mechanism. Separation could be purely mechanical, with springs.

> I also don't understand how you plan to re-light the engines on the 3 falcon cores for a second burn (required for the delta-v you propose) and the fuel economics.

Reignite only the second stage. Instead of putting the payload in orbit, put it on a suborbital trajectory with a high apogee, then boost down to hit the atmosphere at the desired speed and angle.

> I also don't understand the trajectory you envision. Even if you could re-light the FH engines and couple Orion to it, I don't understand how you would get the re-entry angle correct.

You have the delta-v - just use it in the right orientation. An Orion is lighter than the payload to LEO of the FH, so there will be a lot of propellant for the boost up and the boost down.

> Regarding the mass simulator, it's not clear by your description how the shields would be tested in that scenario.

The shield doesn't care what's inside the Orion - it cares about mass. You might need some attitude control (you can use flywheels) and parachutes if you want to recover anything, but all the rest is optional.

[gaigalas]

> A mechanical coupling is not that difficult to design

[citation needed]

> Reignite only the second stage.

Baby delta-v. Weaker than my Uno Mille with a staircase on top.

> right orientation

Trying to re-orient a low earth orbit into a reentry-from-moon-insertion is like trying to bend the path of a bullet.

Get your shit together, play some Kerbal Space Program at least.

> The shield doesn't care what's inside the Orion - it cares about mass.

[citation needed]

---

Buddy, I don't have time for Elon fantasies.

[rbanffy]

> Get your shit together, play some Kerbal Space Program at least.

I assumed you had actual knowledge of how orbital mechanics work. Please, continue playing your kideogames.

A Falcon Heavy can deliver more than 20 tons to GEO and an Orion capsule weigths about 10 tons. GTO is usually about 10 km/s at perigee of 200 km, meaning even with a full payload, a FH can place an Orion at an orbit that coasts above most of the atmosphere at about 90% of the speed of a returning Orion - and that on a stable-ish orbit - a suborbital trajectory would allow a higher apogee and a higher return speed. Now assume my mechanical design skills allow me to mount the capsule with less than 10 tons of material - this would mean we still have enough propellant on the second stage to give the ship a sizable boost if we so wanted. As for the maximum thrust, a high apogee suborbital trajectory would allow plenty of time for that - a good couple hours at least. That's way more than the longest burn the Merlin engine is rated for. I could dig up the exact numbers for these parts, but the margins seem more than ample enough.

> Buddy, I don't have time for Elon fantasies.

I'm not impressed by your insults. Bring in the math.

[gaigalas]

> I'm not impressed by your insults.

It's not an insult. You're overestimating SpaceX capabilities and I'm correcting you. There's no shame in that. I do find strange that you're insisting on it though.

> Bring in the math.

Falcon Heavy never carried anything similar to Orion. It never performed a second-stage "second burn trick" [sic]. There has never been a shield test like you described. Those things were never even hypothesized formally.

You made the claim that it can do those things with insufficient evidence. You need to back that up. I'm not going to fall for a reversal of an onus that you, and you alone, should prove.

[rbanffy]

All the evidence required is the mass of the object and the total kinetic energy the second stage can add to the object - rockets are like that: they don't care what they are pushing or in which direction - it's possible to get the required speed with a 20 ton payload. The idea was never proposed because of numerous reasons (one of them not thinking it would yield a better understanding of how the Orion heat shield works - they thought it was perfectly fine to test their theory with a crew on board, and I applaud their confidence).

There never was a shield test like this. The only other crewed capsule in operation today has had a few uncrewed flights without incident before taking astronauts on board, under much more forgiving reentry profiles. I sincerely hope the Artemis II shield shows no chipping and is well within the expected behaviors according to their current understanding, but, then, again, Artemis III will carry a new design, with changes informed by the first Artemis flight (and near failure - it was uncomfortably close to burning through the hull). And it will have astronauts on board on its first flight.

Doing a shield study on the lines I proposed would be politically complicated for NASA and would undoubtedly serve as an argument to further cut funding to Orion, as it would show they don't trust their designs, or don't completely understand them. I would also delay the next launch, which is, again, a politically charged thing.

I trust their math, but there are incentives for cutting corners here. Both Challenger and Columbia were lost because people forgot they were experimental vehicles operating under conditions we don't fully understand. They were treated like 737s.