sevenperforce

Unless you have full or nearly-full reuse, no rich private client will be able to afford it. The exception is if you find a way to monetize the moon. If you monetize the moon, all bets are off. The real issue with Apollo 13 was life support failure. The CSM had enough dV to perform the necessary course corrections, I believe. And if you do Earth-Lunar-Orbit-Rendezvous, like Constellation, then you can still have the same single-stack redundancy. Dual-Lunar-Orbit-Rendezvous, where the LM is sent to lunar orbit before the CM and you do double rendezvous-and-docking in lunar orbit, lacks the backup life support option which saved Apollo 13 but you still have the free-return abort. Honestly? These days? Probably. Then you need LOP-G with multiple ascent/descent vehicles and pre-placed rovers and habs. Basically the whole Martian/Ares mission profile, but local.

Easily. I mean, as easily as such a thing can be done. Block 4 FH can deliver 3500 kg on a Pluto flyby at solar periapse, flying fully expendable. Block 5 FH can probably deliver a little more (but not much). Flying partially reusable or trying to hit Pluto on its way toward solar apoapse would lower the payload significantly.

Question: did you start all the asteroids in circular prograde orbit? Suppose you place a body that is completely stationary at the very edge of Earth's gravitational sphere of influence, then give it a tiny nudge inward. Earth's gravity will pull it steadily, and it will impact the atmosphere at escape velocity. If it has a slight tangential velocity when it enters the SOI, then it will swing by perigee at well over escape velocity and then slingshot out. Think about entering orbit around a planet after a transfer: you need a burn to slow down at or near perigee, or you will not be enter orbit. In order for a moon to be captured, some portion of that orbital energy needs to be used up. This usually happens in one of three ways: Collision. If the secondary hits something on its way by, then it will lose energy and be captured. It can hit an existing moon, or it can hit the planet itself. If impact with the primary is more than a glancing blow, the secondary will usually be ripped into shreds and will re-form as a new body (which is what happened when Thea struck proto-Earth, resulting in the formation of our moon). Note that this is equivalent to aerobraking/lithobraking a spacecraft. 3-body interaction. Another way a moon can be captured is if it imparts some of its orbital energy to something else. For example, if a dwarf planet swings through a planet's SOI and comes close to an existing moon (but doesn't collide), it can transfer some of its velocity to that moon and thus be captured. This will change the existing moon's orbit, often ejecting it from the system altogether; if not ejected, a future collision between the two is likely. You use this effect in KSP when you capture at Jool by getting a gravity assist off Tylo or Laythe. Rarely, this also happens if the incoming moon-to-be is a tight binary; one member is ejected with excess hyperbolic velocity while the other member is slowed and captured. This is what likely happened for the asteroid-moons of Mars. Tidal magic. If you have a sufficiently large secondary passing very close to the primary on its swingby, the second-order tidal effects can warp the shape of the secondary (and sometimes the primary as well), converting part of the orbital energy into rotation and part of it into internal heat. This can sometimes be enough for a capture.

2 + 2 = 4.00000006 +/- 0.00000007

You need to get above 100 proof to burn in air so you'd probably want something closer to 150-190 proof. The Walter HWK 109-509 rocket engine used in the Messerschmitt Me 163 Komet interceptor burned a hypergolic mixture of hydrazine, alcohol, and HTP. At full throttle, burning 177 pounds of propellant per second, it could develop 14.7 kN of thrust, so that's a specific impulse of around 185, give or take. A homemade alcohol-peroxide rocket would be a horrible, horrible idea, because you will very likely blow yourself up, but it could probably break 120 seconds of specific impulse.

Man-rating a launch vehicle is kind of a different ballgame. You're looking at a completely different contingency set. Well, we know what NASA was comfortable with back during Apollo, and we know what they were considering during Constellation. Who knows if they'd still be comfortable with it. What do they want? Duplicate everything? Triplicate?

It's really neat that you got a 5:3 resonance just out of the starting conditions.

These number have not changed since before the Block 5 update. So those are Block 3/4 Falcon Heavy numbers. They are practicing.

IMHO was originally "In my humble opinion" and meant either that they were taking a non-dogmatic stance, or that they were being sarcastic because they really were quite certain of themselves. However, after the acronym "TBH" (which really doesn't serve anything more than a syntactic role in sentences) became popularized, standing for "To be honest", the definition of "H" in "IMHO" began to warp. For those who had been on the internet since its infancy, "IMHO" meant "In my humble opinion" and nothing more; for younger people who had seen the acronym but never knew what words it stood for, they interpreted it (and began using it) as "In my honest opinion". In theory, this makes for a big problem. If one group of people is talking about honesty and the other group is talking about humility, and both groups misinterpret what the other is saying...well, that's linguistic anarchy! It would be as if half the internet understood "troll" to refer to a manipulative, inflammatory person while the other half understood "troll" to refer to those cute little singing creatures. How have we survived? The answer, of course, is that "IMHO" has become sufficiently divorced from either "honest" or "humble" that it has developed a meaning all its own. Its use in a sentence is to set up and call attention to an opinionated statement; it has no more to do with humility or honesty (positively or negatively) than phrases like "on the other hand" or words like "anyway".

Since Falcon Heavy will not be man-rated, you'd need multiple launches and docking regardless. Was just considering whether Falcon 9 alone can do the job that FH would previously have been needed for. Though my numbers were off; see other thread.

26476 km/h at T+26:57 32403 km/h at T+27:39 dV of 1646 m/s So it only burned 6.87 tonnes of propellant for the injection, meaning it burned 100.63 tonnes before SECO, meaning that MECO took place at LEO-6.44 km/s, way more than my earlier estimate of 5.5 km/s. Max payload to LEO is likely closer to 15.2 tonnes. Had me excited there.

Ah, crap. Now I need to go in and manually check the transfer injection burn dV.

Updated numbers give 6.57 tonnes to lunar transfer on a recoverable Falcon 9 Block 5. If you launch nothing but a naked S2 with a docking adapter (to allow another vehicle to mate with it) to act as a transfer stage, it reaches orbit with 17.6 tonnes of residuals. That's enough to send a payload of 9.822 tonnes on lunar transfer.

It occurred to me that I had not re-run the calculations using Block 5's enhanced capabilities. We saw Block 5 deliver a 7.075-tonne payload to GTO. Assuming this was a nominal transfer orbit with typical inclination, this predicts the following capabilities for Block 5 with droneship recovery: Low earth orbit: 22.76 tonnes Geostationary transfer orbit: 7.08 tonnes Lunar transfer orbit: 6.57 tonnes Earth escape orbit: 5.04 tonnes Venus transfer orbit: 4.27 tonnes Geostationary earth orbit: 3.29 tonnes Mars transfer orbit: 2.98 tonnes Again, that's with droneship recovery.

With Block 4? Reusable on the single-stick; fully-reusable on one of the FHs, core-expendable on the other FH. With B5 you could probably manage full reuse on all three launches. One thing you can do is launch a Dragon 2, then do another launch, dock and mate the Dragon 2 to the second stage, and restart the second stage. Maximum of 4-6 hours between launch and restart, which has already been demonstrated. No use of S2 BLEO. The very first step would be the production of a drop-in propulsion pallet using clustered Dracos, a single SuperDraco, or something like a Rutherford (if LOX boil-off can be managed). Basically a fuel-only service module you can lego in. Then you can figure the capabilities of such a module and calculate accordingly.

That looks......very 21st-century.

I did the math once before, using Block 4 numbers, and IIRC it could be done with two Falcon Heavy launches and one Falcon 9 launch. With Block 5 it would probably still be the same, but with better margins.

Dragon 2 has no good lunar surface sortie options; you really need an airlock. It also doesn't have enough dV for even a one-way trip, and its SuperDracos are A) not vacuum-optimized, and B) far too thrusty. That being said, it would probably be easier to convert the Dragon 2 into a lunar descent/ascent module than anything else. It would just be a lot of work: If NASA funded it, they would do it. It wouldn't be reusable, though, and it would need another D2 in lunar orbit for a rendezvous. It also would need to be dropped off in low lunar orbit, and it would have to launch unmanned inside a fairing.

Looks like I was wrong.... https://www.cnbc.com/2018/08/15/sec-has-reportedly-served-tesla-with-a-subpoena-after-elon-musks-take.html

BLASPHEMY

There's actually very little space in the trunk; the top of S2 protrudes upward into the trunk rather significantly. I supposed you could fit a BEAM in there since they've done that before. It would have to have a weird dual mating thing; the mating attachment for externally-manifested payload is inside the trunk so that would have to be moved to the top of S2. But the flip-and-grab should be easy enough. S2 has enough pointing capability with RCS alone to hold position. Well, obviously. How else?

I suppose you are one of the "H is humble" people then, too? It's just mind-boggling to me that the majority of people now interpret IMHO as "In My Honest Opinion". THE HYPE IS REAL

Or you can cluster the F1Bs and then you have a Falcon 9. You need a pair of F1 engines to equal the thrust of a single five-segment SRB. Of course they burn for much longer, so much more dV. RS-25s are impressively difficult to start and are not vacuum-optimized. This would have been WAY better than the whole STS program. Especially if they figured out a way to capture and reuse the skirt.

Another useful analogy: Let's say you're on a bicycle and you're stopped on the side of a gigantic, smoothly sloping hill. Suppose you try to pedal as hard as you can for 10 seconds. Which direction will get you moving faster -- pedaling straight up the hill, or pedaling sideways around the circumference of the hill?

My thoughts exactly. Give lunar astronauts a hab and a fuel depot. Maybe do drop tanks for the skycrane initially. Might be worth it to put a stripped-down Dragon 2 (no aeroshell or heat shield) there to act as the descent/ascent hab.