sevenperforce

Mercury had no translation thrusters for changing its position in space, only pitch, yaw, and roll jets. However, they did have a total of six solid motors strapped (literally with leather straps) under the heat shield, 3 posigrade and 3 retrograde. The posigrade motors separated from the booster and performed final circularization; the retrograde motors deorbited. The larger nozzles are the retrograde motors; the smaller ones are the posigrade motors.

The Atlas booster made it to orbit but rapidly decayed. The Mercury capsule had two solid motor packages, one for circularization and one for deorbit. The deorbit module had three different motors in case one failed.

Crew Dragon already has enough onboard dV to do a return from NRHO though not from LLO. Trouble is there's no way to get anything from the trunk into Dragon 2. Connection between the trunk and the capsule only transfers electricity and coolant, no water or ECLSS expendables. So it's not very useful. I wonder if you could use a Dragon XL on FH. It can carry up to 5 tonnes of pressurized cargo to NRHO. If we suppose it carries the same propulsion unit as Dragon 2 minus the SuperDracos, that's 1.4 tonnes of propellant, which corresponds to 8.9 tonnes total mass (assuming 500 m/s of dV at 300 s) and therefore a dry mass of 2.5 tonnes, just slightly more than half the mass of Dragon 1 (which makes sense if you strip off the aeroshell, chutes, and heat shield). Sent up empty on a center-core-expended FH, Dragon XL would reach LEO with about 54 tonnes of residuals in the upper stage. Let's call it 50 for margin and boiloff. Send up a Dragon 2 outfitted for a lunar mission (packed internals and extra ECLSS), and dock the two in LEO, nose to nose. Total mass is 23.4 tonnes plus residuals. FH upper stage has nearly 4 km/s of dV, more than enough to push to TLI with an eyeballs-out burn. Once on TLI, Dragon XL separates from FHUS. Total mass is 18.9 tonnes. Dragon XL provides extra living space for the coast to cislunar space and some insertion dV. Probably not enough though. I wonder if they could build a Dragon XXL with extra props.

It wouldn't be able to comanifest any sort of airlock or extended hab. I guess you could man-rate Falcon Heavy and put a hab on top, between the trunk and the top of S2, then do a transposition-and-docking a la Apollo, but that would mess with the OML. That doesn't sound likely. Effectively multiple auto-detatch operations and shifting cargo at the moment of abort. I'd be surprised. I think it likely depends on the release mechanism. Ah, here's a pic: Based on that, I reverse my original assessment. It looks like the release mechanism is specific to each individual piece of cargo. They wouldn't rely on the cargo to self-jettison. So cargo is likely pulled away with the trunk. Of course SpaceX could easily enough design a trunk with a quick-release port inside.

I had wondered that a long time ago and I looked around to figure it out but came up empty. I imagine they jettison. Abort can push something like 6 gees but it is limited to 3 or 4 gees in most aborts.

I am assuming Skylab would have been heavier if they'd had more margin. Who doesn't want extra payload? If there is any indication of the Saturn V's max monolithic lift to LEO then I will adjust. Actually it looks like the monolithic lift capability of Saturn V was 118 tonnes, so I made the adjustment. If we were launching Hubble today and intended it to be serviceable with additional missions, it could launch with an IDA and a simple airlock. Then Starliner or Crew Dragon can do the work. Why launch an airlock and orbiting laboratory every single time if the airlock can just stay with the satellite? That's what I used in my table, which gives the Saturn V a gross mass to LEO of 154 tonnes, dwarfing SLS Block 1B and the Shuttle at 115 tonnes each. Note that SLS Block 1B and the Shuttle both have the same gross mass to orbit, if the Shuttle is launched fully loaded. It's amazing how inefficient SLS is. Note that the Atlas that launched John Glenn actually has a mass-to-orbit lower than the gross mass of the capsule, since the capsule had to provide the final circularization burn. It is tricky to figure out what mass to use for the capsules/vehicles. Dragon 2 will be the only vehicle capable of comanifesting cargo until Block 1B. Incidentally this is one area where Starliner is more capable than Dragon 2. Starliner can, theoretically, dock to a mobile airlock and move it somewhere since it has aft thrusters. Crew Dragon's only aft thrusters have major cosine losses. That was for the Shuttle-C configuration. It's italicized since it was never actually used.

IIRC the moon is in the shadow of the Earth's magnetic field about a third of the time. Van Allen belt radiation is higher than interplanetary space. Mars has no magnetic field so radiation is the same there as interplanetary space.

Here you go. Made a few tweaks. https://drive.google.com/file/d/1wLD3sPMQ6aY8F-w4xywW2l5vNzVMv4Ak/view?usp=sharing Should be downloadable by anyone. Readme in spoiler. EDIT: I think I accidentally put the upper-stage engine with the lower stage when staging. You might wanna fix that.

Often a vehicle's LEO payload is a matter of structural limitations and TWR. Skylab was 77 tonnes, which is what I have listed since it was the largest thing launched by Saturn V. As @tater pointed out, you can get a better idea of gross lift by including the final stage mass to LEO. Hence the various column breakout. I will post it tomorrow.

Here, I threw this together. Human Launch Vehicle Liftoff Thrust Gross Mass to LEO Cargo to LEO (uncrewed) Comanifested Cargo Crew Vehicle Crew Vehicle Mass Crew Operation Atlas LV-3B 1881 1360 0 0 Mercury 1400 1 1962-1963 Titan II GLV 1900 10201 7900 0 Gemini 3790 2 1965-1966 Saturn 1B 7100 31600 21000 0 Apollo CSM 14690 3 1968-1975 Saturn V 35000 153500 118000 16400 Apollo CSM 28800 3 1968-1972 STS 30250 114509 104000 24310 Orbiter 78000 7 1981-2011 Ares I 15000 41287 25400 0 Orion 26520 4 N/A Falcon 9 B5 7607 27300 22800 6000 Dragon 2 15525 7 NET 2020 Atlas V N22 7204 15437 17211 0 Starliner 13000 7 NET 2020 SLS Block 1 39440 98490 95000 0 Orion 26520 4 NET 2021 SLS Block 1B 39440 115205 105000 11000 Orion 26520 4 NET 2025 Italicized values are theoretical/not-demonstrated. To get on the list, a vehicle must have been an orbital-class crewed launch vehicle that had at least one test launch from US soil. Operational period refers to actual crewed orbital flight, not launch vehicle activity generally.

Unless you are in a parking orbit aligned with the moon's orbital plane, then there are only ever two choices for your TLI burn: the ascending node and the descending node. Those only line up with the moon's actual position twice a month. So avoiding radiation is just a matter of looking at your precise planned trajectory and asking "Is this one of those 1-in-20 times when we run smack dab into the belts? Oh, it is? Okay, let's go two weeks later."

Sometimes when I am building a clone of a real-world rocket and have too much dV, I will do two tank parts, designating the upper tank as the oxidizer tank and the lower as the prop tank, which feels sorta cool. I really wish we could designate all tanks as either oxidizer, fuel, or monoprop. One reason Starship has the LOX tank on the bottom is to help push the CoM toward the tail on entry and landing. You still want your CoM farther forward so you need less gimbal for the same amount of control.

My Crew Dragon alone has 300+ parts.

The decoupler is attached directly to the base of the upper-stage tank and translated down; it has zero-force decoupling and is autostrutted to the Crew Dragon for stability. Staged decoupling is off. The interstage (built from a fairing) is attached to the decoupler and translated up to hide it; its staging is also obviously off and it is autostrutted to the upper-stage tank. The engine assembly (it's actually 15 parts and has the same puffy, crinkly foil of the one we're used to) is surface-attached to the base of the upper-stage tank. A pusher rod with three struts is surface-attached to the interstage; it has a circular grip pad and a tiny-sized nose cone on the end. I use an action group to decouple and extend the rod simultaneously, pushing the upper-stage engine free of the interstage. Then I spacebar to stage the engine.

You don't need to avoid the Van Allen belts. Most Apollo missions went around them, but Apollo 14 went straight through with no ill effects. The VA belts are inclined at 11.4 degrees, the Cape is inclined at 23 degrees, the ISS is inclined at 52 degrees, and the moon is at 5 degrees, so it is actually pretty hard to hit the inner belts at all when launching from the Cape, and extremely hard from the ISS. The way you control your insertion inclination at the moon actually depends on the argument of periapsis you give to your trans-lunar injection. Whether you're burning from a Cape-launched parking orbit or burning from the ISS, you'd still perform your TLI roughly from the point along the line of intersection between your orbital plane and the moon's. But timing is key. If you are doing a classic figure-8 free-return, aiming just ahead of where the moon will be (as opposed to just behind, which would slingshot you to Earth escape), your parking orbit inclination will be reversed during your flyby. If you burn just before your ascending node, your Hohmann will have an apogee that is slightly above the plane of the moon's orbit and thus your flyby will be at a higher latitude than it otherwise would have been, bending your lunar orbit more toward polar. If you burn just after your ascending node, you will pass low and so the reverse will be true.

Yes, I made it for the challenge though I won't be able to fly it unless I can scare up an ISS to send it to. I used a lot of subassemblies so I am not sure of the final part count but I think it is probably somewhere around 1100. Maybe as low as 800. I wanted to use an actual crawler for the Falcon 9 as well as using a stock Tesla Model X to take Bob and Doug from the Astronaut Complex to the pad, but that was a bit too much.

They have just brought Falcon 9 to vertical so looks like it is time for me to do the same... Doug and Robert aren't in the Crew Dragon; they're in the observation deck module on top of the crew access tower. Crew Dragon is integrated fully filled to save time, but Falcon 9 is unfilled and must be lifted to the vertical first, or the (Transporter)-Erector won't have enough juice to lift it. The Crew Access Arm is fully articulating and they walk down it and climb in before the vehicle is filled. Tanks are filled from the reservoir in the access tower. At T-2, the engines ignite; at T=0, the clamps release, the giant decoupler ring unlocks, the erector arms retract and pull back, and Falcon 9 lifts off. At stage separation, the first-stage engines are shut down, RCS is activated, the upper stage is decoupled, and a pusher rod shoves the upper stage engine away. RCS on the Crew Dragon is not activated until it separates. There are no active reaction wheels on the vehicle (although they are activated in case of aborts to stabilize because we don't have differential thrust guidance on the SuperDracos). It uses three-engine boostback, entry, and landing burns. Grid fins are fully functional and provide roll, pitch, and yaw authority. Landing legs deploy and lock into place and cannot be refolded. After reaching orbit, Crew Dragon separates, activates its own RCS, and opens its nose cone using a powered hinge, exposing and activating the four primary Draco thrusters. They are automatically turned off when the nose cone is closed. Docking and undocking are straightforward. During re-entry, steering is accomplished by roll control only. A hatch pops off the base of Crew Dragon to expose the drogues, which are jettisoned with a decoupler when the mains pop. 100% stock. Does anyone have a low-part-count stock ISS I can borrow?

Looks like I have good timing...

The Shuttle could have dragged the ET to orbit, too, though without any significant internal payload...and, indeed, there were suggestions of doing so in order to use the ETs as orbital habs. So "could" is not a great metric. F9's first stage "could" enter orbit as an SSTO. Let's see here: Vehicle | Crew Vehicle | GLOW | Gross Mass to LEO | Cargo to LEO (uncrewed) | Cargo to LEO (crewed) | Crew Vehicle Mass | Crew Capacity Atlas LV-3B Titan II GLV Saturn 1B Saturn V STS Ares I Falcon 9 Block 5 Atlas V N22 SLS Block 1 SLS Block 2

The only trouble is that then the Shuttle's payload is amped up by its 9.5 tonnes of engine that were decidedly NOT part of the payload in any meaningful way. You almost want to have four different measures: payload (total mass to LEO including terminal stage), uncrewed cargo (amount of deliverable upmass to LEO without crew), crewed cargo (amount of deliverable upmass to LEO along with a crew vehicle), and crew capacity.

Yes, easily. When you're going cislunar, inclination really doesn't matter at all. You don't have to change inclination because you can predetermine your flyby to do literally any plane change, completely free. There's a phasing issue at high inclinations but it's not serious. ISS altitude is a little more dV-costly for TLI than a super-low parking orbit but not so much that an apogee dive is worth it.

They could have dropped off the used SSMEs at the ISS and used a Canadarm to mount the SSMEs inside an empty Shuttle bay once every dozen missions or so. Logistical nightmare though.

Liked but not liked.

Methane tank is on top and feed line is internal, so the only thing capable of burning that low would be GSE.

If you do the math, using the CM for lunar orbit insertion is absolutely the most dV-efficient, if both vehicles use the same type of props. The only reason Constellation would have used the lander for LOI was that Altair was hydrolox, which made it more mass-efficient (also because Ares I). Continuing to use a legacy component from a cancelled architecture is a great idea if it gives you excess capacity. Continuing to use an underpowered legacy component is stupid. It would be like paying triple to refurbish reusable SSTO engines only to be expended. Oh, wait.