sevenperforce

Getting off-topic...

I find it unlikely that Bezos will not have some sort of refueling and prop management system in place. Pretty sure that with two launches it could throw more to cislunar space than even Block 1B.

It's just a typo. The RD-171 comes in just under 8,000 kN so this is just over.

If it's rotating slowly enough then CG management is less of a problem.

We could suppose that Starship is delayed. New Glenn could represent the upper limit of what we are allowed in terms of putting something monolithic in LEO. Full artificial gravity may be out, but "minigravity" may be feasible. Build it in a design which works well under tension, then put a very very slight rotation on it...low enough that the core of the station won't make you dizzy and gives you the full microgravity experience, but significant enough that you (and objects around you) tend to settle to the floor if you are bunked at the outer cabins. Canadarm construction and inflatable habs are both proven tech. Orbital assembly of the actual pressure vessels is definitely unproven tech but if someone was able to manage it, more power to them.

An interesting possibility would be a "steel zipper" approach, where the unfolding panels join interlocking teeth. The teeth could be painted with some sort of thermal bonding agent...perhaps an inhibited thermite analogue. Internal seal would tend to be the challenging point.

Honestly New Glenn is an SLS-killer and may launch before BFR. Even Vulcan-ACES could kill SLS with distributed launch, though it likely will not be operational before BFR. Counterpoint: SLS has no VHLV payloads. Orion is not very heavy; it's just heavy if you are trying to throw it to the moon.

Those are some nifty animations for sure!

Really good question! Took me a moment of thinking to see where the glitch was. Good job. The difference has to do with the Shell Theorem. An elliptical orbit only holds true as long as the entire mass of the primary remains inside the orbital path. In the right-hand case, the smaller elliptical orbit would begin to deviate from the elliptical path as soon as it entered the surface.

Here's a question that moves away from debates over business case. With present tech, is it feasible at all to construct pressure vessels in space, or do all modules need to be lofted intact? For example, it would obviously be very nice (whether we are looking at a tourism case, a crew sanity case, or pretty much any other application) to have at least one very large atrium, probably at or near the center of the station. This would be limited to a diameter of 4.6 meters if launched on a SpaceX or ULA rocket and 6.2 meters if launched on New Glenn. 4.6 meters is not too shabby--larger than the Kibo module on the ISS--but still rather constricting. If it were possible to construct pressure vessels in space, this could be greatly enhanced. Note that an expandable module a la Bigelow is not ideal due to the lack of windows. You'd probably want to go with a fold-open design, but you'd still need some way to actually seal the seams.

Exactly where I didn't want this thread to go. There's fierce disagreement on whether a business case for LEO tourism (or LEO human presence at all) closes, and we've spun round and round in numerous threads. Let's avoid repeating those arguments. For the purposes of this thread, let us suppose that there is a solid business case for placing a space station in orbit and visiting it regularly. As with any business case, money is not unlimited. We can assume that the station will have some sort of tourism value, though that may or may not be its primary business case. Those are the parameters. /endrant

This is random, but in terms of scaling near-future vehicles to KSP in stock, I use the Vector for both Raptor and the SSME (they have nearly the same thrust IRL), the Mastodon for BE-4, two Mainsails for the RD-180, the Cheetah for the RL-10, and eight Bobcats arranged concentrically (to form 9 visible nozzles) for the SL Merlin 1D. Works very well; just scale approx. one size down (3.6m rockets become 2.5m ingame, etc.).

The whole quarantine process for the ISS is something I hadn't thought about until I saw it discussed in the Dragon 2 launch webcast. There's no room for pathogens on the ISS and so the crew have to be completed segregated with everyone they contact being health-screened and wearing masks. Imagine if someone ended up with the flu....

Massive. And even moreso given that it could literally lift a house. Like, if you strip a typical two-story house and mount it on blocks, and then mount that very Raptor underneath (plumbed to tanks of course), the house...will...rise...into...the...air. A monster of an engine for heavy lifting purposes, the Mainsail's power rivals that of entire small nations. The Raptor has more than DOUBLE the thrust per unit area of the F-1.

Starship will definitely be a gamechanger, if it gets up and running. For the moment, though, we're limited to what can be flown on existing hardware. With respect to inclination...higher is better for universal access. You can access a near-polar orbit from the Cape; you just need to do a bit of a dogleg, which Falcon 9 can certainly do. If you do an 80-85° inclination, then you can burn due south (or even south-southeast) because there's enough of a circumferential component to the orbital velocity that you don't need to cancel Earth's rotation like you do with a true polar orbit. Nonzero orbital eccentricity could be very interesting if the argument of periapsis was equal to the inclination. Then, your farthest distance from Earth takes you (nearly) over the south pole and you zip at high speed over the north pole. Heat management remains the same year-round and the "night" portion of the transit is brief. For certain portions of the year, there is no night on the space station at all. You get the visual impact of eccentricity but there isn't much trouble with phasing at launch because each launch site has roughly the exact same parameters for each launch window. One of the earlier comments involved air circulation; you need fans to move air around or it will just sort of pool up. Another discussed artificial gravity, and another reaction control. There could be a way to handle all simultaneously. If the station is constructed as a torus with an open hallway running all the way around the circumference, then fans could be designed to push air around the hallway to induce a very, very slight breeze. The moving air would be enough to produce a small rotation of the station...not enough to cancel the sense of weightlessness, but enough that objects naturally settle outward rather than floating endlessly. You could adjust orientation by reversing the fans, etc. With respect to heat and power management, I guess the question is whether you'd be looking at gimballed radiators a la ISS, or panel radiators like on the Dragon 2 trunk. It would also be really cool (no pun intended) if the station dispensed with traditional solar arrays altogether and used circulating coolant from sunside to shadeside as its primary power source.

Yep, you were right. You can conduct a ring station modularly.

There's no penalty for firing the SuperDracos multiple times -- they are hypergolic, after all. So they could do a few quick bursts just after going subsonic, to make sure everything is firing properly. If it all checks out, commit to propulsive landing, reignite and throttle-up the engines, and translate over to OCISLY under continual power. If there are any issues, pop the drogues and proceed to a nominal splashdown.

There have been numerous threads about people in space, and reasons for people to be in space, and how it could possibly be economical to put people in space. There hasn't ever been much of a consensus. However, we now (with the launch, mission, and splashdown of Dragon 2) have a way to put people in space, commercially, at a price that is at least reasonably low in comparison to every other possible launch provider in history. Of course there isn't much of a destination at this point, other than the ISS. So let us suppose, just for the sake of this thread, that someone constructs a business model for flights to a LEO commercial space station, and they execute. What would that station look like? I can think of a lot of different variables. Should you choose a low or a high inclination? With a polar orbit, can reach it from any point on the globe without a plane change, and the views are tremendous, but it's more challenging than a low-inclination orbit. It also limits return in a way that a lower-inclination orbit does not. There are many more questions: Eccentric or circular? Orbital period? Artificial gravity -- partial, none, or complete? Cartesian assembly or circular? Power management? Heat management? I'm sure I'm missing many more...but if any group would be able to propose a lot of good ideas for a commercial space station (assuming, always, that the budget is large but not unlimited) it would be this group. What do you guys think?

News on Dragon 2 propulsive landings... By this I assume he means that the code is written and programmed in for a SuperDraco hoverslam to be triggered at first indication of chute failure, but activation of that code during actual crewed missions is subject to NASA's whims. I heard the callout for Dragon going subsonic prior to drogue deployment so the SuperDracos need to provide less than 340 m/s of dV for a propulsive landing. Scott Manley to the rescue: So...dare I say it...we may see propulsive landings after all! NASA wants new Dragon 2s for each crew mission so SpaceX will reuse old crew capsules to continue their CRS contract. We could very well see OCISLY doing double-duty as a Dragon wrangler. Aim just off; use propulsive landing for translation to the deck or abort to chutes and splashdown if needed.

I agree. There's a chance that they will use the current vehicle for short hops and then add a fairing for higher hops, but more likely it's a new vehicle.

Are they going to livestream the opening of the hatch? I bet Elon posts video of the re-entry with Ripley's audio.

Related: LOL sandbagging. EDIT: Actually more shade than sandbagging....

Super toasty! More...browned...than I had anticipated. Though less so than Soyuz. Looks like some significant regmaglypting on the sharper edges like the lip around the SuperDraco pods. I wonder if aeroshell reuse is possible. With those big windows that must have been quite a ride. Can't wait until they download the footage.

Hopper is actually moving to the launch pad right now as we speak... Evidently engines will be installed at the pad? Work continues on the nose cone. I suppose it will be transferred separately but the hopper will do initial hover tests without it.

Depends on whether they have a chance of fouling, I suppose. Congrats to SpaceX and NASA!! The seats actuate for entry and landing, actually. There were quite a few occasions during the entry interface where you could see flashes coming off Dragon trailing in the plasma stream. I wonder if those were pieces of TPS or paint or what......