sevenperforce

Plasma thrusters. Xenon has next to no thrust. Presumably the "repulsors" (somehow) pull in the surrounding air, ionize it, and then fire it out. Ridiculously high energy with massive heat losses. Clearly involves a lot of room-temperature superconductors.

Which will never happen. Amusingly, it would be much cheaper to loft Orion unmanned on FH, send up crew on a Dragon 2 with F9, and then send up a Centaur, Falcon 9, or NG for the TLI burn, than to ever launch SLS. Once BFS is flying, it eats every launch market, obviously. But in the meantime, I hope we see a distributed-launch competition between a NG-derived BLEO taxi and a Centaur/ACES BLEO taxi. You only need about 300 m/s to brake from TLI into NRHO. That's well within range of solid kick stages for a 5-8-tonne hab, I believe. Or you could buy a cheap hypergolic stage from the Russians. They're supposed to be partnering with this stuff, after all. I've been building every launch that happens as it happens, over in Mission Reports, and I have not yet seen any decent US terminal delivery stages. Are there any US contractors with hypergolic upper stages for GEO insertion or other BLEO destination braking burns?

I sure as hell hope not. The proposal is not "NASA-backed BFR" but rather "NASA-funded BFR launch" where NASA buys a payload delivery service and supplies the payload but doesn't directly fund the launch vehicle. With F9, NG, BFR, and to a lesser extent Vulcan, we are beginning to see the possibility of LV-agnostic payload services. NASA needs to say "We don't care how it gets there; we just want to know who can put this payload into this orbit at this time while satisfying our reliability assurance criteria." Europe Clipper could be delivered direct to Jupiter, more cheaply, and sooner, with two reusable Falcon Heavy launches. Or one F9 launch and one Atlas V launch. But since NASA probably wouldn't buy distributed launch for Clipper, then yeah, it might fly on SLS. EM-1 and Clipper, if EUS is developed. If they only fly ICPS, Clipper will more likely fly on an Atlas V 551 and just do a longer transit. SLS will never fly a Europa Lander, since the lander will not be designed (let alone built) until well after Clipper arrives. Flying the spaceship disposable would not quite beat SLS simply because the upper-stage mass ratio is remarkably poor compared to the EUS. But if you fly the booster disposable as well, you blow SLS out of the water. Especially Block I with ICPS. Elon said BFR (before the recent stretch) could put 250 tonnes into orbit by expending both the booster and the upper stage. With the stretch and engine uprating, you're probably looking at 275 tonnes. Clipper is under ten tonnes; 265 tonnes of propellant at 375 seconds Isp is enough to deliver Clipper direct to Jupiter, including the insertion burn. After, I'm sure. I agree that it's gotta fly at least once. Yeah, that's just stupid. EDIT: By which I mean, the $40B dev cost is stupid, not dev stipends and cost per launch. This will be a re-use of the Zuma booster.

My prediction: BFS flies suborbitally, then NG flies orbitally, then BFR flies orbitally, then SLS Block 1 drags its underpowered self around the moon once and dies.

"You're gonna need a bigger flame trench." "Cool."

There is little to no significant dV difference between a standard TLI and a NRHO TLI. Falcon 9 Block 5 can send up to 6.3 tonnes on TLI and still stick the ASDS landing. It can put over 16 tonnes in LEO with ASDS landing. Falcon Heavy can send 21 tonnes to LEO or 8 tonnes to TLI, both with triple-core recovery. Expend the core and FH is throwing 22 tonnes onto TLI. Falcon 9's upper stage goes toe-to-toe with Centaur on TLI because its mass ratio is so much better even though the RL-10 has so much more Isp than the MVac. Obviously the MVac suffers for stuff like direct injection because of duration issues. Can Centaur get to the moon on its own? I think ACES will be needed before it can actually manage a week-long lifetime.

Interestingly, an expander-cycle linear aerospike has no geometric limit on the nozzle area/chamber volume ratio, and so you could conceivably get a very high isp hydrolox aerospike running on an expander cycle. Then you just need a couple of COTS SRBs to get TWR off the pad, and there's your launch vehicle.

Distributed launch is not a free lunch; it is, rather, a pretty expensive lunch. But it is hella cheaper than the alternative, and (more importantly) it isn't nearly so subject to the whims and changing tides of Congress.

I would assume that for a very, very high-margin mission (like, 2 tonnes to LEO, where S1 can do a single-engine boostback burn and a single-engine landing burn and still hit RTLS) then RTLS would be a better choice.

I wonder what that means, exactly. I think it means that given the choice between an RTLS landing and an ASDS landing on a high-margin mission, ASDS recovery is easier on the booster because it allows more propellant to be reserved for a longer, gentler single-engine landing burn. But maybe it has something to do with the stresses of a long-duration boostback burn.

IT'S HAPPENINGGGGGGGGGGGGGGGG

Maybe so, then.

Sure, just like regional jets do. But there is still a real volume issue.

Likely the only way Vulcan can beat NG (given that they're using the same engines and ULA is paying extra) for any purpose is if they can master IVF. KSP players take IVF for granted.

I just don't see there being a market for 500 people all wanting to pay that kind of premium for international flights, no matter how brief. And definitely not multiple flights per day. Are there really thousands of business-class travelers flying internationally every day between every major route?

@tater has it right. Anything beyond SLS Block 1 is at least as notional and vaporous as ACES or Vulcan or NG or BFR. Man-rating DIVH is kinda a non-starter because of how temperamental (and prone to flame-belching) those RS68s are. I am still of the opinion that Orion is simply not needed. Better to spend development time and dollars on a reusable, dockable hab and IVF tech. But EOR is where the future is. Seriously. We have been flying EOR with the ISS for how many years now? Enough already. If NASA had simply funded the development of ACES (or an earlier cryogenic IVF and prop trans system) to begin with, we'd be so much further ahead already.

Nice. Sure, rate of flight is great and all, but it reminds me of selling lemonade at a loss and making it up in volume. If the fuel costs of a single flight approach the maximum possible revenue from a single flight, enhanced flight rate is hardly a help. And is the market really big enough to support thousands of business-class-priced tickets between NYC and Sydney each day?

It's a hydrolox VTVL SSTO, so...no. If it was, say, a tripropellant aerospike SSTO, then maybe.

I remember a really weird conspiracy theorist a while back who claimed that because of n-body dynamics, no actual true orbital trajectory or position was knowable, and so moon missions and rendezvous and reusability and boostback burns and landings were impossible, BUT Arianespace launched comsats direct to "approximate" orbits and they lasted for a while and so that was good enough for communications purposes. Go Arianespace!

SCUBA is neutral-buoyancy and you're not actively depending on aerodynamic lift to maintain heading. I'd imagine that holding a big prop mechanism in front of you while flying would be extremely strenuous, bordering on impossible. Plus, you need your hands free to maneuver your forward winglets. Damn, that's cool. Why not have an electric ducted fan with a mass injection system to boost thrust? You only need a few seconds of high thrust (TWR > 1.5) to get off the ground and get moving. You'd need a smallish GN2 around your lower back and a smallish water reservoir strapped to each thigh. Stand up straight, spin up your electric ducted fans, and then push a button to open the valve on the nitrogen tank, forcing water out of the reservoirs and into the fan exhaust at high pressure. A few seconds of flow is all you need to get up into the air and moving forward, and then you can close the valve and let your ducted fans keep you moving forward fast enough to use your wingsuit for lift. Might need a fold-out wing extension to get enough lift for positive climb, but it wouldn't be too difficult.

New Glenn will always use droneship recovery.

Which is why I said this. Because it was originally posted in Science & Spaceflight.

The original post-Shuttle crew vehicle was the Crew Exploration Vehicle (CEV), which received bids from Boeing in partnership with Northrup Grumman and from Lockheed Martin. The original CEV was to mass 8.9 tonnes, but with a smaller service module that made total vehicle mass lower than the Apollo CSM. Little is publicly known about Boeing's losing bid (LM won in August 2006) but what is published shows a capsule essentially identical to CST-100. The CEV survived the cancellation of Constellation, but in its evolution to the Orion MPCV it gained 17% more mass in its capsule and about a tonne more mass in its service module.

ICPS just doesn't have enough throw weight to get a heavy enough payload onto TLI to actually do something useful. No one said it would be peaches and cream. But they would have been flying. And flying actual Shuttle hardware, too...not just the engines.

DIRECT was actually intended to use existing Shuttle hardware off the shelf and get flying right away. Four-segment SRBs, a core essentially identical to the Shuttle ET, and only as many engines as you need for a given mission. All with the stated purpose of getting astronauts flying (whether to LEO or beyond) immediately, with the smallest possible gap between the STS and its replacement. With DIRECT, we could have been sending Orion or Orion Lite to the ISS for the past six years, while building on that infrastructure to send payloads BLEO as well. But it doesn't have the dV or the thrust for co-manifesting payloads.