In my PM piece (and in my piece for The New Atlantis), I continue to make this point:
Beyond that, a single-vehicle architecture is as fragile as the Shuttle was: What if something happens to the heavy lifter that shuts it down for months or years (as happened twice with the Shuttle)? We are out of business until it comes back on line. And suppose that we build such a vehicle for the moon, and then decide to go to Mars? Do we need yet a bigger vehicle? Where does this fetish for heavy lift end?
I never get a response to it from the heavy-lift fetishists. So I throw it out, once again, this time on its own, to make it more difficult to ignore.
Well, one possible approach is to appeal to multinational sources of supply and select a size for your heaviest payloads that you can obtain launches for from more than one “heaviest” national booster. Looking at the Ariane 5 scale-up plan it would be credible to coordinate to 50t class launch from both U.S. and European sources for your occasional big piece — and if the U.S. “heavy” is heavier than that — the propellant supply is always thirsty and you can always choose to put more/less propellant in the tanks.
If the “big enough” booster is a “heavy” variant of a 25t class booster with a largish fairing that has other customers supporting the production line, it may well be affordable to keep more than one such booster in use for exactly the reason you suggest, Rand.
Of of course there are many missions that can be done with 25t pieces; just not clear that all of them can be done that way; may well be practical to architect transport system so that if you lose your heavier booster for a time, that doesn’t interfere with keeping whatever infrastructure you’ve already put up there crewed and operating.
It is worthwhile to point out that having multiple, redundant suppliers of astronaut transport kept the IIS program going while the shuttle program stood down. It also prevented stranding astronauts due to the stand down.
Having redundant spacecraft capability is something worthy to design into any succeeding exploration architecture (indeed, propellant depots could be redundant). Doing things like apollo would be needlessly dangerous
You ask “Where does this fetish for heavy lift end?”
Orion, clearly.
Of course, the Greens will want us to use Hydrogen propellants, which makes the whole idea a bit unlikely, unless one considers Hydrogen Fusion to be a Hydrogen Propellant.
OK, so I’m being a bit facetious. But if your goal is really heavy lift, isn’t that the only way to go?
Actually, if you’re really into heavy lift, Sea Dragon is the way to go.
> Actually, if you’re really into heavy lift, Sea Dragon is the way to go.
I have no idea what scale it’d need to be to even approach being cost-effective, but I’ve sometimes wondered if SpaceX’s Merlin engines would work for a Sea Dragon-style approach. They’re designed for sea recovery, although no idea if it would even be possible to design them for in-sea firing.
Actually, if you’re really into heavy lift, Sea Dragon is the way to go.
Well… the original Orion would have to hold that title. I think it should launch and land at sea myself (which I don’t think anybody in the original concept thought of.) A huge floating platform could take ALL the world’s rockets to orbit in one launch.
Very cool concepts.
No way the environmentalists would let Sea Dragon launch these days. From Wikipedia … “substantial noise attenuation” from the underwater Sea Horse launch likely translates into deafening/killing the whales/dolphins/other cuddly sea beasts.
With respect to Orion, I’m not terribly keen myself on detonating a bunch of nukes in the atmosphere even if it worked as planned. The folks that go ballistic over plutonium power packs in spacecraft would have a collective stroke!
A cloudy day radiates more people than a well designed Orion ever would. Imagine using an Orion launch system (no shock absorber required) to put a fully assembled conventional chemical spaceship into orbit ready for fuel and crew. Or perhaps a dozen.
The folks that go ballistic over plutonium power packs in spacecraft would have a collective stroke!
A feature, not a bug. But getting back to Rand’s point, we don’t need heavy lift (unless we face extinction, then it could suddenly become very sexy.)
Put a dozen or so Bigelow modules in orbit; tie them together and add a propulsion module and you have enough interior space to go almost anywhere in the solar system in style.
We could do this easily in the next decade if we wanted to.
You might want heavy lift for the ultra big fairings that could carry very bulky items such as heatshields in one piece. I imagine there is a limit to how big a hammer head fairing can be. Other heavy and/or bulky items could include super-insulated cryotanks, enormous telescopes, nuclear reactors, ultra large solar arrays, and (for the truly daring) nuclear pulse rockets. Unfortunately, there seems to be little or no demand for such payloads yet. _Sigh_
As best I could see, NOTHING planned for Constellation fundamentally required shuttle-derived heavy lift, except (possibly) missions to land on Mars. Going to the Moon or even the moons of Mars appears straightforward with EELV-class launch vehicles, if you are willing to use propellant depots and fairly modest on-orbit assembly.
Cheap access to space seems to be a far more pressing need than heavy lift.
Looking at the Ariane 5 scale-up plan it would be credible to coordinate to 50t class launch from both U.S. and European sources for your occasional big piece
ESA and Arianespace appear to be moving away from plans for a bigger launch vehicle with Ariane 6. It is supposed to be EELV-like, with a smaller common core than Ariane 5 and small solid strapons. The three core configuration could still launch big payloads. The mid-life update of Ariane 5 will still be bigger than the current Ariane, allowing it to continue to do dual payload launches even if satellites get heavier. But with Ariane 6 it will be single payload launches of heavy satellites.
We will eventually need heavy-lift for the same economic reasons that the airlines needed widebody aircraft. But that’s a problem decades in the future and can’t be really addressed unless we get reliable and reusable vehicles.
We will however need an EDS. Basing that on a new common upper stage for Atlas and Delta gives you EELV Phase 1, which just happens to be a 40-50mT HLV. It’s not the 40-50mT itself we need, but that is what rolls out naturally. And fortunately the launch vehicles scale down to non-HLV levels in single core configuration. They would even be very interesting for crew launches.
Martin – I’m no sure I understand your post, so I apologize if I got it wrong, but couldn’t you launch the EDS unfueled and refuel on orbit? Or launch the EDS as a “self-deploying” module?
By self-deploying, I mean that the EDS leaves Earth as the 3rd stage of a rocket and expends most if not all of its fuel getting itself into orbit. The now-empty stage is refueled and send on its way.
Sure, but you still need an EDS. Modifying an upper stage seems to be the cheapest way to get an EDS. A Centaur or DCUS with a lunar mission kit might be the simplest thing to do, but you’d have to launch it fueled. That appears to be the minimal EDS you could use for exploration and could be a good first step.
If you want it to be refuelable (and you do if you want to create a thriving launch market), you are going to need to make more modifications. You’ll also need a depot to refuel from, which would require more modifications. While you’re at it you might as well max out the size of the EDS while making sure it still fits on both Atlas and Delta.
Strike “3rd” in my post above and replace with “2nd.” Bottom line – the EDS is just a rocket- it can help lift itself to orbit.
There are some old Boeing and LM papers on the ULA website that describe the modifications that would be needed to turn an upper stage into an EDS. It would need another power system that will allow it to loiter for a couple of days at least, and preferably one to two weeks. It would need some boil-off mitigation, automated rendez-vous and docking, upgraded flight software, perhaps more engines.
We will eventually need heavy-lift for the same economic reasons that the airlines needed widebody aircraft. But that’s a problem decades in the future and can’t be really addressed unless we get reliable and reusable vehicles.
I don’t think you analogy hold up. The first widebody airliners were planes like the 747. One of the biggest factors that made them so successful was the introduction of high-bypass ratio turbofan engines which featured significantly better fuel consumption values. They could carry more passengers at a far lower cost than previous airliners. Those engines are now common on much smaller airliners.
The big disconnect in your analogy is that those widebody airliners were flown very regularly on high density, long-haul routes. A heavy lift space booster might only fly once or twice a year. Low flight rates combined with high R&D and production costs result in very expensive boosters.
Eric Weder,
Actually there is a solution to the noise problem for Sea Dragon. Clipperton Island. It has an enclosed lagoon too acidic for anything other microbes. Build a lock system into it and you could launch all the Sea Dragons you want without noise leaking into the ocean. It also solves the problem of wave action.
larry j – exactly. Once the volume of stuff that needs to go up to Earth orbit increases to the the point that launching a heavy lift on a more than “once in a blue moon” schedule makes sense, we’ll “need” heavy lift. That day is a long way coming.