Super heavy-lift launch vehicles - What do you launch on them?

[Codraroll]

I think this discussion has sprung up off-topic in several threads, but not had a thread of its own that I know of (I'm comparatively new here, but I'm fairly sure we haven't had anything in the recent couple of months, at least). So I figured... why not create a thread for it?

 

So, we're all quite aware of SpaceX's development of the Falcon Heavy, touting the capacity to send just short of 64 metric tons to low Earth orbit, and a little less than half that to GTO. NASA's questionably-fated Space Launch System promises to (well, intends to, at the very least) send 70 tons or more to the same place, on a mounting plate 8.4 meters in diameter. Blue Origin has a slightly smaller bird than those two in development with the New Glenn, and the Russian Energia corporation has also spoken about building a super heavy-lift launch vehicle (I' using Wikipedia's term here, I hope it's the correct one).

Now, big rockets are fun and all (that very fact is presumably part of the reason why most of us are right here right now), but common criticism against these projects goes along the lines of "they have no payload". This might be true for the SLS in particular, since it's very big and very capable, but not built to the specifications of any mission. The Falcon Heavy has also been mentioned to have problems integrating the heavy payload - lifting it to space is not an issue, but lifting the rocket from a horizontal to a vertical position might be. Let's just assume that the rockets work as intended without significant payload integration problems for the purpose of this thread.

In this thread I'd like to discuss what all this super-heavy launch capacity could be used for. What could you possibly (or feasibly, or economically) bolt to the tip of such large rockets and send into orbit with a meaningful purpose? I suppose "recreating the Apollo missions" could be an answer, but let's try to be more creative than that. Besides, the Saturn V was even larger than the SLS, so presumably the latter wouldn't even be suitable for that purpose.

 

I presume an obvious payload candidate would be whatever will success the ISS. Some perhaps-not-directly-applicable-to-real-life KSP experiences suggest that you can get away with fewer launches to build a space station if you assemble more of it on the ground and launch it in fewer, heavier parts, but volume might be an issue. Also, with limits of 8.4 meters and 70 tons to play with, you could probably launch a very big and capable space telescope. Or perhaps another rocket stage with a smaller payload destined for some far-off location - but where, and how?

What do you think?

[Spaceception]

I think large probes could be sent out, like the ultimate probe, think Cassini, both Vikings, and throw in a few Junos too, why not. Then send it Saturn's way, to study the planet, its rings, Landers for Titan, and Enceladus, with a few of orbiters for Mimas and Iapetus, and general purpose stuff.

Alternatively, you could send a smaller probe anywhere in the solar system really fast,  with potentially enough fuel to get into a decent orbit.

You could also send up really large spacecraft for crewed missions, for large space stations and bases, but that's obvious, and unfortunately not under what the public wants

TL;DR There's lots of possible payloads, the problem, really, is public interest.

[CSE]

I expect the Long March will lift a manned mission to Lunar orbit, and perhaps beyond. I don't really expect any of the others to launch a super-heavy payload.

Given the expected price tag of an SLS launch, I can't really imagine any customers other than the US government. Potentially the US NRO might have something in mind, though I would have thought that the Vulcan Heavy would be enough for them. If there were any other mission requiring upwards of a hundred tonnes of LEO payload, even in the very earliest phases of planning, it would be the most wildly ambitious goal in current spaceflight and surely everyone would be talking about it.

For the Falcon Heavy, I always had the impression that the target audience would be medium payloads (~8t) to high orbit (GTO etc) at fully reusable prices. We'll see com sats and Earth-observers. In a few years' time, if we're lucky, we may see some new mission ideas from groups for whom the reusable price tag has brought previously-unavailable payload/orbit combinations within budget reach for the first time.

6 minutes ago, Spaceception said:

There's lots of possible payloads, the problem, really, is public interest.

Yes. Really big payloads need really broad-based support to make them happen, and I think that means we're limited to one at a time from any given support base. In the east, China has its moon program (if I've understood the program motivation correctly). In the west, we have the JWST; I think it needs to fly, successfully, before we can move on to any concrete thinking about what the next mega-payload should be.

[sevenperforce]

I have a few thoughts....

The issue of payload capability goes hand-in-hand with the issue of launch cadence. The reason SpaceX promises success with reuse is that it can loft payloads which are in high demand: specifically, large comsats to GTO. Something like 70% of SpaceX's launch manifest is commercial, and GTO missions compose the majority of those.

Ideally, a super-heavy lift vehicle would be able to sustain a high enough launch cadence to avoid bankrupting due to downtime. So the ideal solution to the super-heavy payload problem is a combination of payloads and cadence.

All that to say: commercial payloads are really needed to enable the optimal use of SHLVs. But what heavy commercial payloads are there, really? Is there any commercial viability in sending a bunch of really ridiculously large comsats to GTO? I kinda doubt it. Is there any commercial value in going to the moon? Not really. What about asteroid mining? That's promising, but it wouldn't support a high launch cadence.

If you can figure out a way to fund a network of commercial space stations, on the other hand...

[StrandedonEarth]

A moon base, and the associated equipment to build it. Followed by SpaceBus loads of passengers and tourists. And supplies for them. Really, the only payload I can see sustaining a decent cadence is people-moving. and for that you need somewhere to take them to and bring them back from.

Edited June 27, 2017 by StrandedonEarth

[sevenperforce]

Someone just needs to invent a quantum supercomputer (or a cold MHD fusion reactor) that can only work in microgravity.

Then sit back and watch the money pour in.

[Bill Phil]

Multiple payloads. Or heavy station/moon base stuff. I'm not really a big supporter of putting people on bombs that big.

[Starman4308]

Large scientific probes, space tourism, and space station construction & resupply come to mind. I'm skeptical that super-heavies will start to become very common, but with the recent drop in cost, I suspect demand will go up a bit.

One thing I suspect will help is that a lot of the recent heavy-lift vehicles and proposed vehicles are based on lighter-weight vehicles with higher operational tempos; Falcon Heavy and Delta IV Heavy are basically three lighter LVs bolted together, I think there's a similar proposal with ULA's new Vulcan booster, the Atlas (and Vulcan) can use a variable number of SRBs, etc.

[StupidAndy]

super heavy things

self explained

[tater]

This is really the primary issue. Building an arbitrary capability, then looking for payloads doesn't make sense. If the goal is a "real" space station, a large torus for example, then several hundred tons to LEO is useful. Propellant depots, etc. The problem is that different possible projects have different sized parts, and volume also matters.

[sevenperforce]

1 hour ago, tater said:

This is really the primary issue. Building an arbitrary capability, then looking for payloads doesn't make sense. If the goal is a "real" space station, a large torus for example, then several hundred tons to LEO is useful. Propellant depots, etc. The problem is that different possible projects have different sized parts, and volume also matters.

Precisely. We didn't go to the moon because we had a Saturn V; we built a Saturn V in order to go to the moon.

[Kryten]

Medium-sized payloads to high-energy destinations are a lot more likely than huge LEO payloads, for cost reasons more than anything else. The cost for space station in hundred+ ton modules would make an SHLV dev budget look like spare change. The DST plan for SLS is a good example of this.

[DerekL1963]

5 hours ago, sevenperforce said:

Precisely. We didn't go to the moon because we had a Saturn V; we built a Saturn V in order to go to the moon.

Yes, and no...  We went to the moon (that is Kennedy chose it as a goal) in large part because most of the puzzle pieces were already undergoing research and development (the LM being the notable exception).  We went to the moon because we were pretty sure the Saturn V was possible.

[Hannu2]

It is a chicken and egg problem. It is not reasonable to develop heavy payloads because there are no rockets to lift them to orbit and visa versa. If there were reasonable priced possibilities to launch heavy payloads, I am sure that there would be new innovations on next decades which could utilize it. Like tourism flights, test units for asteroid mining, space station parts or maybe some massive super capable communication satellites. But I think that development of heavy vehicles must be paid by making they able to put heavy commercial satellites on GTO in fully reusable mode with low costs. If someone needs massive special payloads, like scientific probes, manned crafts or spy satellites, they can buy an expendable launch.

[YNM]

I'm thinking some super-flagship missions to outer reaches of the Solar System, supplemented (or supplementing) yet another grandeur manned mission. It is indeed true that it'll starts as a chicken-and-egg problem ; hence you need to start with both. Give the system a couple few-years worth of cargo, and I'm more than sure that the other cycle (egg then chicken, or chicken then egg) will follow suit. I mean, come to think on it, when there wasn't even rockets, did making satelites sensible ? Someone needs to kick the system into movement.

Edited June 28, 2017 by YNM

[magnemoe]

2 hours ago, YNM said:

I'm thinking some super-flagship missions to outer reaches of the Solar System, supplemented (or supplementing) yet another grandeur manned mission. It is indeed true that it'll starts as a chicken-and-egg problem ; hence you need to start with both. Give the system a couple few-years worth of cargo, and I'm more than sure that the other cycle (egg then chicken, or chicken then egg) will follow suit. I mean, come to think on it, when there wasn't even rockets, did making satelites sensible ? Someone needs to kick the system into movement.

Yes, you don't plan heavy missions as you don't have the launcher, you don't plan an heavy lifter as you have no missions.
Exception is the obvious ones like an manned moon mission who require an heavy lifter or docking two modules in orbit. 

[monophonic]

14 hours ago, StrandedonEarth said:

A moon base, and the associated equipment to build it. Followed by SpaceBus loads of passengers and tourists. And supplies for them. Really, the only payload I can see sustaining a decent cadence is people-moving. and for that you need somewhere to take them to and bring them back from.

Yeah, very much so. But I'll fly another spaceline please. Btw. never noticed before but the logo is a face that seems to be kissing the sun... kinda foreshadowing, isn't it?

[YNM]

18 hours ago, magnemoe said:

Yes, you don't plan heavy missions as you don't have the launcher, you don't plan an heavy lifter as you have no missions.
Exception is the obvious ones like an manned moon mission who require an heavy lifter or docking two modules in orbit. 

But then you have the question on whether to send someone there in the first place - you do need probes. And whether you should send one anyway.

 

If they really want it they need to put their money into the system, not only the object.

[kerbiloid]

Bulky, poor-designed and cheap communication sats.
Bulky, poor-designed and cheap probes running fast to outer planets.
Swarms of cheap and poor-designed orbital minibots to every planet (let them feel the Power of Kessler) to make distributed recon networks around the planets.
Near-Sun probes. Also Mercury probes.
Thick-skinned Venus lander, with several weeks lifetime (say, on a mountain peak or so).
Several trucks of radioactive wastes to Europa and Enceladus - just to melt down and make a nice steam fountain.
Ceres lander with several rovers to study that pit near a heap digged out by aliens.
Rescue missiion to 67P to save Rosetta and Philae.

Edited June 29, 2017 by kerbiloid

[tater]

"Whatcha gonna send to space in that huge rocket?"

"Stuff."

"What kinda stuff?"

"Space stuff."

[ARS]

Single launch space station

[magnemoe]

10 minutes ago, ARS said:

Single launch space station

Or at least fewer launches. 
Raises an interesting question regarding communication satellites. If launch cost for heavy launch go down will they make heavier and more capable satellites? 
 

[Kryten]

1 hour ago, magnemoe said:

Raises an interesting question regarding communication satellites. If launch cost for heavy launch go down will they make heavier and more capable satellites? 

 Communications sats grow with market demand, not with launch capability. You could already put up a ~9.5 metric ton sat with an Ariane ECA if dual launch isn't used-and sat operators have shown they're willing to pay for that-but this has only been deliberately done once, with Terrestar-1 in 2009. It only weighed ~7 metric tons (i.e. didn't use all the launch capability by a long shot), and the company soon went bust; it was too big to be supported by the market at the time.

Now sats of about that size are commercially viable, and the second sat of the same design was bought and launched by Echostar a few months back, after having sat in a warehouse for years.

[Casualnaut]

We talking Roscosmos? Well they are working on the Federation and FEDOR.

Up there, is Federation, it isn't too heavy. The landing legs reminds me of a KSP mod... 

This my friend, is your favorite space comrade FEDOR! He will ride on the Federation!

[kerbiloid]

Spoiler

Jets look turning down 90° after releasing from horizontal nozzles.

Magnetic plasma redirector enabled?