SLS vs. Falcon Heavy

[Lunniy Korabl]

Yeah, I was thinking the same thing. Even Mr. Musk has done the maths and decided FH is "not big enough" for the kinds of payloads they want to send to Mars. He has recently alluded to a Moon mission with FH though, saying something along the lines of not being that interested in the Moon compared to Mars but that they'll probably go there just to prove the capability.

[Nibb31]

Neither FH, nor SLS, nor even the Musk's MCT, have any payloads, nor do they have anyone willing to pay for them.

These sorts of expensive engineering projects only get a green light when there are a certain number of firm orders and a flight manifest. Boeing or Airbus don't start building a new airliner until they have a few hundred firm orders. The F35 only started when a number of militaries signed an agreement to purchase a minimum number of aircraft. The only exception I can think of is actually SLS, where an expensive development program is underway with no minimum number of units being agreed to. And that is what will probably cause its demise after one or two flights.

As for FH and MCT, they both have a flight manifest of zero. Powerpoint rockets are cool and exciting, but there is no point in building a rocket that nobody wants to buy.

Edited March 17, 2014 by Nibb31

[Albert VDS]

As for FH and MCT, they both have a flight manifest of zero. Powerpoint rockets are cool and exciting, but there is no point in building a rocket that nobody wants to buy.

But that doesn't mean that there is no need for them.

[Nibb31]

But that doesn't mean that there is no need for them.

In economical terms, need is expressed by demand, which is equivalent for people willing to pay for a product or service. Although missions to Mars are exciting, the economical demand is not high enough to sustain a market of several heavy launchers.

There might be actual demand for one sample return mission, but science mission planners are not going to base their mission architecture around an unproven new launcher that only exists on paper, because if that launcher is cancelled, they lose several years of work. Therefore, if a sample return mission ever happens, it will be designed to go on a proven existing launcher, like Atlas V, Delta IVH... or SLS if they can afford it.

Also, don't forget that science missions work on shoestring budgets. A bigger payload means a bigger budget, what NASA calls "flagship missions", and nobody can afford a 50 ton or 130 ton science payload.

As for Red Dragon, it has an estimated payload of 1 ton to Mars surface, which is basically the same as Curiosity that launched on an Atlas V. A single ton payload is hardly sufficient to carry enough delta-v to return to Mars orbit and to dock with a return vehicle. The Red Dragon concept seems cheap because it reuses off-the-shelf SpaceX hardware, but it still has to be highly modified, requires new dedicated hardware, and doesn't provide any new capability that we don't already have.

Edited March 17, 2014 by Nibb31

[rhoark]

Personally, I think that it is better to assemble any heavier hardware in-orbit and thus above a certain threshold, the capability to lift more weight in one go becomes irrelevant. An I think that with falcon 9 heavy, so that it is cheaper to launch 3 falcons heavy with 3 parts plus the equipment necessary to dock them together in-orbit than to launch one SLS. Thus pushing SLS to a very narrow niche of launching special stuff that can't reasonably be assembled in-orbit.

NASA's trade studies disagree. A manned mars mission will likely use 3 SLSes, so you're looking at a minimum of 9 EELVs. That's before you account for how the smaller volume limitations impact the design of each module. Each component connection also means 4 months of practice in the buoyancy tanks.

[Winter Man]

The turnaround on a Falcon Heavy is much much better than an SLS though. You only have to build one and you get multiple launches per week. You could build something dwarfing the ISS in a fortnight for a fraction of the cost, then send it on its way to Mars the following week.

[78stonewobble]

The turnaround on a Falcon Heavy is much much better than an SLS though. You only have to build one and you get multiple launches per week. You could build something dwarfing the ISS in a fortnight for a fraction of the cost, then send it on its way to Mars the following week.

I could easily imagine that reusability would become a liability if smallish budgets only allow for few and rare launches (ie. around 4 launches total with 6 months to a year between).

It can make sense if there's plans to launch often over a longer period.

I haven't voted because I haven't seen how either performs and whether any of the guesstimates hold up.

[Woopert]

Studies through 2012 indicated that a heavy-lift rocket capable of delivering approximately 140 t to LEO is needed for NASA's manned mission to Mars. The third stage, beyond LEO engine, for the interplanetary leg of this mission, tasked with transporting cargo and crew from earth orbit to Mars orbit, and back, is being studied at Marshall Space Flight Center with project simulations on nuclear thermal rocket (NTR) engines and the goal of developing a Nuclear Cryogenic Propulsion Stage. The project will see rocket engines at least twice as efficient as their most efficient chemical counterparts, a level of thrust and efficiency required for propelling the necessary mass of cargo to support exploration during crewed missions to Mars and beyond. NTR engines, such as the Pewee of Project Rover, were selected in the Mars Design Reference Architecture (DRA).[52][53][54] An NTR equipped Mars transfer vehicle would cut down on trip times and therefore reduce the amount of time the crew would be exposed to the most penetrating cosmic rays, it would also save money as over $1.5 billion of investment on their development and successful ground testing was spent during Project Rover and related projects.[55]

Yes, it's Wikipedia so the reliability might be sketchy, but this is an excerpt worth reading.

http://en.wikipedia.org/wiki/Space_Launch_System#Upper_stage

[Albert VDS]

In economical terms, need is expressed by demand, which is equivalent for people willing to pay for a product or service. Although missions to Mars are exciting, the economical demand is not high enough to sustain a market of several heavy launchers.

There might be actual demand for one sample return mission, but science mission planners are not going to base their mission architecture around an unproven new launcher that only exists on paper, because if that launcher is cancelled, they lose several years of work. Therefore, if a sample return mission ever happens, it will be designed to go on a proven existing launcher, like Atlas V, Delta IVH... or SLS if they can afford it.

Also, don't forget that science missions work on shoestring budgets. A bigger payload means a bigger budget, what NASA calls "flagship missions", and nobody can afford a 50 ton or 130 ton science payload.

As for Red Dragon, it has an estimated payload of 1 ton to Mars surface, which is basically the same as Curiosity that launched on an Atlas V. A single ton payload is hardly sufficient to carry enough delta-v to return to Mars orbit and to dock with a return vehicle. The Red Dragon concept seems cheap because it reuses off-the-shelf SpaceX hardware, but it still has to be highly modified, requires new dedicated hardware, and doesn't provide any new capability that we don't already have.

FH will be cheaper than any rocket with same payload capabilities. There is always demand for cheaper in space flight, specially if it's as reliable or better than current rocket with the same payload capabilities.

If you work on shoestring budgets than a FH would get a lot more mission approved than any other launcher. Or even get a bigger payload, more science for less money.

Did you you even read the article? It's about a study on how viable a mission with a FH and RD would be. It also explains that the RD would only land on Mars and that a sample return rocket would be launched from the RD.

The article also states that there would be minimal modifications needed to a RD.

[Nibb31]

FH will be cheaper than any rocket with same payload capabilities.

Nobody knows that yet. The economics are far more complicated than they seem.

For prices to actually come down, SpaceX needs to reach a certain volume of launches. They aren't there yet, and the reusability thing complicates the matter, because it actually hurts their mass production goals. It's not clear whether reusability will be economically viable or whether turn-around times will be shorter.

Falcon Heavy can only exist if a certain number of launches exists. One sample return mission, or one or two private payloads, is not enough. And nobody is going to build a 50 ton payload that requires Falcon Heavy until a dozen of other people start building 50 ton payloads that require a Falcon Heavy, because otherwise, they might get stuck with a 50 ton payload and nothing to launch it with.

SLS is facing the same problem. It has 2 exploration flights and maybe a DoD flight on its manifest. Three flights is not enough to build the confidence for other government agencies to start designing 70-130t payloads for it. It takes years to build confidence and even more years to build payloads.

There is always demand for cheaper in space flight, specially if it's as reliable or better than current rocket with the same payload capabilities.

If you work on shoestring budgets than a FH would get a lot more mission approved than any other launcher. Or even get a bigger payload, more science for less money.

Payloads will only appear for the rocket when the rocket is actually available. SLS is having the same problem, yet it is actually available. Even if they were actually offered an SLS launch for free, JPL couldn't afford a 70t flagship science mission.

And the market for launches to LEO or GEO is not growing at an exponential rate. It's a competitive market, so if SpaceX drops their prices, the others will follow. It's not clear whether the market is big enough to support all the suppliers that are on the market, and launch providers that are backed by government subsidies might turn out to be more robust that private companies.

The market analysis is much more complex than "build it and they will come" (which has more often failed than succeeded).

Did you you even read the article? It's about a study on how viable a mission with a FH and RD would be. It also explains that the RD would only land on Mars and that a sample return rocket would be launched from the RD.

The article also states that there would be minimal modifications needed to a RD.

I understand that. What I said was that you need to get a sample return rocket with enough delta-V to reach Mars orbit, plus the hardware to rendez-vous and dock with an Earth Return Stage, into a 1-ton package. You also need to build a robotics package that will deploy the rocket from the Dragon, and actually pick up the sample and load it on the rocket, plus the power and comm and avionics packages, all in that 1-ton payload.

You also need to develop an autonomous Earth Return Stage that will wait on orbit for your sample carrier rocket and bring it back. And don't forget, it needs some sort of capsule and parachute system to actually get the sample back to Earth.

While it is possible to fit all that onto a Falcon Heavy, it still isn't a "cheap" option, and the actual launcher would only be a small part of the project.

[Nibb31]

The turnaround on a Falcon Heavy is much much better than an SLS though. You only have to build one and you get multiple launches per week.

That is pure conjecture. Nobody knows what the turnaround times for Falcon stages will be, or how many times they will be able to reuse them. They don't even know if an empty stage can handle the landing or aerodynamic forces without sustaining any damage yet.

The Falcon Heavy probably won't use reusable stages anyway, because it seriously cuts into the payload capability, which negates the point of using a heavy launcher. The F9-R will have a 7t to orbit capability instead of 13t for the F9 1.1. This puts it in the same category as Soyuz or Ariane 6. I'm guessing that a reusable Falcon Heavy would be closer to good old Proton and Ariane 5 than to the full 50-ton non-reusable Falcon Heavy.

You could build something dwarfing the ISS in a fortnight for a fraction of the cost, then send it on its way to Mars the following week.

[Albert VDS]

@Nibb31: You assume it's a cycle of no rocket > no demand > no demand > no rocket > etc.

If that's the case then we wouldn't have commercial airliners, because a 100 years ago there was no demand to fly from one place to the next.

It wasn't the demand which made it grow into what it is today, it's the way it got funded and build upon so that the need raised and the price dropped.

SpaceX is taking the same route. 10 years ago there was no need for a company like SpaceX and a 100 years from now we wont be able to imagine living without it.

[Nibb31]

@Nibb31: You assume it's a cycle of no rocket > no demand > no demand > no rocket > etc.

If that's the case then we wouldn't have commercial airliners, because a 100 years ago there was no demand to fly from one place to the next.

It wasn't the demand which made it grow into what it is today, it's the way it got funded and build upon so that the need raised and the price dropped.

SpaceX is taking the same route. 10 years ago there was no need for a company like SpaceX and a 100 years from now we wont be able to imagine living without it.

That's wrong. Actually, 100 years ago, there was a lot of demand for travel. People were cramming themselves into ocean liners by the thousands and railways were being built all over Europe and America.

At first, planes were expensive, but they filled a niche because they were fast. From the start, they served a purpose that was obvious to everybody. It took decades for planes to become more and more affordable, over the 60's, 70's, and 80's, but the demand to get quickly from point A to point B was always there.

However, the analogy doesn't work for space because space isn't a destination and rockets aren't a form of transport for the masses. People use air travel to actually go somewhere where you can visit family, do tourism, or conduct business. A rocket takes you to orbit, which can be seen as a joyride for a small customer base, it's not an actual destination for mass transport.

Currently, there is no demand for frequent launches because there is nothing much to be done in space that can't be done better and cheaper or Earth. For demand to exist, there must be an incentive, a business model. There are lots of ideas, but none of them are viable yet because it's so expensive to get to orbit. Getting to orbit will always be expensive, because the amount of energy that is required to accelerate to 27000km/h is huge, and handling huge amounts of energy like that will always be out of reach of the masses.

Don't get me wrong. I think that SpaceX is on the right path for wanting to cut costs, but even if they manage to be 10 or 20% cheaper than the competition, it will take much more than that for any mass-scale business model to emerge.

Edited March 17, 2014 by Nibb31

[NASAFanboy]

@Nibb31: You assume it's a cycle of no rocket > no demand > no demand > no rocket > etc.

If that's the case then we wouldn't have commercial airliners, because a 100 years ago there was no demand to fly from one place to the next.

It wasn't the demand which made it grow into what it is today, it's the way it got funded and build upon so that the need raised and the price dropped.

SpaceX is taking the same route. 10 years ago there was no need for a company like SpaceX and a 100 years from now we wont be able to imagine living without it.

Except, Space isn't exactly an destination.

People brought the airline tickets for travel. Why? Because there was an bunch of industrialized centuries old world powers on the other end of the pond. Because there was an destination, and because they had busniess or love affairs or ambitions that had to be made there. Because there was people, because there was opportunity across the sea.

Space has no people. When NASA takes off for Mars in the 2030's, there aren't going to be saloons floating in the path of the spacecraft. There aren't going to be rest stops or attractive humans of the opposite gender. There aren't going to be new fortunes to be made in an fortnight.

When the planes flew, we already had a destination.

Unfortunately, we don't have a destination in space. Unless we make one.

[LORDPrometheus]

In the end it comes down to which is actually going to be built and not scrapped by budget cuts. The falcon heavy will likely fly within two years and with the way NASAs funding works the SLs will likely be cancelled soon

[SargeRho]

Actually, the SLS can't be cancelled at this point.

[Red Iron Crown]

Actually, the SLS can't be cancelled at this point.

How do you figure? There may be penalty clauses in the contracts, but a determined administration could certainly axe the program.

[SargeRho]

First off, Congress is pretty fond of it. Secondly, if I remember right, they introduced a bill preventing the cancellation of the SLS.

[Red Iron Crown]

First off, Congress is pretty fond of it. Secondly, if I remember right, they introduced a bill preventing the cancellation of the SLS.

As I understand it, that bill prevents it being cancelled without Congressional approval, which is not the same as being uncancellable. If for whatever reason Congress decided it needed axing, it would go.

[maccollo]

As I understand it, that bill prevents it being cancelled without Congressional approval, which is not the same as being uncancellable. If for whatever reason Congress decided it needed axing, it would go.

H. R. 3625

https://www.govtrack.us/congress/bills/113/hr3625/text

[Albert VDS]

That's wrong. Actually, 100 years ago, there was a lot of demand for travel....

There wasn't demand for travel via plane, because it didn't exist. It was an example how something, which didn't have a demand for, turned into some cheap and everyday.

[Nibb31]

There wasn't demand for travel via plane, because it didn't exist. It was an example how something, which didn't have a demand for, turned into some cheap and everyday.

It was a bad example because demand for fast and safe transportation has always existed. Air travel arrived as a solution to that problem. Routine space flight is (unfortunately) a solution looking for a problem.

[xenomorph555]

I'm sorry, but this thread is very wrong. SLS and FH are completely different rockets for different purposes, now I am in no way a supporter of SLS (personally I see it as a waste of money that could go to a large titan/europa mission) however it is important to note that SLS is a super heavy lift rocket (130 MT) for interplanetary missions (or super space stations ), FH on the other hand is a COMMERCIAL heavy lift LEO rocket (50 MT), and yes while I know about Elon's mars sample return mission it is still very limited as well as the prospect of little money from it. However I'm all for spacex, great company and Musk is a great guy (modern day Braun/Korolov) and i'm sure his reusable rocket scheme will work fine. Xeno out!

[Nibb31]

How do you figure? There may be penalty clauses in the contracts, but a determined administration could certainly axe the program.

I doubt it gets the axe before it flies. There is really to much at stake at this point. It would probably be the final straw after 3 decades of cancelled launch vehicles.

I think we will probably get EM-1, EM-2, and that top secret DoD flight (which is probably the only reason Congress insists on a 130 ton capability), and that's it.

[architeuthis]

I'm sorry, but this thread is very wrong. SLS and FH are completely different rockets for different purposes, now I am in no way a supporter of SLS (personally I see it as a waste of money that could go to a large titan/europa mission) however it is important to note that SLS is a super heavy lift rocket (130 MT) for interplanetary missions (or super space stations ), FH on the other hand is a COMMERCIAL heavy lift LEO rocket (50 MT), and yes while I know about Elon's mars sample return mission it is still very limited as well as the prospect of little money from it. However I'm all for spacex, great company and Musk is a great guy (modern day Braun/Korolov) and i'm sure his reusable rocket scheme will work fine. Xeno out!

Since the J2X got canned by congress's budget the SLS is largely an LEO rocket as well. The current block SLS will use a centaur upper stage with a single RL-10 motor. In terms of payload delivered to destinations in the outer solar system it is not radically better than a Delta IV-Heavy.