SLS vs. Falcon Heavy

[xenomorph555]

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.

Ah, well in that case power to the musk-eteers!

[SargeRho]

The J2X didn't get cancelled. Due to the delayed need for the J2X, its development got halted for now. The engine is mostly done anyway I think.

[problemecium]

I vote FH because it already exists, while the SLS is in development. Okay, TECHNICALLY so is the FH, but with the Falcon 9 already done and some test flights under its belt it's a lot closer to finished.

[LikeASpaceDog]

The Space Launch System is a big red herring in terms of the direction space travel should be going. The age of Apollo, where people launched giant expensive super-rockets in order to prove their nations' technical superiority, and, indeed, the feasibility of manned space travel, is over. It would be folly to bring this back, when we are on the verge of the next step into space - a practical and sustainable network of transportation of humans around the solar system. It is not enough to just "visit" an asteroid, or a Lagrangian point, these places are useful for real reasons, more than just propaganda. While not definite, the Falcon Heavy certainly COULD enable the long-term usage of these resources, thru inexpensive and frequent launches, while the SLS seems geared toward just "getting footprints on something".

[ScallopPotato]

How expensive is the Falcon Heavy vs the SLS even if the FH's boosters aren't reused or turnaround isn't as cheap as expected? I'm very much skeptical of big reusable systems because of what happened with the space shuttle. Now, space shuttle and FH are apples to oranges, but the concern remains the same.

[Rakaydos]

How expensive is the Falcon Heavy vs the SLS even if the FH's boosters aren't reused or turnaround isn't as cheap as expected? I'm very much skeptical of big reusable systems because of what happened with the space shuttle. Now, space shuttle and FH are apples to oranges, but the concern remains the same.

The shuttle was originally intended to be made of titanium, not foamed glass. A certain senator however, demanded the plan be scrapped for "some cheaper alternative", and NASA had to spend millions finding said alternative.

Not being bound by crazy political overhead, or by a plan that puts crew below falling ice, SpaceX is already ahead of NASA in saftey.

[78stonewobble]

The Space Launch System is a big red herring in terms of the direction space travel should be going. The age of Apollo, where people launched giant expensive super-rockets in order to prove their nations' technical superiority, and, indeed, the feasibility of manned space travel, is over. It would be folly to bring this back, when we are on the verge of the next step into space - a practical and sustainable network of transportation of humans around the solar system. It is not enough to just "visit" an asteroid, or a Lagrangian point, these places are useful for real reasons, more than just propaganda. While not definite, the Falcon Heavy certainly COULD enable the long-term usage of these resources, thru inexpensive and frequent launches, while the SLS seems geared toward just "getting footprints on something".

The demand for anything other than commercial satelites consists of a few billionaires who are willing to pay somewhat big money to go to space and some millions other people who might pay something more than airplane tickets to do the same.

That demand will never pay for anything along the lines you're describing.

It would be like sitting around and waiting for ordinary powercompanies to spend the tens or hundreds of billions to build a working fusion powerplant (the expensive iter and demo plants category).

[Skyrunner27]

The Space Launch System is a big red herring in terms of the direction space travel should be going. The age of Apollo, where people launched giant expensive super-rockets in order to prove their nations' technical superiority, and, indeed, the feasibility of manned space travel, is over. It would be folly to bring this back, when we are on the verge of the next step into space - a practical and sustainable network of transportation of humans around the solar system. It is not enough to just "visit" an asteroid, or a Lagrangian point, these places are useful for real reasons, more than just propaganda. While not definite, the Falcon Heavy certainly COULD enable the long-term usage of these resources, thru inexpensive and frequent launches, while the SLS seems geared toward just "getting footprints on something".

This argument goes both ways except the FH has no payloads planned. It is just a smaller version of the SLS, but a bit cheaper in pounds to orbit. The Falcon 9 can launch Dragon. So the FH has nothing to do.

[SargeRho]

Currently there are three Falcon Heavy launches on SpaceX' launch manifest. One test flight, one US Airforce payload and one (for) Intelsat, this year, 2015 and 2017 respectively. And lots of Falcon 9 launches.

[Naten]

Falcon Heavy FTW. Actually working side boosters without R-7 Soyuz launcher-style sidetanks (like KW's... :wink) is OP, SpaceX pls nerf

[SargeRho]

There's another possible payload for the Falcon Heavy. Asteroid mining craft will likely be pretty heavy. If DSI or Planetary Resources, or some new guy, works out, the FH would be the perfect launcher.

[RuBisCO]

SLS is a great idea it just came half a decade to late, the whole fiasco with Constellation verse Direct eventually ended with Direct winning (and becoming SLS), but by then the Shuttle contracts had laps, now it makes little sense to make a directly shuttle derived rocket. If Constellation had never been started and instead we had worked on making a single directly shuttle derived booster of starting lift of 60+ tons instead of the Ares I and Ares V we would likely have an SLS rocket today. Mike Griffen wagered he could get the money for a fully redesigned rockets and he lost that bet, if he had shot for Direct/SLS to begin with his chances would have been better.

Now if SpaceX can come through past their delays and big talk and launch a Falcon 9 Heavy and provide it within the price range they claim, then SLS will be functionally dead. The initial SLS will have 33% throw capacity compared to the F9H, true, but it will cost many times more per launch then a F9H. Develop an orbital fuel depo system and we could launch missions to the moon an beyond with 2-3 Falcon 9 Heavies per mission for a price less then one SLS.

[ScallopPotato]

Have any conceptual design studies been done on making components for a mars mission launch by Falcon Heavies? I know there's studies done for ~140 ton launch vehicles and even one from Skylon flights, but nothing in the ~50-55 tons to LEO range.

[SargeRho]

I don't think any such studies were done, at least none publically available. Mars One was going to use the FH though.

Musk also has plans for a 150-200 ton class launcher, using a 10 meter core with 9 Raptor engines. That's slightly more thrust than the Saturn V's first stage with higher Isp. It would be used to build the "Mars Colonial Transporter", a spacecraft intended to carry up to 100 people per trip to Mars.

Edited March 18, 2014 by SargeRho

[RuBisCO]

Have any conceptual design studies been done on making components for a mars mission launch by Falcon Heavies? I know there's studies done for ~140 ton launch vehicles and even one from Skylon flights, but nothing in the ~50-55 tons to LEO range.

Skylon can only lift 15 tons to orbit, so if you found a mars mission using skylon then even a Falcon 9 could do it!

There are studies on fuel depos using the Atlas and Delta rockets even, I would think Falcon 9 heavy could do it too, only better.

[rhoark]

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.

J2X was not canned, it was shelved because its finished far in advance of any rocket to put it on. Its computer will be retrofitted to RS-25's later this year. Block I and Ib SLS don't use J2X because its inferior to RL10 for deep space. RL10 is lower thrust / higher ISP. It's using J2X that would make SLS a LEO rocket. You'll see it if/when SLS launches space stations or a multi-part mission assembled in LEO.

The age of Apollo, where people launched giant expensive super-rockets in order to prove their nations' technical superiority, and, indeed, the feasibility of manned space travel, is over. [...] While not definite, the Falcon Heavy certainly COULD enable the long-term usage of these resources, thru inexpensive and frequent launches, while the SLS seems geared toward just "getting footprints on something".

Don't forget Tsiolkovsky. If you want to go far, you have to build big - exponentially so. Right now there are niches for rockets that are big and rockets that are frequent, but probably not a rocket that is both. For SpaceX cost is a primary figure of merit, and it does well at that. SLS is different - its about capability. That doesn't mean cost is ignored (its cheaper per kg than Delta IV Heavy), but that the costs that scale with n constrain the design less when n is small. If the shuttle taught us anything, its that reusability is expensive, both in monetary and technical budgets.

To recap: the further the destination, the bigger the vehicle. The bigger the vehicle, the less frequent the launch. The less frequent the launch, the less reusability makes sense. The less reusability is required, the more capable the vehicle. The more capable the vehicle, the further the possible destination.

Edited March 19, 2014 by rhoark

[Red Iron Crown]

To recap: the further the destination, the bigger the vehicle. The bigger the vehicle, the less frequent the launch. The less frequent the launch, the less reusability makes sense. The less reusability is required, the more capable the vehicle. The more capable the vehicle, the further the possible destination.

I'm not sure any of these are as self-evident as you think.

While it is true that the rocket equation dictates that the more delta V required, the larger a vehicle must be to carry the same payload, there is no rule that says it has to launched in a single rocket.

There is no reason a large rocket cannot be launched as frequently as a smaller one.

Reusability is orthogonal to launch frequency. Either it reduces costs per launch, or it doesn't. Whether it's 5 or 50 launches doesn't really matter.

Less reusability results in less capability only if capability is defined in payload fraction. Cost is a more important factor, IMHO.

IMHO, SLS will only be a better option than Falcon Heavy for payloads that cannot be divided into modules small enough to be lifted by Falcon. Cost per kg is king for every other scenario.