What do you think of the SLS?

[cantab]

It's not important that the risk be real, or even particularly reasonable to expect. What matters is how the potential customers percieve it. The comparison isn't refurbished Falcon vs Space Shuttle, it's refurb Falcon vs brand-new Falcon (if SpaceX will offer it and I expect they will if it's demanded), refurb Falcon vs Ariane, Atlas, Delta, Proton, etc.

I admit anyone choosing the Falcon is already prepared to accept some uncertainty on the risk front, compared to other launchers that have made many more launches.

[Skyrunner27]

Is there any data relating to how big the flight manifest for Apollo looked prior to the first launch of Saturn-V. The Apollo 13 movie makes it sound as if they didn't know if Apollo 14 was going to happen. IIRC it was one of two heavy lift vehicles to actually be launched and the only one to be launched with a crew Energia being the other one. So if we look at the Saturn V development we can accurately judge the current development of the SLS. I do wish more payloads and mission plans were actually being developed but there is only so much money.

[sp1989]

Lets just be clear the SLS is basically a modern twist on the Saturn V. It is a huge heavy lift rocket with the potential to rocket astronauts and payloads into deep space. If you compare it to the Saturn V the only reason it is shorter is because it doesn't have a LEM. NASA has gone back to what it knows which is designing HUGE rockets. The issue right now is funding. If NASA were to be properly funded or even get 40% of what they got during the space race to get us to the moon we could be back on the moon within the next two years and launching a mars mission before the end of the decade. Now I love the SLS I think its a great way to get us back launching rockets I just want it sooner rather than later.

[deadshot462]

I agree that NASA needs more funding to get missions running, but they also need to change the way they acquire the hardware. Right now, major projects like the SLS are awarded based on Congressional direction. This needs to change where every project is open for proposals and awards are given based on the most qualified product/proposal. This of course would mess up the established companies working on SLS, but that's the fault of those companies for being dependent on a very narrow type of technology.

[KASASpace]

Space Launch System Block II upper stage will be 8.4 meters wide. The first stage of the Saturn V was 10.1 meters wide.

The SLS is not a waste of time, not at all. It is another step in the right directions for Mars, which if we don't get there, we are failing. Falcon Heavy doesn't have the Oomph, and the Falcon XX and such aren't even being developed, they're just concepts. They actually ARE making the SLS, it's going to happen.

Um, I said that the SLS will have a "stage".

I did not say which one, apparently.

The Core Stage is much longer than the S-IC, and while it may be not as wide, it more than makes up for it in length. Plus it has those SRBs, and I'm guessing it also has those O-Rings on them. Now, imagine Challenger, but with a bigger EXT, and an LH2 Upper Stage.

Yeah, not a good idea.

[Duxwing]

Um, I said that the SLS will have a "stage".

I did not say which one, apparently.

The Core Stage is much longer than the S-IC, and while it may be not as wide, it more than makes up for it in length. Plus it has those SRBs, and I'm guessing it also has those O-Rings on them. Now, imagine Challenger, but with a bigger EXT, and an LH2 Upper Stage.

Yeah, not a good idea.

If you're so worried about an explosion that you would rather the SLS not fly, then you should be willing to back away from the rocket.

-Duxwing

[KASASpace]

I thought the same thing, but with a proper and traditional launch escape system, they SHOULD be able to abort rather quickly if they solid rocket boosters fail (which isn't likely, they've learned a lot about O-rings since then; another safety "feature" is that the Orion MPCV is not piggybacked, so there won't be any foam coming off and knocking away the heat shield... and the heatshield is already not exposed like the Space Shuttle's wings.

Wow, double quote.......

Okay, let me point this out right now: Even the Apollo LES wasn't guaranteed to save the crew, in fact, it was doubtful if it at all would. Small rockets work well with LES', but not HUGE ones.

If the Orion capsule is more massive than the Apollo (which it IS) than more thrust is needed for the solids on the LES, and thus more weight. Plus, having a small nuclear bomb blast underneath you isn't the safest thing on the block.

[KASASpace]

If you're so worried about an explosion that you would rather the SLS not fly, then you should be willing to back away from the rocket.

-Duxwing

I'd rather ride a man-rated Falcon 9 or Atlas-V into Orbit, rendezvous with a craft such as NAUTILIUS-X built using EELVs and some Falcon Heavy launches (to get the heavy stuff).

It's safer, and it doesn't require a massive LV, just a few mediums and maybe two to three heavy launches.

Now, an LV like this would only be useful if you wanted a large fabrication facility. But even then, you could just launch an inflatable version, and launch the equipment afterwards.

Oh, and:

Inflatable Spacecraft for the WIN! I personally think it's what we should be focusing on, build a sort of Had module for Deep-Space, and not worrying about LVs. (for NASA, that is)

And also, why does NASA absolutely have to contract out?

[Duxwing]

I'd rather ride a man-rated Falcon 9 or Atlas-V into Orbit, rendezvous with a craft such as NAUTILIUS-X built using EELVs and some Falcon Heavy launches (to get the heavy stuff).

It's safer, and it doesn't require a massive LV, just a few mediums and maybe two to three heavy launches.

Why? If the sand hits the fan, then the LES will pull you off the SLS, which will be Man-Rated, just as well as off the Falcon.

Now, an LV like this would only be useful if you wanted a large fabrication facility. But even then, you could just launch an inflatable version, and launch the equipment afterwards.

Oh, and:

Inflatable Spacecraft for the WIN! I personally think it's what we should be focusing on, build a sort of Had module for Deep-Space, and not worrying about LVs. (for NASA, that is)

We are building inflatables for Mars and the Moon.

And also, why does NASA absolutely have to contract out?

It is cheaper and spurs commercial development.

-Duxwing

[Armchair Rocket Scientist]

Um, I said that the SLS will have a "stage".

I did not say which one, apparently.

The Core Stage is much longer than the S-IC, and while it may be not as wide, it more than makes up for it in length. Plus it has those SRBs, and I'm guessing it also has those O-Rings on them. Now, imagine Challenger, but with a bigger EXT, and an LH2 Upper Stage.

Yeah, not a good idea.

"Those O-rings" haven't been flown since Challenger. After the accident, the SRBs were redesigned to prevent that type of failure happening again.

In addition, the orbiter was destroyed because as the rest of the stack disintegrated it was forced into a very high angle of attack and was torn apart by aerodynamic loads. In addition, the crew cabin remained intact, and the crew alive, until impact with the water. This suggests that even if the LES failed to fire, a capsule-type vehicle would have survived the initial breakup, and could have deployed its parachutes once it was clear of the fireball.

A greater risk would be a violent explosion of one of the SRBs, enveloping the vehicle in a cloud of burning chunks of propellant. Pieces of solid propellant can keep burning for much longer than aerosolized liquid propellant, and could puncture or melt a capsule's parachutes. However, while this can occur with graphite-epoxy casing like the Delta II, all the instances I know of where it happened on a steel-case SRB (what the shuttle/SLS use) were because Range Safety intentionally blew the SRB up.

[KASASpace]

Why? If the sand hits the fan, then the LES will pull you off the SLS, which will be Man-Rated, just as well as off the Falcon.

Smaller rocket, smaller explosion. After all, riding a rocket is just riding controlled explosions. Less controlled explosions needed, or less powerful ones, than the more safe it is.

We are building inflatables for Mars and the Moon.

To go there, not living on there.

It is cheaper and spurs commercial development.

-Duxwing

No, it isn't. The corporations want money, so they increase the actual price required. If it did spur development, than why hasn't Lockheed built their own LV for their own uses, or for more commercial uses? Sure, big corporations can launch satellites, but what about the medium sized ones?

[KASASpace]

"Those O-rings" haven't been flown since Challenger. After the accident, the SRBs were redesigned to prevent that type of failure happening again.

In addition, the orbiter was destroyed because as the rest of the stack disintegrated it was forced into a very high angle of attack and was torn apart by aerodynamic loads. In addition, the crew cabin remained intact, and the crew alive, until impact with the water. This suggests that even if the LES failed to fire, a capsule-type vehicle would have survived the initial breakup, and could have deployed its parachutes once it was clear of the fireball.

A greater risk would be a violent explosion of one of the SRBs, enveloping the vehicle in a cloud of burning chunks of propellant. Pieces of solid propellant can keep burning for much longer than aerosolized liquid propellant, and could puncture or melt a capsule's parachutes. However, while this can occur with graphite-epoxy casing like the Delta II, all the instances I know of where it happened on a steel-case SRB (what the shuttle/SLS use) were because Range Safety intentionally blew the SRB up.

I know what happened to Challenger. But even so, something could, and, as one KSP'er has as a sig, "Do not take Murphy's Law in vain". That in mind, everything will go wrong. Everything. Eventually, at least. Which means:

Once at least one, that's right, ONE multi-billion dollar LV goes up in flame with crew aboard, or even no crew, NASA dies. More than that, the USA would have no more space interest.

Challenger was an Orbiter. It didn't have tons of LH2 sitting right beneath it with only a few tiny solids to pull it away. Now, think of this:

If there are TONS of LH2 beneath you, with LOX as well (which can burn on itself!) than what would happen if it all goes up in flame?

Let me ask you this as well:

Have you seen

Skip to around 19:03. That's a big explosion.

Now, imagine that, except at least 10 times bigger. I would not want to ride a single one of those SLS'.

[sp1989]

I honestly don't know what the arguments are right now? Is it that you object to the SLS because of the SRB's and that we should wait to develop a more advanced type of propulsion to get us into space? Because I as well find Solid Rockets to be inherently unsafe. However in terms of generating massive amounts of thrust efficiently currently there are few alternatives. Without proper funding we just can't wait for alternative forms of propulsion to catch up with the necessity for manned space flight. Currently SpaceX is on amazing pace in bringing us back into low earth orbit and docking with the ISS without relying on the Soyuz. But if we want to get back to exploring our solar system and beyond we need to get back there sooner rather than later. Would have Apollo been better off if they had waited another 5 to 10 years for the technology to be better? Of course! They went to the Moon at a time where they had no realistic business going to the Moon. They shouldn't have gone it was dangerous, impossible, illogical, and impractical. But they did and that is what NASA is about. We are destined to explore and question. It is in our DNA to want to know what is going on the in universe. So as much as technology has advanced from Apollo to today are we still really fully prepared to truly reach for the stars and begin deep space missions? No but we should do it "not because it is easy but because it is hard" not because we don't have the technology, but do it however we can, because it needs to get done and because we should do it, and in 50 years people will be talking about how we had no business going to Mars and beyond because the technology was primitive but we did it and it was amazing.

The other issue is we can't dwell on failure. NASA especially is not going to launch a vehicle into space that is beyond the acceptable risk for manned space flight. NASA has an impeccable track record when it comes to the manned program. Out of the hundreds of manned launches there has only been one catastrophic failure that resulted in the loss of life at launch, and by most accounts the reasons for the Challenger disaster go beyond damaged or defective o'rings. The true failure of Challenger was entirely political. Time constraints, budget cuts, delays, and the launch schedule for military projects being extremely behind resulted in ignoring a problem that dozens of NASA engineers and scientists expressed concerns about. Any concerns directed towards the SLS by us lay people have been addressed, are being addressed, solved and readdressed by all of the amazing and brilliant people at NASA. NASA is not going to put a single soul inside of that Orion capsule until it has been tested hundreds of times and then retested. So we can talk about mitigating risk via different forms of propulsion, but whatever NASA chooses I think we can all rest assured it is the most realistic and safest choice for a launch system.

Edited April 27, 2014 by sp1989

[ScallopPotato]

The concerns about the solid boosters really can be limited by choosing one of the liquid booster options for the advanced boosters. The dual F-1B boosters are estimated to outmatch the performance of the advanced solids in terms of tons to LEO.

I'm sure NASA will be very vigilant about safety for EM-1 and EM-2, but the slip-ups are more likely to occur later. Like, at first, things are dangerous, then they become routine and people become complacent.

[Dodgey]

It's not important that the risk be real, or even particularly reasonable to expect. What matters is how the potential customers percieve it. The comparison isn't refurbished Falcon vs Space Shuttle, it's refurb Falcon vs brand-new Falcon (if SpaceX will offer it and I expect they will if it's demanded), refurb Falcon vs Ariane, Atlas, Delta, Proton, etc.

I admit anyone choosing the Falcon is already prepared to accept some uncertainty on the risk front, compared to other launchers that have made many more launches.

You've lost me, what is your argument?

[maccollo]

Challenger was an Orbiter. It didn't have tons of LH2 sitting right beneath it with only a few tiny solids to pull it away. Now, think of this:

If there are TONS of LH2 beneath you, with LOX as well (which can burn on itself!) than what would happen if it all goes up in flame?

It would certainly be more safe than the Shuttle was. That thing had the entire underside lined with explosives.

Being radially attached, the orbiter had maximum surface area exposed to a potential explosion. If either the external tank or the solids went you'd have absolutely no chance of survival.

The SLS seems quite safe by comparison.

The abort system, and the parachutes are shielded from a potential explosion, whereas the wings on the orbiter were not.

Orion is exposed to the smallest possible surface area of the fuel tank.

Also the side of a capsule shaped pressure vessel is the most likely point of rupture.

This is why pressure vessels (and hotdogs) usually tear along on the side of the cylinder, and the side is where the orbiter was, and Orion is not.

Edited April 27, 2014 by maccollo
typos

[Jouni]

The main problem with the SLS is that it's way too cheap. Make it 10x more expensive, and the people at NASA will start finding all kinds of interesting payloads for it.

Maybe something like that will happen, if China decides that it might want to do something ambitious in space.

[cantab]

You've lost me, what is your argument?

That this is a valid concern:

That schedule is way too optimistic. SpaceX has yet to recover a booster. After that, it will be a while before they get to a stage where they are confident enough to reuse it. They will need to tear down the first couple of recovered stages, x-ray the parts, check everything, and rebuild and test them. They will also need to find a customer who is actually willing to risk their payload on a reused stage. NASA won't, and I don't think DoD will either. That kind of limits the point of reusability.

[metaphor]

Smaller rocket, smaller explosion. After all, riding a rocket is just riding controlled explosions. Less controlled explosions needed, or less powerful ones, than the more safe it is.

The Falcon Heavy has more rocket fuel in it than the SLS. Kerosene and LOX or any other combination of rocket fuels can explode just as well as LH2 and LOX.

The abort system of the Orion can sense anomalies and initiate an abort in 10 miliseconds. It can accelerate away from an exploding vehicle at 18 g's. It can basically outrun any explosion.

The Orion/SLS is probably going to be one of the safest crewed spacecraft ever flown. It's much safer than the Shuttle, which had 2 SRBs and a giant LH2/LOX tank right next to it with zero abort capability on pad or ascent.

[KASASpace]

It would certainly be more safe than the Shuttle was. That thing had the entire underside lined with explosives.

Being radially attached, the orbiter had maximum surface area exposed to a potential explosion. If either the external tank or the solids went you'd have absolutely no chance of survival.

The SLS seems quite safe by comparison.

The abort system, and the parachutes are shielded from a potential explosion, whereas the wings on the orbiter were not.

Orion is exposed to the smallest possible surface area of the fuel tank.

Also the side of a capsule shaped pressure vessel is the most likely point of rupture.

This is why pressure vessels (and hotdogs) usually tear along on the side of the cylinder, and the side is where the orbiter was, and Orion is not.

http://www.learneasy.info/MDME/MEMmods/MEM30006A/Materials_General_files/pressure_vessels.JPG

http://www.scubaengineer.com/pictures/scubatanks/ali_explo_small.jpg

No, it would not be safer than the shuttle was. If you have a large rocket, with tons of fuel, literally tons, and the explosion is almost instant, 10 milliseconds will not be a good safety margin. Plus, what if the computer can't detect anything wrong? Yeah, I know it's fairly advanced and should do it, but from what I hear the software development is getting crappy treatment.

And, who in their right mind would call SLS safe? The S-V wasn't even close to safe, but it was flown. Sure it had few problems, but that was because they actually had the money to do it right. Here, they have a shoestring budget and are trying to develop a huge rocket.

Heck, every single Apollo lunar flight had an almost fatal problem. Apollo 11 almost got stranded on the moon. It was pure luck they happened to have a pen on the craft.

Apollo 13 had a LOX tank rupture, but they pulled through, but BARELY.

So, even if you manage to get Orion to LEO, it could still have safety issues. Not to mention waning political support will probably shut it down.

[SargeRho]

Yes, it would be much, much safer than the Shuttle. The LES of Orion fires BEFORE the rocket actually explodes. As soon as the tanks breach or anything of the sort, the LES fires. Orion will be moving away from the rocket before it fails.

[KASASpace]

The Falcon Heavy has more rocket fuel in it than the SLS. Kerosene and LOX or any other combination of rocket fuels can explode just as well as LH2 and LOX.

The abort system of the Orion can sense anomalies and initiate an abort in 10 miliseconds. It can accelerate away from an exploding vehicle at 18 g's. It can basically outrun any explosion.

The Orion/SLS is probably going to be one of the safest crewed spacecraft ever flown. It's much safer than the Shuttle, which had 2 SRBs and a giant LH2/LOX tank right next to it with zero abort capability on pad or ascent.

Yes, a PAD abort test. It is more probable that tons of debris will go flying towards the capsule faster than the capsule can accelerate away.

The shuttle had two total launch failures.

How is it going to be the safest? That's completely ridiculous. A HUGE explosion, as big if not bigger than a tactical nuclear warhead, is somehow safe?

Yeah, PERFECTLY LOGICAL.

[KASASpace]

Yes, it would be much, much safer than the Shuttle. The LES of Orion fires BEFORE the rocket actually explodes. As soon as the tanks breach or anything of the sort, the LES fires. Orion will be moving away from the rocket before it fails.

Before it fails? How much acceleration will each piece of debris experience? Much more than Orion's LES can offer the capsule. Plus, you have all the fuel burning and the LOX burning itself and everything hitting the fan. All at once. A huge fireball. Bigger than even the smaller rockets (IE Delta) which have large explosions.

[sp1989]

No, it would not be safer than the shuttle was. If you have a large rocket, with tons of fuel, literally tons, and the explosion is almost instant, 10 milliseconds will not be a good safety margin. Plus, what if the computer can't detect anything wrong? Yeah, I know it's fairly advanced and should do it, but from what I hear the software development is getting crappy treatment.

And, who in their right mind would call SLS safe? The S-V wasn't even close to safe, but it was flown. Sure it had few problems, but that was because they actually had the money to do it right. Here, they have a shoestring budget and are trying to develop a huge rocket.

Heck, every single Apollo lunar flight had an almost fatal problem. Apollo 11 almost got stranded on the moon. It was pure luck they happened to have a pen on the craft.

Apollo 13 had a LOX tank rupture, but they pulled through, but BARELY.

So, even if you manage to get Orion to LEO, it could still have safety issues. Not to mention waning political support will probably shut it down.

I don't know how you can say that SLS isn't safer than the shuttle. The space shuttles most fatal flaw was being downgrade of everything. As was the failure of columbia and challenger, along with the fact that there was no way to do an emergency abort with the space shuttle. Also to one of your other points about the survivability of an enormous explosion, I think that you can agree that the oribter could not have gotten any closer to the source of the explosion during challenger and their is good evidence that the crew survived the explosion. The emergency oxygen was masks were used and the recovered data said that the from the pilot seat Scobee was trying to fly that thing all the way to the ground. So if the shuttle had some sort of emergency escape system they might have lived. The fact that the Challenger crew survived means that if there is an explosion I would much rather be at the top and in a capsule than in a orbiter strapped to the side. It worked for a very long time but it was just a horrible design in terms of safety. With Columbia, because the vehicle was downgrade it was extremely vulnerable to falling debris and it was only a matter of time before something struck the heat shield. Believe it or not most launches the ship returned with tiles missing. The very first launch the ship returned with nearly 100 tiles missing. These issues are unique to the Space Shuttle and that vehicle served NASA very well for over 30 years with only two catastrophic failures both due in large part to the location of the orbiter on the rocket and that there was no ability to abort or detach from the ship. Wasn't there a plan to make it so that the crew cabin could detach from the orbiter in case of a catastrophic failure to the orbiter? It would have saved both crews. The SLS will be the safest ship NASA has ever made to fly because of the political reasons you mentioned. People might be able to accept the loss of a spacecraft but the loss of a crew would be a death blow to NASA. They are not going to launch a ship that kills the program!

[Duxwing]

Smaller rocket, smaller explosion. After all, riding a rocket is just riding controlled explosions. Less controlled explosions needed, or less powerful ones, than the more safe it is.

The bigger the fuel tank, the bigger the LES. This danger is trivial.

To go there, not living on there.

Would you please elaborate? The inflatables are for space travel.

No, it isn't. The corporations want money, so they increase the actual price required.

Corporations can arbitrarily raise prices only in a monopoly; whereas in such competitive markets as NASA launch vehicles, only the cheapest satisfactory seller gets any money and all sellers therefore seek to lower their prices just enough to win. In case you were wondering, the same principle applies elsewhere; e.g.,

Alice wants some apples and has some money.

Bob, Charlotte, and Dan have some apples and want some money.

Bob offers Alice a price of 1 dollar per apple.

Charlotte offers Alice a price of 2 dollars per apple.

Dan offers Alice a price of 3 dollars per apple.

Alice rationally chooses to buy her apples from Bob, whose apples are cheapest.

Replace Alice with NASA, Bob, Charlotte, and Dan with some LV companies, and you get the aforementioned LV market. Its companies wage something called a price war, which in the analogous apple market would be:

Charlotte and Dan get nothing and therefore reconsider their pricing.

In real time, Charlotte reprices her apples at 99 cents.

Alice rationally switches from Bob to Charlotte.

Dan, noticing Charlotte's price change, reprices his apples at 98 cents

Bob, noticing Dan's price change, reprices his apples at 97 cents

...

Charlotte cannot sell her apples for less than 90 cents and therefore bankrupts.

...

Dan cannot sell his apples for less than 80 cents and therefore bankrupts.

...

Finally, Bob cannot sell his apples for less than 70 cents, and the apple market reaches equilibrium because Bob is its only seller.

Obviously, Bob could raise his price because he lacks competition, causing Alice to want cheaper apples; fortunately for Alice, if Bob raises it enough, then whatever barrier to entering the apple market will not stop someone else from seizing the opportunity to sell Alice cheaper apples, and the price war will resume.

If it did spur development, than why hasn't Lockheed built their own LV for their own uses, or for more commercial uses? Sure, big corporations can launch satellites, but what about the medium sized ones?