The SLS and its usage

[GigaG]

So I'm sure we all know of the SLS (known to anti-abbreviation people as the Space Launch System), NASA's upcoming MOAR PAYLOAD rocket. Now, a lot of people think it is a bit useless, being that the only current payload is Orion, which is rather roughly planned for now. (I think the SLS can be good if it is used wisely and reliably and can launch spacecraft that can give us great scientific results.) At the risk of discussing the "Big Bad P" (politics), what do you think the future holds for SLS?

I think the future of SLS kind of hinges on the success of its first flight in 2018 (recently delayed from 2017), considering that is the only planned flight before it begins to carry humans. Luckily, we have the opportunity for ground testing and computer simulations, not to mention that the SLS (particularly the core) is based on already-flown technology. (Although I'm kind of suspicious about throwing away SSMEs, I'm guessing that the RS-25E that will be used after the current stock of SSMES rests in pieces in an ocean will be cheaper.)

If NASA can succeed in getting the public interested and the SLS can demonstrate success for its first flight, then NASA might have a good shot at getting a decent beyond-LEO program.

Of course, other missions are also proposed things to be put atop this monster of a rocket - a Europa probe would have to use a gravity assist trajectory with the Atlas V, AFAIK, so the SLS is being considered. Not to mention Mars sample return. I hope that those fly - again, the launch of these in the near future depends on the 2018 flight succeeding.

So what do you think the future holds for SLS?

[astropapi1]

We've had thousands of discussions about the SLS before. It all boils down to how much the government is willing to spend on it AFTER its completion. Some people have mockingly called it the "Senate Launch System" because the people who made NASA do it basically don't give a damn about what the rocket will do, as long as its development provides jobs for people, which in turn guarantees them a re-election.

We all know the cost of rockets depends on how many of them are needed per year. Remember a certain spacecraft called the Space Shuttle (STS)? Well, it was meant to have a turn-around time of about a week. Yeah, NASA planned to have weekly launches, but it didn't quite work that way, remember? The shuttle ended up being a huge black hole for NASA's money, but that's another discussion for another thread.

Having the capability to launch 70t payloads (and then 130t) is nothing to laugh about, and there's lots of proposals for payloads (ARM and EML-2 station come to mind), so as I said, it all depends on how much Congress is willing to give NASA.

With the marginal funding NASA is given these days, we won't hear much about the SLS for a long time. I'd be surprised if they manage one launch a year, and it's going to cost them a lot.

At least I'm happy we're going back to rockets. After 40 years we're finally picking up where we were at the end of Apollo. The ISS has been an incredible source of scientific knowledge and technical developments for the world, but it's time to go beyond LEO.

Edited December 8, 2014 by astropapi1

[K^2]

I think it's worth the time developing, even if just plugging in the hole for now. In the end, if there is going to be demand for it, we'll see private sector catching up. Falcon Heavy is supposed to be 53T already. I suspect, we'll see something that matches Block I SLS before Block II becomes reality. But existence of SLS project is a catalyst to make that happen. For private sector to build these rockets, there have to be projects that need them. And nobody is going to invest in missions that there are no rockets for. That's kind of the situation we've been in for the past few decades.

[tg626]

Nobody buys tvs if there's no channels to watch, no one builds a tv station if there's no audience.

[Frozen_Heart]

Technically it seems like a good rocket. Especially once upgraded with liquid boosters.

However what I'm very worried about is that it will be cancelled after the first launch or two. Either once its filled its role at supplying a large amount of jobs or when the next government comes around who have their own plans for space (or more importantly where the industry goes)

[Reddragon]

I think if it really was only about jobs, cancelling it is the least they would want. If the government really wants to keep it's old NASA contractors busy which also creates jobs then running the program throughout years is exactly what they need. Also the tools for continuous production are almost all ready. I'm not saying cancelling it isn't possible after but it wouldn't doesn't make too much sense.

[Lunniy Korabl]

Technically it seems like a good rocket. Especially once upgraded with liquid boosters.

I remember when the shuttle was going to be upgraded with liquid boosters. It's not hard to imagine SLS will go the same way.

[Reddragon]

I remember when the shuttle was going to be upgraded with liquid boosters. It's not hard to imagine SLS will go the same way.

SLS is meant to have liquid boosters powered by the F-1B I believe. That's for a 150-160mt to LEO version. Though I don't know what it will be used for.

Edited December 8, 2014 by Reddragon

[Nibb31]

One of the reasons there are no payloads is because nobody in the science community wants to design a mission that relies on it because it might be cancelled. The reason it might get cancelled is because there aren't any payloads for it. It's a vicious circle.

[Tommygun]

I've never had an issue with the SLS. Ideally if NASA had a bigger budget it should have the SLS, but NASA can't afford both the SLS and have money left over to do any really big projects at the same time.

With the funding they have, I think they would have been better off upgrading the Delta IV to a 100 ton payload rocket and learning to build smaller modular spacecraft.

[King Arthur]

One of the reasons there are no payloads is because nobody in the science community wants to design a mission that relies on it because it might be cancelled. The reason it might get cancelled is because there aren't any payloads for it. It's a vicious circle.

Let's be fair here, the lack of missions and payload for the SLS is a self-inflicted problem because NASA has not laid out a solid plan for the SLS. The SLS isn't a "please contract me!" launcher like the ones the ULA operate, if NASA doesn't provide missions and payload for the SLS there is very little reason for its existence besides politics.

Also, I've heard (though I've not gone about confirming this) that the market for heavy lifters is really low in demand with the Delta IV Heavy not flying as often as one would think given it is the heaviest lifter in the world at the moment. If the D4H is having problems finding customers, what chance does the SLS have?

[Kerbart]

I remember when the shuttle was going to be upgraded with liquid boosters. It's not hard to imagine SLS will go the same way.

You mean the SLS program being shut down?

[Tiberion]

NASA absolutely has plans for the SLS. It and Orion seems to be their focus for long-duration human spaceflight experimentation in the post-ISS era. I wrote about it in the Flight-test thread, but it bears repeating; NASA director Bolden was speaking before the launch attempts on both days, and it seems the plans are thus:

Use the iSS through 2024 for human flight duration missions, with the goal to learn about how best to survive during longer and longer missions away from Earth. Continue robotic missions to Mars to learn as much about Mars in this time frame, as well as send robotic missions to an asteroid with the goal of putting one into orbit around the Moon. Flight test Orion to get it man-operational before this deadline.

After the primary human spaceflight mission on ISS ends around this date, transfer the human spaceflight missions to Orion with those missions being Lunar-centric (orbital missions.) This will include manned missions to the asteroid and missions to simulate the long trip to Mars.

He also hopes they can find a partner who wants to go to the Moon. Maybe another nation or space agency, maybe a private company. They would use SLS to send a lander to the moon for them, and lend them their technical expertise and in the event of a manned mission, maybe even send another a couple of astronauts.

All of that being the "Path" to an eventual Mars missions in the 2030+ timeframe.

Of course, these are roughly detailed plans from a TV interview and that's 9-10 years away at least. That's possibly 2 additional presidents and many changes in Congress, so no one really knows what will happen. But there's certainly more to it than building the SLS and then going "Now what?"

[SciMan]

I've heard that we can get by with smaller launch vehicles if we put together stuff from multiple launches. That might work for the payload.

It won't work for the transfer stage for reasons that I'll explain below. The transfer stage basically needs to be a single launch, which demands a rocket in the SLS payload class.

And if you've got a big rocket to launch the transfer stage, you might as well use it for launching the payload too.

Manned missions demand minimizing transit time, which means a really big transfer stage compared to using a plain old Hohmann transfer orbit.

You can't assemble a transfer stage on orbit if it's using LH2/LOX, because a lot of the LH2 will boil off before you even get the whole thing put together. Adding equipment to prevent that boil off will significantly reduce the performance of the transfer stage (every kilogram of boil-off prevention equipment is a kilogram that can't be payload).

Also, you're pretty much stuck with the LH2 problem even if you use NTR's or a VASIMR, because both of those use LH2 as fuel also.

You could send up just the engines and guidance on a smaller launcher, but you still have to send up the fuel tanks on a super-heavy lift launch vehicle like (you guessed it) the SLS.

In this case, the solution really is "MORE BOOSTER". And the "MORE BOOSTER" we have chosen is the SLS.

Life imitating art, yet again.

[Scotius]

With Earth-Mars transfers taking up to several months, boil-off will happen anyway. So, either we need better tanks, able to keep cryogenic substances in (i'm looking at you, you pesky slippery hydrogene) - or we need to switch to another kind of fuel. One that doesn't escape so readily - methane maybe? And NTR and VASIMR can work on other kinds of propellant - from noble gases to our old buddy methane.

[Woopert]

Take a look at this.

http://www.boeing.com/assets/pdf/defense-space/space/sls/docs/sls_mission_booklet_jan_2014.pdf

They're just concepts at this point but they are very well done, believable, and gives an idea of what the SLS can do.

[Fuzzy Dunlop]

Take a look at this.

http://www.boeing.com/assets/pdf/defense-space/space/sls/docs/sls_mission_booklet_jan_2014.pdf

They're just concepts at this point but they are very well done, believable, and gives an idea of what the SLS can do.

That was cool, but the point remains that without extra money none of these payloads can be built. Which makes SLS itself a white elephant.

[SciMan]

Fuzzy, I doubt anyone is going to fund any big missions for SLS until it actually flies.

That being said, a lot of the missions in that PDF have alternatives available if the SLS isn't around for them, and are therefore not dependent on the existence of the SLS for their own funding. Not using the SLS just means they take longer to get where they're going.

Of course, for sending an Orion MPCV to the ISS, the SLS is way overkill.

I'm almost certain that would be taken care of with a Delta-IV in a config very close to the EFT-1 config, and a smaller SM than used on a mission beyond LEO.

Even then, the Orion MPCV will likely only visit the ISS if none of the commercial crew launch systems are up and running.

[Frozen_Heart]

Fuzzy, I doubt anyone is going to fund any big missions for SLS until it actually flies.

That's the problem. It will take 10-20 years to build a payload, and in the meantime the SLS and all related things are just sitting there, eating money while doing nothing.

To make a successful heavy lift vehicle you have to guarantee that it won't be cancelled and that deadlines will be met. That way people will be confident enough to develop payloads. NASA and its related contractors have a very poor track record when it comes to continuing with programs...

[cantab]

I don't think any of the Moon or Mars stuff will happen I'm afraid. It's been talked about for decades but I just don't see the will to fund it.

And much as happened to the Shuttle, I doubt we'll see anything beyond the Block I SLS, with the solid boosters.

The SLS could be useful for constructing ISS2, allowing fewer launches and larger interior spaces. I can see a combination of SLS and Falcon Heavy launches working very well for that. Then again, the pessimistic side of me sees there being no ISS2.

It would also be great for launching a big space telescope, thanks to the wide payload fairing, but the timing is wrong for that. JWST is already designed to go up on the Ariane 5, and it'll be a decade at least before there's another large space telescope. I guess there might be some interest in a big spy satellite.

[Kerbart]

One of the problems with all these projects is that they take forever, which is why there is ample room to cut into their budgets and cancel them. Orion has made its first flight this month. After eons of development. And the first manned flight is not expected to take place before 2020! That's six years from first unmanned flight (way into the program's development) to first manned flight. The Apollo program took eight years from announcement to reaching its objectives. Why does everything take forever now?

[Reddragon]

Why does everything take forever now?

What everybody mentioned before. During Apollo almost the entire NASA budget went into that single program, and that amount of money was enormous. In 1966 NASA got about 6 billion '1966 dollars' (!), today they get about 17 and only roughly 2.5 goes to the SLS/Orion development.

[Darnok]

One of the problems with all these projects is that they take forever

Well that is sad http://en.wikipedia.org/wiki/Budget_of_NASA

[Tommygun]

One of the problems with all these projects is that they take forever, which is why there is ample room to cut into their budgets and cancel them. Orion has made its first flight this month. After eons of development. And the first manned flight is not expected to take place before 2020! That's six years from first unmanned flight (way into the program's development) to first manned flight. The Apollo program took eight years from announcement to reaching its objectives. Why does everything take forever now?

Well as technology gets more advanced it takes longer to design and test it. The P-51 took 102 days to design and build the first prototype, the F-22 took about 11 years just to make it's first flight.

[Nibb31]

Let's be fair here, the lack of missions and payload for the SLS is a self-inflicted problem because NASA has not laid out a solid plan for the SLS. The SLS isn't a "please contract me!" launcher like the ones the ULA operate, if NASA doesn't provide missions and payload for the SLS there is very little reason for its existence besides politics.

It isn't NASA's job to lay out its own plans. NASA gets its goals from laws that emanate from the US Congress, which are either followed up or not with funding. If Congress can't get its act together (see what I did there?), it's not NASA's fault.