NASA teams evaluating ISS-built Exploration Platform roadmap

[LegendCJS]

NASA can't afford to pay for 2 ISS's, especially if one of them is hundreds of thousands of miles away. Meanwhile, ISS is slated to run at least until 2020, and most likely be extended to at least 2028. And why throw it away then? B-52's last 50 years or more. Why can't the ISS?

Unfortunately, for this analogy to work the B52s would have to have been in the air flying continuously for 50 years never landing or receiving any kind of ground based maintenance.

[Warren Platts]

NASA can't afford to pay for 2 ISS's, especially if one of them is hundreds of thousands of miles away. Meanwhile, ISS is slated to run at least until 2020, and most likely be extended to at least 2028. And why throw it away then? B-52's last 50 years or more. Why can't the ISS?

Unfortunately, for this analogy to work the B52s would have to have been in the air flying continuously for 50 years never landing or receiving any kind of ground based maintenance.

Except that they did log a lot of hours flying those strategic air patrols continuously. Also, ISS "air frame" doesn't have to contend with air, nor with the stress of landings and takeoffs.

And why throw it away then? B-52's last 50 years or more. Why can't the ISS?

A simple search would help explain why... There is no comparison between a B52 and the ISS. It cannot last 50 years, let alone more.

Well, OK, I'll take your word for it, but evidently it can last at least until 2028, or else they wouldn't be talking about extending it that far. Feel like waiting that long to launch the Gateway? No? But what about the IP's? Has anyone asked them for their opinion on extending the ISS versus launching an L2 space station instead?

My guess is that the international political pressure will favor extending ISS until at least 2028, then they'll play it by ear from there. YMMV of course.

EML-2 outpost is much smaller than the ISS, does not have scientific payloads and the idea is to be inhabited for long periods, meaning lots of robotic operations. It is not (should not!) be on the same cost category as the ISS.

Except for the fact that running supplies and crews all the way out to L2 is going to be hellaciously expensive, especially if they plan on using SLS/Orion for that....

[LegendCJS]

NASA can't afford to pay for 2 ISS's, especially if one of them is hundreds of thousands of miles away. Meanwhile, ISS is slated to run at least until 2020, and most likely be extended to at least 2028. And why throw it away then? B-52's last 50 years or more. Why can't the ISS?

Unfortunately, for this analogy to work the B52s would have to have been in the air flying continuously for 50 years never landing or receiving any kind of ground based maintenance.

Except that they did log a lot of hours flying those strategic air patrols continuously. Also, ISS "air frame" doesn't have to contend with air, nor with the stress of landings and takeoffs.

Logging lots of hours is not even comparable to never landing at all in 50 years.  And the ISS "air frame" (as you called it) has to deal with the cycle of thermal expansion and contraction every 90 mins over a 200 C range. Those stresses are major, and accounts from Mir (during power outages when it could be heard) was that it makes the entire structure sing, jump, and pop.

[JohnFornaro]

And why throw it away then? B-52's last 50 years or more. Why can't the ISS?

A simple search would help explain why... There is no comparison between a B52 and the ISS. It cannot last 50 years, let alone more.

I object.  The two artifacts can certainly be compared.  B-52's require a high level of maintenance, and the various upgrades are mostly inside the airframe.

Barring some rather large, destructive impact, why couldn't ISS, with a high level of maintenance, and various upgrades in the 'space'frame, last for fifty years?

One point of analogy would be the stress of the B-52 airframe, compared with the stress of the ISS 'space'frame.  Both artifacts are designed to accomodate their specific stresses.

What happens if a thermal joint on the ISS fails?  Has that happened yet?  Obviously, they can cordon off portions of the station.

Oh, and Hector.  Nice first post.  Ya gotta be fast to beat this crowd.  But you need to realize that the White House hasn't approved the L2 gateway yet.  It may never, but at the same time, you don't have Mr. Obama saying "No way", publicly.  Plus, you need also to consider the source.

[LegendCJS]

And why throw it away then? B-52's last 50 years or more. Why can't the ISS?

A simple search would help explain why... There is no comparison between a B52 and the ISS. It cannot last 50 years, let alone more.

I object.  The two artifacts can certainly be compared.  B-52's require a high level of maintenance, and the various upgrades are mostly inside the airframe.

Barring some rather large, destructive impact, why couldn't ISS, with a high level of maintenance, and various upgrades in the 'space'frame, last for fifty years?

One point of analogy would be the stress of the B-52 airframe, compared with the stress of the ISS 'space'frame.  Both artifacts are designed to accomodate their specific stresses.

The only way they are keeping the B52s in service that long is that they can do very detailed periodic inspections of the air frame, things like put the entire frigging plane in an X-ray machine to make sure the air frame its still in good shape.  And yes they do these inspections every so often to approve each and every plane for more years of service.  The ISS can't go back to a hanger for a health checkup to approve it for longer service.  Airplanes can.  The analogy works only if you can find a B52 that has been flying in the air for 50 YEARS with NEVER a chance to land!  There is no reasonable upkeep and maintenance comparison to be made otherwise.

And there is a whole heck of a lot more than just the "space frame" of the ISS that can not be replaced on orbit.

[Robotbeat]

Zvezda was built in the mid-1980s. It will be over forty years old once ISS is finally deorbited (around the end of the 2020s).

Voyager 1&2 are also pretty old, may be about 50 years old when they stop functioning (and no physical repair/maintenance is possible for them).

A gateway at EML1/2 will have many fewer thermal cycles per year compared to ISS. It could be made to last a very long time. Just depends on how you design it.

ISS goes through a bunch of hot/cold/hot cycles every day. It's aluminum, so this eats into its usable life. There's also atomic oxygen, orbital debris, material degradation of various sorts, friction in various moving parts, etc. It has a limited life, though ~30 years is still a pretty significant length of time.

[Lobo]

NASA can't afford to pay for 2 ISS's, especially if one of them is hundreds of thousands of miles away. Meanwhile, ISS is slated to run at least until 2020, and most likely be extended to at least 2028. And why throw it away then? B-52's last 50 years or more. Why can't the ISS?

EML-2 outpost is much smaller than the ISS, does not have scientific payloads and the idea is to be inhabited for long periods, meaning lots of robotic operations. It is not (should not!) be on the same cost category as the ISS.

Yea, I think I would agree with with.  Much of the enormous cost of hte ISS was the two Proton rocket launches and some 35 STS construction missions to assemble it.  That cost much more than the actual hardware. 
The cost of maintenance of the ISS current is what?  THe commercial crew and cargo program, what Russia is charging us for Soyuz rides, and the actual staff and hardware of NASA's ISS operatin's command and control?  How much is that?

It really depends on what an EMLP station would look like.  But really it could be assembled in 2 or 3 SLS Block 1 missions with 2 or 3 ISS module sized or larger section.  I think even Block 1 has a pretty good BLEO throw capacity of launched to a highly eliptical orbit before the EDS burn by iCPS and the sections wouldn't have to be put into particularly fast trajectories as they would be crewed.  And they could be assembled at the L-point remotely like Mir was.    Design it to operate uncrewed, so it wouldn't have to be continuously crewed.
I think the operation costs of it wouldn't be that high in comparison to the ISS.  Little more than a major satellite in fact when unmanned.  It would just need occasional Orion missions to refuel and resupply it depending on the rate of crewed missions to it.

[Warren Platts]

Well the thing about ISS is that it's modular, isn't it? So in principle it seems as if they could replace modules once they go bad, one at a time.

The other thing is this: if they deorbit ISS, there will still be pressure for a LEO space station. Right? Aren't we supposed to have a permanent crewed presence in LEO? If we deorbit ISS, we'll be making the same mistake we made with Apollo and Shuttle: build up this great infrastructural system, and then decommission the whole thing. With limited budgets, we can't afford to keep scrapping major systems. We want to keep capabilities, and then add on to them so the total capability keeps increasing through time.

I think the real problem is here is the ongoing cost of ISS. What we need to do is figure out a way to get the annual cost down to $1B/year or less.

[Robotbeat]

Can't take apart ISS piecemeal. It's got arteries and nerves all throughout. It'd be incredibly impractical, probably easier to make another one.

A new station? Maybe. If Bigelow actually ever does anything, NASA may well buy space on such a station. I just wish they would launch /something/, though the CCiCap dragging on and the switcheroo between different docking standards isn't helping.

[spectre9]

The truth is ISS will and is falling to bits.

People can bury their heads in the sand all they like.

That ammonia cooling system is a nightmare just by itself and going to cause bigger issues as it ages.

Spending money to keep it going past it's useful life should be shut down before it's even considered. The lessons we learnt by MIR, space stations rot just like any accommodation built to permanently house humans. Houses need constant cleaning because humans shed skin/hair and emit gases and odours. All those little bacteria on our bodies eventually find their way down to the bare metal and start eating it.

Do you think the astronauts have the time to strip everything back and clean the mould?

EML2 station is a bad idea.

Building production lines for cheap(light) disposable hardware is what should be done.

Deep space habs, landers and storable propulsion stages rolling out ready to visit every asteroid from here to Ceres with an easy step to Mars orbit.

C'mon NASA get you act together here.

This pipe dream of ZBO liquid hyrogen CPS is just that. Nobody is funding them so stop trying to tell people you can build missions with them. The same goes for giant SEP arrays 

[joek]

People can bury their heads in the sand all they like.

OTOH, some see those issues as challenges we need to overcome if we are to have a sustainable presence in space.  Unless of course your definition of sustainable is an indefinite chain of disposables.

[spectre9]

Nobody has proven me wrong on my opinion of "disposable all the way"

It fits with the laws of physics nicely.

The rocket equation doesn't suffer bloat easily. It's exponential, you just end up justifying Ares V. 

[joek]

Nobody has proven me wrong on my opinion of "disposable all the way"

You haven't proven yourself right either.

[sdsds]

The other thing is this: if they deorbit ISS, there will still be pressure for a LEO space station. Right?

In the United States? Not much pressure, no.

Aren't we supposed to have a permanent crewed presence in LEO?

Who's "we"?
http://www.russianspaceweb.com/opsek.html

[Robotbeat]

Nobody has proven me wrong on my opinion of "disposable all the way"

It fits with the laws of physics nicely.

The rocket equation doesn't suffer bloat easily. It's exponential, you just end up justifying Ares V. 

LOL.

Expendable got us Saturn V as well, not much of an improvement.

Without reuse, we can only hope to leave a few relics on distant worlds but perish as a species on Earth.

I am all in favor with doing expendables early on, but it MUST be done with an eye to more reuse in the future.

[spectre9]

Reuse is a natural evolution of hardware as actual usage proves out lifetimes and reliability.

I wouldn't have a hard drive that doesn't kick the bucket for 5 years+ right now if we didn't go through tech developments like the IBM Deathstar.

It's difficult for the ISS to get things working reliably and they have a huge budget if you count it from the start of the program 20+ years ago.

Reuse adds mass, adds cost, adds complexity, adds development time and makes qualification processes much more intensive.

Making reusable versions of hardware that doesn't exist is just warped thinking.

[Robotbeat]

No, your mantra is wrong. Reuse can lower qualification and testing costs, since you can test the same thing several times. This aspect is useful even in expendable systems.

And a craft that can operate for three years in deep space is hardly different than one that can operate for a couple decades. Look at Opportunity... Designed for 90 days, still going almost 9 YEARS later. Once you get it designed to handle the mission for a minimum length of time, many times reuse happens nearly automatically. You are overstating the cost of reuse while understating its transformative potential.

[A_M_Swallow]

Reuse is a natural evolution of hardware as actual usage proves out lifetimes and reliability.

I wouldn't have a hard drive that doesn't kick the bucket for 5 years+ right now if we didn't go through tech developments like the IBM Deathstar.

It's difficult for the ISS to get things working reliably and they have a huge budget if you count it from the start of the program 20+ years ago.

Reuse adds mass, adds cost, adds complexity, adds development time and makes qualification processes much more intensive.

Making reusable versions of hardware that doesn't exist is just warped thinking.

You get most of reusability if the engine can be restarted multiple times and the tanks refilled whilst in flight.

[spectre9]

No, your mantra is wrong. Reuse can lower qualification and testing costs, since you can test the same thing several times. This aspect is useful even in expendable systems.

And a craft that can operate for three years in deep space is hardly different than one that can operate for a couple decades. Look at Opportunity... Designed for 90 days, still going almost 9 YEARS later. Once you get it designed to handle the mission for a minimum length of time, many times reuse happens nearly automatically. You are overstating the cost of reuse while understating its transformative potential.

Unmanned vs manned.

The size and expense of manned spaceflight hardware is prohibitive.

Life support systems are not simple like the few heating circuits that Mars rovers need to survive.

Oxygen generation, carbon scrubbing and zero G toilets are extremely expensive and unfortunately have not shown high reliability even after all the billions that has been spent on ISS.

These things will only get better if and when they're more widely used not just one machine out on ISS. I'm guessing SpaceX has plans to standardise and mass produce parts of their life support systems.

A rocket engine is only useful up to a certain point. Non-coking cryogenic engines that can be reused are still very expensive immature technology.

Almost everything in spaceflight is a custom one off. Making such custom parts for long life from the start is unrealistic. First get standardised mass produced HAB modules with standard mass produced life support and then start advocating 30 years of deep space usage, there's no reason at all it would be better or cheaper to make that 30 year hab from the beginning. Make a 30 day HAB, then a 500 day hab, then a 900 day hab then start looking at habs that can be reused.

Missions like opportunity are given a length of time to get things done that's not the actual life of the rover. Obviously there's quite a bit of margin built in there. Curiosity might last 25 years but as I've already said life support systems are quite a bit more intensive than planetary rovers. They don't have all that nasty bio-material coating them on a daily basis for starters.

[Warren Platts]

Non-coking cryogenic engines that can be reused are still very expensive immature technology.

Incorrect. DC-X reused LH2/LO2 RL-10's multiple times. OTS RL-10's are rated for 25 restarts, but the fact is that no one knows how many times an RL-10 will restart before it breaks down because no one has taken an RL-10 and tried it out to see.