Poll: Do We Need A New International Space Station?

[oldAtlas_Eguy]

A major focus of constructing ISS was the gaining of experience in long term space habitation. ISS has barely been completed; calling for it to be retired is akin to buying a computer on Monday and then on Tuesday throwing it away because it is no longer state of the art. Experience must be gained in living and working in space and this includes meeting the challenges of maintaining our environment. In these matters we would do best to follow the lead of our Russian partners who kept the short term Mir station operational far past its original planned lifespan.

What concerns me most, however, is that ISS was designed and constructed with a limited lifespan in mind. The expenditure of money, resources, and yes, life that was invested should have resulted in a station that could be maintained as a whole for a far more indeterminate lifespan; Disguarding modules as they age and become unservicable and replacing them with new; Adding new segments to the whole as new requirements and uses are identified; thus creating a station that starts from an established baseline and grows as demands require it. This is what I understood my ISS tax dollars were buying me.

Unfortunately, no participating nation is any longer spending money developing or improving module designs with the exception of changing out the docking systems after Shuttle ends so that all the docking ports would be the same and support the new standard. So when a module fails and it can’t be repaired then that functionality if it is not being performed by another module the capability will be lost. This could completely halt some experiments/projects.

 

[AnotherWorld]

I miss this option:

No, we do not need a new ISS because we need to invest all space funds into an allready invented technology called a VASIMR based propulsion system powered by a hipowering nuclear reactor so we can send spacecraft to mars with a 30day travel route and even begin to think about traveling beyond and start a REAL space age instead of making silly probes and rovers.

And srry yes they are silly when the technology is allready known to make propulsion engines like VASIMR.

 

[Skyskimmer]

I miss this option:

No, we do not need a new ISS because we need to invest all space funds into an allready invented technology called a VASIMR based propulsion system powered by a hipowering nuclear reactor so we can send spacecraft to mars with a 30day travel route and even begin to think about traveling beyond and start a REAL space age instead of making silly probes and rovers.

And srry yes they are silly when the technology is allready known to make propulsion engines like VASIMR.

X2 but that would make sense be higly logical, and it's the only thing remaining for nasa to develope, as it's the only thing commerical isn't good at.

 

[oldAtlas_Eguy]

I miss this option:

No, we do not need a new ISS because we need to invest all space funds into an allready invented technology called a VASIMR based propulsion system powered by a hipowering nuclear reactor so we can send spacecraft to mars with a 30day travel route and even begin to think about traveling beyond and start a REAL space age instead of making silly probes and rovers.

And srry yes they are silly when the technology is allready known to make propulsion engines like VASIMR.

VASIMR is just a high ISP engine that requires a large and heavy electrical power source. For it to be advantageous the power source has to be able to produce 1kw for each 1kg weight. Use of a transmitted power to a rectenna on the spacecraft meets the 1kw per kg requirement in current known technology. So far no nuclear proposals can. New research is needed to achieve these very light weight reactors. Not just for the containment vessel but for the generators, coolant and radiators, all of which current technology would bust the weight budget by a factor of 20 to 100. To lower the weight by 2 orders of magnitude is just not feasible in the next 20 to 50 years.

 

[SJQ]

How much Isp is really necessary for ISS orbit maintenance? While Dawn is orders of magnitude less massive than the ISS, it (and a couple of other probes) have demonstrated the virtues of "acceleration with patience". It's not like the ISS is going anywhere fast, so to speak. After all, the periodic boosts given to the ISS now do not have the split-second windows of opportunity constraining launches, and we do not have to add umpteen meters per second delta-v all at once, right now.

So park an ion thruster at the back end of the ISS, and let it run. The same boost fuel mass in xenon, thrusting continuously, would at least extend the interval between any necessary chemical-propellant boosts, and with less shaking of the ISS. Since the acceleration is so low, directional control doesn't require split-second timing and consequent lateral thrusts, either.

The xenon is merely medium for momentum exchange - the real thrust is ultimately solar power, and while the net efficiency is not great, the solar panels are already there. A couple of kilowatts applied over time should be very effective. If continuously ion-thrusting the ISS could eliminate only every third or fourth chemical-propellant boost, there is a significant cost saving to be had - one less launch dedicated to fuel, or more mission-specific payload per launch. And we build operating experience with ion engines in vacuum, where we can get at them to analyze what went wrong.

 

[oldAtlas_Eguy]

VASIMR on the ISS would be the same practice as currently modern GEO comm satellites that use ION engines for station keeping. While traditional ION engines use xenon the VASIMR uses the cheaper and more abundant argon. Also since ISS needs the power for other things when VASMIR would not be in use the weight for the power source is not a detractor for using VASIMR for ISS station keeping. You are right in that VASIMR would reduce the cargo weight needed to fuel chemical station keeping engines, either reducing the frequency of cargo flights or using the extra cargo capability for other things.

 

[jonto2012]

The ISS is absolutely fantastic, but it sure became a money drain. I can't imagine people wanting to throw it away. If it were to be scaled down farther in the future, ISS mods could be used on planetary missions. It was great to hear this very thing mentioned during the NASA direction discussions by Flexble Path proposal leaders. A great way to give extra room on such voyages without direct expense.

 

[stevekk]

there are two problems with using vasimr engines on the ISS , the engines produce very little thrust so any needed adjustments in orbit will take a long time to complete and most experiments in the ISS don't want a long thrust period or the vibrations included . Plus the fact that they require a lot of power 200kw you say ? And one more thing it isn't as if a vasimr engine doesn't use up anything , it uses argon gas .

I understand why the ISS is in the orbit it's in but I do think a more permanent booster would be in order rather than getting pushes from the soyuz .

The reboost operations are really the least of our problems. With the shuttle retiring, and no other heavy lifter available for several years, the number of small resupply ships to headed to the ISS is huge. There is a new ship there every month, if not more. All of these resupply ships have the capability to boost the ISS into a higher orbit, although only the Progress is probably capable of refueling the thrusters on the Russian segment.

The only real reason for a significantly higher orbit is to get above as much space junk as possible. But if we go too high, then it reduces even further the amount of cargo each supply ship can carry. There are already concerns about resupply after the shuttle retires.

My biggest worry with the ISS right now is the FGB and that aging guidance computer. Spares for that thing are probably harder to find that the Shuttle right now.

 

[SJQ]

"Spares for that thing are probably harder to find that the Shuttle right now." -- stevekk

Stevekk hit a nail on the head. In my own experience with military/government contracts, spares are the first thing sacrificed to make the price tag palatable. If our marketing weenies don't slash that line item out of the proposal, the customer's bean-counters will. It doesn't matter how often you show either group the true costs of not having sequestered spares inventory: the almighty bottom line now rules.....

Neither the marketing weenies nor the bean-counters are responsible for the subsequent effort to re-engineer/re-qualify any remaining stock, or re-invent the wheel because the original widget is just not available anymore (assuming there's still a few of us grey-haired old farts around who remember how it worked).

This lack of up-front responsibility is wrong: if it were the "clerks" asses on the line for the true life-cycle costs, the situation would be different, but the clerks don't have to worry - they "save" (pick a number) 10% on the all-up price, and they get promoted out of the way because of it. When a spare is needed, it will be some other group of clerks bitching at the engineering/production crowd about the exhorbitant cost to replace an x-year-old widget.

Ever notice how rarely it is that the end-users of your widget are the ones who get to make the detail specification decisions?

 

[stevekk]

"Spares for that thing are probably harder to find that the Shuttle right now." -- stevekk

Stevekk hit a nail on the head. In my own experience with military/government contracts, spares are the first thing sacrificed to make the price tag palatable. If our marketing weenies don't slash that line item out of the proposal, the customer's bean-counters will. It doesn't matter how often you show either group the true costs of not having sequestered spares inventory: the almighty bottom line now rules.....

Neither the marketing weenies nor the bean-counters are responsible for the subsequent effort to re-engineer/re-qualify any remaining stock, or re-invent the wheel because the original widget is just not available anymore (assuming there's still a few of us grey-haired old farts around who remember how it worked).

This lack of up-front responsibility is wrong: if it were the "clerks" asses on the line for the true life-cycle costs, the situation would be different, but the clerks don't have to worry - they "save" (pick a number) 10% on the all-up price, and they get promoted out of the way because of it. When a spare is needed, it will be some other group of clerks bitching at the engineering/production crowd about the exhorbitant cost to replace an x-year-old widget.

Ever notice how rarely it is that the end-users of your widget are the ones who get to make the detail specification decisions?

There were spare parts available for the guidance computer, but I'm pretty sure we have used the spares already. All they can do is try to repair any failed boards to make them the new spares. Unfortunately, since it was designed with 15-20 year old Russian electronics technology, you might not be able to get the components to repair a failed board.

From the pictures, it looks like most of the stuff on the US side of the ISS is run by laptop computers. At least it's possible to swap these things out with newer models when they are available.

 

[SJQ]

All they can do is try to repair any failed boards to make them the new spares. Unfortunately, since it was designed with 15-20 year old Russian electronics technology, you might not be able to get the components to repair a failed board.

My point, exactly. How much would it have cost to run a dozen(?) extra sets while the "production line" (these widgets are not necessarily in mass production) was in full swing. Realizing that a program of this magnitude is very likely to get extended repeatedly? I doubt that even the US government is insane enough to build the ISS and then de-orbit it as soon as it's finished. Although, judging by some of the noises out of Washington, I could very well be wrong on that.

I realize that the necessary additional labour is the primary cost driver for spares; the material cost, even for space-qualified widgets, is comparatively small; either way, a larger set of spares wouldn't have come "for free". But how much does it cost to re-engineer a solution with current technology? With inexperienced people? Slap down/check out the "feature creep"? And if you manage to break something else while integrating the new stuff? Betcha the extra spares are starting to look cheap.....

From the pictures, it looks like most of the stuff on the US side of the ISS is run by laptop computers. At least it's possible to swap these things out with newer models when they are available.

Possible, but not guaranteed successfully. As one simple example, consider how much machinery was developed using RS-232 serial communications. Low data rate, but simple and effective. Try buying a laptop with an RS-232 serial port now. And get Vista or Windows 7 to talk to it (it's not just hardware issues - those are the easy problems).

From personal experience, the COTS USB/PCMCIA adapters to RS-232 aren't worth a damn.... Besides being something else to break or forget. Given the length of the ISS design cycle, there's a lot of legacy machinery up there.

I don't mean to sound negative, but the senior decision makers are all too often glorified bean-counters with their heads so far up their butts, it's a wonder they don't see daylight. The bigger the picture, the farther from reality....