ISS cutbacks

clark · 2004-07-26 09:59:47

Okay, mayve someone can tell me- how many Shuttle flights do we need to complete the ISS now?

Commodore · 2004-07-26 10:09:05

Okay, mayve someone can tell me- how many Shuttle flights do we need to complete the ISS now?

I've heard 25 to 30 launchs. Thats quite a few in a little under 5 years.

clark · 2004-07-26 10:23:08

I've heard the same, but I was wondering if that number had changed with the recent ISS agreement... it seems to me that they may have cut back on the final configuration some.

Commodore · 2004-07-26 14:15:10

I found this. Minus the US HAB and X-38 nothing else seems to be missing.

http://www.nasa.gov/pdf/62847main_ISS_c … 04.pdf]ISS Configuration

Maybe they can work something out with Bigelow so that there Nautilus prototype will be slumber party ready.

Grypd · 2004-07-26 15:25:24

just to let you think a bit.

Each shuttle flight costs between 500 to 1500 million US$

25 to 30 shuttle flights will cost about 25 to 30 Billion $

That is a lot of cash, the main reason is that the shuttle may only carry about 24 Mtons, A shuttle C would carry 80 to 100 Mtons. You could pay for the development of a shuttle C with the cost savings you get by sending a lot of cargo up. I estimate that the flights could be dropped to between 13 to 18 flights. To get construction crews up could be done by use of Russian soyuz modules.

Oh and we a have a heavy lifter.

GCNRevenger · 2004-07-26 16:21:39

It sounds like a great idea to use Shuttle-C, but there are some problems...

The remaining ISS modules rely on Shuttle to get them the last mile to the last inch. Shuttle-C will be a pure cargo hauler, with no ability for redevous, docking, fine guidence, robot arm/manipulators, etc. All the remaining pieces are unguided themselves, so you have to have some way to get them from the Shuttle-C faring to the ISS and dock.

Then, the payloads themselves were designed to ride in the Shuttle cargo bay, bolted to the sides, not pushed from the bottom... Trivial sounding, but its not considering the extreme G-forces involved.

And finally, it would take too long to develop Shuttle-C... if Shuttle doesn't start launching the rest of the componets right away, then ISS will simply get too old to be worth the effort.

Not that it was worth the effort anyway.

Grypd · 2004-07-26 16:37:05

So what you are saying is we need a space tug. Which was supposed to be part of the ISS when created, but due to cost was cut back. I knew that decision would hurt.

Still how long would it take to create a shuttle C, i seriously doubt that it will be possible to put 25 to 30 shuttle missions into space in just 5 years, more like 10.

So what we are saying is the ISS is doomed well we should get some decent use out of it before it has gone.

Space tug and Shuttle C

Commodore · 2004-07-26 16:46:48

Yeah, and certain elements need the shuttles arm to put together and support the EVAs needed to hook them up.

A cradle could be developed to enable launch from existing launchers, including a second stage to get it to the ISS, could be developed for less than the cost of all those Shuttle launches.

Depending on how fast the launch sites could be reprepped, it could be finished in one extended mission.

GCNRevenger · 2004-07-26 16:56:52

Not just a space tug, but modification to the US nodes so that the tug could guide the modules to within a few inches of target.

One of the issues with the cost of Shuttle is the fixed cost of operation which doesn't change with the number of launches... If we fly four Shuttles a year for $4.5Bn, and eliminate half the flights, the remaining two are going to cost much more than $1.1Bn a flight... the actual main tank and SRBs are pretty cheap. Simply eliminating half of them is not going to cut the Shuttle bill down to $2.3Bn/yr.

Now, developing a tug able to haul 16-18MT payloads is not as easy task, considering the amount of time we'd have to design it. Oh yes, and since the ISS is at such a highly inclined orbit, that basicly cuts your payload mass by 1/3rd as opposed to equitorial launch, so that cradle with the remove-control clamps and attitude control system and power system and communications system and deorbit system will not be light weight... I think that its unclear if you could carry the cradle AND the module using a Delta-IV HLV, and may be hard to cram two of them onto Shuttle-C.

We aren't going to get any use out of ISS no matter what happens without a HAB module, a new cargo ship, docking port modifications on the US nodes, and $100-200M a year to Russia to buy Soyuz-TMA/Progress-B, which is currently illegal.

And how long will all this take to build? The ISS isn't going to last beyond 2020 for sure, and I think that 2015 is looking optimistic without heavy cargo capacity or a new service module... unless you can send up all the remaining pieces plus one more launch for the tug and HAB in the before 2010, then you might as well stick with Shuttle... a measly five years of research time is bad enough as it is.

Yang Liwei Rocket · 2004-07-26 17:13:16

Moscow is saying that there is still much going on and that new equipment will be installed soon and the crew of the International Space Stationwill conduct a spacewalk on August 3, good on those brave men up there ( US astronaut Michael Finke and Russian Gennady Padalk ) to install the equipment for the scheduled arrival of a european cargo vessel . The walk in outer space is scheduled to take around six hours long.

The craft know as the automated transfer vehicle (ATV), will bring fuel, water and provisions for the crew. The craft is going to also correct the station's orbit and compensate for its losses of altitude. This will be launched into orbit from Kourou in French Guiana South America.

hope it all goes ok
:up:

RobertDyck · 2004-07-26 17:22:19

If you did use Shuttle-C or Delta-IV Large, the tug would not be launched with modules. The tug already in orbit would rendezvous, grapple, pull the pallet to ISS, then leave the pallet just close enough so that CanadArm2 could pull pieces off one at a time to put them in place. That means the tug could dock anywhere: a Shuttle port, Soyuz port, or just use a robot hand to hold onto one of the grapple posts.

A tug would be nice, but congress appears to be committed to using Shuttle. Even without X-38, two Soyuz craft would permit 6 crew. You could do some real science with 6 crew.

Grypd · 2004-07-26 17:31:44

http://www.orbitalrecovery.com/]Orbital Recovery

Interesting company they will be launching there space tug concepts in 2007. Seems they launch as spare weight on Arianne 5s.

So the first space tugs going up, oh paid for by ESA

Will these have the capacity to push ISS components close enough for grabbing by the canadarm?

GCNRevenger · 2004-07-26 19:15:49

No, see, when you launch somthing into space it MUST have attitude control, at the very least. If you don't have that, then when you launch it up there and the 2nd stage shuts down, the whole thing risks going into a spin. And I bet you'll want a deorbit option too. And you'll need power for all this. And communications to Houston. And probobly a docking beacon too... You can't simply bolt them down to a truss and stick that on a booster.

Orbital Recovery's tug is an ion powerd tug, which isn't much good really. Considering that the modules will weigh five or six times as much as a typical satelite, chemical rockets with storable propellants are a must. An ion drive would be too slow.

If you are going to use the CanadaArm to connect smaller bits (truss segments), then the launch "tray" will have to physicly attach to the ISS. You simply can't have the thing floating around at all when you are removing parts from it for assembly.

And even if Bigelow came through with a HAB and launched it on a Falcon-VA, you STILL can't get heavy or signifigant cargo up without Shuttle or a cargo pod+node modifications, since the science racks, gyros, batteries, etc are too big to fit through the Russian hatches, which the ESA ATV also uses.

And THEN-then, you need a way to get cargo back DOWN.

RobertDyck · 2004-07-26 20:24:19

Ok, enough attitude control to prevent spin. If station gyros are a concern, could you use the gyros themselves to stabilize attitude? If a particular load doesn't include gyros, how bid would an attitude control pod have to be? The RCS thruster pods on Shuttle include multiple redundancy, 3 or 4 thrusters for each position. The tanks are small relative to the 104.3 tonnes of the Shuttle plus 16 tonnes of cargo for an ISS mission. RCS thrusters are sized to not only control attitude, but provide fine control for docking. How big would an attitude control system be for an unmanned cargo tray?

GCNRevenger · 2004-07-26 20:31:45

Its not so much the size really as the cost and extra complexity. The "tray" has suddenly become a powerd, maneuvering, computer-controlled/remote-controlled spacecraft alluvasudden. It doesn't matter really the size of the engine pods on the corners, since they will add cost and add complexity (and failure modes) and development time no matter if the engines are little satelite RCS thrusters or larger ones. You still need several engines reguardless of size, you still need power for several days, you need the control system & wiring (space rated!), communications system, docking beacons/clamps, and probobly a deorbit motor too. 10N or 1,000N or whatever thrust, you still need the same size electronics, and the engines won't cost that much different.

As for using the ISS gyros for tray attitude control... nuh-uh, too much trouble.

Mad Grad Student · 2004-07-26 20:35:52

I'm confident that the Chinese could build a decent hab if they put their minds to it. Even if they couldn't, what about using one of Bigelow's inflatable modules? If that isn't availible in time, there's always the Russians, or the ESA, or JAXA. In any case, the cold shoulder we gave to China was not the best thing to do, we should share some partnership with them.

Sure, adding a hab to the station would require another shuttle flight. So what? It will already take 25 to 30 flights to complete the ISS, adding one more won't affect the economics too much, and the station will be a much better value. Again, we can pay $3.00 for a kiddie-size meal no one wants or we can add 10 cents to biggie-size it into something useful.

Why is it that retiring the shuttle would render the ISS helpless? As far as I can tell, the only advantage that it has over Progress or an ATV is that it can carry more stuff and has someone in the cockpit. An Ariane V can lift as much as a shuttle, if you sent a robotic transfer vehicle (Preferably reusable, but not necessarily) into orbit with it, what disadvantage would it have versus the shuttle?

Commodore · 2004-07-26 21:44:46

Sure, adding a hab to the station would require another shuttle flight. So what? It will already take 25 to 30 flights to complete the ISS, adding one more won't affect the economics too much, and the station will be a much better value. Again, we can pay $3.00 for a kiddie-size meal no one wants or we can add 10 cents to biggie-size it into something useful.

Indeed. Does anyone know how close it was to being done?

GCNRevenger · 2004-07-26 22:08:02

The big problem is the hatch and down-mass... the Progress-B and ESA ATV both use the Russian docking hatches, which have specialty guidence hardware that the American node ports do not... they don't need it for Shuttle's robot arm. Hence, they are NOT suitable for docking.

The ISS laboratories are built around the standard science rack, a big cabinate sized package that holds the experiments in an essentially self contained, drop-in box. Just hook up the umbilicals and screw it into place.

Problem: The science racks do not fit through the Russian hatches. The science racks do not fit through the Russian hatches. Neither do the batteries very well. Or gyroscopes. Or other large hardware.

Problem: The ISS requires signifigant quantities of water to generate oxygen and drinking supplies for a full compliment of crew. Without the US HAB modules' fancy recycling LSS system, this is not going to change. Shuttle uses fuel cells, which basicly allow it to bring several tons of water to the ISS for "free" as it makes it on orbit, saving lots of bulk mass.

Problem: To do useful science on ISS, you must have a means of getting signifigant payloads back down to Earth intact. Soyuz simpy cannot fulfill this role, nor is any other cargo ship. Only Shuttle can do this.

Euler · 2004-07-26 22:32:33

Problem: The ISS requires signifigant quantities of water to generate oxygen and drinking supplies for a full compliment of crew. Without the US HAB modules' fancy recycling LSS system, this is not going to change. Shuttle uses fuel cells, which basicly allow it to bring several tons of water to the ISS for "free" as it makes it on orbit, saving lots of bulk mass.

ATV should be able to handle the water supply. Anyway, I remember reading that the Russian modules are actually much closer to having a closed loop life support system than the American ones. Recycling was a goal on Mir and on the Russian modules, while the Americans used the philosophy that if you needed something, you could just sent it up from Earth.

GCNRevenger · 2004-07-26 22:40:21

That might have been true of Mir, but it isn't true of the current working LSS of the International Space Station. It does recycle water from the humidity and some from human waste, but to make fresh oxygen it still cracks water and dumps the hydrogen overboard. The oxygen bound up in exhaled carbon dioxide and likewise not recycled.

RobertDyck · 2004-07-26 23:55:40

Its not so much the size really as the cost and extra complexity. The "tray" has suddenly become a powerd, maneuvering, computer-controlled/remote-controlled spacecraft alluvasudden. It doesn't matter really the size of the engine pods on the corners, since they will add cost and add complexity (and failure modes) and development time no matter if the engines are little satelite RCS thrusters or larger ones. You still need several engines reguardless of size, you still need power for several days, you need the control system & wiring (space rated!), communications system, docking beacons/clamps, and probobly a deorbit motor too. 10N or 1,000N or whatever thrust, you still need the same size electronics, and the engines won't cost that much different.
As for using the ISS gyros for tray attitude control... nuh-uh, too much trouble.

Launch vehicle is the cost, so size really is the issue. Shuttle has 14 primary RCS thrusters in the nose and 12 in each OMS pod for a total of 38. That level of redundancy may be nice if you're maintaining a reusable manned Shuttle, but an unmanned single use tray doesn't need that. Apollo had 4 thruster quads for 16 engines, and could operate on just 2 quads. Satellite RCS thrusters are all you need. As for space rated electronics, did I mention that Stanford University has already launched 2 satellites with the same microcontroller as we use at work for our miniature UAV autopilots? If you don't want to use that one, there is a 1kg single board computer from Maxwell Technologies that's already radiation and vibration hardened; it's already space rated.

Remember, this tray does NOT have to last days. It only has to last hours while waiting for the tug to grab it. The only reason for ANY onboard manoeuvring capability is to facilitate docking the tug. After that the tug takes over. Same with clamps: the tug has clamps, the tray has a post or two with a knob on the end.

De-orbit engines: let's make the thing work. The last ditch option if it can't be docked with ISS is to let the tenuous atmosphere in LEO deorbit it. That would take a couple years to fall out of orbit.

Docking beacon: trivial. Do you know how cheap electronics is these days? Remember this doesn't have to last days or years in orbit, just hours while waiting for the tug.

The autopilot we make may not be space rated, but it does include solid state gyros and accelerometers in 3 dimensions, GPS receiver, as well as power regulators and processor all weighing 28 grams and cost $5,000 US funds. Size is 1.5" x 4". That includes servo outputs with 8 channels (expandable to 24), serial interface, processor, RAM, and flash memory. It even includes a temperature sensor for each gyro, and voltage sensors for servo power and electronics power supplies. The GPS antenna and disc battery to store GPS configuration are included in the price but not the 28 gram weight. The R/C receiver and spread-spectrum radio modem are extra. The price also includes ground station software. Hell, we sell a ready to fly UAV with ultrasonic altitude sensor, wireless video camera system and 2.4GHz radio modem data link for $12,250. So you're saying the computer control system would cost how much?

GCNRevenger · 2004-07-27 11:20:15

It will still be a nontrivial thing to engineer even if the pieces were free. Since the thing will be pretty heavy, I don't know if regular satelite stationkeeping jets will be enough... a small rocket can't be super-cheap, and you will still several of them any which way. And their fuel is usually kinda toxic ($$$). And you will need some kind of power generation ability, since the payload will take 2-3 days to "catch" the ISS on a transfer orbit just like any other spacecraft. And you will need an uplink to NASA still. And docking clamps built custom for each payload. And the thing has to survive launch. And the thing has to be built on short order... And then you need the tug.

RobertDyck · 2004-07-27 12:04:05

This still sounds like you're adding extra unnecessary crap just to make the mission not feasible. Designing a successful mission means identifying obstructions or unnecessary costs and eliminating them. To keep stuff standard, have the tug use the same robot hand as CanadArm and CanadArm2. They grapple a rod with a knob on top. Any onboard thrusters do not have to keep station, rendezvous, or maneouver; they just have to prevent tumbling. If operating on orbit for days is a concern, then don't. Fuel handling a problem, there are several fuels to choose from. This system doesn't need high performance, just enough to stablize the pallet long enough for the tug to dock.

BWhite · 2004-07-27 12:16:30

One of the issues with the cost of Shuttle is the fixed cost of operation which doesn't change with the number of launches... If we fly four Shuttles a year for $4.5Bn, and eliminate half the flights, the remaining two are going to cost much more than $1.1Bn a flight... the actual main tank and SRBs are pretty cheap. Simply eliminating half of them is not going to cut the Shuttle bill down to $2.3Bn/yr.

Exactly!

So we use SDV and ADD additional SDV based missions in the same time period for a small additional incremental cost.

In a given year fly 2 or 3 SDV to ISS (with 4 or 6 ISS payloads) and fly 2 SDV to the Moon or elsewhere. Practice landing cargo and rovers on Luna launched by SDV at the incremental cost of "the actual main tank and SRBs (which) are pretty cheap." Right?

Edit: Accomplish the vision faster and end up in 2010 or 2011 with a proven HLLV all within the current STS/ISS budget.

= = =

By mass, shuttle C can carry 3 ISS payloads to 51 degrees and 2 by volume. Launch 2 nodes and stuff the in between space with granular payload mass.

clark · 2004-07-27 12:29:11

Where do we get the money to build SDV? From Shuttle savings? That means the Shuttle isn't flying and nothing is being done to complete the ISS- and we don't know for sure that the end SDV will come in on time, on budget, and be able to do what we think it will...

Meanwhile, the ISS will only be staffed by two people, and we will limp along hoping nothing major happens that causes it to be abandoned or deorbited.

The idea has merit, but it has to much inherent risk.

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Re: ISS cutbacks

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