Author Topic: Applicability of the ISS to exploration missions  (Read 7163 times)

Offline mmeijeri

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Applicability of the ISS to exploration missions
« on: 10/20/2009 02:32 PM »
A new thread to discuss how various aspects of the ISS, such as details of its orbit impact its suitability for integration into an exploration architecture.
« Last Edit: 10/20/2009 02:57 PM by mmeijeri »
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Offline Robotbeat

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Re: Applicability of the ISS to exploration missions
« Reply #1 on: 10/20/2009 03:38 PM »
The great benefit of the ISS is that it already has virtually everything you need for building something in space. It has redundant life support, (somewhat) redundant power, redundant air locks (sort of), and docking ports for both the Russians and the Americans. That big CanadArm thing is pretty useful, too, when you don't have a Shuttle.

ISS's current orbit for exploration purposes is quite useful for getting the Russians to help refuel in case commercial space doesn't work out. Heck, if you had a hypergolic exploration vehicle attached to the ISS with the right plumbing, you could just fuel up from Progresses, although that'd take quite a while (and a lot of money, maybe $5 billion at 50 Progresses and $100 million a pop) for a 100-ton fuel capacity. It might work for getting an international exploration architecture working, though.

In a fantasy world where you can add more solar power, you could use VASIMR to change your inclination if you wanted to (although it'd take a LONG time). How much delta-V does it take to change the ISS's orbit? How much delta-V is burned every year by atmospheric drag? Admittedly, this is probably just a fiction, since the power budget on ISS is pretty thin to be using much of it for the VASIMR, as far as I know. ...not to mention that the Russians wouldn't let you do it, since the station is about half theirs.
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Offline Archibald

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Re: Applicability of the ISS to exploration missions
« Reply #2 on: 10/20/2009 04:40 PM »
The ISS orbit inclination (51.6°) may not really be a problem. Somewhere on this board I've red that the delta-V penalty is only 3%.
I'll try to browse the thread :)


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Offline Analyst

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Re: Applicability of the ISS to exploration missions
« Reply #3 on: 10/20/2009 04:49 PM »
Closer to 5%, but still pretty much irrelevant.

Analyst

Offline Archibald

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Re: Applicability of the ISS to exploration missions
« Reply #4 on: 10/20/2009 04:57 PM »
Closer to 5%, but still pretty much irrelevant.

Analyst

Yeah, 5 %
http://forum.nasaspaceflight.com/index.php?topic=18822.msg492208#msg492208

http://forum.nasaspaceflight.com/index.php?topic=17546.msg441101#msg441101

Quote
but still pretty much irrelevant.

Why ?

The DPT/ NEXT Gateway station was to be launched by an EELV, then checked out by a shuttle crew in LEO. After what it went to EML-1 with electric thrusters.
We can certainly use the ISS for the role. If electric thrusters can't do the job, belbruno trajectories may be an option.
« Last Edit: 10/20/2009 04:58 PM by Archibald »
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Offline sdsds

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Re: Applicability of the ISS to exploration missions
« Reply #5 on: 10/20/2009 05:19 PM »
The ISS orbit inclination (51.6°) may not really be a problem.

The ISS orbit inclination was chosen carefully (although not necessarily rationally).  Obviously ISS needed an orbit that could be reached without undue penalty from both KSC and Baikonur.  Physics prevents Baikonur from launching directly to lower inclinations; range limits prevent KSC from launching directly to higher inclinations. 

Notes:
 * Direct descending node launch from KSC to ISS is already outside range limits.
 * Direct ascending node launch from KSC  to ISS incurs a survivability penalty, since an abort could conceivable splash in the inhospitable North Atlantic.
 * Russia will eventually stop launching from Baikonur, but Vostochny is just as far north and thus will have similar launch constraints.  Conceivably though a Russian contribution to an exploration mission could launch from CSG in French Guiana.
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Offline alexterrell

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Re: Applicability of the ISS to exploration missions
« Reply #6 on: 10/20/2009 07:23 PM »

In a fantasy world where you can add more solar power, you could use VASIMR to change your inclination if you wanted to (although it'd take a LONG time). How much delta-V does it take to change the ISS's orbit? How much delta-V is burned every year by atmospheric drag? Admittedly, this is probably just a fiction, since the power budget on ISS is pretty thin to be using much of it for the VASIMR, as far as I know. ...not to mention that the Russians wouldn't let you do it, since the station is about half theirs.
I can't find the paper, but a study was done about using an electrodynamic tether to change the orbital inclination of the ISS.

Basically, you boost for half the orbit and brake for the other half. You need a large battery but then most of your energy is free.

Aren't the Russians negotiating to use Kourou?

Offline Jorge

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Re: Applicability of the ISS to exploration missions
« Reply #7 on: 10/20/2009 07:30 PM »

Aren't the Russians negotiating to use Kourou?

Not for manned flights.
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Offline Analyst

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Re: Applicability of the ISS to exploration missions
« Reply #8 on: 10/20/2009 08:48 PM »
Quote
but still pretty much irrelevant.

Why ?

Because 5% are pretty much irrelevant. You have a big, ~$60 to 100 billion asset in orbit. You don't built a new one just because of 5%. This is almost in the noise, a little bit above your performance margin.

Analyst

Offline Robotbeat

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Re: Applicability of the ISS to exploration missions
« Reply #9 on: 10/20/2009 09:11 PM »
Quote
but still pretty much irrelevant.

Why ?

Because 5% are pretty much irrelevant. You have a big, ~$60 to 100 billion asset in orbit. You don't built a new one just because of 5%. This is almost in the noise, a little bit above your performance margin.

Analyst

Good point! We need more in-space resources like the ISS that we can reuse. Assuming you could get everyone to agree with it politically (and bureaucratically... I'm looking at you, JSC), could you dock a large exploration craft with empty hypergolic fuel tanks at ISS, transfer crew to the craft, refuel it propellant and water with Progresses (or similar craft like ATV) docking to the other end of the exploration craft, test all the subsystems, and launch? Then, after the trip, could you dock again with the station and have the crew transfer to another craft capable of reentry, like a Soyuz or a Dragon capsule or something?
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Offline Lampyridae

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Re: Applicability of the ISS to exploration missions
« Reply #10 on: 10/21/2009 03:00 AM »
The ISS is also a terrific testbed for long-duration spaceflight experiments. The VASIMIR testing would also be very useful. If only we had the CAM... but we don't. And it would take a modified ATV to bring it up anyway, if it did get rebuilt.
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Offline sdsds

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Re: Applicability of the ISS to exploration missions
« Reply #11 on: 10/21/2009 04:55 AM »
Quote
but still pretty much irrelevant.

Why ?

Because 5% are pretty much irrelevant. You have a big, ~$60 to 100 billion asset in orbit. You don't built a new one just because of 5%. This is almost in the noise, a little bit above your performance margin.

Analyst

Good point! We need more in-space resources like the ISS that we can reuse. Assuming you could get everyone to agree with it politically (and bureaucratically... I'm looking at you, JSC), could you dock a large exploration craft with empty hypergolic fuel tanks at ISS, transfer crew to the craft, refuel it propellant and water with Progresses (or similar craft like ATV) docking to the other end of the exploration craft, test all the subsystems, and launch? Then, after the trip, could you dock again with the station and have the crew transfer to another craft capable of reentry, like a Soyuz or a Dragon capsule or something?

You're right there are political issues that would need to be overcome to assemble an exploration mission at ISS, but there are also pragmatic issues.  ISS is a huge asset, and its owner-operators aren't particularly inclined to expose it to danger.  A spacecraft with enough propellant to climb out of LEO could potentially experience an "unplanned energetic dis-assembly" that would pose a considerable risk.

Thinking back on what was said when Space Station Freedom was on the drawing boards, there was plenty of talk of using the station as a place to prepare (or repair) other vehicles.  But back then, it looked like this:



Times sure have changed!

EDIT:  Those wacky wiki people seem to have moved the image referenced above. It is now at http://commons.wikimedia.org/wiki/File:Dualkeel86.JPG:
« Last Edit: 04/26/2010 03:09 AM by sdsds »
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Offline Robotbeat

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Re: Applicability of the ISS to exploration missions
« Reply #12 on: 04/26/2010 03:02 AM »
Necro-bumping this thread so we don't have to rehash the inclination penalty issue.

So, now that the new plan seems to be using the ISS as a central part of NASA perhaps even while exploration missions are underway and now that Orion is being somewhat continued...

Can an exploration craft be built at ISS (does this even make sense)? Is this congruent with the current Obama plan? There's already tons of fuel being stored on the ISS.

What do the experts think about an exploration architecture being staged from the ISS?
 
One or two benefits: after commercial crew to the ISS is going, any launch vehicle can be used for exploration hardware without worrying about man-rating requirements. Any parts of "lifeboat-only Orion" related to the launch escape system or even astronaut ground ingress can be removed since crew would be launched on other vehicles (unless commercial crew falls through or LM uses Orion or something). De-coupling the exploration architecture from any one crewed launch vehicle (could use Soyuz to man the mission even if there was a problem with Dragon crew, if that wins commercial crew) may help increase the robustness of the architecture to failures.

Also, it provides its own lifeboat for early testing or Mars-analogue missions.

Perhaps it may offer a place to refurbish a used exploration craft, though that would likely require some sort of tug to retrieve the exploration craft from a solar orbit or a Lagrange point (after the crew return in the Orion).

EDIT: Maybe also a good location to assemble a large heatshield for Mars?
« Last Edit: 04/26/2010 03:30 AM by Robotbeat »
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Offline pathfinder_01

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Re: Applicability of the ISS to exploration missions
« Reply #13 on: 04/26/2010 11:52 PM »

One or two benefits: after commercial crew to the ISS is going, any launch vehicle can be used for exploration hardware without worrying about man-rating requirements. Any parts of "lifeboat-only Orion" related to the launch escape system or even astronaut ground ingress can be removed since crew would be launched on other vehicles (unless commercial crew falls through or LM uses Orion or something). De-coupling the exploration architecture from any one crewed launch vehicle (could use Soyuz to man the mission even if there was a problem with Dragon crew, if that wins commercial crew) may help increase the robustness of the architecture to failures.

Also, it provides its own lifeboat for early testing or Mars-analogue missions.


I was thinking of another benefit of Orion as a lifeboat\Crew return craft. It now only needs enough life support for return to earth instead of for the whole mission. The craft would need 4-6 days of life support, and some deep space modifications in terms of micrometeorite and perhaps some radiation. It also only needs enough propellant to return from a reasonable distance to earth. It's requirements could be less than those of Apollo or the Original Orion.


 
« Last Edit: 04/26/2010 11:54 PM by pathfinder_01 »

Offline kraisee

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Re: Applicability of the ISS to exploration missions
« Reply #14 on: 04/27/2010 12:44 AM »
The primary usefulness for ISS is as a location in space for practical testing of certain subsystems.   High efficiency propulsion systems, long-duration life support systems, water recycling, hydroponics research, zero-g fire suppression systems, propellant transfer capabilities etc.   All of these things need to be perfected and ISS is an optimal testbed site for such prototype engineering.

But as a hub for actually staging missions in LEO, this station's design is a long way from being ideal.   ISS is designed to be a research outpost -- and it should remain one.

Ross.
« Last Edit: 04/27/2010 12:46 AM by kraisee »
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Offline Rabidpanda

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Re: Applicability of the ISS to exploration missions
« Reply #15 on: 04/27/2010 02:04 AM »
The primary usefulness for ISS is as a location in space for practical testing of certain subsystems.   High efficiency propulsion systems, long-duration life support systems, water recycling, hydroponics research, zero-g fire suppression systems, propellant transfer capabilities etc.   All of these things need to be perfected and ISS is an optimal testbed site for such prototype engineering.

But as a hub for actually staging missions in LEO, this station's design is a long way from being ideal.   ISS is designed to be a research outpost -- and it should remain one.

Ross.

Why is it 'a long way from being ideal'? Back up your statements please.

Offline robertross

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Re: Applicability of the ISS to exploration missions
« Reply #16 on: 04/27/2010 02:15 AM »
The primary usefulness for ISS is as a location in space for practical testing of certain subsystems.   High efficiency propulsion systems, long-duration life support systems, water recycling, hydroponics research, zero-g fire suppression systems, propellant transfer capabilities etc.   All of these things need to be perfected and ISS is an optimal testbed site for such prototype engineering.

But as a hub for actually staging missions in LEO, this station's design is a long way from being ideal.   ISS is designed to be a research outpost -- and it should remain one.

Ross.

Why is it 'a long way from being ideal'? Back up your statements please.

I'm sorry, but you're kidding right?

Orbits & inclinations aside, if you follow the docking and undocking of just the shuttle, you'll see how careful they need to be with plume impingement on the science experiments and viewing windows. If you use the station as a staging point, you also introduce large quantities of propellants that will be transferred, greater risk of unnecessary traffic, debris generation, and collision.

The purpose of ISS is for science.

Build a lunar gateway station of you want to explore the stars...
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Offline Robotbeat

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Re: Applicability of the ISS to exploration missions
« Reply #17 on: 04/27/2010 02:35 AM »
The primary usefulness for ISS is as a location in space for practical testing of certain subsystems.   High efficiency propulsion systems, long-duration life support systems, water recycling, hydroponics research, zero-g fire suppression systems, propellant transfer capabilities etc.   All of these things need to be perfected and ISS is an optimal testbed site for such prototype engineering.

But as a hub for actually staging missions in LEO, this station's design is a long way from being ideal.   ISS is designed to be a research outpost -- and it should remain one.

Ross.

Why is it 'a long way from being ideal'? Back up your statements please.

I'm sorry, but you're kidding right?

Orbits & inclinations aside, if you follow the docking and undocking of just the shuttle, you'll see how careful they need to be with plume impingement on the science experiments and viewing windows. If you use the station as a staging point, you also introduce large quantities of propellants that will be transferred, greater risk of unnecessary traffic, debris generation, and collision.

The purpose of ISS is for science.

Build a lunar gateway station of you want to explore the stars...
There are already tons of propellant stored at the ISS. Just because you have to be careful docking doesn't mean it's a bad place to launch an exploration craft. Since when wouldn't you want to be careful docking?
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Offline A_M_Swallow

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Re: Applicability of the ISS to exploration missions
« Reply #18 on: 04/27/2010 03:16 AM »
There are already tons of propellant stored at the ISS. Just because you have to be careful docking doesn't mean it's a bad place to launch an exploration craft. Since when wouldn't you want to be careful docking?

Careful is a relative term.  A quick look at the ISS's silhouette shows that it has not been designed for visits by SEP cargo tugs with kilometre long solar arrays.  Transferring cargo and propellant massing many tons is likely to disturb the (still) microgravity environment.

A gateway is likely to have 4 docking ports - Earth, interplanetary, escape and spare.

Offline pathfinder_01

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Re: Applicability of the ISS to exploration missions
« Reply #19 on: 04/27/2010 06:07 AM »
I guess I view it differently. The ISS has docking ports, and a robot arm. I don’t view the ISS as being like a grand central station in space or like a full fledged construction yard.

I view it as supporting the occasional deep space mission, not as being the place where deep space missions depart daily. 

Propellant I think should be loaded elsewhere just for the safety of the crew. The only propellant that should be loaded at the ISS should be enough to get the craft in a position where it can be fueled\refueled elsewhere.

A kilometer long solar array will present issues anywhere. You could dispatch an ATV modified to be a tug to your SEP craft and transfer the cargo between the two.  From the ISS samples could be loaded into Dragons, Soyuz’s, or other earth returnable craft. This could greatly increase the amount of sample that could be taken from a lunar or other deep space mission since you no longer need to squeze it in with your returning deep space crew nor do you need to build or lauch a dedicated sample return craft out to deep space.

Likewise the ISS could serve as a temporary place to put equipment until a tug arrives. This could give greater flexibility about scheduling.

I also don’t think the exploration craft has to be fully built at the ISS. It could be brought to a state where it is man tenable (sort of like the ISS before it could support crew).   Once it is man tenable, a tug could pull the craft a safe distance apart.  From that point on, crews could either be launched from earth to work on the craft under construction or crews could depart from the ISS to work on the craft.

If the craft has docking ports, airlocks, and a robot arm it can in theory build itself and in theory help build any other craft needed (like the kilometer long SEP tug). .  I don’t view tons of equipment being regularly moved about. Once the craft is man tenable, it should be able to accept ATV shipments directly.   

It would be cheaper than building a dedicated lunar gateway station. Once enough traffic is in place perhaps one should be built, but I would prefer not waiting on congress to agree with that.
« Last Edit: 04/27/2010 07:14 AM by pathfinder_01 »

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