Author Topic: ITS in space repair  (Read 3309 times)

Offline oldAtlas_Eguy

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ITS in space repair
« on: 06/18/2017 03:50 PM »
Because of its 3+ month travel in deep space, the ITS may experience failures or damage requiring repair of critical systems prior to the critical EDL event at Mars or Earth.

The questions are:
1.  What are the critical systems?

2. What is the likelihood of failure or damage requiring repair?

3. How would such systems be repaired?

This thread had the beginnings of the discussion
http://forum.nasaspaceflight.com/index.php?topic=41304.msg1691018#msg1691018

Offline guckyfan

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Re: ITS in space repair
« Reply #1 on: 06/18/2017 05:07 PM »
Has any ISS habitat been punctured? I think not. Likelihood in interplanetary space is a lot smaller than that. I don't think puncturing the tank or habitable volume is a big risk with 4cm of carbon composite walls.

Any exposed systems, like the solar panels or the heat rejection system may be more at risk.

Offline flyright

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Re: ITS in space repair
« Reply #2 on: 06/19/2017 04:27 AM »
ISS Habitat has MMOD shielding. Not sure how a presumably single layer of carbon fiber structure on ITS would compare to shielded ISS habitat.
Also, trying to quantify MMOD risk in LEO and deep space. Found this document which specifies baseline risk = 0.5% or 1 in 200 over 14-day mission in LEO:
https://ston.jsc.nasa.gov/collections/TRS/_techrep/TM-2009-214785.pdf


Online Robotbeat

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Re: ITS in space repair
« Reply #3 on: 06/19/2017 04:37 AM »
ISS Habitat has MMOD shielding. Not sure how a presumably single layer of carbon fiber structure on ITS would compare to shielded ISS habitat.
Also, trying to quantify MMOD risk in LEO and deep space. Found this document which specifies baseline risk = 0.5% or 1 in 200 over 14-day mission in LEO:
https://ston.jsc.nasa.gov/collections/TRS/_techrep/TM-2009-214785.pdf
??
ITS will be extensively covered in TPS with margin to last probably dozens of entries/reentries (one on each end, 12-15 cycles). Not just carbon fiber.
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Offline flyright

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Re: ITS in space repair
« Reply #4 on: 06/19/2017 05:28 AM »
ISS Habitat has MMOD shielding. Not sure how a presumably single layer of carbon fiber structure on ITS would compare to shielded ISS habitat.
Also, trying to quantify MMOD risk in LEO and deep space. Found this document which specifies baseline risk = 0.5% or 1 in 200 over 14-day mission in LEO:
https://ston.jsc.nasa.gov/collections/TRS/_techrep/TM-2009-214785.pdf
??
ITS will be extensively covered in TPS with margin to last probably dozens of entries/reentries (one on each end, 12-15 cycles). Not just carbon fiber.
Good point, but wouldn't the TPS also be susceptible to micrometeroid or orbital debris damage that could endanger the vehicle? I'm thinking that having a device to do inspection and repair of the TPS might be a good idea, but trying first to understand the risk. Possibly the ITS TPS is not near as fragile as shuttle TPS?

Offline jpo234

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Re: ITS in space repair
« Reply #5 on: 06/19/2017 05:46 AM »
ISS Habitat has MMOD shielding. Not sure how a presumably single layer of carbon fiber structure on ITS would compare to shielded ISS habitat.
Also, trying to quantify MMOD risk in LEO and deep space. Found this document which specifies baseline risk = 0.5% or 1 in 200 over 14-day mission in LEO:
https://ston.jsc.nasa.gov/collections/TRS/_techrep/TM-2009-214785.pdf
??
ITS will be extensively covered in TPS with margin to last probably dozens of entries/reentries (one on each end, 12-15 cycles). Not just carbon fiber.
The TPS is only applied to the "black side", isn't it?

Offline Coastal Ron

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Re: ITS in space repair
« Reply #6 on: 06/19/2017 06:08 AM »
Something to keep in mind is that Musk has stated that there won't be just one ITS spacecraft normally traveling between Earth-Mars and Mars-Earth, but an every growing fleet of spacecraft.

So if one ITS spacecraft has an issue then the crew could be transferred to another spacecraft for safety purposes. I don't know enough about orbital mechanics, but perhaps the damaged ITS could be diverted away from landing directly, and enter some sort of orbit around Earth so that a repair crew could get to it and assess the situation - or the ITS is able to gradually move into a closer orbit to Earth for R&R assessment.

However it's possible that there won't be an ability to repair certain types of damages, and that they just park them in a holding orbit for later salvage, either at Earth or at Mars.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline MP99

Re: ITS in space repair
« Reply #7 on: 06/19/2017 07:31 AM »
Has any ISS habitat been punctured? I think not. Likelihood in interplanetary space is a lot smaller than that. I don't think puncturing the tank or habitable volume is a big risk with 4cm of carbon composite walls.

Any exposed systems, like the solar panels or the heat rejection system may be more at risk.
ISS deals with this by having Soyuz lifeboats on permanent standby in case of a danger to life.

ITS will need to use a different strategy, unless there are multiple ships flying in convoy.

Cheers, Martin

Edit: and even then, loss of the cargo in an ITS could be life critical for the crew for the rest of the flight and on the ground, or for people already on the ground.
« Last Edit: 06/19/2017 07:33 AM by MP99 »

Offline guckyfan

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Re: ITS in space repair
« Reply #8 on: 06/19/2017 07:43 AM »
ISS deals with this by having Soyuz lifeboats on permanent standby in case of a danger to life.

ITS will need to use a different strategy, unless there are multiple ships flying in convoy.

Cheers, Martin

I am well aware of the life boats. But the risk in interplanetary space is much smaller and my point was, that even in its long lifetime, the main pressure vessels were never punctured. So the risk would be very small, to the point of being acceptable. Punctures in the passenger compartment can be fixed. The landing propellant is in separate inner tanks, so even a puncture would not compromise that propellant, further reducing that risk.

Edit: and even then, loss of the cargo in an ITS could be life critical for the crew for the rest of the flight and on the ground, or for people already on the ground.

How so for the crew? How can cargo be lost and the crew in danger by that?

Loss of a single cargo must never be allowed to be life threatening to the colony. Stores must be adequate, just like they are on the ISS.

Offline jpo234

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Re: ITS in space repair
« Reply #9 on: 06/19/2017 10:31 AM »

ITS will need to use a different strategy, unless there are multiple ships flying in convoy.


Initially a manned ITS will have to deal with a mishap from on board resources. If this is not enough to save the mission, they will have to deal with it like Apollo was prepared to do: http://news.bbc.co.uk/2/hi/science/nature/390634.stm

Or to quote Elon: "It's dangerous and probably people will die – and they'll know that. ".

 
« Last Edit: 06/19/2017 10:36 AM by jpo234 »

Offline flyright

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Re: ITS in space repair
« Reply #10 on: 06/19/2017 07:15 PM »
ISS deals with this by having Soyuz lifeboats on permanent standby in case of a danger to life.

ITS will need to use a different strategy, unless there are multiple ships flying in convoy.

Cheers, Martin

I am well aware of the life boats. But the risk in interplanetary space is much smaller and my point was, that even in its long lifetime, the main pressure vessels were never punctured. So the risk would be very small, to the point of being acceptable. Punctures in the passenger compartment can be fixed. The landing propellant is in separate inner tanks, so even a puncture would not compromise that propellant, further reducing that risk.

Edit: and even then, loss of the cargo in an ITS could be life critical for the crew for the rest of the flight and on the ground, or for people already on the ground.

How so for the crew? How can cargo be lost and the crew in danger by that?

Loss of a single cargo must never be allowed to be life threatening to the colony. Stores must be adequate, just like they are on the ISS.

...added bold to quote...

The ITS will also spend time in LEO. Shuttle required detailed inspection of the TPS prior to being cleared for reentry. This  after just a couple weeks in orbit.

TPS for ITS may not be fragile as shuttle tiles, or may not cover as many critical structures.
I think it is likely that ITS will need to have, at the very least, a means of detecting and inspecting if impact damage has occurred.  This could be implemented on the non-TPS areas using a thin film piezoelectric “strike detector”, possibly as part of an MLI blanket. TPS areas may need an equivalent of the Shuttle’s Orbital Boom Sensor System, for inspection. I think this might be easier implemented as a small vehicle rather than a boom.

Offline guckyfan

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Re: ITS in space repair
« Reply #11 on: 06/19/2017 07:37 PM »
The Shuttle heat shield was mainly dangerous when hit at locations like the wing tips. No such structural weak spot on the ITS. But yes, detection should be part of the system. No problem I think. A number of impact sensors should take care of this. Also while still in LEO there are always rescue options available. Again, the hull of ITS is strong and not easily penetrated, compared to ISS modules. Though likely not as well defended as Bigelow modules.

I stay with my opinion that structural components like the solar panels are most at risk and they will have some redundancy, no doubt.

Offline eric z

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Re: ITS in space repair
« Reply #12 on: 06/19/2017 08:07 PM »
 Maybe they could use a space "pod" a la "2001", that is equipped with a RMS-Canadarm! People could take turns going outside to relieve that "cooped-up" feeling... ;D

Offline jeffreycornish

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Re: ITS in space repair
« Reply #13 on: 06/19/2017 08:17 PM »
ISS deals with this by having Soyuz lifeboats on permanent standby in case of a danger to life.

ITS will need to use a different strategy, unless there are multiple ships flying in convoy.

Cheers, Martin

I am well aware of the life boats. But the risk in interplanetary space is much smaller and my point was, that even in its long lifetime, the main pressure vessels were never punctured. So the risk would be very small, to the point of being acceptable. Punctures in the passenger compartment can be fixed. The landing propellant is in separate inner tanks, so even a puncture would not compromise that propellant, further reducing that risk.

Edit: and even then, loss of the cargo in an ITS could be life critical for the crew for the rest of the flight and on the ground, or for people already on the ground.

How so for the crew? How can cargo be lost and the crew in danger by that?

Loss of a single cargo must never be allowed to be life threatening to the colony. Stores must be adequate, just like they are on the ISS.

...added bold to quote...

The ITS will also spend time in LEO. Shuttle required detailed inspection of the TPS prior to being cleared for reentry. This  after just a couple weeks in orbit.

TPS for ITS may not be fragile as shuttle tiles, or may not cover as many critical structures.
I think it is likely that ITS will need to have, at the very least, a means of detecting and inspecting if impact damage has occurred.  This could be implemented on the non-TPS areas using a thin film piezoelectric “strike detector”, possibly as part of an MLI blanket. TPS areas may need an equivalent of the Shuttle’s Orbital Boom Sensor System, for inspection. I think this might be easier implemented as a small vehicle rather than a boom.

on thing to remember about the Shuttle Tiles, and to keep the contrast with PICA-X, is the STS TPS were bleeding edge foamed silica blocks.  I don't know if you've ever encountered one.  they are absolutely fragile and crumbly.  that's why the STS TPS took so much effort to maintain--it was massive and it was terribly fragile.

PICA-X is more like the Apollo TPS, and having seen a Dragon capsule at the Seattle Museum of Flight a couple years ago, does not look nearly as fragile.

I'd think that having pressure envelope inside the carbon fiber outerhull would make sense for the ITS. 

Offline sanman

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Re: ITS in space repair
« Reply #14 on: 06/20/2017 08:55 AM »
Good point, but wouldn't the TPS also be susceptible to micrometeroid or orbital debris damage that could endanger the vehicle? I'm thinking that having a device to do inspection and repair of the TPS might be a good idea, but trying first to understand the risk. Possibly the ITS TPS is not near as fragile as shuttle TPS?


What would an inspection device look like? Some kind of Space Roomba crawling over every square inch of the exterior surface? Maybe it could adhere to the hull surface by electrostatics, or even VanDerWaals forces(gecko-style).

With a bunch of ITS rockets flying together, then could they inspect each other? Could you have some specialization in roles among the various ships comprising this caravan?

Would it be useful to have the bunch of ships flying in formation, where they could all keep their TPS facing the inside of the formation(ie."belly in") to minimize TPS exposure to potential damage?

What if they could do more than just fly in formation - what if they could be linked together at common hardpoints? They could then fly together as a cluster, and then detach prior to Mars arrival.
« Last Edit: 06/20/2017 08:59 AM by sanman »

Offline IRobot

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Re: ITS in space repair
« Reply #15 on: 06/20/2017 11:31 AM »
With a bunch of ITS rockets flying together, then could they inspect each other? Could you have some specialization in roles among the various ships comprising this caravan?

Would it be useful to have the bunch of ships flying in formation, where they could all keep their TPS facing the inside of the formation(ie."belly in") to minimize TPS exposure to potential damage?

What if they could do more than just fly in formation - what if they could be linked together at common hardpoints? They could then fly together as a cluster, and then detach prior to Mars arrival.
Maybe a specialized ship, with common stuff (supplies, parts, facilities) for all others and with mating adapters/extenders for 5-6 surrounding ITS.
It could also have a large unpressurized compartment for large retractable solar panels and larger communication antenna, as well as suitports or an airlock.

The problem of such structure is when do you attach it? Before leaving earth is hard, as engines from all ITS would be on, creating structural issues. Docking afterwards could also be problematic, as they would have to leave at the same time, with same acceleration, on a close formation.

Offline guckyfan

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Re: ITS in space repair
« Reply #16 on: 06/20/2017 12:28 PM »
This is a separate topic. I suggest you produce a new thread.

Offline flyright

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Re: ITS in space repair
« Reply #17 on: 06/20/2017 01:30 PM »
The inspection device I was thinking of would be a sphere with compressed gas RCS and a camera.
Such devices have been flown previously on shuttle and they would also be similar to the SPHERES devices frequently flown inside the ISS.
Here is a link to a good document on the subject and the NSF thread I found it in.  :)
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120002583.pdf
https://forum.nasaspaceflight.com/index.php?topic=42484.0

If used for actually doing minor repairs, I don't think it would need to anchor to the surface being repaired. It could have an applicator sticking out with a sticky patch on the end of it. It would line up and bump against the spot to be repaired in order to apply the patch/plug/liquid (whatever works for the situation).
This would be similar to how the OSIRIS-Rex spacecraft take a sample from an asteroid with negligible gravitational attraction.

Offline philw1776

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Re: ITS in space repair
« Reply #18 on: 06/20/2017 02:02 PM »
My bet is that toilets and ECLSS will have the most in space repairs.  That's why I favor multiple smaller ECLSS setups with aggregate capacity exceeding # of passengers.  Lots of spare parts.  Perhaps the au courant magic unicorn 3-D printing might facilitate replacement of some components.  Probably not.

As to outside pre-TMI PICA-X inspection, a small drone vs a costly to develop and certify 2001 style sci-fi pod seems more SpaceXy.  Not sure what the options are should PICA-X fail inspection.  At worst another ITS could unload passengers for Earth return.
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Offline sanman

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Re: ITS in space repair
« Reply #19 on: 06/20/2017 02:25 PM »
The inspection device I was thinking of would be a sphere with compressed gas RCS and a camera.
Such devices have been flown previously on shuttle and they would also be similar to the SPHERES devices frequently flown inside the ISS.
Here is a link to a good document on the subject and the NSF thread I found it in.  :)
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120002583.pdf
https://forum.nasaspaceflight.com/index.php?topic=42484.0

If used for actually doing minor repairs, I don't think it would need to anchor to the surface being repaired. It could have an applicator sticking out with a sticky patch on the end of it. It would line up and bump against the spot to be repaired in order to apply the patch/plug/liquid (whatever works for the situation).
This would be similar to how the OSIRIS-Rex spacecraft take a sample from an asteroid with negligible gravitational attraction.

Ah, thanks for that - never knew about SPHERES:



Does SPHERES make use of reaction-sphere tech?

http://forum.nasaspaceflight.com/index.php?topic=42842.0

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