Author Topic: Commercial Crew Program (CCP-CTS-CCT) Requirements  (Read 139757 times)

Offline docmordrid

  • Senior Member
  • *****
  • Posts: 6334
  • Michigan
  • Liked: 4207
  • Likes Given: 2
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #120 on: 08/27/2011 02:12 am »
Not to mention that the mass of a docking camera display today could mean anything from steroscopic LCD/OLED goggles to something akin to a stowable iPad with a heavier case. Not exactly the mass game-breaker an old-school display would be.
« Last Edit: 08/27/2011 02:13 am by docmordrid »
DM

Offline erioladastra

  • Full Member
  • ****
  • Posts: 1413
  • Liked: 222
  • Likes Given: 0
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #121 on: 08/27/2011 08:57 pm »
As has already been stated before, there were real concrete reasons for needing a window in the docking process in the first place.

Except there isn't. As I said, cameras are small and cheap, so you can put four fully redundant cameras, each with its own separate string to the control panel, and it would still have less than 1/10 the mass impact on the vehicle as forward-looking window. And frankly, if they loose any major sensors during flight, docking will be aborted anyways, regardless of any windows.


Cameras are not neccessarily better.  Yes, cameras *may* have less mass, but you trade that against power and data transfer for the camera plus an extra crew display.  So you might not be less mess and you are trading against critical items like power and increasing the complexity of the system (which means cost, risk) etc.
Yeah, the trade could go different ways. But don't you think it should be up to the commercial crew provider to find the most cost-and-performance-optimal solution that meets the required level of safety?

Absolutely agree.  However, there are a few items like windows, pressure suits (probably) etc that will be required, regardless of merit.

Online oldAtlas_Eguy

  • Senior Member
  • *****
  • Posts: 5304
  • Florida
  • Liked: 5005
  • Likes Given: 1444
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #122 on: 08/28/2011 05:50 pm »
In another thread

http://forum.nasaspaceflight.com/index.php?topic=26552.0

A NASA study for man rated LV avionics shows some interesting things about the reliability factors and driving items that the LV and crew vehicle must be able to achieve. This study would also have implications for Commercial Crew, since it represents NASA’s opinion on the reliability capability of computerized avionics archetectures.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110014793_2011015526.pdf

Quote
After examination of multiple DRMs and requirement documents, high-level driving requirements were determine to be:
-   The avionics architecture shall be human-rateable,
-   The avionics architecture shall, at a minimum, be fail-operational after one arbitrary fault,
-   The avionics architecture shall, at a minimum, be fail-safe (for abort initiation) after a second arbitrary fault,
-   The avionics architecture shall be highly reliable to meet Loss of Crew (LOC) and Loss of Mission (LOM) for various NASA missions.

This is a fairly good summary of the driving concerns for the requirements in a nutshell what NASA is looking for. If your LV or crew vehicle doesn’t meet these NASA will probably down select you.

Quote
Reliability analysis showed all architectures except one were at a reliability level of least
0.9999 for short duration (i.e. 24 hour, preflight plus time to orbit) reliability but varied
significantly (0.3576 to 0.6669) if a longer duration (i.e. 9 month, departure stage for
Mars DRM) was needed. For all architectures, the flight computers were the largest
contributor to failure. Reliability analysis assumed all architectures to be 1-fault tolerant
by design but the number of 2-fault cases varied from 21 to 160 depending on the
chosen architecture. The reliability of the architectures is related directly to the level of
cross-strapping in the various architectures.

NASA will probably use some of this data to specify reliability values for the computerized architectures for LV’s and spacecraft.

From the standpoint of LV’s does anyone know more details of the F9 triple redundant avionics architecture so to determine what NASA considers its relative reliability is?

How about the Atlas V avionics?

Offline dks13827

  • Full Member
  • ****
  • Posts: 468
  • Phoenix
  • Liked: 16
  • Likes Given: 60
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #123 on: 08/28/2011 07:28 pm »
Why the heck would they exclude a hatch window?

Does NASA want an affordable commercial crew program, or not?
They mean the hatch window does not count for the purposes of this requirement.   It does NOT mean there is no hatch window.

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39270
  • Minnesota
  • Liked: 25240
  • Likes Given: 12115
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #124 on: 08/29/2011 04:17 am »
Why the heck would they exclude a hatch window?

Does NASA want an affordable commercial crew program, or not?
It does NOT mean there is no hatch window....
I know.
Quote
They mean the hatch window does not count for the purposes of this requirement. 
And why the heck not?
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline arnezami

  • Full Member
  • **
  • Posts: 285
  • Liked: 267
  • Likes Given: 378
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #125 on: 08/29/2011 05:03 am »
Quote
They mean the hatch window does not count for the purposes of this requirement. 
And why the heck not?

Maybe this is a convoluted way of saying the spacecraft needs at least two windows?

1) You need a hatch
2) You need a window in every hatch
3) You need at least one window (not counting hatch-windows)
--> ergo: you need at least two windows.

Or do they mean the docking port "hatch"? Since just before docking you can't see (the rest of) the station because you're looking at the docking port of the station?

Not sure why hatch windows don't count for this requirement.

Offline DaveH62

  • Full Member
  • ***
  • Posts: 309
  • Liked: 23
  • Likes Given: 55
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #126 on: 09/02/2011 07:30 pm »
Maybe the hatch windows don't count since MPCV was already made that way?

Offline joek

  • Senior Member
  • *****
  • Posts: 4869
  • Liked: 2782
  • Likes Given: 1096
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #127 on: 09/02/2011 09:24 pm »
Maybe the hatch windows don't count since MPCV was already made that way?

Maybe indirectly but it couldn't be justified simply on the grounds that MPCV just happens to be built that way.

I expect MPCV and CST-100 have windows in the places they do because there are/were NASA requirements they had to satisfy for the original CxP/OSP/whatever programs.  Those requirements probably fall under the "crew health and safety" or "mission safety and success" categories.

NASA attempting to now relax those classes of requirements for CCP could be extremely difficult, and would likely fuel the "commercial isn't safe" crowd.

Offline DaveH62

  • Full Member
  • ***
  • Posts: 309
  • Liked: 23
  • Likes Given: 55
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #128 on: 09/02/2011 10:33 pm »
Maybe the hatch windows don't count since MPCV was already made that way?

Maybe indirectly but it couldn't be justified simply on the grounds that MPCV just happens to be built that way.

I expect MPCV and CST-100 have windows in the places they do because there are/were NASA requirements they had to satisfy for the original CxP/OSP/whatever programs.  Those requirements probably fall under the "crew health and safety" or "mission safety and success" categories.

NASA attempting to now relax those classes of requirements for CCP could be extremely difficult, and would likely fuel the "commercial isn't safe" crowd.

Part of the challenge with long term planning horizons, is the ability to create alternate scenarios based on opinion, rather than designs facts. It is very hard to prove that a camera system could be 99.999% reliable. It is not a solid state solution, like a window, so it can malfunction. A camera should provide better visibility and provide more functional value, but it could have issues.
That said, it is difficult to imagine a scenario where adequate redundancy could not be built in to provide at least 5 9s. It also seems likely that an event that would damage cameras, camera wiring, or associated computers taking the video feed, would impact either windows or the avionics of the ship as a whole. If something smashed a camera outside the ship, then that would be safer than something smashing a window. You could still turn around and go home.

Offline joek

  • Senior Member
  • *****
  • Posts: 4869
  • Liked: 2782
  • Likes Given: 1096
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #129 on: 09/02/2011 11:20 pm »
Part of the challenge with long term planning horizons, is the ability to create alternate scenarios based on opinion, rather than designs facts. It is very hard to prove that a camera system could be 99.999% reliable. It is not a solid state solution, like a window, so it can malfunction. A camera should provide better visibility and provide more functional value, but it could have issues.
That said, it is difficult to imagine a scenario where adequate redundancy could not be built in to provide at least 5 9s. It also seems likely that an event that would damage cameras, camera wiring, or associated computers taking the video feed, would impact either windows or the avionics of the ship as a whole. If something smashed a camera outside the ship, then that would be safer than something smashing a window. You could still turn around and go home.

True, but let's not miss the forest for the trees.  The fact remains that NASA has previously established specific requirements related to crew and mission safety, and requires certification to those requirements.  Even if the intent can be met by alternate means, it may be politically infeasible, and would at minimum require the NASA Astronaut Office to change their requirements.

There is a fundamental difference between the NASA approach (certification) and the FAA's current approach (licensing).  The FAA entertained a certification approach--essentially modifying FAR's to include commercial spaceflight--which was wholey rejected by commercial providers years ago.  There is a significant difference in approaches depending on whether you're viewing through NASA's lens or the "purely commercial" FAA lens.  NASA is primarily concerned with ensuring crew safety and the ability to safely and reliably accomplish a specific mission.  The FAA is primarily concerned with public safety (less with crew safety, and little or no concern with "mission").

What NASA, the FAA and providers are trying to work towards is a common set of criteria that doesn't impose overly-burdensome NASA-specific requirements on providers that makes it difficult or impossible for those providers to cost-effectively translate their offerings to the commercial sector, while still ensuring NASA's and FAA's objectives are met.  The debate on which approach is appropriate and at what point in time to apply "licensing" or "certification" goes back over 10 years.1

If a provider says "that NASA-specific requirement makes our offering infeasible and not cost-effective for use by other commercial customers", then we have a problem.  Until then (and as I've suggested before), everyone--NASA, FAA, and commercial providers--are still working to figure this out, so let's cut them some slack.


1 If you want the gory details, see the archives of the FAA's Commercial Space Transportation Advisory Committee (COMSTAC) meeting minutes and presentations.

edit: clarify NASA and FAA objectives.
« Last Edit: 09/03/2011 01:09 am by joek »

Offline joek

  • Senior Member
  • *****
  • Posts: 4869
  • Liked: 2782
  • Likes Given: 1096
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #130 on: 09/17/2011 07:13 am »
Per the Sep 16 2011 CCP Forum...

Final requirements release expected end Nov 2011 with RFP by end of 2011.  Unfortunately details om the updated requirements are behind a NASA/FBO firewall and there isn't much more publicly available than what's in the presentation:
Quote
Significant changes to 1130 requirements
- Manual Control   
- Abort Effectiveness
- Mission Duration
- Loss of Crew/Loss of Mission
- Health and Medical Requirements
- Emergency Entry
- Failure Tolerance
No mention of windows.

If you're interested in contracting issues (e.g., SAA vs. FAR), it's worth viewing the webcast (link above) and the July 20 2011 forum feedback and responses (here and here), the OMB whitepaper (here), and the NASA IG report (here).

Please direct comments related to SAA vs. FAR to this thread (would like to keep this thread focused on requirements).
« Last Edit: 09/17/2011 07:36 am by joek »

Offline joek

  • Senior Member
  • *****
  • Posts: 4869
  • Liked: 2782
  • Likes Given: 1096
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #131 on: 10/04/2011 08:48 pm »
The Oct 4 CCP Requirements Workshop presentation has been posted (warning pptx; pdf attached).

Offline baldusi

  • Senior Member
  • *****
  • Posts: 8356
  • Buenos Aires, Argentina
  • Liked: 2539
  • Likes Given: 8273
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #132 on: 10/04/2011 09:05 pm »
Quote
•Updated the following mission and system capabilities:
–Support multiple back-to-back launch opportunities in a two week period in order to accomplish a single mission
This means that if it has to scrub a launch it has to be able to recycle within two weeks?

Quote
•Updated phasing time consistent with CCT-REQ-1130
–The CTS spacecraft will nominally be capable of transporting NASA crew to the ISS within 24 hours of launch
This means that it has to have the capability of a fast mission, but might elect a slower orbital profile for better performance?

Offline baldusi

  • Senior Member
  • *****
  • Posts: 8356
  • Buenos Aires, Argentina
  • Liked: 2539
  • Likes Given: 8273
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #133 on: 10/04/2011 09:23 pm »
My impression from reading is that they are pointing to a taxi model. Does that seems right or I am reading too much between the lines?

Offline joek

  • Senior Member
  • *****
  • Posts: 4869
  • Liked: 2782
  • Likes Given: 1096
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #134 on: 10/04/2011 10:24 pm »
Quote
•Updated the following mission and system capabilities:
–Support multiple back-to-back launch opportunities in a two week period in order to accomplish a single mission
This means that if it has to scrub a launch it has to be able to recycle within two weeks?
I believe the requirement still holds to support multiple launch attempts on "consecutive calendar days" in CCT-REQ-1130 sec 3.1.4.2 or "back-to-back" as they say in the presentation, which would imply ~24hr turnaround after a scrub.  I'm not sure, but assume that "two week period" update both provides a time limit as to how long the provider is required to maintain launch readiness, and formalizes the rationale given in CCT-REQ-1130 sec 3.1.4.3(?).

Quote from: baldusi
Quote
•Updated phasing time consistent with CCT-REQ-1130
–The CTS spacecraft will nominally be capable of transporting NASA crew to the ISS within 24 hours of launch
This means that it has to have the capability of a fast mission, but might elect a slower orbital profile for better performance?
That appears to be the case, based on the rationale (presentation pg 44):
Quote
- 24 hours is a “design point” to accommodate ISS phasing
- Rationale addresses Industry recommendation to allow operational flexibility in mission-to-mission rendezvous timeline

My impression from reading is that they are pointing to a taxi model. Does that seems right or I am reading too much between the lines?
It seems more like a rental car model to me.  With a taxi, the driver and vehicle typically don't stay with you for the duration once you reach your destination (it also appears NASA crew will be driving).

Offline baldusi

  • Senior Member
  • *****
  • Posts: 8356
  • Buenos Aires, Argentina
  • Liked: 2539
  • Likes Given: 8273
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #135 on: 10/04/2011 10:36 pm »
My impression from reading is that they are pointing to a taxi model. Does that seems right or I am reading too much between the lines?
It seems more like a rental car model to me.  With a taxi, the driver and vehicle typically don't stay with you for the duration once you reach your destination (it also appears NASA crew will be driving).
Yes, but it also happens that the service provider is in charge of the crew from staging area on. And the same for almost every nominal return case. Only to be accompanied by NASA's medical personnel. Thus, the big fear that it would become commercial only in name, seems not to be the case.
What I understood by car rental, was that NASA would be in charge of the launch ops. This doesn't seems to be the case. It seems more like everything except the pilot (and that's not clear one way or another), is provided and managed by the service provider. A very good development, if you ask me.

Offline erioladastra

  • Full Member
  • ****
  • Posts: 1413
  • Liked: 222
  • Likes Given: 0
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #136 on: 10/05/2011 08:32 pm »
"No mention of windows."

Updated to be two (or meet the intent) class A science windows with no electronic observation for piloting or blockage of windows.  So got mught tighter.  However, likely to change.

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39270
  • Minnesota
  • Liked: 25240
  • Likes Given: 12115
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #137 on: 10/05/2011 08:44 pm »
"No mention of windows."

Updated to be two (or meet the intent) class A science windows with no electronic observation for piloting or blockage of windows.  So got mught tighter.  However, likely to change.
Why did it change to become tighter?
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline yg1968

  • Senior Member
  • *****
  • Posts: 17266
  • Liked: 7123
  • Likes Given: 3064
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #138 on: 10/19/2011 02:22 pm »
The popular mechanics article on the commercial crew development procurement method is also relevant to this thread:
http://forum.nasaspaceflight.com/index.php?topic=27108.0
« Last Edit: 10/19/2011 02:22 pm by yg1968 »

Offline arnezami

  • Full Member
  • **
  • Posts: 285
  • Liked: 267
  • Likes Given: 378
Re: Commercial Crew Program (CCP-CTS-CCT) Requirements
« Reply #139 on: 01/24/2012 03:41 am »
Here is a pic of the window in the hatch.

http://www.spacex.com/panorama/index.html


Tags:
 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
0