Commercial Crew - Discussion Thread 1

[Robotbeat]

Btw, is not oxygen but CO2 poisoning one of the problems. The other being humidity control (with water extraction being, of course, the hard one).

20,000 PPM CO2 is considered safe. 70,000 PPM + is potentially fatal. Do the calculation on how long it will take 1 astronaut to generate that amount of CO2 in a 350 cubic foot cabin at STP.

so, 2% and 7%. I'll assume it's by mass, a conservative assumption. In 350 ft^3 at 1.2kg/m^3 density there is 11kg of air. Average person expels roughly 1kg of CO2 a day, so... 0.22 kg is the limit for safe, .77kg is limit for fatal. Better do fast rendezvous! Astronaut has just a bit over 5 hours at safe levels, and 18.5 hours before fatal levels. "Just" bring a few scuba rebreather scrubber cartridges and put them in front of the recirculation fans (which Dragon already has for ISS).

It is parts per million, so it is by volume or molar. For this purpose, they are interchangeable. If an astronaut consumes 19 cubic feet of oxygen per day, he generates 18 cubic feet of CO2 per day or  .75 cubic feet per hour. This represents a .75/350 hourly increase of the proportion of CO2 or 2142 ppm/hour.

To clarify a bit:
0-20,000: no noticeable effects or very little incumberance
20,000-70,000: symptoms of CO2 intoxication
70,000 +: CO2 poisoning, loss of consciousness, death, etc.

It will reach the 20,000 level in 9 hours and the 70,000 mark in 32 hours.

Soyuz' fast rendevous is 6 hours.

I'm a physicist doing a quick estimation, that's my excuse for PPMv=PPMm.
So it looks like you could do 3 astronauts with quick rendezvous, they'd just be a bit loopy by the time they got up there... 3 astronauts for a couple hours (enough to get back, provided someone rigged together a way to control the arm and release it from the ground) would be totally fine.

EDIT:Not that I'm suggesting we do it... It's just that they most likely could survive.

[QuantumG]

The CST-100 pressure vessel is just another component. So far Boeing hasn't integrated anything.

From public information that is what people would conclude.

If you have other information, share it. If not, you're just making a unverifiable claim.

[mkent]

The CST-100 pressure vessel is just another component. So far Boeing hasn't integrated anything.

From public information that is what people would conclude.

I disagree.  With publicly available information, anyone with experience in the field knows pretty much where they are in the development process.

If you have other information, share it. If not, you're just making a unverifiable claim.

Just look at their CCiCap milestones:

4) Software Integrated Engineering Release 2.0
5) Landing, Recovery, & Ground Communication Design Review
7) Integrated Stack Force & Moment Wind Tunnel Test
10) Spacecraft Primary Structures CDR
11) Service Module Propulsion System CDR
13) Launch Vehicle Adapter CDR
16) Avionics Software Integration Lab Multi-String Demonstration Test
17) Pilot-in-the-Loop Demonstration
18) Software CDR

In addition, Boeing has taken the launch-pad and crew-access mods...

http://www.americaspace.com/?p=62533

...and the ISS docking adapter to a CDR level.

http://boeing.mediaroom.com/2014-8-26-Boeing-Continues-Progress-on-Improved-Space-Station-Docking-System

Then there's the big one:

19) Integrated CDR

Structures, propulsion, avionics, software, mission control interface, launch vehicle adapter, docking adapter, and launch pad mods all at CDR, plus the integrated CDR.

SpaceX is ahead on some testing, but Boeing is ahead on the design.  Sierra Nevada is nowhere close on either.

[the_other_Doug]

>
I'm confident that SpaceX will be able to design and install the needed systems, but it's not a given that it will be easy.  Learning from history, some of them may require some redesign along the way and become real pacing items for a 2017 launch.  And as with most things, the items that will rear up and bite them in the butt aren't necessarily on their (or our) radar at the moment.

-Doug

SpaceX is using an ECLSS made by Paragon SDC, and developed during COTS-1 for commercial spacecraft. IIRC they're also providing systems for Orion.

Good, and I hope their products work well and need very little tweaking.  I wasn't trying to forecast doom for the ECS (or whatever acronym you wish to use for it, I tend to use the Apollo acronyms out of habit).  I was just coming up with the first example that came to mind.

There are, of course, a lot of other systems that SpaceX will have to add to their cargo version of the spacecraft to make it a manned spacecraft -- just as Boeing has to develop the same kinds of systems for their spacecraft.  It doesn't surprise me that they might be using the same contractors for some systems, either.  But every manned space vehicle America has produced to date has dealt with major rework issues in critical systems late in their development cycles, most of which have caused delays in the flight schedules.  As I said, I'd bet you any money that the things that pop up as critical, last-minute reworks are probably not even on their radar right now.

It's just hard to plan for that kind of thing, ya know?  If you knew what was going to become your major pain-in-the-ass beforehand, you would know to fix it earlier and then something else would come to the forefront as the pacing item.  You can try to leave room in the schedules for this kind of thing, but you really can only let it play itself out the best you can.

-Doug

With my shield, not yet upon it

[QuantumG]

Just look at their CCiCap milestones:

[..]

SpaceX is ahead on some testing, but Boeing is ahead on the design.  Sierra Nevada is nowhere close on either.

None of your listed milestones support the argument that Boeing has done any hardware integration or software integration of the on-orbit stages of flight. That's the claim that people keep making about Boeing and for which there is no evidence at all. Boeing hasn't been contracted for that work yet, and Boeing doesn't do work before they have a contract in hand. They learnt that mistake the hard way.

[mkent]

Just look at their CCiCap milestones:

[..]

SpaceX is ahead on some testing, but Boeing is ahead on the design.  Sierra Nevada is nowhere close on either.

None of your listed milestones support the argument that Boeing has done any hardware integration or software integration of the on-orbit stages of flight. That's the claim that people keep making about Boeing and for which there is no evidence at all. Boeing hasn't been contracted for that work yet, and Boeing doesn't do work before they have a contract in hand. They learnt that mistake the hard way.

Huh?  I'm not trying to be mean, but do you not know what a CDR is?

[sublimemarsupial]

Just look at their CCiCap milestones:

[..]

SpaceX is ahead on some testing, but Boeing is ahead on the design.  Sierra Nevada is nowhere close on either.

None of your listed milestones support the argument that Boeing has done any hardware integration or software integration of the on-orbit stages of flight. That's the claim that people keep making about Boeing and for which there is no evidence at all. Boeing hasn't been contracted for that work yet, and Boeing doesn't do work before they have a contract in hand. They learnt that mistake the hard way.

Huh?  I'm not trying to be mean, but do you not know what a CDR is?

A CDR is a powerpoint, nothing more. You don't have to (necessarily) do dev testing, and you certainly don't QTP or ATP anything. QuantumG is totally right here.

[joek]

A CDR is a powerpoint, nothing more. You don't have to (necessarily) do dev testing, and you certainly don't QTP or ATP anything. QuantumG is totally right here.

You cannot state that CDR involves only "a powerpoint, nothing more";. What is required for CDR is program-specific.  All we know is that Boeing passed CDR--as defined by NASA as part of the CCiCap milestones and schedule--and that others did not.

[QuantumG]

So, we again come back to the fact that everyone who is claiming Boeing has done more work than the other competitors has no way to prove their claims. As long as everyone agrees to this, I think we know how we should treat these claims.

[jongoff]

Btw, is not oxygen but CO2 poisoning one of the problems. The other being humidity control (with water extraction being, of course, the hard one).

The trick they're using for humidity control is super clever and simple. Not sure if it's public knowledge though, so I'd want to check with my source before I blab details.

~Jon

[Atomic Walrus]

I'm a bit dismayed that a lot of people here haven't bothered to learn much about NASA program management.  Here's a short overview: (Please shorten the link, breaks site format - Chris).

A critical design review is a lot more than a Powerpoint presentation.  It's a review that you do when the design is substantially done.  The reason for the review is that it's a lot more expensive and difficult to fix problems after you've started fabricating hardware.  These processes seem burdensome, but they were developed from painful, expensive experience on the part of the military and NASA when developing high technology projects. 

It's true that we don't know the exact content of Boeing's CDR.  We do know that SpaceX and SNC have not completed their CDRs.  If the CDR is a cakewalk with no real content, it does not reflect well on those companies to not have completed it yet. 

[QuantumG]

If the CDR is a cakewalk with no real content, it does not reflect well on those companies to not have completed it yet.

Who said it was a cake walk? I've heard it described as a PhD confirmation where the audience is full of undergraduates.

[Sesquipedalian]

Boeing hasn't been contracted for that work yet, and Boeing doesn't do work before they have a contract in hand. They learnt that mistake the hard way.

What incident are you referring to by "learning the hard way"?

[QuantumG]

Boeing hasn't been contracted for that work yet, and Boeing doesn't do work before they have a contract in hand. They learnt that mistake the hard way.

What incident are you referring to by "learning the hard way"?

I had in mind the EELV program.. but I've heard Boeing people say it and don't know what they had in mind.

[woods170]

A critical design review is a lot more than a Powerpoint presentation.  It's a review that you do when the design is substantially done.  The reason for the review is that it's a lot more expensive and difficult to fix problems after you've started fabricating hardware. 

Correct. But it's even more expensive and more difficult to fix problems, resulting from the CDR, after you've begun INTEGRATING your hardware components into an integrated spacecraft.
And that's why Boeing had done only marginal integration activities (at best) before completion of their CDR.
Meaning that as of the end of august (this year) Boeing had no integrated CST-100 spacecraft (not even a partially integrated one) to show off, unlike SpaceX at their Dragon 2 presentation. Hence the mock-up only display when Boeing officially presented the CST-100 in last June, two months before completion of their CDR.

[yg1968]

The CST-100 pressure vessel is just another component. So far Boeing hasn't integrated anything.

From public information that is what people would conclude.

If you have other information, share it. If not, you're just making a unverifiable claim.

He is in a position to know.

[yg1968]

A CDR is a powerpoint, nothing more. You don't have to (necessarily) do dev testing, and you certainly don't QTP or ATP anything. QuantumG is totally right here.

You cannot state that CDR involves only "a powerpoint, nothing more";. What is required for CDR is program-specific.  All we know is that Boeing passed CDR--as defined by NASA as part of the CCiCap milestones and schedule--and that others did not.

SpaceX is on the verge of completing its CDR. I suspect that they will be done by the time CCtCap actually starts (when the protest is over).

[LouScheffer]

Huh?  I'm not trying to be mean, but do you not know what a CDR is?

CDRs, and testing, are both ways to try to catch bugs before they create a big problem.   Both are needed and both are used on critical projects.  A CDR has a group of smart and experienced designers see if there is any problem they can think of with a design.  It can work well, but it can miss problems that people just don't think of (for example, the Fregat stage of the recent Galileo failure doubtless went through a CDR, but they did not spot this problem.)

Testing can find bugs that no-one thought of, but can miss problems, too, since not all combinations of circumstances can be tested (or example, the Fregat stage of the recent Galileo failure was tested, and similar models used extensively, but a problem still occurred.)

Testing and relevant experience can help at CDRs - "How do we know that tank won't freeze?  Here's our temperature data from previous missions using that tank configuration..."  and CDRs can help direct testing to places the designer may not have though of.

The fastest path to a working system - how much testing to do before the CDR, and how much after - is a matter of engineering judgement.  Just knowing that Boeing has completed their CDR, but SpaceX is scheduling their abort tests earlier, is not enough to tell who is ahead.  You'd need a very detailed look into both efforts to tell that.

[baldusi]

Huh?  I'm not trying to be mean, but do you not know what a CDR is?

CDRs, and testing, are both ways to try to catch bugs before they create a big problem.   Both are needed and both are used on critical projects.  A CDR has a group of smart and experienced designers see if there is any problem they can think of with a design.  It can work well, but it can miss problems that people just don't think of (for example, the Fregat stage of the recent Galileo failure doubtless went through a CDR, but they did not spot this problem.)

Testing can find bugs that no-one thought of, but can miss problems, too, since not all combinations of circumstances can be tested (or example, the Fregat stage of the recent Galileo failure was tested, and similar models used extensively, but a problem still occurred.)

Testing and relevant experience can help at CDRs - "How do we know that tank won't freeze?  Here's our temperature data from previous missions using that tank configuration..."  and CDRs can help direct testing to places the designer may not have though of.

The fastest path to a working system - how much testing to do before the CDR, and how much after - is a matter of engineering judgement.  Just knowing that Boeing has completed their CDR, but SpaceX is scheduling their abort tests earlier, is not enough to tell who is ahead.  You'd need a very detailed look into both efforts to tell that.

From what I read about the article, NASA thought that not having an integrated system before CDR is a feature, not a bug. As it reads, it would seem that they consider that if they found anything at CDR having to redo the integration is costlier and require more time than catching it at CDR. Thus, Boeing is doing it the NASA way and they feel more confident on that way of doing things. Given their experience on doing hard stuff, they might have a point. I would be very careful to dismiss this as "old thinking".

[TomH]

CDRs, and testing, are both ways to try to catch bugs before they create a big problem.   Both are needed and both are used on critical projects.  A CDR has a group of smart and experienced designers see if there is any problem they can think of with a design.  It can work well, but it can miss problems that people just don't think of (for example, the Fregat stage of the recent Galileo failure doubtless went through a CDR, but they did not spot this problem.)

If I am not mistaken, Boeing used this approach in development of the 787. The entire design was refined down to the last detail in 3-D on CAD programs before anything was fabricated. Other than the battery problem, which this would not have detected, the transition from CAD to CAM was very smooth. The plane has performed remarkably well (other than battery). Back in the days when pressurized cabins and jet turbines were new, you drew two dimensional elevation plans from all three axes, built prototypes, did some testing, then went into production, hoping not to face catastrophic failures like the De Havilland 106 Comet. The 787 integrates the best of everything that has been learned about aircraft design over the last 65 years with cutting edge technology like carbon composite materials. The CAD created prior to production of the plane is infinitely more sophisticated than just a collection of Power Point Presentations and Word Documents.

I would think that Boeing has taken a similar approach with CST-100. While I admire the pluck taken by SNC and SpaceX, I can see why NASA would see the Boeing design as the safest, based on proven design, and also why NASA would have complete confidence in Boeing's design process. As has been said, the purpose is not to demonstrate innovation, but to provide access to ISS. This is not to say that I do not have concerns over the price or that I doubt some politicians stuck their fingers in the pie. I don't doubt those things at all. Nevertheless, I can see a logic by which this design was chosen.