SpaceX Dragon 2 Updates and Discussion - Thread 3

[Wolfram66]

....

Unconventional thinking ($2.6B) versus conventional thinking ($4.2B). Why do you think the Crew Dragon pressure suit looks cool whereas the Starliner suit does not less so.

I called the Boeing spacesuit a "Smurf" suit considering the exterior colour.

The SpaceX spacesuit looks like some Zhodani battle armour from the Traveller RPG universe.

I think the Boeing suits look like Space Teletubbies, whilst SpaceX are a direct rip-off of the Peacekeeper uniforms from Hunger Games 2 & 3

[Comga]

Regarding pure oxygen.. if I was to design a capsule, I would demand that everything inside can sustain pure oxygen without going up in flames. Oxygen and nitrogen are stored separately. If N2 gets damaged and can't release gas, the atmosphere would become pure oxygen over time. Or there is a oxygen leak that increases the oxygen content uncontrollably or there is a cabin breach and there is not enough N2 for a sensible mixture.. there are many scenarios where pure oxygen can happen. In these cases, you don't want your crew to burn alife.
I am also pretty sure that pure oxygen is not the intended design, so I would guess it is for contingency only.

I used to have a very strong opinion on spacecraft atmospheres until I did some reading on the subject.
We can raise the level of discussion here and the educational value if we swap out for “If I was in charge...” an inquiry to the experts on the forum, who are second to none. While there are some “appeals to authority” and annoyance at answering some questions multiple times, most are more than willing to share their experience and help us all come up to speed

So given that Dragon 2 like Drago 1 will have an open hatch to the ISS, which I believe has a near sea level interior atmosphere, what is it likely to have

[Norm38]

I have a compromise. Why does Dragon2 need to carry any compressed nitrogen gas for the cabin?  Nitrogen isn’t consumed.
So the D2 is sealed with sea level air. During its time in space, CO2 is scrubbed, O2 added.  N2 just sits there. In the event there was an air leak, once sealed, pressurize to 3.5psi O2. Can still dock to ISS, just need to bleed in ISS air to raise the pressure. Is there a way to do that slowly?  The bends only happens on depressurization, but no need to rush it.

Could that explain D2 possibly having O2 gas only?

[Semmel]

Regarding pure oxygen.. if I was to design a capsule, I would demand that everything inside can sustain pure oxygen without going up in flames. Oxygen and nitrogen are stored separately. If N2 gets damaged and can't release gas, the atmosphere would become pure oxygen over time. Or there is a oxygen leak that increases the oxygen content uncontrollably or there is a cabin breach and there is not enough N2 for a sensible mixture.. there are many scenarios where pure oxygen can happen. In these cases, you don't want your crew to burn alife.
I am also pretty sure that pure oxygen is not the intended design, so I would guess it is for contingency only.

I used to have a very strong opinion on spacecraft atmospheres until I did some reading on the subject.
We can raise the level of discussion here and the educational value if we swap out for “If I was in charge...” an inquiry to the experts on the forum, who are second to none. While there are some “appeals to authority” and annoyance at answering some questions multiple times, most are more than willing to share their experience and help us all come up to speed

So given that Dragon 2 like Drago 1 will have an open hatch to the ISS, which I believe has a near sea level interior atmosphere, what is it likely to have

Ok fair enough. I included that statement to make sure that my statement is perceived as speculation. Of course I would also prefer the statement of experts familiar with the subject and I would not made my statement if there was an expert coming forwards and solving this mystery.

[SimonFD]

I was a little surprised by one of the pictures in the Teslarati spacesuit article. Dragon 2 will use a pure oxygen environment?
https://www.teslarati.com/spacex-crew-dragon-simulator-spacesuit-gallery/#jp-carousel-81456

I'm wondering if there's confusion here between the normal flight environment and the requirements of the suit in a depressurization scenario. I believe I read (although I now can't seem to find the reference) that NASA want the suits to use 100% oxygen at 3.5psi.

So, if the capsule seals fail, the suits can deliver the required 20% oxygen (via partial pressure)

[pospa]

Three pics from media event today: CD upper hatch, training cabin interior from Hawthorne (to me more realistic then the unit in JSC) and interior design sketches.

Correct, the HQ simulator is more up to date than the JSC one. Still no hand-rails, camera holders and seat-mounted flight controls though (sorry, couldn't resist the dig    )

Wrong. Besides the hand rail around the side hatch, I hope Woods you noticed 2nd picture of this L2 post: https://forum.nasaspaceflight.com/index.php?topic=46190.msg1847212#msg1847212 
Seat arm rest containing 6 buttons for communication. (sorry, couldn't resist the dig  )

[abaddon]

Communication != “flight controls”.

[woods170]

Three pics from media event today: CD upper hatch, training cabin interior from Hawthorne (to me more realistic then the unit in JSC) and interior design sketches.

Correct, the HQ simulator is more up to date than the JSC one. Still no hand-rails, camera holders and seat-mounted flight controls though (sorry, couldn't resist the dig    )

Wrong. Besides the hand rail around the side hatch, I hope Woods you noticed 2nd picture of this L2 post: https://forum.nasaspaceflight.com/index.php?topic=46190.msg1847212#msg1847212 
Seat arm rest containing 6 buttons for communication. (sorry, couldn't resist the dig  )

Touché.
But I will point out that buttons for communication hardly qualify as "seat mounted flight controls".

[su27k]

Haven't seen these flight control photos posted, they seem to be from the non-capsule simulator and is more up to date then the controls in the JSC mockup. Too bad the resolution is not high enough to read the text on 0813-spacex-2476-1.jpg, it seems to be a manual or check list?

Image Credit: Roberto Baldwin / Engadget

[kdhilliard]

Those Engadget photos are great!

Note the clear plastic shields/guards/covers over the buttons.  As I earlier posted in the Spacesuit Revealed thread, 01:32 into the intro video for the Commercial Crew crew assignment announcement there is a 5 second clip showing Sunita Williams (suited, with gloves on, visor almost closed) operating controls.  She is show opening the cover for the inboard right control group by pressing down on the bottom tab of the cover to start it down, then pulling down on the top.  They appear to open about 135°, limited by the bottom tab resting against the panel.  They are not spring-loaded but remain down until they are closed by hand.

[Herb Schaltegger]

I have a compromise. Why does Dragon2 need to carry any compressed nitrogen gas for the cabin?  Nitrogen isn’t consumed.
So the D2 is sealed with sea level air. During its time in space, CO2 is scrubbed, O2 added.  N2 just sits there. In the event there was an air leak, once sealed, pressurize to 3.5psi O2. Can still dock to ISS, just need to bleed in ISS air to raise the pressure. Is there a way to do that slowly?  The bends only happens on depressurization, but no need to rush it.

Could that explain D2 possibly having O2 gas only?

I don’t know that D2 has a nitrogen tanks but while N2 isn’t metabolically consumed, it is still lost through normal and designed-for cabin leak rates. N2 and O2 are replenished accordingly to maintain both ppO2 as well as total atmospheric pressure. D2’s nominal mission duration and tested leak rates may make this issue insignificant enough that N2 isn’t carried for ISS missions but any use beyond LEO would almost certainly require N2 if SpaceX wants to avoid a pure-O2 cabin atmosphere.

[vt_hokie]

I hope there's a safeguard for the cut mains beyond just the "use only after landing" warning next to the button!

[zack]

I am guessing you have to select the desired function, e.g. "Cut Mains" and then you have to execute it by pressing the "Fire Pyro" button.

[jpo234]

I hope there's a safeguard for the cut mains beyond just the "use only after landing" warning next to the button!

They would still have the Super Dracos. Could they be used for a powered landing in an emergency (like originally planned)?

[woods170]

I hope there's a safeguard for the cut mains beyond just the "use only after landing" warning next to the button!

They would still have the Super Dracos. Could they be used for a powered landing in an emergency (like originally planned)?

I wouldn't bet on it.

[woods170]

I am guessing you have to select the desired function, e.g. "Cut Mains" and then you have to execute it by pressing the "Fire Pyro" button.

Correct, it is a multi-step procedure.

[Robotbeat]

I was a little surprised by one of the pictures in the Teslarati spacesuit article. Dragon 2 will use a pure oxygen environment?
https://www.teslarati.com/spacex-crew-dragon-simulator-spacesuit-gallery/#jp-carousel-81456

I'm wondering if there's confusion here between the normal flight environment and the requirements of the suit in a depressurization scenario. I believe I read (although I now can't seem to find the reference) that NASA want the suits to use 100% oxygen at 3.5psi.

So, if the capsule seals fail, the suits can deliver the required 20% oxygen (via partial pressure)

Bingo. If you didn't have an elevated oxygen percentage at 3.5psi, the astronauts would suffocate. To maintain sea level oxygen levels, you need 3psi. Anything below 1psi for any length of time would be fatal no matter how acclimated the astronauts were, and 1psi out of 3.5psi is still a higher oxygen percentage than Earth's atmosphere.

Effectively, we're talking 3.5psi ~pure oxygen.

In fact, aren't the pressure suits still fed near-pure oxygen at cabin pressure so that there's enough oxygen in there if there's a sudden depressurization event?

[gongora]

Some recent contract details:

1. The purpose of this modification is to add the requirements to provide the capability to mount or stow Ammonia Emergency Response (AER) hardware.  Note: The AER requirement also affects CLIN 001 and PCM task orders. See NNK14MA74C Mod 050, NNK16MA03T PCM -1 Mod 010 and NNK16MA58T PCM 2 Mod 010.

This one modified the CCTCap contract and all of the PCM task orders.  The mods for PCM-1 and PCM-2 had funding attached (about $600k total).

1. The purpose of this modification is to change the Post Certification Mission 1 (PCM-1) Milestone Values which occur as a result of CR6, changes to CCT-REQ-1130 and JSC 22538 Health Stabilization requirements.
Note: The CR6 CCT-REQ-1130 and JSC 22538 Health Stabilization requirement changes also affect CLIN 001 and PCM task orders. See NNK14MA74C Mod 047, NNK16MA58T PCM-2 Mod 008 and NNK17MA01T PCMs 3-6 Mod 001.

This one also modified the CCTCap contract and all of the PCM task orders.  It increases the cost of each mission by around $80k.

[Alexphysics]

I don't know if this has been talked about and answered anywhere on the forum, but I find this info interesting enough. Facebook user Michael Grabois has posted this on the SpaceX facebook group talking about who will be in charge of the procedures on Dragon, Starliner and all of that during launch, ascent and when docked to the ISS. Pretty much what one would expect, but a further confirmation is always good. I'll quote here his post just in case anyone can't read it directly on facebook.

Can't find the original discussion topic about Capcoms and keep-out zones at the ISS, but I talked to a NASA Flight Director this morning about general operations between the various Mission Controls for the commercial crew launches.

The TL;DR version: Starliner is similar to the Shuttle, while Dragon is similar to a Soyuz.

For Starliner's mission, Boeing has contracted mission operations to MCC-H. ULA will man the Booster console (or whatever it'll be called) from KSC, and all of the powered flight rocket stuff will go through them while all of the crew and Starliner vehicle stuff will be handled by JSC's ascent team. Upon final staging, the ULA team is done and JSC controls all aspects of the vehicle through docking, undocking, and landing.

For Crew Dragon, SpaceX has control of the vehicle (launcher and capsule) from prelaunch until docking. NASA will have representatives at MCC-X just like they do at MCC-M for a Soyuz launch, because it's NASA's crew. Once Dragon gets into the Keep Out Zone around the ISS, MCC-X is still in charge of the Dragon but now has to defer to MCC-H to get a go/no-go for docking. Post-docking, during quiescent operations, MCC-H is in charge of Dragon, but MCC-X controllers are on 2-hour standby in case they're needed. I don't know (because I didn't ask) anything about who monitors Dragon systems during quiescent ops or if/when the vehicle is periodically powered up for system status checks. Following all docked operations, when the crew is ready to come home, MCC-X will re-take control of Dragon for powerup, and after MCC-H gives the go for undocking, it's MCC-X's vehicle again through recovery operations.

The details are buried within various Flight Rules documents, which I have not dug into yet (and to the best of my knowledge are not available online).

[Coastal Ron]

I don't know if this has been talked about and answered anywhere on the forum, but I find this info interesting enough. Facebook user Michael Grabois has posted this on the SpaceX facebook group talking about who will be in charge of the procedures on Dragon, Starliner and all of that during launch, ascent and when docked to the ISS. Pretty much what one would expect, but a further confirmation is always good. I'll quote here his post just in case anyone can't read it directly on facebook.

Can't find the original discussion topic about Capcoms and keep-out zones at the ISS, but I talked to a NASA Flight Director this morning about general operations between the various Mission Controls for the commercial crew launches.

The TL;DR version: Starliner is similar to the Shuttle, while Dragon is similar to a Soyuz.
...

Congrats on finding that, and very interesting indeed. And it makes sense given the way Boeing and SpaceX have created the transportation systems.