SpaceX Falcon 9 / Dragon 2 : SpX-DM2 : May 27, 2020 : DISCUSSION

[Nomadd]

Is this only for DM-2 spacecraft or is it a final value for Crew Dragon? what' s the problem with its solar panels?

Expected degradation of solar panels by atomic oxygen if I understood it correctly. Not sure if it only impacts the DM-2 vehicle.

Is there a source for a concern about atomic oxygen or inadequate solar cell performance?
None have been indicated here.
It sounds like straight forward engineering conservatism combined with a lack of need.

Q: Why are solar arrays so limited?
A: NASA... All solar arrays degrade over time. The particular cells on this Dragon trunk given early are "worst case scenario" numbers. "Will watch their performance in flight and make a decision on data."

NASA wants to launch USCV-1/Crew-1 with 4 astros ASAP and they will bring DM-2 back a month before that, just enough time to review data. They don’t anticipate needing more time but will consider it if the need arrives and the data supports it.

Maybe just a certification that was never made. If it's determined to be a baseless concern after seeing how they do with a few months operation, would there be any problem using that data to certify them for longer and extend the mission even more if needed?
 I know the ISS mains have degraded much slower than originally assumed they would.

[Comga]

Expected degradation of solar panels by atomic oxygen if I understood it correctly. Not sure if it only impacts the DM-2 vehicle.

Is there a source for a concern about atomic oxygen or inadequate solar cell performance?
None have been indicated here.

The source is one of yesterday's press events on NASA.

Nothing specific points to either of those.
Do you have a particular press event, or better yet a time stamp, for any mention of atomic oxygen or solar cell quality?

Both are doubtful
Because the Dragon 2 solar cells have fixed orientations all normal to the long dimension of the ISS and the nominal velocity vector, exposure to atomic oxygen is going to be low.
SpaceX has been flying their own solar panels on Dragon 1 for a decade, albeit for shorter durations.
What is new is the conformal coating to protect the solar cells during ascent. My (educated) guess would be a low level concern about darkening from UV exposure or mechanical damage due to thermal cycling.


And yes, Nomadd. It was stated that NASA will monitor the performance of the solar panels on orbit and extend that limit if warranted. My (uneducated) guess is that it  won’t happen because it won’t be necessary.

[Alexphysics]

Expected degradation of solar panels by atomic oxygen if I understood it correctly. Not sure if it only impacts the DM-2 vehicle.

Is there a source for a concern about atomic oxygen or inadequate solar cell performance?
None have been indicated here.

The source is one of yesterday's press events on NASA.

Nothing specific points to either of those.
Do you have a particular press event, or better yet a time stamp, for any mention of atomic oxygen or solar cell quality?

Both are doubtful
Because the Dragon 2 solar cells have fixed orientations all normal to the long dimension of the ISS and the nominal velocity vector, exposure to atomic oxygen is going to be low.
SpaceX has been flying their own solar panels on Dragon 1 for a decade, albeit for shorter durations.
What is new is the conformal coating to protect the solar cells during ascent. My (educated) guess would be a low level concern about darkening from UV exposure or mechanical damage due to thermal cycling.


And yes, Nomadd. It was stated that NASA will monitor the performance of the solar panels on orbit and extend that limit if warranted. My (uneducated) guess is that it  won’t happen because it won’t be necessary.

Mission overview briefing. It was mentioned both by Steve Stich and Zeb Scoville. I'm sure it has to be somewhere on Youtube.

[Alexphysics]

And probably uneducated guesses about what thousands of engineers are concerned about saying it is not necessary isn't the right way to act. Idk, maybe they know more than the guys around here that have never even touched any of that hardware. They said the concern is low, just a monitor thing. Don't make it a bigger deal than it is but don't be complacent about it and say that monitoring won't even be needed.

[Comga]

Expected degradation of solar panels by atomic oxygen if I understood it correctly. Not sure if it only impacts the DM-2 vehicle.

Is there a source for a concern about atomic oxygen or inadequate solar cell performance?
None have been indicated here.

The source is one of yesterday's press events on NASA.

Nothing specific points to either of those.
Do you have a particular press event, or better yet a time stamp, for any mention of atomic oxygen or solar cell quality?

Both are doubtful
Because the Dragon 2 solar cells have fixed orientations all normal to the long dimension of the ISS and the nominal velocity vector, exposure to atomic oxygen is going to be low.
SpaceX has been flying their own solar panels on Dragon 1 for a decade, albeit for shorter durations.
What is new is the conformal coating to protect the solar cells during ascent. My (educated) guess would be a low level concern about darkening from UV exposure or mechanical damage due to thermal cycling.


And yes, Nomadd. It was stated that NASA will monitor the performance of the solar panels on orbit and extend that limit if warranted. My (uneducated) guess is that it  won’t happen because it won’t be necessary.

Mission overview briefing. It was mentioned both by Steve Stich and Zeb Scoville. I'm sure it has to be somewhere on Youtube.

Thanks
Here at 30:30-32:20
Stitch says that atomic oxygen is an issue, which is curious, but says that current worst case projections are ~120 days lifetime, and that they will monitor it on orbit. 
The odds are they will get enough data to refine the estimate upward but not need to test to it.
There was no mention at that time about any issues with the specific lot or type of solar cells.

[CorvusCorax]

Slightly off topic, buuuut yet very related.

In the Mission Overview briefing with Benji from May 1st.

Mission overview (archived video):

You can see various equipment being transported back and forth in the background, the majority of it is dishes for the cafeteria, garbage and cleaning materials, and the occasional trolley with equipment.  But then this: 37:00

What is this? Obviously a combustion chamber with throat and engine nozzle - but which one?
Is that a Merlin? Looks almost like one, except it kinda looks way too small for a Merlin. (There are merlins in the far background for size reference)
Raptor also looks different. Super Draco has a completely different design.

Is that a new engine design? Considering everyone is wondering about the side mounted lunar descent engines ... did SpaceX plant an easter egg in this video?

[Nomadd]

 Looks exactly like a Merlin to me. They're not that big.
 Spacex.com/news

[The Vorlon]

Maybe a MVac?

[Alexphysics]

Maybe a MVac?

MVac is much larger than that if it had a nozzle and if not it would be shorter. That thing has a nozzle so... you can guess it

[FutureSpaceTourist]

Nine years ago, SpaceX called its shot on capturing the flag
“I understand Atlantis also brought a unique American flag up to the station.”

ERIC BERGER - 5/4/2020, 3:51 PM

In the middle of the final flight of NASA's space shuttle, President Obama called up to the International Space Station to congratulate the crew on their mission. During the call on July 15, 2011, President Obama referenced a flag the four-person crew of STS-135 had brought with them into orbit.

“I understand Atlantis also brought a unique American flag up to the station, one that was flown on the very first shuttle mission and one that will reside on the ISS until an American commercial space company launches astronauts to the station,” President Obama said.

https://arstechnica.com/science/2020/05/final-shuttle-pilot-poised-to-return-us-flag-left-in-space-nine-years-ago/

Image caption:

Inside the International Space Station's Node 2, the STS-135 crew presented the Expedition 28 crew this special US flag and mounted it on the hatch leading to Atlantis.

[Joffan]

Maybe SpaceX should leave a flag for Boeing to pick up... I suggest this slight variation...

[Tommyboy]

Maybe SpaceX should leave a flag for Boeing to pick up... I suggest this slight variation...

Not just leave, but hide it on the ISS and give Boeing a good old pirate map, where the SpaceX-X marks the spot.

[atsf90east]

I do like that both Doug Hurley and Chris Ferguson were both on the STS-135 mission that left the flag.  No matter who gets there first, Boeing or SpaceX, it is returning to Earth with someone who placed it on the ISS.  That being said, I'm glad it's SpaceX who will get there first

[whitelancer64]

None of the press conferences directly addressed a question I submitted to#AskNasa about the command/control structure between NASA/SpaceX on this mission but it sounds like operations will be run from Hawthorne with SpaceX having dedicated individuals speaking to the crew, called COREs (the spelling is a guess).  Hopefully these details will be expanded in future briefings. 

On a second note, it was repeated stated by briefers that additional safety precautions were in place for Doug and Bob during training.  If you watched the video leading up to the crew press conference, NONE of the individuals helping with the training were wearing masks or gloves....

The videos of Bob and Doug are probably not recent. Those could have been from many months ago.

there was video of him doing NBL (pool) training which has to be recent

I've got a tweet from February of NBL training

https://twitter.com/NASA_Johnson/status/1231277497985183746

[Hog]

I do like that both Doug Hurley and Chris Ferguson were both on the STS-135 mission that left the flag.  No matter who gets there first, Boeing or SpaceX, it is returning to Earth with someone who placed it on the ISS.  That being said, I'm glad it's SpaceX who will get there first

hear, here, on the Ferguson/Hurley bit.
Yes, that flag was left there by people on an actual Shuttle Orbiter Vehicle.  STS was such a symbol of American tech. prowess.   Getting ISS crew rotation/safe haven capability back to America is very important. Space X also has the advantage(IMO) of using an American engine.

[Herb Schaltegger]

I know the ISS mains have degraded much slower than originally assumed they would.

Initial requirements for every on-orbit major element of Space Station Freedom was 30 years. During the design morph/de-scoping process that resulted in “ISS”, station lifetime was reduced to a nominal 15 years. However, the 30 year life had long-since been baked into the requirements for truss-mounted PV arrays, TCS radiators, pressurized module structures, etc. 

I was part of WP1 (pressurized elements, Boeing), not WP2 (truss and external systems, McDonnell Douglas), so I have only general awareness of the PV array life requirements.

That said, I would not at all be surprised that the initial 30 year design lifetime plus a healthy design margin is the reason why the PV arrays have performed better over time than planned for.

[billshap]

Is there a Press Kit available anywhere for DM-2?  Can anybody steer me to additional information about the flight well be controlled—capcoms, flight directors, Dragon console positions, flight control room, etc.?

[Steven Pietrobon]

Is there a Press Kit available anywhere for DM-2?  Can anybody steer me to additional information about the flight well be controlled—capcoms, flight directors, Dragon console positions, flight control room, etc.?

SpaceX normally release their two page press kits 24 hours before launch. I expect there will be a joint NASA/SpaceX press kit, but I don't know when that will be released. Hopefully a bit earlier than 24 hours before launch and longer than two pages!

[FutureSpaceTourist]

This should be interesting, given how hard Lori fought to make CC happen (such as not down selecting to only Boeing ...)

https://twitter.com/exploreplanets/status/1258811670006075393

The #CrewDragon countdown begins!

We discuss the exciting development with former @NASA Deputy Administrator @Lori_Garver on a new episode of Planetary Radio.

Listen where you get podcasts or at https://www.planetary.org/multimedia/planetary-radio/

[cebri]

I'm going to get a very nice birthday present if it finally launches on the 27th.