SpaceX Falcon 9/Dragon CRS-2 SpX-2 MISSION GENERAL DISCUSSION

[Jim]

p.s. Those numbers exclude the weight of racks, ECLSS, power, etc.  Those likely add significant mass, but I haven't seen any credible numbers.

Those are part of the basic Dragon mass and not charged to the payload

Right, specifically per CRS: "customer cargo" is without packaging; "cargo" is with packaging.  NASA pays for "cargo" exclusive of the racks, etc.  (In any case, if as previously someone suggests that lack of cargo indicates a shortfall in capability, the etc among other things needs to be considered.)

No, that is not what I meant.  The basic Dragon has all the cargo accommodations already in it.  It isn't reconfigured for each launch.  The "packaging" isn't racks, ECLSS, power, etc, but the cargo transfer bags and the foam in them.

[john smith 19]

No, that is not what I meant.  The basic Dragon has all the cargo accommodations already in it.  It isn't reconfigured for each launch.  The "packaging" isn't racks, ECLSS, power, etc, but the cargo transfer bags and the foam in them.

That's some pretty heavy foam. 

[SpacexULA]

That's some pretty heavy foam. 

It is quite common for packaging even for commercial goods to outweigh the product being shipped.  I don't know how many times I have pealed 100lb of wood/foam/plastic off a 80lb server rack.

Considering the cargo will go though 8g of force, and the devices being shipped are often very delicate, and much of the packing is not really reusable (They don't use packing peanuts, they use packaging more akin to the way a computer/monitor is shipped.  The packaging is high volume and not repurposable). I could very easily see in some cases the packaging quadrupling the volume and doubling the mass

[Norm38]

A lot of the stuff we have shipped to us now comes packed surrounded by those sealed air bags.  Lots of volume, very little mass.  And once the bags are popped they compress down to almost nothing for disposal.  I wonder if something akin to that could help keep weight down?

[SpacexULA]

A lot of the stuff we have shipped to us now comes packed surrounded by those sealed air bags.  Lots of volume, very little mass.  And once the bags are popped they compress down to almost nothing for disposal.  I wonder if something akin to that could help keep weight down?

Those bags have horrible failure modes, if they pop you then have item bouncing around in the box.  They are pretty much there to only prevent the object from shifting, they don't really protect the object.

They use higher mass padding because the ISS receives many one of a kind items, and when shipping such items the last thing you want to explain to the interested parties is their experiment was lost because NASA tried to save money on packaging.

Cygnus is going to be the "Star" when it comes to pressurized payload up mass anyway.

[joek]

No, that is not what I meant.  The basic Dragon has all the cargo accommodations already in it.  It isn't reconfigured for each launch.  The "packaging" isn't racks, ECLSS, power, etc, but the cargo transfer bags and the foam in them.

Right; apologies I wasn't clear, as that's what I meant (we appear to be in violent agreement).  It's spelled out in the CRS contract:

NASA will provide internal cargo to the Contractor including packing materials (bags, foam, flight support equipment). Cargo combined with packing materials and/or flight support equipment is referred to as "customer cargo". NASA will provide external cargo to the Contractor without flight support equipment, referred to as "usable cargo".

[joek]

That's some pretty heavy foam. 

It is quite common for packaging even for commercial goods to outweigh the product being shipped.  I don't know how many times I have pealed 100lb of wood/foam/plastic off a 80lb server rack.

Based on totals for COTS-2/3 and CRS-1, packaging does not appear to be onerous...

--- Up
Cargo = 860kg
Cargo w/packaging = 974kg
Packaging = 114kg = 11.7% of cargo w/packaging
--- Down
Cargo = 13891379kg
Cargo w/packaging = 1565kg
Packaging = 186kg = 11.9% of cargo w/packaging

edit: correct down-mass.

[IRobot]

Total Up Cargo: 575 kilograms / 1268 pounds
Total Up Cargo+Packaging: 677 kilograms / 1493 pounds

Total Down Cargo: 1210 kilograms / 2668 pounds
Total Down Cargo+Packaging: 1370 kilograms / 3020 pounds

More down cargo also means more fuel for de-orbit. Is that taken in consideration?

[Lars_J]

Of course. Do you really think that they aren't aware of the propellant margins??

[QuantumG]

Of course. Do you really think that they aren't aware of the propellant margins??

I believe IRobot was referring to the armchair quarterbacks questioning the payload capability of the Dragon.

[joek]

For those keeping score (edit: references COTS-2/3, SpX-1, SpX-2)...

[beancounter]

For those keeping score (edit: references COTS-2/3, SpX-1, SpX-2)...

Ah!  Was the cargo taken up and back in COTS 2/3 part of their CRS contract?

Edit:  Ok we're looking at the % of packaging.  My bad   

[Geron]

Hello All,

Does anyone know when the back up launch windows are if March 1 doesn't work out for weather or other reasons? I am going to Florida March 7-11 and am hoping for a little luck that might make a viewing possible!!

PS. Totally off topic but I just got a model s performance and fyi the car is totally amazing and I highly recommend it. I feel like I'm in a space ship every time I drive to work:)

[IRobot]

Of course. Do you really think that they aren't aware of the propellant margins??

I believe IRobot was referring to the armchair quarterbacks questioning the payload capability of the Dragon.

Yes, I wasn't questioning if SpaceX was aware of that, I was questioning if the contract takes it in consideration...

[Chris Bergin]

For those keeping score (edit: references COTS-2/3, SpX-1, SpX-2)...

Ah!  Was the cargo taken up and back in COTS 2/3 part of their CRS contract?

Edit:  Ok we're looking at the % of packaging.  My bad   

Yes. SpaceX was paid for the upmass and downmass provided, per the $/kg in their CRS contract. (I'm told

[Lars_J]

Of course. Do you really think that they aren't aware of the propellant margins??

I believe IRobot was referring to the armchair quarterbacks questioning the payload capability of the Dragon.

Yes, I wasn't questioning if SpaceX was aware of that, I was questioning if the contract takes it in consideration...

SpaceX has a contract to deliver a certain amount of cargo over a certain number of flights. From NASA's perspective it does not matter how much propellant is used to do so.

[oiorionsbelt]

It looks like the 677kg up mass for Dragon does not include the Two Heat Rejection Subsystem Grapple Fixtures (HRSGFs) in Dragons trunk. Does anyone know their mass?

[Silmfeanor]

From the SpaceX twitter:

https://twitter.com/SpaceX/status/305033979826946048

#Dragon launches 3/1 – Submit your questions by video & we'll play during live launch webcast! #AskSpaceX pic.twitter.com/Knabrq7EGb

Perhaps some video-savvy members here want to ask something? Or even questions about SpaceX in general...

[mlindner]

In advance of the launch, NASA will host a briefing on NASA's human
deep-space exploration progress at 2 p.m. Wednesday, Feb. 27, at the
agency's Kennedy Space Center in Florida. On Thursday, Feb. 28, NASA
will host a mission science briefing at 1 p.m. and a prelaunch news
conference at 3 p.m. All three briefings will be carried live on NASA
TV and the agency's website.

Regarding the Feb. 27 briefing, is there any significance to them doing this directly before CRS flight? Are they trying to avoid making NASA look bad by not having vehicles of its own?

[collectSPACE]

Regarding the Feb. 27 briefing, is there any significance to them doing this directly before CRS flight?

They are going to have media gathering at KSC for the launch; they have a captive audience, so they are using it.