SpaceX Falcon 9/Dragon CRS SpX-1 MISSION GENERAL DISCUSSION

[Antares]

I think anyone blaming NASA constraints for the brief Orbcomm life needs to watch Congressional hearings occasionally.  These are missions to resupply the Space Station, not launch secondaries.  SpaceX and Orbcomm knew what the constraints were and launched anyway.  I don't think the failure or constraints had anything to do with it being a NASA primary, though it had everything to do with insufficient time to react to a Station conjunction possibility.

Also, where do you get 1 in 20?  Once the 1st stage is off-nominal, previous analyses of likelihood go out the window.

Extinguishing one chamber / half the thrust on the other possible CC launcher would definitely cause LOM but doubtful it would cause LOC.  Black zones were eliminated a long time ago.  Depending on the abort logic the remaining chamber could even gimbal to null rates before an emergency MECO and getting the crew carrier off the stack.

[Kaputnik]

Also, where do you get 1 in 20?

"While there was sufficient fuel on board to do so, the liquid oxygen on board was only enough to achieve a roughly 95% likelihood of completing the second burn, so Falcon 9 did not attempt a restart," says SpaceX

source: http://www.flightglobal.com/news/articles/spacex-details-incorrect-orbital-insertion-377615/

[rickl]

It's clear that if it was anything other than a launch to the ISS, the second stage could have reignited and would likely have boosted the Orbcomm satellite to a useful orbit.

I don't blame NASA for their caution.  It would have been reckless to endanger a $100 billion asset and the lives of the astronauts for the sake of a test satellite.  Orbcomm was just unlucky in this case.

[Lars_J]

Regarding the discussions about the F9 performance margin for this mission - This NASA press conference video linked to in this thread/post ( http://forum.nasaspaceflight.com/index.php?topic=30184.msg972720#msg972720 ) suggests that the Spx-1 mission was ballasted as well, to make up for a lighter than usual Dragon load.

[cd-slam]

Dragon's Hatch is Closed
At approximately 3:55AM PT tomorrow morning, astronauts will detach the spacecraft from the space station using the station’s robotic arm. Tune in here beginning at 4:00AM PT for live coverage of deberthing and reentry activities.

Presume there's a typo in there somewhere. Earlier in this thread unberthing time was given as 7:55am Eastern, that would be 4:55am Pacific.

[go4mars]

Late tonight, station astronauts will depressurize the spacecraft.

Okay, I'm curious.  Why is this done?  Isn't the pressurization good for the cargo and for the spacecraft's integrity during and after reentry?

http://forum.nasaspaceflight.com/index.php?topic=30059.msg972869#msg972869

Beat me to the question Lee Jay.  I'm curious about that too.  It seems like a strange thing to do.  Maybe if there is no structural reason for internal pressure, it's just handy being just a little bit lighter?  Hopefully those 400 urine bags are strong...

[rickl]

They must be referring to the vestibule.  It makes no sense to depressurize Dragon.  It wouldn't save that much weight.

[Lee Jay]

Okay,  I'm curious.  Why is this done?  Isn't the pressurization good for the  cargo and for the spacecraft's integrity during and after reentry?

The word "vestibule" was likely omitted accidentally?

They must be referring to the vestibule.  It makes no sense to depressurize Dragon.  It wouldn't save that much weight.

Okay, so this makes a whole bunch more sense to me.

[BobCarver]

Dragon's Hatch is Closed
At approximately 3:55AM PT tomorrow morning, astronauts will detach the spacecraft from the space station using the station’s robotic arm. Tune in here beginning at 4:00AM PT for live coverage of deberthing and reentry activities.

Presume there's a typo in there somewhere. Earlier in this thread unberthing time was given as 7:55am Eastern, that would be 4:55am Pacific.

Might be a daylight time issue. Europe goes off daylight time tonight while the US stays on. What a snafu to have different times to go off DST between the US and Europe!

[mlindner]

Okay,  I'm curious.  Why is this done?  Isn't the pressurization good for the  cargo and for the spacecraft's integrity during and after reentry?

The word "vestibule" was likely omitted accidentally?

They must be referring to the vestibule.  It makes no sense to depressurize Dragon.  It wouldn't save that much weight.

Okay, so this makes a whole bunch more sense to me.

Depressurizing the Dragon could probably destroy a lot of the equipment/samples inside the spacecraft. I doubt plastic bags of urine wouldn't explode in a depressurized environment.

[StephenB]

A bag of urine would only burst if there were air in it. Fluids are much less compressible. The urine is frozen in this case anyway.

[Nomadd]

A bag of urine would only burst if there were air in it. Fluids are much less compressible. The urine is frozen in this case anyway.

Like you said, it's frozen. But fluids being less compressible doesn't help since fluid would fast become gas at zero pressure.

[mlindner]

A bag of urine would only burst if there were air in it. Fluids are much less compressible. The urine is frozen in this case anyway.

Like you said, it's frozen. But fluids being less compressible doesn't help since fluid would fast become gas at zero pressure.

Wouldn't the frozen urine sublimate in zero pressure?

[StephenB]

I stand corrected. 

[Joffan]

Did the three new ISS crewmembers get a chance to look around the Dragon? The hatch closed about a day? after their arrival so there could have been time...

[Garrett]

Wouldn't the frozen urine sublimate in zero pressure?

Not if it's in an airtight bag. It needs to be exposed to low* pressure to sublimate.

* I use the term "low" because there's no such thing as "zero" pressure.

[DaveJ576]

Note to Elon Musk and his PAO: Improve your EOM coverage! More updates! Also, get a plane in the air and get some good live video of the chutes and splashdown. It would go a long way to maintaining interest...

[Lars_J]

Note to Elon Musk and his PAO: Improve your EOM coverage! More updates! Also, get a plane in the air and get some good live video of the chutes and splashdown. It would go a long way to maintaining interest...

The plane in the air during the C2 mission was a NASA asset. I think it was up to them [NASA] to provide the same live video as last time.

[Garrett]

Note to Elon Musk and his PAO: Improve your EOM coverage! More updates! Also, get a plane in the air and get some good live video of the chutes and splashdown. It would go a long way to maintaining interest...

SpaceX is focused on reducing mission costs. Live EOM coverage hardly makes sense in that context. Remember, live video from a Pacific Ocean location requires expensive satellite bandwidth.
When future versions of Dragon can land on land, then we'll get to see some good video of chutes and touchdown. Need to be patient and wait until about 2015 for that to happen, all going well.

[DaveJ576]

I know. I just wanted to see some eye candy!