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

[beancounter]

A bit off topic for SPX2 but a general SPX question.

SPX2 is planned to go up on 3/1 and come back down on 3/25. SPX1 didnt stay attached to the ISS for very long either. However, Dragon is supposed to be able to stay in LEO for a considerable time. Are there plan to keep one of the SPX mission attached to the ISS for an extended period of time? To see how the craft will do after a long time in space.

I wouldn't have thought that that would be a requirement of CRS.  This is a contract for cargo resupply, not further development of the Dragon Cargo spacecraft. 

[beancounter]

Interesting.  About double the downmass for CRS SpX-2 than upmass.

[IRobot]

Around Feb 8 anik's ISS schedule which references CBS News shifted the capture of the CRS-2 Dragon from Flight Day 3 to Flight Day 2.  Actually it is T+ 20 hours 20 minutes to capture.

That sounds very good for future man rated flights! Spending up to 3 days on Dragon with 6 crew mates would not be pleasant.

[Lars_J]

Will this be the first flight with unpressurized trunk cargo, or was that pushed back to CRS3?

[ChefPat]

Will this be the first flight with unpressurized trunk cargo, or was that pushed back to CRS3?

It looks like it'll be on this flight.
finely crafted link

[Robotbeat]

What's the junk in the trunk this time?

https://twitter.com/molliway/status/302205953644847104

[Joffan]

What's the junk in the trunk this time?

I refer you to this even more finely-crafted webpage 

CRS-2 will debut the use of Dragon’s Trunk section, capable of delivering unpressurized cargo, prior to the payload being removed by the ISS’ robotic assets after berthing.

Per L2 manifest documentation, this mission will carry two Heat Rejection Subsystem Grapple Fixture (HRSGF) – Grapple Bars in Dragon’s Trunk, for installation on the Mobile Base System (MBS) Payload and Orbit Replaceable Unit Accommodation (POA).

No downmass has yet been allocated for Dragon’s Trunk for CRS-2 or CRS-3, the latter set to carry three sets of science payloads alongside its compliment of primary upmass that will ride – as per usual – in the Dragon’s pressurized section.

And I'd still like to know... Is the trunk already loaded? I could see it being awkward loading now the Dragon is vertical, and they won't want to hold up integration to the stack long I guess.

[Robotbeat]

What's the junk in the trunk this time?

I refer you to this even more finely-crafted webpage 

CRS-2 will debut the use of Dragon’s Trunk section, capable of delivering unpressurized cargo, prior to the payload being removed by the ISS’ robotic assets after berthing.

Per L2 manifest documentation, this mission will carry two Heat Rejection Subsystem Grapple Fixture (HRSGF) – Grapple Bars in Dragon’s Trunk, for installation on the Mobile Base System (MBS) Payload and Orbit Replaceable Unit Accommodation (POA).

No downmass has yet been allocated for Dragon’s Trunk for CRS-2 or CRS-3, the latter set to carry three sets of science payloads alongside its compliment of primary upmass that will ride – as per usual – in the Dragon’s pressurized section.

And I'd still like to know... Is the trunk already loaded? I could see it being awkward loading now the Dragon is vertical, and they won't want to hold up integration to the stack long I guess.

Ah, yes. I looked on the link but skimmed too fast, I guess. Thanks! BTW, the link I gave above is a twitter post by a SpaceX employee who did some of the wiring for the unpressurized section.

[bjornl]

Interesting.  About double the downmass for CRS SpX-2 than upmass.

Not really surprising as they haven't had much downmass capability since the Shuttles retired.

[Star One]

Interesting.  About double the downmass for CRS SpX-2 than upmass.

Not really surprising as they haven't had much downmass capability since the Shuttles retired.

Must be a bit of a backlog of stuff to come down?

[Lar]

I wouldn't have thought that that would be a requirement of CRS.  This is a contract for cargo resupply, not further development of the Dragon Cargo spacecraft. 

I don't think it's a requirement. But it would be helpful if NASA/ISS allowed some long duration attachment. However I could see them declining to do so because of the risk to the downmass if long duration caused a failure in, say, the parachutes. OR declining to do so because they don't have the ports to spare. I got the impression that ISS is somewhat port constrained and can't support surplus vehicles just hanging around.

[Antares]

A major consideration for ISS on-orbit duration limits required by NASA is the MMOD shielding.  The requirements are levied on a statistical basis: likelihood of a particle of X energy in Y days.  The longer one wants to be a part of Station (be it private visiting vehicle or permanent module), the worse case the particle might be, the heavier the shielding must be.  So for the time attached to Station it's a trade off of vehicle dry mass, size of launch vehicle and duration attached to Station.

SpaceX makes marketing statements for what SpaceX believes its capabilities to be.  The limit of NASA concurrence with those statements can be inferred from what NASA allows Dragon to do near and at Station.

[Robotbeat]

Cargo Dragon has no windows, its heatshield is almost entirely covered. I think it could do pretty well as far as MMOD.

[happyflower]

I wouldn't have thought that that would be a requirement of CRS.  This is a contract for cargo resupply, not further development of the Dragon Cargo spacecraft. 

I don't think it's a requirement. But it would be helpful if NASA/ISS allowed some long duration attachment. However I could see them declining to do so because of the risk to the downmass if long duration caused a failure in, say, the parachutes. OR declining to do so because they don't have the ports to spare. I got the impression that ISS is somewhat port constrained and can't support surplus vehicles just hanging around.

I didnt consider down mass time limits and other engineering considerations that Antares shared. Thanks.

Not that NASA has to help SpaceX with anything they shouldn't, but at some point it will be good to see if SpaceX has been representing the Dragon fairly well in regards to its stay in orbit capabilities. Especially if they decide to move people around.

[krytek]

Why would SpaceX need NASA co-op to prove long duration? I don't see why they can't prove it on a zero down mass flight after detaching from ISS.

[Lar]

Why would SpaceX need NASA co-op to prove long duration? I don't see why they can't prove it on a zero down mass flight after detaching from ISS.

Good point. Are any of the flights zero downmass (or maybe just garbage downmass that has no risk of loss) that we know of at this time? I've seen some manifest stuff on L2 but it's pretty high level.

Earlier flight is better than later, of course.

[mr. mark]

This is way off topic and has nothing to do with the SpX-2 mission.Please take this conversation to the SpaceX general discussion.

[Mader Levap]

Still 1 march? They are being less and less late with each launch.

[stone]

600kg is as empty as the last resuply flights of the Dragon. The Falcon 9 V1.0 will never show what it can lift. 3000kg lack of performance between the written performance and the shown one is really astonishing. As this is the last launch the numbers should be corrected by SpaceX soon without losing to much credibility. 6,622 kg - 10,454 kg to LEO is more likely like to be 6,622 kg - 7,454 kg.

[Lar]

MEDIA ADVISORY: M13-029

...

SpaceX's Dragon capsule will be filled with about 1,200 pounds of
supplies for the space station crew and experiments being conducted
aboard the orbiting laboratory.

Why only 1200 pounds of upmass? I think I missed why. Seems low.