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

[QuantumG]

Out of curiosity QuantumG, have you ever actually developed software yourself?

Yes, do it for a living.

I've also gone through "code review" for a government agency.

I know their pain first hand.

[ChefPat]

How much software can dance on the head of a pin?

Well, say a typical NAND flash chip is about 1 cm2 and has a capacity of 32 GB. The head of a pin is about 1 mm2, so that's about 32 MB. Allowing for file system overhead and whatnot, that's about 30 MB of software on the head of a pin.

Is that pin [head] round in the shape of a disc or round in the shape of a ball?

[MP99]

How much software can dance on the head of a pin?

Well, say a typical NAND flash chip is about 1 cm2 and has a capacity of 32 GB. The head of a pin is about 1 mm2, so that's about 32 MB. Allowing for file system overhead and whatnot, that's about 30 MB of software on the head of a pin.

Is that pin [head] round in the shape of a disc or round in the shape of a ball?

Ooh - too subtle there!! Had to read it a couple of times (while composing my own response) before I got it.

cheers, Martin

[sojourner]

New software is worthy of a bump in the major version number. Show me a software shop where every patch requires a new version number. Not gonna happen.

Sorry about dredging this up a week later, but the irony of reading this on FireFox 15 was just too good to pass up.

[oldAtlas_Eguy]

The software versioning system used is arbitrary, which is that the meaning behind what the difference in a version identification value means is also arbitrary and is defined by the software developer team. Normally for a normal systems development on a cost plus NASA contract software is a deliverable with a very large set of requirements associated with it as to how it is written including the versioning system to be used. But SpaceX software is not a deliverable and does not have NASA specific requirements other than indirect requirements based on the VV requirements for ISS. There are also some detailed interface specifications that control SpaceX software design between the ISS and SpaceX flight hardware as well as interface specifications for between SpaceX ground control and NASA systems it must interface with. Adopting the NASA versioning control system may make it easier to deal with NASA but it is not a requirement.

[baldusi]

The software versioning system used is arbitrary, which is that the meaning behind what the difference in a version identification value means is also arbitrary and is defined by the software developer team. Normally for a normal systems development on a cost plus NASA contract software is a deliverable with a very large set of requirements associated with it as to how it is written including the versioning system to be used. But SpaceX software is not a deliverable and does not have NASA specific requirements other than indirect requirements based on the VV requirements for ISS. There are also some detailed interface specifications that control SpaceX software design between the ISS and SpaceX flight hardware as well as interface specifications for between SpaceX ground control and NASA systems it must interface with. Adopting the NASA versioning control system may make it easier to deal with NASA but it is not a requirement.

You can also have a version for your interface, and you can coordinate that with the NASA CVS. At the same time, I think, that the next software uptdate for the ISS was going to make a common packet to communicate with VV given the amount that they have to support (Soyuz/Progress/ATV/HTV/Dragon/Cygnus/Commercial Crew).

[manboy]

Approximately one month until launch.

[mikes]

How much software can dance on the head of a pin?

Well, say a typical NAND flash chip is about 1 cm2 and has a capacity of 32 GB. The head of a pin is about 1 mm2, so that's about 32 MB. Allowing for file system overhead and whatnot, that's about 30 MB of software on the head of a pin.

You're an order of magnitude out - there are 100 mm² in a cm².
If it's a circular pinhead with diameter 1mm, pi*r² = 0.78mm2
At 32GB/cm² that's 257MB (minus overhead).

Are we off topic yet?

[Ben the Space Brit]

How much software can dance on the head of a pin?

Well, say a typical NAND flash chip is about 1 cm2 and has a capacity of 32 GB. The head of a pin is about 1 mm2, so that's about 32 MB. Allowing for file system overhead and whatnot, that's about 30 MB of software on the head of a pin.

You're an order of magnitude out - there are 100 mm² in a cm².
If it's a circular pinhead with diameter 1mm, pi*r² = 0.78mm2
At 32GB/cm² that's 257MB (minus overhead).

Are we off topic yet?

This is what you get if you ask a bunch of engineers a rhetorical question. 

[Salo]

http://www.nasa.gov/missions/highlights/schedule.html

Date: October 7
Time: 8:34 p.m.
Mission: SpaceX-1 Commercial Resupply Services flight

0034UTC October 8

[corrodedNut]

Pardon my laziness, but do we know if there is to be any unpressurized/external cargo on this mission, or not until CRS-2?

[spacetraveler]

Why is the payload only 1000 pounds?

Does the station not need any more supplies?

[TrueBlueWitt]

Why is the payload only 1000 pounds?

Does the station not need any more supplies?

I am curious about that myself.. Is this Dragon up-mass limit on F9 v1.0 or is this cargo volume limited?

[yg1968]

Jim talked about Falcon 9 version 1.0 underperforming before. Perhaps this is what he meant.

[tigerade]

Jim talked about Falcon 9 version 1.0 under performing before. Perhaps this is what he meant.

It is true that 1.0 is underperfoming and that is why they are upgrading to 1.1.

However, I doubt that is the reason for 1,000 pounds of cargo this time.  Last time they had about 1300-1400 pounds of cargo with less fuel to work with.  This time SpaceX does not need need to perform the COTS2 objectives, they've already done that.  This time they are pretty much going to just approach and berth normally.  For that reason, I don't think underperformance is the issue here.  It's probably just that NASA doesn't need as much cargo as Dragon can actually take.

But then again, who is to care.  SpaceX is driving the UPS truck.  They aren't concerned with what's in it, just about getting the delivery safely there.  Though, I am also curious what cargo will be on this flight.  Hopefully we'll have the full cargo manifest soon.

[Joffan]

... It's probably just that NASA doesn't need as much cargo as Dragon can actually take.

But then again, who is to care.  SpaceX is driving the UPS truck.  They aren't concerned with what's in it, just about getting the delivery safely there.  Though, I am also curious what cargo will be on this flight.  Hopefully we'll have the full cargo manifest soon.

I'm not saying you're wrong about the requirements of the ISS being low at present, but it's kind of surprising that NASA are low-balling this one and then going ahead with another SpaceX supply run in December or January. As well as whatever they pack onto the Orbital demonstration run, if that happens in the same period.

Of course, it's entirely possible that 1000 pounds of the right sort of material has high value and NASA are perfectly happy to get that much into the station, with lower-value stuff waiting until (say) there's more space/personnel up there.

By comparison, the downmass capability of Dragon would seem to me to be immensely valuable. Perhaps that's the focus.

[tigerade]

By comparison, the downmass capability of Dragon would seem to me to be immensely valuable.

It is.  No other existing vehicle has significant downmass capability.  Remember that Progress, ATV, HTV, and Cygnus all burn up on re-entry. 

[Ben the Space Brit]

Pardon my laziness, but do we know if there is to be any unpressurized/external cargo on this mission, or not until CRS-2?

IIRC, the first trunk payload is going to be on SpX-3 next year.

CORRECTION:
I've just seen the article on the front page.  The first trunk cargo will be SpX-2 which could be as early as the end of this year, although I understand that there are some NASA documents that are saying mid-January 2013.

[IRobot]

Why is the payload only 1000 pounds?

Does the station not need any more supplies?

Volume limited?

[dasmoth]

Is there still supposed to be some late-load cargo on SpX-1?

Could the 1000lbs be a baseline figure chosen to make sure there is plenty of space/mass margin for late-loaded stuff?