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

[LouScheffer]

This being America, we can put a price on anything.  It look like the primary customer (NASA) paid $133.3M and got exactly what they paid for.  It looks like OrbComm paid at most $3.5M (They said the satellite cost $6.5M and the insurance of $10M would cover satellite + launch costs).  So if we consider OrbComm a complete failure, then the score for this mission is 133.3/(133.3+3.5) = 97.4%.

1.  Costs are not the methodology used to compute mission success
2.  Anyways, your numbers are wrong.  OrbComm launch and spacecraft costs must be included since the NASA number also included all costs.  Or just use about $50 million for NASA launch costs.

First, why not use costs?  In a perfect world, you could hire someone to launch your satellite.  If it gets into the specified orbit, you pay them.  If not, you pay nothing.  This seems like the fairest cost model, though it's not traditional in rocketry.

So in this case, the score for SpaceX the company (assuming Dragon makes it back) is $133.3M out of $136.8M possible, or 97.4%.

As you point out, the score for the Falcon 9 alone is different.  If they had sold the mission to a primary customer for $54M, then they would get 54/(54+3.5) = 93.9% of the possible money.  Had this been the situation, however, there would not have been the second burn constraint.  In this case, if we take SpaceX at their word they had a 95% chance of completing the second burn, then the score is (54+0.95*3.5)/(54+3.5) = 99.7%.

[Jim]

1.  First, why not use costs?  In a perfect world, you could hire someone to launch your satellite.  If it gets into the specified orbit, you pay them.  If not, you pay nothing.  This seems like the fairest cost model, though it's not traditional in rocketry.

2. As you point out, the score for the Falcon 9 alone is different.  If they had sold the mission to a primary customer for $54M, then they would get 54/(54+3.5) = 93.9% of the possible money.  Had this been the situation, however, there would not have been the second burn constraint.  In this case, if we take SpaceX at their word they had a 95% chance of completing the second burn, then the score is (54+0.95*3.5)/(54+3.5) = 99.7%.

1.  Wrong.  launch vehicle providers get their money whether the launch is successful or  not.  So money is not a relevant measure for determining mission success.  Meeting requirements that is what is used.

2.  The 95% does not enter in the equation.

[joek]

1.  Wrong.  launch vehicle providers get their money whether the launch is successful or  not.  So money is not a relevant measure for determining mission success.  Meeting requirements that is what is used.

Are you speaking to commercial contracts in general or NLS et. al.?  I was under the impression that full payment under NLS et. al. typically requires successful delivery of the payload to the intended destination or xfer orbit, otherwise the provider receives a subset of the total amount?  E.g., under CRS there are progress payments but the final payment(s) are contigent on successful completion of the mission.

[MP99]

1.  Wrong.  launch vehicle providers get their money whether the launch is successful or  not.  So money is not a relevant measure for determining mission success.  Meeting requirements that is what is used.

Are you speaking to commercial contracts in general or NLS et. al.?  I was under the impression that full payment under NLS et. al. typically requires successful delivery of the payload to the intended destination or xfer orbit, otherwise the provider receives a subset of the total amount?  E.g., under CRS there are progress payments but the final payment(s) are contigent on successful completion of the mission.

Because CRS is not a launch contract - it's a contract for Dragon to deliver cargo to ISS?

cheers, Martin

[hrissan]

1.  Wrong.  launch vehicle providers get their money whether the launch is successful or  not.  So money is not a relevant measure for determining mission success.  Meeting requirements that is what is used.

Are you speaking to commercial contracts in general or NLS et. al.?  I was under the impression that full payment under NLS et. al. typically requires successful delivery of the payload to the intended destination or xfer orbit, otherwise the provider receives a subset of the total amount?  E.g., under CRS there are progress payments but the final payment(s) are contigent on successful completion of the mission.

Because CRS is not a launch contract - it's a contract for Dragon to deliver cargo to ISS?

cheers, Martin

Good point. In light of this the price of 133 millions does not seem too big, though it is more than flight of F9 itself.

[A_M_Swallow]

Having useless (excess) fuel on board sounds wasteful.

No, it's a good idea and it's called margin. Without margin the Dragon's mission would have been lost too.

I'm sure he's saying excess fuel over the O2 to burn it.

The prop left for the restart is a small proportion of the total upper stage prop at launch. I suspect it needs only a tiny imbalance of consumption of O2 over kero during ascent to just leave a slight imbalance of kero over O2 for the restart. Thus, enough kero but not enough O2.

cheers, Martin

So a little more LOX in the upper stage and the Falcon 9 could have delivered both payloads.

How much more LOX was needed to increase the probability of orbiting the OrbComm satellite from 95% to 99% ?

The extra mass will effect the first stage.  Can future Falcon 9 missions use the increased margins to increase reliability?
Or will the maximum mass of secondary payloads need reducing?

[Jim]

Wrong. There is no need to add more LOX, just not burn the upperstage longer than planned due to the problemd with the first stage. 

[Robotbeat]

Wrong. There is no need to add more LOX, just not burn the upperstage longer than planned due to the problemd with the first stage. 

Hoping theyll neer have another engine out is not an option. There will be engine-outs in the future, and adding margin is going to be needed. Falcon 9 v1.1 should be capable of enough margin.

[MP99]

Wrong. There is no need to add more LOX, just not burn the upperstage longer than planned due to the problemd with the first stage. 

Hoping theyll neer have another engine out is not an option. There will be engine-outs in the future, and adding margin is going to be needed. Falcon 9 v1.1 should be capable of enough margin.

They don't intentionally load mismatched lox & kero. There is a call during both first & second stage f9 ascent, something like "propellant usage active", signalling they are adjusting MR to ensure lox & kero are exhausted at the same time. You see the same on ULA telemetry as RL10 MR adjusts.

ISTM it only needs to get this fractionally out to end up with the tiny imbalance they suffered. Maybe related to this still being a young LV.

cheers, Martin

[kevin-rf]

Wrong. There is no need to add more LOX, just not burn the upperstage longer than planned due to the problemd with the first stage. 

Hoping theyll neer have another engine out is not an option. There will be engine-outs in the future, and adding margin is going to be needed. Falcon 9 v1.1 should be capable of enough margin.

What? The engines should be at least as reliable as they are on other vehicles. We don't know that data point yet. The answer if you fear another engine out is to reduce the size of the payload so it will not be adversely affected by a "reasonable" vehicle under performance.   

[Robotbeat]

Wrong. There is no need to add more LOX, just not burn the upperstage longer than planned due to the problemd with the first stage. 

Hoping theyll neer have another engine out is not an option. There will be engine-outs in the future, and adding margin is going to be needed. Falcon 9 v1.1 should be capable of enough margin.

What? The engines should be at least as reliable as they are on other vehicles.

There are nine of them, though. So in ten or twenty flights youll have one or two engine outs. Unless you're a lot better than other engines.

We don't know that data point yet. The answer if you fear another engine out is to reduce the size of the payload so it will not be adversely affected by a "reasonable" vehicle under performance.   

And sell the margin at a reduced price to secondaries which aren't as risk sensitive. Which is exactly what Spacex did.

[kevin-rf]

Sure thing! Lets write petition to SpaceX so their launch will end up like this one if they got problem with engine. So there will be no need to burn upper stage longer :
<YouTube Video Snipped>
It is always better to not delivery any payload!

That was a solid motor letting go (and it had 9), not a liquid engine failure. Not even the same mode of failure. It was a sudden rapid loss of pressure in a solid motor case, followed by activation of the FTS, not a RUD

Btw. I am sure Jim can quickly answer this, on a Delta II if a solid hangs up and does not separate does the payload make it's desired orbit? So if you have to drag a dead liquid engine all they way through staging do you get to your desired orbit if you lack the margin to do so?

[peter-b]

Quick query -- although the Dragon is scheduled to remain on station for an extended period, is it possible that mission control may decide to bring undocking and reentry forward if all loading/unloading tasks are completed a long way ahead of the planned departure date?

[ugordan]

on a Delta II if a solid hangs up and does not separate does the payload make it's desired orbit?

As with any such type of event that leads to either engine underperformance or greater weight dragged along than expected, the outcome will depend on vehicle performance margins. For Delta II, the scenario you mention happened in August 1995 with launch of Koreasat 1 which was placed in a lower than planned orbit.

So if you have to drag a dead liquid engine all they way through staging do you get to your desired orbit if you lack the margin to do so?

The mass of the engine is already factored in, whether it's burning or not so it's different than a case of strap-on booster failing to jettison. What really hurts you is lowered thrust leading to increased gravity losses. Again, either you have enough margin to cover for this or you don't. Obviously, if you "plan" for an early engine failure, you need bigger margins to cover for it than if the engine fails late in the stage burn.

[Jim]

Btw. I am sure Jim can quickly answer this, on a Delta II if a solid hangs up and does not separate does the payload make it's desired orbit? So if you have to drag a dead liquid engine all they way through staging do you get to your desired orbit if you lack the margin to do so?

It happened on Koreasat.  The spacecraft had to burn some of its propellant to get to a useable orbit.

[douglas100]

They don't intentionally load mismatched lox & kero. There is a call during both first & second stage f9 ascent, something like "propellant usage active", signalling they are adjusting MR to ensure lox & kero are exhausted at the same time. You see the same on ULA telemetry as RL10 MR adjusts.

ISTM it only needs to get this fractionally out to end up with the tiny imbalance they suffered. Maybe related to this still being a young LV.

cheers, Martin

Yes, in my original post on this I was thinking only about propellant margin and not about LOX/kero usage ratio. I doubt it is possible to control mixture ratio accurately enough so that one propellant component is not left "wasted." (Anyone who knows otherwise feel free to correct this assumption.)

Anyway, it's all water under the bridge. I don't know of any other plan to carry another large secondary payload on an ISS Dragon. This particular situation will probably not arise again.

So this incident has highlighted why margin is important (not just propellant, but mass--the Dragon was probably not carrying is maximum payload). They were lucky. Dragon got the good luck and Orbcomm just missed out. If the failure had happened even 20 seconds later, they might both have made it.

[Prober]

Wrong. There is no need to add more LOX, just not burn the upperstage longer than planned due to the problemd with the first stage. 

think he worded the question wrong Jim.   Should SpaceX add more margin in the 2nd stage?

[Garrett]

Wrong. There is no need to add more LOX, just not burn the upperstage longer than planned due to the problemd with the first stage. 

think he worded the question wrong Jim.   Should SpaceX add more margin in the 2nd stage?

This was a once off mission, wasn't it? Isn't it possible that future secondaries for different companies will only need the lower orbit, therefore eliminating the need for a restart? Or maybe just a restart for orbit circularization and a small altitude (<50 km say) boost.

[Jim]

Wrong. There is no need to add more LOX, just not burn the upperstage longer than planned due to the problemd with the first stage. 

think he worded the question wrong Jim.   Should SpaceX add more margin in the 2nd stage?

No, my point still stands, because it was a secondary payload.  If you want more margin, then the secondary payload needs to be smaller.

[kevin-rf]

Wrong. There is no need to add more LOX, just not burn the upperstage longer than planned due to the problemd with the first stage. 

think he worded the question wrong Jim.   Should SpaceX add more margin in the 2nd stage?

No, my point still stands, because it was a secondary payload.  If you want more margin, then the secondary payload needs to be smaller.

Considering the short life of the upper stage and secondary, what are the chances that future secondaries will not be on ISS bound missions?

It does raise an interesting question for me, what are the expected secondary lifetimes of SpaceX GTO missions. The perigee on those missions should be quite low, correct?