SpaceX COTS Demo 2/3 Updates (THREAD 2)

[2552]

So I guess the others will be added to the dedicated Orbcomm flight in the second half of 2012?

[Antares]

It must be frustrating for SpaceX. Not too long ago, they thought they were going to be launching as soon as Dec 19, but just a few days ago, they were still receiving new requirements constraining the rendezvous profile. How weird is it that such basic mission parameters are still in flux at this very late stage in the game?

Yes, butters, what new requirements are you talking about?  I'm calling bravo sierra without proof.  SSP 50808 was completed prior to COTS in 2006.  It has been updated 3 times since then, but the COTS partners have negotiating power on any changes.

Is this delay NASA's or SpaceX's fault? If SpaceX keeps missing their launch dates, they are likely to lose commercial launch customers! (something we don't need in this economy....)

See above.  Requirements written long ago, taking SpaceX longer than expected.  However, since NASA serves as both legislator and judge in this case, SpaceX may be suffering from NASA saying "no that's not what we meant."  However in the other direction, SpaceX too has had 5 years to ask NASA what it meant.

I don't think this is a reflection of how commercial launch dates might go as commercial spacecraft integration is a lot simpler.

[ugordan]

I don't think this is a reflection of how commercial launch dates might go as commercial spacecraft integration is a lot simpler.

I think he means these delays will inevitably push everything else even more to the right, which could be more than some customers are willing to accept. SES comes to mind.

[Comga]

Aviation Week article says only one secondary payload, not two

AvWeek....

That's a definitive statement on one vs two Orbcomm secondary payloads. Would that be a significant improvement in safety or could it be driven by other SpaceX constraints like mass, deployment sequencing, or attachment development?  If one is safe, a second should increase the risk by less than a factor of two, and could they be operating where that is critical.

[Comga]

Aviation Week article says only one secondary payload, not two

It also says nadir berthing. Is that new or has it always been that way?  I recall the SpaceX images showing it at the zenith port. Is there a preference now that they don't have to accomodate the Shuttle?

[Space Pete]

Aviation Week article says only one secondary payload, not two

It also says nadir berthing. Is that new or has it always been that way?  I recall the SpaceX images showing it at the zenith port. Is there a preference now that they don't have to accomodate the Shuttle?

Nadir berthing was always the plan (as it is for all cargo vehicles). Zenith is a back-up port in case A) a vehicle becomes stuck at Nadir, or B) two vehicles are at ISS simultaneously.

[Robotbeat]

(Regarding 2 secondaries versus 1)... Maybe it has to do with spreading the risk a little bit... The Orbcomm payloads are mostly for demonstration purposes. By putting them on two separate launches (maybe? I just made that part up), they both are likely to get early data on the Orbcomm sats and they get a much greater chance of at least one being put into orbit. Plus, it should be slightly less risky for ISS on the first launch, and once the data from the first flight is analyzed, it should make the second one a lot less risky. But the first time a secondary is launched, there will always be a little extra potential risk involved, so it's good they're getting it taken care of with the demo flight instead of an operational flight (when all the pressure will be on keeping everything the same).

I'm glad that they're trying to demonstrate this sort of thing on this flight. It's a demo flight, that's what it's for! But we shouldn't be surprised when NASA asks for extra analysis, etc. That's just being responsible. It should also exercise SpaceX's analysis capabilities a bit.

[sdsds]

(Regarding 2 secondaries versus 1)... Maybe it has to do with spreading the risk a little bit...

Good thought.  Maybe there's also a per-payload cost (in terms of staff hours if nothing else) that SpaceX incurs doing the ISS risk analysis in a way that satisfies all the stakeholders?

[Antares]

The way I read it is that the Orbcomms were pulled entirely (my guess is that SpaceX did not want to spend the additional time convincing NASA that they were safe). I think the secondary Morring mentions is something without propulsion that will stay below the Station. Anyone know of a university-type payload that has been talked about for this launch?

I could be wrong. I don't think Orbcomm would go for being dropped off that low.

[RocketJack]

The way I read it is that the Orbcomms were pulled entirely (my guess is that SpaceX did not want to spend the additional time convincing NASA that they were safe). I think the secondary Morring mentions is something without propulsion that will stay below the Station. Anyone know of a university-type payload that has been talked about for this launch?

I could be wrong. I don't think Orbcomm would go for being dropped off that low.

ISS did the work to verify the initial deployment altitude was acceptable. SpaceX then decided there was too much mission risk to the docking to try to deploy in a higher orbit then descend down to ISS orbit. Prop margins were too low.

[MP99]

ISS did the work to verify the initial deployment altitude was acceptable. SpaceX then decided there was too much mission risk to the docking to try to deploy in a higher orbit then descend down to ISS orbit. Prop margins were too low.

Interesting, I had assumed Falcon would deploy Dragon below ISS, then boost apogee of the secondaries when safely separated.

cheers, Martin

[subzero788]

ISS did the work to verify the initial deployment altitude was acceptable. SpaceX then decided there was too much mission risk to the docking to try to deploy in a higher orbit then descend down to ISS orbit. Prop margins were too low.

What's your source on this?

[2552]

Now that the combined mission and Feb. 7 launch date are official, what time of day is the launch scheduled for?

[Apollo-phill]

Now that the combined mission and Feb. 7 launch date are official, what time of day is the launch scheduled for?

Using current TLEs for ISS (but may change with on orbit thrusting to maintain rbit) suggests that launch would probably be early morning EST (5-8am) period since ISS overflies Florida in that period a couple of times (NW to SE) ?


AP

[Apollo-phill]

More opportunities occurr later in day around 7pm to 9pm EST with ISS going over Florida SW to NE

AP

[Jim]

Dragon more than likely isn't going to do a standard launch and rendezvous and therefore the launch time isn't as predictable.  Dragon will launch and do some standalone maneuvering and ops away from the ISS.

[Jim]

Now that the combined mission and Feb. 7 launch date are official, what time of day is the launch scheduled for?

Using current TLEs for ISS (but may change with on orbit thrusting to maintain rbit) suggests that launch would probably be early morning EST (5-8am) period since ISS overflies Florida in that period a couple of times (NW to SE) ?


AP

wrong azimuth

[ugordan]

What's the launch constraint on launching into ISS orbit descending node? Is that azimuth forbidden from CCAFS?

Ah, it is.

[Apollo-phill]

More likely be in one of the later passes when ISS is moving SW to NE . Would seem suggest a night launch - would they try that ?

A later date would seem more preferable  if a daylight launch prefrred?

AP

[Apollo-phill]

They could of course launch during daylight on 7th Feb but would leave with a fair bit of catch up and maybe plane changes? Need  look at bit closer in detail figure out more 'optimum times' rather than these quick back-envelope looks 

AP