Quote from: Robotbeat on 10/08/2012 09:59 pmVery interesting, and not quite what anyone speculated about as a reason. ...not caused by a failure of the upper stage, not even necessarily because of extra gravity losses but because of ISS safety constraints.Don't you think that is caused by a lack of propellant?
Very interesting, and not quite what anyone speculated about as a reason. ...not caused by a failure of the upper stage, not even necessarily because of extra gravity losses but because of ISS safety constraints.
Quote from: joek on 10/08/2012 09:50 pmORBCOMM press release in updates thread. Interesting bit:QuoteHowever, due to an anomaly on one of the Falcon 9’s first stage engines, the rocket did not comply with a pre-planned International Space Station (ISS) safety gate to allow it to execute the second burn. For this reason, the OG2 prototype satellite was deployed into an orbit that was lower than intended. Could anyone explain a little more about what's meant by the ISS "safety gate"?
ORBCOMM press release in updates thread. Interesting bit:QuoteHowever, due to an anomaly on one of the Falcon 9’s first stage engines, the rocket did not comply with a pre-planned International Space Station (ISS) safety gate to allow it to execute the second burn. For this reason, the OG2 prototype satellite was deployed into an orbit that was lower than intended.
However, due to an anomaly on one of the Falcon 9’s first stage engines, the rocket did not comply with a pre-planned International Space Station (ISS) safety gate to allow it to execute the second burn. For this reason, the OG2 prototype satellite was deployed into an orbit that was lower than intended.
For modemeagle: in your simulations if F9v1 loses thrust from two engines at T+1:20 does the payload reach any orbit at all?
Quote from: cscott on 10/08/2012 08:48 pmFolks haven't mentioned this AFAICT, but it's worth noting that the Orbcomm "silence" may in fact be Orbcomm's fault/decision, not SpaceX's. SpaceX has been very forthcoming about their part of the flight, but they may well have contractual obligations (or just a need to have releases vetted by Orbcomm executives) which prevent them from speaking as freely about the Orbcomm-related aspects of the flight. Folks here have noted that Orbcomm was in a information blackhole even before the flight, with SpaceX's preflight materials not mentioning the Orbcomm satellite.Putting on my wild guessing hat, I'd suspect that the Orbcomm delivery was not in fact "nominal" but fell squarely under the terms of service SpaceX was contracted to provide. Secondary payloads get best-effort delivery, and off-nominal orbit insertion is one of the most likely results. Orbcomm may or may not have chosen to cover for that possibility with thrust resources on its own satellite (at the expense of a shorter lifetime in-orbit), but that was its own choice.Orbcomm will need to spin this even more than SpaceX, though. It knew this was a likely outcome of flying as a secondary payload but the wordsmiths are going to be very busy crafting a press release which all of SpaceX, Orbcomm, Orbcomm's executive which approved flying as a secondary payload, Orbcomm's insurance, and Orbcomm's investors are satisfied with.I don't believe OrbComm originally signed up as a secondary payload. They got screwed once already because SpaceX cancelled the F1, where they would have been the primary payload.
Folks haven't mentioned this AFAICT, but it's worth noting that the Orbcomm "silence" may in fact be Orbcomm's fault/decision, not SpaceX's. SpaceX has been very forthcoming about their part of the flight, but they may well have contractual obligations (or just a need to have releases vetted by Orbcomm executives) which prevent them from speaking as freely about the Orbcomm-related aspects of the flight. Folks here have noted that Orbcomm was in a information blackhole even before the flight, with SpaceX's preflight materials not mentioning the Orbcomm satellite.Putting on my wild guessing hat, I'd suspect that the Orbcomm delivery was not in fact "nominal" but fell squarely under the terms of service SpaceX was contracted to provide. Secondary payloads get best-effort delivery, and off-nominal orbit insertion is one of the most likely results. Orbcomm may or may not have chosen to cover for that possibility with thrust resources on its own satellite (at the expense of a shorter lifetime in-orbit), but that was its own choice.Orbcomm will need to spin this even more than SpaceX, though. It knew this was a likely outcome of flying as a secondary payload but the wordsmiths are going to be very busy crafting a press release which all of SpaceX, Orbcomm, Orbcomm's executive which approved flying as a secondary payload, Orbcomm's insurance, and Orbcomm's investors are satisfied with.
Quote from: modemeagle on 10/08/2012 06:11 pmQuote from: alexterrell on 10/08/2012 05:57 pmQuote from: MP99 on 10/08/2012 05:20 pmDepending on the payload, and if the engine failed early (ie navigation predicts it can't hit the target orbit even using all margin), I wonder if navigation might keep all eight engines firing - not do a MECO-1 at all and just hope everything survives the G overload (which could be up to 1.14 x nominal, ie 8/7ths).Reminder: all speculation from first principles.The 1.14 G overload would only cause stress (or rather compression) above plan at the cabin end. This might be an issue with tourists but hopefully not for cargos.At the engine end, the force on the frame is what the engines produce. It will be designed for 9 engines. 8 engines firing compared to 7 is still 8/9th of launch compression, even if the acceleration is higher. Simulating the flight, I get the following times:Engine out (9 drop to 8 engines): 80 seconds5G limit engine out (8 drop to 7 engines): 191.6 secondsS1 MECO: 195.3 secondsSkipping the 5G limit shutdown gives a Meco of 194.7 seconds and 47.4m/s acceleration.Run with an estimated payload of 6.6 tonnes.If it reaches 5G at 191.6s, then 47.4 m/s @ 194.7s can't be right because I make that only 4.8G.cheers, Martin
Quote from: alexterrell on 10/08/2012 05:57 pmQuote from: MP99 on 10/08/2012 05:20 pmDepending on the payload, and if the engine failed early (ie navigation predicts it can't hit the target orbit even using all margin), I wonder if navigation might keep all eight engines firing - not do a MECO-1 at all and just hope everything survives the G overload (which could be up to 1.14 x nominal, ie 8/7ths).Reminder: all speculation from first principles.The 1.14 G overload would only cause stress (or rather compression) above plan at the cabin end. This might be an issue with tourists but hopefully not for cargos.At the engine end, the force on the frame is what the engines produce. It will be designed for 9 engines. 8 engines firing compared to 7 is still 8/9th of launch compression, even if the acceleration is higher. Simulating the flight, I get the following times:Engine out (9 drop to 8 engines): 80 seconds5G limit engine out (8 drop to 7 engines): 191.6 secondsS1 MECO: 195.3 secondsSkipping the 5G limit shutdown gives a Meco of 194.7 seconds and 47.4m/s acceleration.Run with an estimated payload of 6.6 tonnes.
Quote from: MP99 on 10/08/2012 05:20 pmDepending on the payload, and if the engine failed early (ie navigation predicts it can't hit the target orbit even using all margin), I wonder if navigation might keep all eight engines firing - not do a MECO-1 at all and just hope everything survives the G overload (which could be up to 1.14 x nominal, ie 8/7ths).Reminder: all speculation from first principles.The 1.14 G overload would only cause stress (or rather compression) above plan at the cabin end. This might be an issue with tourists but hopefully not for cargos.At the engine end, the force on the frame is what the engines produce. It will be designed for 9 engines. 8 engines firing compared to 7 is still 8/9th of launch compression, even if the acceleration is higher.
Depending on the payload, and if the engine failed early (ie navigation predicts it can't hit the target orbit even using all margin), I wonder if navigation might keep all eight engines firing - not do a MECO-1 at all and just hope everything survives the G overload (which could be up to 1.14 x nominal, ie 8/7ths).Reminder: all speculation from first principles.
Quote from: mmeijeri on 10/08/2012 10:02 pmQuote from: Robotbeat on 10/08/2012 09:59 pmVery interesting, and not quite what anyone speculated about as a reason. ...not caused by a failure of the upper stage, not even necessarily because of extra gravity losses but because of ISS safety constraints.Don't you think that is caused by a lack of propellant?Well, at first, they said engine one exploded. Engine one didn't exploded but shut down. And then they said second stage didn't restart, now low on fuel. It's getting clear, romney is attacking elon again.
Very possibly. In any case, the situation must have been fairly clear as they didn't spend much time before deciding. According the ORBCOMM press release, separation was "approximately 9:00PM EST", ~L+25min, or ~15min after Dragon separation.
Quote from: Lurker Steve on 10/08/2012 10:03 pmQuote from: cscott on 10/08/2012 08:48 pmFolks haven't mentioned this AFAICT, but it's worth noting that the Orbcomm "silence" may in fact be Orbcomm's fault/decision, not SpaceX's. SpaceX has been very forthcoming about their part of the flight, but they may well have contractual obligations (or just a need to have releases vetted by Orbcomm executives) which prevent them from speaking as freely about the Orbcomm-related aspects of the flight. Folks here have noted that Orbcomm was in a information blackhole even before the flight, with SpaceX's preflight materials not mentioning the Orbcomm satellite.Putting on my wild guessing hat, I'd suspect that the Orbcomm delivery was not in fact "nominal" but fell squarely under the terms of service SpaceX was contracted to provide. Secondary payloads get best-effort delivery, and off-nominal orbit insertion is one of the most likely results. Orbcomm may or may not have chosen to cover for that possibility with thrust resources on its own satellite (at the expense of a shorter lifetime in-orbit), but that was its own choice.Orbcomm will need to spin this even more than SpaceX, though. It knew this was a likely outcome of flying as a secondary payload but the wordsmiths are going to be very busy crafting a press release which all of SpaceX, Orbcomm, Orbcomm's executive which approved flying as a secondary payload, Orbcomm's insurance, and Orbcomm's investors are satisfied with.I don't believe OrbComm originally signed up as a secondary payload. They got screwed once already because SpaceX cancelled the F1, where they would have been the primary payload. I think OG-2 are very cheap satellites, and Orbcomm have 18 of them. i suspect they rather lose 1/3 of the satellites than launch with falcon 1e or Pegasus.
As far as the "ISS safety gate"...The 2nd stage + Orbcomm ended up in the ~200 x 330 km orbit. The intent was for the 2nd stage to relight to boost to 350 x 750 km.If propellant in the 2nd stage was insufficient to complete the burn to 350 x 750 km with margins appropriate for any unknowns, if could instead end up in a ~400-430 x 330 km orbit, which might bring it close to ISS.The "safety gate" was probably related to having enough propellant for be sure that everything ended up in orbits not a hazard to ISS. Since it wasn't met - no relight....
Quote from: joek on 10/08/2012 10:34 pmVery possibly. In any case, the situation must have been fairly clear as they didn't spend much time before deciding. According the ORBCOMM press release, separation was "approximately 9:00PM EST", ~L+25min, or ~15min after Dragon separation.There isn't any "deciding". Launch vehicles are autonomous. There is no ground commanding. The propellant check failed so then the vehicle go on to next task in the flight program
Only one question, why deploy if it was not in the " pre-planned International Space Station (ISS) safety gate".. why detach it from the stage.. ?
Quote from: cordor on 10/08/2012 10:49 pmQuote from: Lurker Steve on 10/08/2012 10:03 pmQuote from: cscott on 10/08/2012 08:48 pmFolks haven't mentioned this AFAICT, but it's worth noting that the Orbcomm "silence" may in fact be Orbcomm's fault/decision, not SpaceX's. SpaceX has been very forthcoming about their part of the flight, but they may well have contractual obligations (or just a need to have releases vetted by Orbcomm executives) which prevent them from speaking as freely about the Orbcomm-related aspects of the flight. Folks here have noted that Orbcomm was in a information blackhole even before the flight, with SpaceX's preflight materials not mentioning the Orbcomm satellite.Putting on my wild guessing hat, I'd suspect that the Orbcomm delivery was not in fact "nominal" but fell squarely under the terms of service SpaceX was contracted to provide. Secondary payloads get best-effort delivery, and off-nominal orbit insertion is one of the most likely results. Orbcomm may or may not have chosen to cover for that possibility with thrust resources on its own satellite (at the expense of a shorter lifetime in-orbit), but that was its own choice.Orbcomm will need to spin this even more than SpaceX, though. It knew this was a likely outcome of flying as a secondary payload but the wordsmiths are going to be very busy crafting a press release which all of SpaceX, Orbcomm, Orbcomm's executive which approved flying as a secondary payload, Orbcomm's insurance, and Orbcomm's investors are satisfied with.I don't believe OrbComm originally signed up as a secondary payload. They got screwed once already because SpaceX cancelled the F1, where they would have been the primary payload. I think OG-2 are very cheap satellites, and Orbcomm have 18 of them. i suspect they rather lose 1/3 of the satellites than launch with falcon 1e or Pegasus.$6.5 Million each per: http://www.sncorp.com/press_more_info.php?id=371
Quote from: Jim on 10/08/2012 11:01 pmQuote from: joek on 10/08/2012 10:34 pmVery possibly. In any case, the situation must have been fairly clear as they didn't spend much time before deciding. According the ORBCOMM press release, separation was "approximately 9:00PM EST", ~L+25min, or ~15min after Dragon separation.There isn't any "deciding". Launch vehicles are autonomous. There is no ground commanding. The propellant check failed so then the vehicle go on to next task in the flight programJim: Is this a statement of fact based on flight telemetry or based on the operations of rockets in general and Falcon 9 in particular?
Can anybody make an educated guess on the orbit that the ORBCOMM's prototype OG-2 could possibly get to?And at this point it can't be said that SpaceX failed in regards to the OG-2 prototype, because it's not clear what it can't do at the lower orbit. It might be that it can complete all of it's tests at the lower orbit, or at least most of them and the important ones.
I'm guessing that your question is "Why not leave the Orbcomm satellite attached to Falcon Upper Stage and try the apogee raise a bit later at the next opportunity that is also safe for the ISS?" Are there limits on how long Falcon US can loiter up there and be effective?
Quote from: upjin on 10/08/2012 11:00 pmCan anybody make an educated guess on the orbit that the ORBCOMM's prototype OG-2 could possibly get to?And at this point it can't be said that SpaceX failed in regards to the OG-2 prototype, because it's not clear what it can't do at the lower orbit. It might be that it can complete all of it's tests at the lower orbit, or at least most of them and the important ones.I looked around and it appears that the OG-2 has a deltav capability of 140 m/s. From what I can tell the with a planned orbit of 350 x 700 km it was going to take about 110m/s to circularize at 700km. With only 140 m/s to use there is no way they can make it to the desired orbit.
in general
