Quote from: Lars_J on 05/07/2014 09:32 pmI find it interesting that this mission will also make a 2nd stage disposal burn, based on this warning: http://forum.nasaspaceflight.com/index.php?topic=34591.msg1194554#msg1194554Previously the F9v1.0 upper stages were allowed to naturally decay - but they seem to explicitly de-orbit the 2nd stage now for LEO (and near LEO) missions. Is this done to:A. Gain confidence in upper stage restarts, or...B. Be a good neighbor and dispose orbital debris quicker, or...C. Practice 2nd stage reentry profiles, or...D. All of the above? (B) is legally required in this case. The satellites will be dropped in a 715km x 715 km orbit. That's too high to meet the requirement for natural decay, which is re-entry within 25 years. So they have to do something, at the very least to bring the perigee below about 400 km. So you may as well burn a little longer and de-orbit deterministically, perhaps for the other reasons.
I find it interesting that this mission will also make a 2nd stage disposal burn, based on this warning: http://forum.nasaspaceflight.com/index.php?topic=34591.msg1194554#msg1194554Previously the F9v1.0 upper stages were allowed to naturally decay - but they seem to explicitly de-orbit the 2nd stage now for LEO (and near LEO) missions. Is this done to:A. Gain confidence in upper stage restarts, or...B. Be a good neighbor and dispose orbital debris quicker, or...C. Practice 2nd stage reentry profiles, or...D. All of the above?
Hmm, what about a small eject able "black box" type of thing that stores the telemetry and is ejected the moment the stage breaks up. This could be triggered something like the launch abort type of trigger system. The data itself could probably fit on a micro SD card, or a combination of several (to provide redundancy), which are very small and lightweight. The bigger challenge might be to bring the thing down in one piece and the even bigger one would be finding it once it has landed, probably somewhere in the middle of the ocean. I am sure there are people on this board that have a better idea why this would or would not work (and what would be required to make it work).
What protects the black box?
The black boxes that I am familiar with.Ruggedize memory surrounded with 2-3 inches of thermal insulation. Encased in a steel body. The conductors to the memory are designed to thermally fuse/disconnect so they no longer conduct heat to the memory. A water activated pinger is external, not sure it would survive reentry.
Quote from: yg1968 on 05/07/2014 06:52 pmCould the second stage eventually land in Australia? Would that be a problem from an ITAR perspective?That would be only applicable to ISS or Orbcomm type trajectories (inclinations in the 50's)
Could the second stage eventually land in Australia? Would that be a problem from an ITAR perspective?
Quote from: Elmar Moelzer on 05/08/2014 02:56 pmHmm, what about a small eject able "black box" type of thing that stores the telemetry and is ejected the moment the stage breaks up. This could be triggered something like the launch abort type of trigger system. The data itself could probably fit on a micro SD card, or a combination of several (to provide redundancy), which are very small and lightweight. The bigger challenge might be to bring the thing down in one piece and the even bigger one would be finding it once it has landed, probably somewhere in the middle of the ocean. I am sure there are people on this board that have a better idea why this would or would not work (and what would be required to make it work).What protects the black box?
Quote from: Jim on 05/07/2014 08:24 pmQuote from: yg1968 on 05/07/2014 06:52 pmCould the second stage eventually land in Australia? Would that be a problem from an ITAR perspective?That would be only applicable to ISS or Orbcomm type trajectories (inclinations in the 50's)Let me remind that Elon Musk plans are to have everything recycled in a matter of hours. This, according to someone, means that you have enough stages ready to form a sort of "roaster" while the other stages are getting back to launch site, but this is not true. Maybe EM will change his mind, but according to what he said, he really meant "single-digit recycle time". And this is because he considers this the only strategy available to REALLY bring the cost of launches down. Organizing a transport from Australia to the US at any launch could make a relevant fraction of the overall cost for mission in HIS plan.Please note I'm not debating if this is reasonable or not. I'm just reporting.
I believe a box like that could collect a lot of data from the thermal sensors, attitude control, etc. and send it via short-distance telemetry to the "black box" that is designed to collect the data, and store and forward it to an aircraft monitoring the test somewhat later.
Well, for early tests SpaceX might do on upper stages that are not expected to survive reentry, but for which they still desire to collect data on the first phase (high-altitude phase) of the test flight, they could make a variation on one of these: Reentry Breakup Recorder.
Quote from: Llian Rhydderch on 05/08/2014 07:15 pmI believe a box like that could collect a lot of data from the thermal sensors, attitude control, etc. and send it via short-distance telemetry to the "black box" that is designed to collect the data, and store and forward it to an aircraft monitoring the test somewhat later. A. The thermal sensors are not standard items, and so the stage would have to be set aside from normal production to install them. That also goes for testing them and the data collection systemb. So you are going to have this box transmit to an airplane?
Quote from: Llian Rhydderch on 05/08/2014 07:15 pmWell, for early tests SpaceX might do on upper stages that are not expected to survive reentry, but for which they still desire to collect data on the first phase (high-altitude phase) of the test flight, they could make a variation on one of these: Reentry Breakup Recorder.Ha! That is exactly what I had in mind! Great find!
Quote from: Jim on 05/08/2014 03:19 pmWhat protects the black box?What about something like the Stardust return vehicle? That looks about a meter in diameter, so probably even smaller.
Quote from: RoboGoofers on 05/08/2014 05:40 pmQuote from: Jim on 05/08/2014 03:19 pmWhat protects the black box?What about something like the Stardust return vehicle? That looks about a meter in diameter, so probably even smaller. And has small sample return not already been looked at in detail, with Russian VBK-Raduga, and the European PARES study?