...It does give me the sense that SpaceX is experimenting with fly-back trajectory shaping to minimize damage to the stage. Note that none of the LZ 1 stages has re-flown to date. - Ed Kyle
I have confirmation that one-half of the fairing was recovered via parachute. My message said it was recovered from the water, intact.
Note that none of the LZ 1 stages has re-flown to date.
Quote from: edkyle99 on 05/01/2017 04:47 pm...It does give me the sense that SpaceX is experimenting with fly-back trajectory shaping to minimize damage to the stage. Note that none of the LZ 1 stages has re-flown to date. - Ed KyleWe know GTO/ASDS boosters (e.g. Thaicom) are in queue to be reused, and we know they get far more damage on entry than RTLS boosters.However, they still certainly could be trying to shape the trajectory to get an easier entry. That would be wise.
So, to the speculation about whether this booster had upgraded fuller thrust: can't Chris or someone simply ask SpaceX for us? Doesn't seem like the kind of thing they are intentionally hiding.
Quote from: envy887 on 05/01/2017 04:56 pmQuote from: edkyle99 on 05/01/2017 04:47 pm...It does give me the sense that SpaceX is experimenting with fly-back trajectory shaping to minimize damage to the stage. Note that none of the LZ 1 stages has re-flown to date. - Ed KyleWe know GTO/ASDS boosters (e.g. Thaicom) are in queue to be reused, and we know they get far more damage on entry than RTLS boosters.However, they still certainly could be trying to shape the trajectory to get an easier entry. That would be wise.Peak heating on GTO entries is higher, but maybe there are other considerations we aren't able to see. A big lofted trajectory with boostback, like today's, will have lower peak heating but might have higher gee forces because it slams into the atmosphere going a lot faster.Quote from: rockets4life97 on 05/01/2017 05:18 pmSo, to the speculation about whether this booster had upgraded fuller thrust: can't Chris or someone simply ask SpaceX for us? Doesn't seem like the kind of thing they are intentionally hiding. Evidently not, based on the acceleration off the pad. Acceleration was pretty much identical to CRS-10.
Well, I learnt something today.I was surprised that even though the main engine cut out at around 65km altitude, the booster gained more altitude AFTER main engine cut out than it had gained for the entire time that the engine was actually burning. This is obviously old news to you experts on the forum, but to me as a layman I just intuitively expected that altitude gains would stop pretty soon after the booster's engine cut out.As it turns out, the booster engine cut out at 65km, but the 1st stage continued up to attain an altitude of 165km or so before it started falling back to Earth.In hindsight it makes sense, as basic physics tells me that vertical speed would only decrease by 10m/s once the thrust disappeared, but it was interesting to see nevertheless. Normally we just see the 2nd stage altitude after MECO.
Odd that I didn't spot any military bods in mission control for an NRO launch. Did Space X keep them out the way somewhere to keep the cool image going.
Stage 2 should have reentered an hour or two or four ago, correct? - Ed Kyle
Quote from: edkyle99 on 05/01/2017 05:49 pmStage 2 should have reentered an hour or two or four ago, correct? - Ed KyleHave you seen L2 re S2 on this flight?
Quote from: LouScheffer on 05/01/2017 04:03 pmI was wondering why we can see the nitrogen jets. After all, nitrogen is pretty transparent (we look through kilometers of it every day). And it can't be that it's cold enough to condense water out of the air, since there is almost no atmosphere until it returns to much lower altitudes.The only thing I can think of is that the free expansion cools the jet so much that droplets of liquid nitrogen condense, and scattering from these drops is what we see. No it doesn't turn to liquid , we see like you can see any gas venting into a vacuum. Just like the other engines.
I was wondering why we can see the nitrogen jets. After all, nitrogen is pretty transparent (we look through kilometers of it every day). And it can't be that it's cold enough to condense water out of the air, since there is almost no atmosphere until it returns to much lower altitudes.The only thing I can think of is that the free expansion cools the jet so much that droplets of liquid nitrogen condense, and scattering from these drops is what we see.
It is well known that nozzle gas sources, such as those employed as attitude control system thrusters, produce a hypersonic flow which condenses when the gas source pressure is sufficiently high for a given gas source temperature. [...] the formation of such species results in enhanced scattering of optical radiation incident upon the plume.
Based upon the electron beam and Raman density data (Fig. 25), approximately 10 to 20 percent of the total flow molecules were in the condensed phase.
And Lou wins an official NSF "I corrected Jim!" T-shirt.Jim, with his amazing knowledge, sets such a high bar that the T-shirts will always be rare.Congratulations, Lou!(Chris, we really need to get those T-shirts printed)