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#260
by
Kabloona
on 23 Jun, 2017 23:23
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It is the vibration that is the main issue AIUI. I'm sure enough money *could* solve the problem... ie moor another ASDS a mile off, and stream from that... but it's not worth the $$$.
Why use another ASDS - why not just have a trailing buoy with an antenna on it, or something?
Can't be that expensive.
because the ASDS is stationary while waiting for the landing. if it was 'under way' sailing at a fixed rate (as BO plan to do) it would work... but stationary, the buoy would just sit there, right next to the ASDS, or have to be deployed well before landing and hope it doesn't drift too close.
And it's not worth the cost of trying to solve. It merely interrupts a few seconds of the live feed, but the full event gets recorded on board for later recovery.
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#261
by
kaiser
on 23 Jun, 2017 23:36
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It is the vibration that is the main issue AIUI. I'm sure enough money *could* solve the problem... ie moor another ASDS a mile off, and stream from that... but it's not worth the $$$.
Why use another ASDS - why not just have a trailing buoy with an antenna on it, or something?
Can't be that expensive.
because the ASDS is stationary while waiting for the landing. if it was 'under way' sailing at a fixed rate (as BO plan to do) it would work... but stationary, the buoy would just sit there, right next to the ASDS, or have to be deployed well before landing and hope it doesn't drift too close.
And it's not worth the cost of trying to solve. It merely interrupts a few seconds of the live feed, but the full event gets recorded on board for later recovery.
Definitely recorded. I can also almost guarantee that post live stream they start sending all the recorded data over the satcom link, and probably have all of the data back in the shop with 15 minutes. It's just a couple of minutes of TM and video, not incredibly large to shove across a link like that.
Getting that data live versus a couple of minutes later isn't worth the cost of a secondary buoy, or support aircraft or whatever the solution would be.
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#262
by
LouScheffer
on 23 Jun, 2017 23:39
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Remember that it's normal for the drone ship cameras to cut out just before touchdown because the satellite link is all that SpaceX can afford.
...because no amount of money can buy you a satellite uplink from the middle of the Atlantic ocean through an ionized exhaust plume as an 18-ton 165-ft tall rocket lands on top of you.
I'd disagree with that. You can build a buoy with your uplink antenna on it, and run a cable back to the ASDS. Get your antenna far enough from the rocket that it doesn't lose signal. It's certainly within the means of SpaceX, just not worth the expense or the recovery team's labor deploying and retrieving it all the time.
No reason to use a buoy or any other complex scheme. Just use an omni-direction antenna to broadcast the video to the control ship 5 km away. Then that ship can have a stable satellite link. Entirely off the shelf, but still not worth the bother.
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#263
by
Nomadd
on 23 Jun, 2017 23:51
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Remember that it's normal for the drone ship cameras to cut out just before touchdown because the satellite link is all that SpaceX can afford.
...because no amount of money can buy you a satellite uplink from the middle of the Atlantic ocean through an ionized exhaust plume as an 18-ton 165-ft tall rocket lands on top of you.
They do have two antennas on opposite ends of the barge, right? If they're Intellian V110s, I might know what the issue is and spent six months solving it on my own boats. They cut out every time hard vibration hit.
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#264
by
Bob Shaw
on 23 Jun, 2017 23:56
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Geometrically Corrected landing image.
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#265
by
Aerospace Dilettante
on 23 Jun, 2017 23:57
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Gunter's page says that this sat had a launch mass of 3669kg, they've recovered boosters before that had carried heavier GTO sat without getting "extra toasty." So what's the deal with this one?
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#266
by
Bob Shaw
on 23 Jun, 2017 23:59
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It is the vibration that is the main issue AIUI. I'm sure enough money *could* solve the problem... ie moor another ASDS a mile off, and stream from that... but it's not worth the $$$.
Why use another ASDS - why not just have a trailing buoy with an antenna on it, or something?
Can't be that expensive.
because the ASDS is stationary while waiting for the landing. if it was 'under way' sailing at a fixed rate (as BO plan to do) it would work... but stationary, the buoy would just sit there, right next to the ASDS, or have to be deployed well before landing and hope it doesn't drift too close.
And it's not worth the cost of trying to solve. It merely interrupts a few seconds of the live feed, but the full event gets recorded on board for later recovery.
Actually, all you need is a buoy with a sea-anchor - it'll depart from the barge under the influence of currents quite quickly.
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#267
by
Bob Shaw
on 24 Jun, 2017 00:01
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It is the vibration that is the main issue AIUI. I'm sure enough money *could* solve the problem... ie moor another ASDS a mile off, and stream from that... but it's not worth the $$$.
Why use another ASDS - why not just have a trailing buoy with an antenna on it, or something?
Can't be that expensive.
because the ASDS is stationary while waiting for the landing. if it was 'under way' sailing at a fixed rate (as BO plan to do) it would work... but stationary, the buoy would just sit there, right next to the ASDS, or have to be deployed well before landing and hope it doesn't drift too close.
And it's not worth the cost of trying to solve. It merely interrupts a few seconds of the live feed, but the full event gets recorded on board for later recovery.
Actually, all you need is a buoy with a sea-anchor - it'll depart from the barge under the influence of currents quite quickly.
Gunter's page says that this sat had a launch mass of 3669kg, they've recovered boosters before that had carried heavier GTO sat without getting "extra toasty." So what's the deal with this one?
No boost-back, presumably...
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#268
by
Kabloona
on 24 Jun, 2017 00:06
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Remember that it's normal for the drone ship cameras to cut out just before touchdown because the satellite link is all that SpaceX can afford.
...because no amount of money can buy you a satellite uplink from the middle of the Atlantic ocean through an ionized exhaust plume as an 18-ton 165-ft tall rocket lands on top of you.
They do have two antennas on opposite ends of the barge, right? If they're Intellian V110s, I might know what the issue is and spent six months solving it on my own boats. They cut out every time hard vibration hit.
You should get in touch with the SpaceX guy who posted about the vibration issue on Reddit.
https://forum.nasaspaceflight.com/index.php?topic=34077.msg1499726#msg1499726
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#269
by
Earendil
on 24 Jun, 2017 00:07
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Maybe higher delta V?
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#270
by
schaban
on 24 Jun, 2017 00:11
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Gunter's page says that this sat had a launch mass of 3669kg, they've recovered boosters before that had carried heavier GTO sat without getting "extra toasty." So what's the deal with this one?
I think SpaceX just knew they are not going to reuse it again so used it to test some boundaries.
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#271
by
Barrie
on 24 Jun, 2017 00:17
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Geometrically Corrected landing image.
Not much clearance under those engines.
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#272
by
Kabloona
on 24 Jun, 2017 00:18
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Geometrically Corrected landing image.
Not much clearance under those engines.
Time for Roomba limbo. How low can it go?
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#273
by
JimO
on 24 Jun, 2017 00:24
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Any videos from central Africa of the post SECO2 fuel dump?
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#274
by
Barrie
on 24 Jun, 2017 00:24
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Geometrically Corrected landing image.
Not much clearance under those engines.
Time for Roomba limbo. How low can it go?
I suspect not low enough for this one. Elon tweeted that most of the crush core had been used up.
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#275
by
Zed_Noir
on 24 Jun, 2017 00:33
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I'm sure elon will want to send a flight proven booster to the Smithsonian one of these days.
You could do an entire SpaceX gallery of milestones, but the problem is where to put it. The Udvar-Hazy is pretty full as it is. Not sure where you would shoe-horn in an entire first stage. Maybe they need an outdoor rocket garden? Only problem then could be proximity to the Dulles runway.
I think SpaceX deserves a hanger like Shuttle. It should have the a Falcon 1, the remains of the satellite that crashed through their shed, the GH1, the SpaceX cowboy, the wheel of cheese, and the first retired block 5 booster. And some space for the future. Someone would have to pay for all that though. Elon?
Not a hangar. Maybe a tower with a lot of windows and interior platforms. A sort of immobile gantry tower for tourists.
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#276
by
ulm_atms
on 24 Jun, 2017 00:34
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No reason to use a buoy or any other complex scheme. Just use an omni-direction antenna to broadcast the video to the control ship 5 km away. Then that ship can have a stable satellite link. Entirely off the shelf, but still not worth the bother.
^^THIS
I have never understood why there was ever sat connections on the barge to begin with. The barge will ALWAYS have the support ship since it cannot get out to sea by itself. So why not just use a cheap omni or large angle sector antennas (90 or 120 degree) that point towards the support ship, and have the support ship do all the more delicate sat up/down links. Can anyone explain why they would not want to do it this way? Any drawbacks? This is one of the things I never quite understood...
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#277
by
Kabloona
on 24 Jun, 2017 00:43
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No reason to use a buoy or any other complex scheme. Just use an omni-direction antenna to broadcast the video to the control ship 5 km away. Then that ship can have a stable satellite link. Entirely off the shelf, but still not worth the bother.
^^THIS
I have never understood why there was ever sat connections on the barge to begin with. The barge will ALWAYS have the support ship since it cannot get out to sea by itself. So why not just use a cheap omni or large angle sector antennas (90 or 120 degree) that point towards the support ship, and have the support ship do all the more delicate sat up/down links. Can anyone explain why they would not want to do it this way? Any drawbacks? This is one of the things I never quite understood...
They want commercial VSATS on the ASDS anyway, so may as well use them for video uplink when it works. And remember when the ASDS broke loose and ran amok...support ships may not *always* be near. Good to know where your ASDS is at all times.
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#278
by
ulm_atms
on 24 Jun, 2017 00:56
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They want commercial VSATS on the ASDS anyway, so may as well use them for video uplink when it works. And remember when the ASDS broke loose and ran amok...support ships may not *always* be near. Good to know where your ASDS is at all times.
From the bolded...That's the part I never understood why. What does the sat connection on the ASDS help/do that could not be done with an omni to support ship connection to allow a more stable sat uplink?
And as far as the run amok...lol I forgot about that...but wouldn't a simple AIS transponder(which i thought it had) do the same ?
This is the last I'll ask in this thread as this doesn't actually have anything to do with this mission.
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#279
by
Kabloona
on 24 Jun, 2017 01:09
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They want commercial VSATS on the ASDS anyway, so may as well use them for video uplink when it works. And remember when the ASDS broke loose and ran amok...support ships may not *always* be near. Good to know where your ASDS is at all times.
From the bolded...That's the part I never understood why. What does the sat connection on the ASDS help/do that could not be done with an omni to support ship connection to allow a more stable sat uplink?
And as far as the run amok...lol I forgot about that...but wouldn't a simple AIS transponder(which i thought it had) do the same ?
This is the last I'll ask in this thread as this doesn't actually have anything to do with this mission.
Adding another link from ASDS to support ship to satellite would be yet one more complication. And they may not have anticipated the vibration-induced loss of signal issue in the original design. The commercial VSATs do advertise some vibration tolerance.
So they probably did a KISS design, keep it simple, VSATs on the ASDS linking directly to the satellites. Then when the vibration caused by the rocket acoustics overwhelmed the VSAT damping capability, well, no big deal. You just get the video/data 30 seconds later.
