Author Topic: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3  (Read 801425 times)

Offline Kabloona

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2000 on: 06/26/2017 06:37 PM »
Interesting that John Insprucker mentioned on the Iridium launch webcast that the ASDS does *not* send any signals to the returning stage; it only receives telemetry from the stage.

We have known this pretty much from the beginning, but some people were skeptical, so it's worth noting that we now have confirmation of the fact directly from SpaceX.
« Last Edit: 06/26/2017 06:39 PM by Kabloona »

Offline guckyfan

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2001 on: 06/26/2017 06:44 PM »
Interesting that John Insprucker mentioned on the Iridium launch webcast that the ASDS does *not* send any signals to the returning stage; it only receives telemetry from the stage.

We have known this pretty much from the beginning, but some people were skeptical, so it's worth noting that we now have confirmation of the fact directly from SpaceX.

Yes, good to have that confirmation. I would still like to know why. Is it because of some patent issue or just because they do not see any advantage in two way communication.

Offline old_sellsword

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2002 on: 06/26/2017 06:48 PM »
Interesting that John Insprucker mentioned on the Iridium launch webcast that the ASDS does *not* send any signals to the returning stage; it only receives telemetry from the stage.

We have known this pretty much from the beginning, but some people were skeptical, so it's worth noting that we now have confirmation of the fact directly from SpaceX.

Yes, good to have that confirmation. I would still like to know why. Is it because of some patent issue or just because they do not see any advantage in two way communication.

Because there's no good reason. ASDS positioning and F9's GPS accuracy seem to be the last of their worries.

Offline Jim

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2003 on: 06/26/2017 06:51 PM »

Yes, good to have that confirmation. I would still like to know why. Is it because of some patent issue or just because they do not see any advantage in two way communication.


Many reasons among them is that:
the actual link can't be checked out before use. 
The stage is autonomous. 
It can go from ASDS to RTLS without changing anything

Online cscott

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2004 on: 06/26/2017 06:52 PM »
I wouldn't completely rule out John's being encouraged to say this to head off the patent threat. In particular, if extra ground-to-rocket comms are getting added to LZ-1, they might want to signal blue origin that they aren't using these at sea, and thus are still clear of BO's patent.
« Last Edit: 06/26/2017 06:53 PM by cscott »

Offline Kabloona

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2005 on: 06/26/2017 06:53 PM »
Interesting that John Insprucker mentioned on the Iridium launch webcast that the ASDS does *not* send any signals to the returning stage; it only receives telemetry from the stage.

We have known this pretty much from the beginning, but some people were skeptical, so it's worth noting that we now have confirmation of the fact directly from SpaceX.

Yes, good to have that confirmation. I would still like to know why. Is it because of some patent issue or just because they do not see any advantage in two way communication.

Because there's no good reason. ASDS positioning and F9's GPS accuracy seem to be the last of their worries.

Yes, we believed from the early days of the ASDS announcement that WAAS GPS signal would be available at the ASDS, enabling sub-meter position knowledge by both the returning stage and the ASDS, and that as long as the ASDS autopilot was able to maintain position within a few meters of the target, all would be well.  And SpaceX has amply proved our optimism to be well-founded.  :)
« Last Edit: 06/26/2017 06:55 PM by Kabloona »

Online leovinus

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2006 on: 06/26/2017 07:34 PM »
It's far easier to get an accurate position of a fixed barge than a moving ship. However, a moving ship could provide a more stable platform in rough seas for a larger scaled vehicle, as well as a more rapid return or longer downrange (lofted, "gentler" EI (no entry burn) using less props for more efficient boost(lifting not ballistic, higher drag/alpha) ).

Or maybe extend the drone ship in a similar way to FLIP http://www.ship-technology.com/projects/flip-ship/ which might enable more ASDS stability in the water i.e. a more stable landing platform?

Online Johnnyhinbos

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2007 on: 06/26/2017 08:07 PM »
And here we go again...
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Offline drzerg

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2008 on: 06/26/2017 11:07 PM »
i swear i heard that droneship at least sends windspeed data to stage

Offline mme

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2009 on: 06/26/2017 11:27 PM »
i swear i heard that droneship at least sends windspeed data to stage
No. Many people have speculated that it does or insisted it "needs to" so many people have believed that. But there has never been any evidence from a credible source to support the idea that the ASDS sends information to the rocket.

Edit: Typo. Thanks CameronD.
« Last Edit: 06/26/2017 11:38 PM by mme »
Space is not Highlander.  There can, and will, be more than one.

Online CameronD

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2010 on: 06/26/2017 11:36 PM »
i swear i heard that droneship at least sends windspeed data to stage
No. Many people have speculated that it does or insisted it "needs to" so many people have believed that. But there has never been any evidence from a credible source to support the idea that the ASDS sends information to the ASDS rocket.

There.. fixed it for you. :)

SpX use windspeed and sea state information to orient the ASDS to receive the incoming booster (and to 'abort' the landing if necessary by getting out of the way).. but that's the extent of it.

« Last Edit: 06/26/2017 11:38 PM by CameronD »
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline rpapo

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2011 on: 06/26/2017 11:39 PM »
Interesting that John Insprucker mentioned on the Iridium launch webcast that the ASDS does *not* send any signals to the returning stage; it only receives telemetry from the stage.

We have known this pretty much from the beginning, but some people were skeptical, so it's worth noting that we now have confirmation of the fact directly from SpaceX.
His exact words were "The drone ship does not send commands to the first stage in flight."  That leaves open whether or not commands are given to the stage after it lands, perhaps as part of safing it.  I'm not sure why that would be necessary though: the safing process could and probably should be entirely automatic.  After all, the rocket knows when it has landed.
« Last Edit: 06/26/2017 11:46 PM by rpapo »
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Offline mme

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2012 on: 06/27/2017 12:01 AM »
Interesting that John Insprucker mentioned on the Iridium launch webcast that the ASDS does *not* send any signals to the returning stage; it only receives telemetry from the stage.

We have known this pretty much from the beginning, but some people were skeptical, so it's worth noting that we now have confirmation of the fact directly from SpaceX.
His exact words were "The drone ship does not send commands to the first stage in flight."  That leaves open whether or not commands are given to the stage after it lands, perhaps as part of safing it.  I'm not sure why that would be necessary though: the safing process could and probably should be entirely automatic.  After all, the rocket knows when it has landed.

Fair point re: safing, etc.
Space is not Highlander.  There can, and will, be more than one.

Offline RDMM2081

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2013 on: 06/27/2017 06:45 AM »
Sorry if I missed it in this mass of ASDS threads, but has there been any attempt made at an estimate of total cost of ASDS, barge + materials + thrusters + avionics + paint etc. I.E. what might SpaceX insure them for (assuming they could get insurance for something they are actively targeting with multiple tons of incoming ballistic "missile") or what might it cost them to replace from the ground up?

I think when they were first announced (ASDS in general) I made a super rough estimate of $3m for a Marmac, $1m for the steel deck plating, $500k for the thrusters, and another $500k for labor, paint and fuel, plus $250k for towing for the first landing attempt mission. 

Anyone else have any guesses or adjustments?

Offline JamesH65

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2014 on: 06/27/2017 10:16 AM »
Interesting that John Insprucker mentioned on the Iridium launch webcast that the ASDS does *not* send any signals to the returning stage; it only receives telemetry from the stage.

We have known this pretty much from the beginning, but some people were skeptical, so it's worth noting that we now have confirmation of the fact directly from SpaceX.

Corollary. Why does the ASDS need to receive telemetry from the stage? It knows it's on its way, it doesn't need to move, it doesn't need to know anything.

Offline rpapo

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2015 on: 06/27/2017 10:23 AM »
Interesting that John Insprucker mentioned on the Iridium launch webcast that the ASDS does *not* send any signals to the returning stage; it only receives telemetry from the stage.

We have known this pretty much from the beginning, but some people were skeptical, so it's worth noting that we now have confirmation of the fact directly from SpaceX.

Corollary. Why does the ASDS need to receive telemetry from the stage? It knows it's on its way, it doesn't need to move, it doesn't need to know anything.
In this case, the ASDS serves as a data relay for SpaceX, since by the time the stage is closing in on the ASDS, it is below the horizon from the launch pad.
An Apollo fanboy . . . fifty years ago.

Offline John Alan

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2016 on: 06/27/2017 02:17 PM »
Sorry if I missed it in this mass of ASDS threads, but has there been any attempt made at an estimate of total cost of ASDS, barge + materials + thrusters + avionics + paint etc. I.E. what might SpaceX insure them for (assuming they could get insurance for something they are actively targeting with multiple tons of incoming ballistic "missile") or what might it cost them to replace from the ground up?

I think when they were first announced (ASDS in general) I made a super rough estimate of $3m for a Marmac, $1m for the steel deck plating, $500k for the thrusters, and another $500k for labor, paint and fuel, plus $250k for towing for the first landing attempt mission. 

Anyone else have any guesses or adjustments?

Since each ASDS has caught one stage... that later has reflown... (two reflown to date)
I think we can safely say that both are nearing cash positive on the Spacex books... all in...  ;)

IOW... Cost to build and maintain both ASDS's... Costs ongoing for two tugs on call and three Go boats on call...
Cost to refurb the stages... Cost of cranes... Cost of port leases and installed fixturing... Cost of labor...

Balance that against not having to build two stages so far... My opinion is close to break even as of today...
Refly another stage and it starts going against the other costs to date company wide...

Just my opinion on question posed...  ;)

Offline elist

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2017 on: 06/27/2017 06:08 PM »
Since each ASDS has caught one stage... that later has reflown... (two reflown to date)
I think we can safely say that both are nearing cash positive on the Spacex books... all in...  ;)

The current JRTI is the second JRTI.  The original JRTI hosted several of the unsuccessful landing attempts.

Offline biosehnsucht

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2018 on: 06/27/2017 09:27 PM »
Weren't the wings and other hardware added to the original moved to the current JRTI?

So you could argue for a ship of Theseus situation, after all, it was the added hardware to the original MARMAC that made it an ASDS, those parts are more what make it an ASDS or JRTI itself than the underlying MARMAC.

Online CameronD

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #2019 on: 06/27/2017 11:32 PM »
Interesting that John Insprucker mentioned on the Iridium launch webcast that the ASDS does *not* send any signals to the returning stage; it only receives telemetry from the stage.

We have known this pretty much from the beginning, but some people were skeptical, so it's worth noting that we now have confirmation of the fact directly from SpaceX.

Corollary. Why does the ASDS need to receive telemetry from the stage? It knows it's on its way, it doesn't need to move, it doesn't need to know anything.
In this case, the ASDS serves as a data relay for SpaceX, since by the time the stage is closing in on the ASDS, it is below the horizon from the launch pad.

Unless I'm much mistaken, it's one of the support ships that performs the data relay function - not the ASDS - since, as you quite rightly mentioned, it is below the horizon from the launch pad.

We know this because, long ago, in a thread not far away from this one, a knowledgeable and determined NSFer (not me!) sorted through the on-line list of SpaceX's FCC RF licence approvals and worked out what was being sent by what to where.  Very impressive it was too!!

Anyways, since it's a proven point already, let's move on shall we?
 
« Last Edit: 06/28/2017 02:35 AM by CameronD »
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

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