Author Topic: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 2 (Read 2878581 times)

Lar · « **Reply #2120 on:** 02/12/2015 10:43 am »

Quote from: aameise9 on 02/12/2015 05:02 am

This appears to be an uncharacteristically irrational tweet. Handle anything on ghe ocean? Merlin ? Presumably born out of intense frustration ...

Elon says funny stuff all the time. I'd read it as that they do intend to upgrade the barge in some way or ways. And the Merlin? Him being funny. Don't overthink it.

Robotbeat · « **Reply #2121 on:** 02/12/2015 11:47 am »

Quote from: Kabloona on 02/12/2015 04:38 am

Quote from: Robotbeat on 02/12/2015 03:15 am
Who said they ever had to achieve a certain number of barge landings before being approved? That's just speculation as far as I can tell.

This is what Elon actually said:

Quote
But before we boost back to the launch site, and try to land there, we need to show that we can land with precision, over and over again.

http://shitelonsays.com/transcript/elon-musk-at-mits-aeroastro-centennial-part-1-of-6-2014-10-24

Which pretty much implies a certain number of required demo landings, because I'm guessing the Range was a little more specific than just saying "over and over" about the number of demo landings they would require. Just because Elon hasn't said the number in public doesn't mean it hasn't already been specified by the Range.

And given SpaceX's major investment in the barge and plans for LC-13, it's hard to imagine that Elon wouldn't have a pretty clear agreement already worked out with the Range about the exact criteria (ie number of successful barge landings, etc) that need to be met before they will allow a terra firma landing attempt.

If your point is that no one has proven that the Range is requiring the demo landings to occur on the *barge* as opposed to in the open ocean, that's true. But would the Range really accept demo landings in the open ocean where the stage falls over and goes "kaboom" and call that good enough? I doubt it.

And if the Range isn't requiring the barge landings, why is SpaceX doing them, instead of merely landing the required number of times in the ocean and then going straight to boostback to the launch site? That would have been a lot easier than the barge landings, which they could have attempted down the road after mastering the easier task of landing on solid not-moving ground back at the launch site.

Thanks!

cscott · « **Reply #2122 on:** 02/12/2015 12:21 pm »

The "success" of the water landing seems to prove that bad weather is no problem for the returning stage. They just need to nail the ASDS side.

kdhilliard · « **Reply #2123 on:** 02/12/2015 12:35 pm »

Quote from: cscott on 02/12/2015 12:21 pm

The "success" of the water landing seems to prove that bad weather is no problem for the returning stage. They just need to nail the ASDS side.

But do we know what the lateral velocity of the stage was when it landed?

robertross · « **Reply #2124 on:** 02/12/2015 12:35 pm »

Quote from: NovaSilisko on 02/12/2015 04:30 am

Personally, I'm wondering how much equipment got swept off the deck by the massive waves...

probably nothing, except maybe a bit of fuel or oil spillage...

Remember, all these containers would be lashed down on deck, or welded.

Rocket Science · « **Reply #2125 on:** 02/12/2015 12:38 pm »

If the landing restraints are similar to the launch restaints (except for sea state) why not ask for the barge to be brought in closer to the pad? Still an issue for the range and how close can they come?

OxCartMark · « **Reply #2126 on:** 02/12/2015 01:03 pm »

So why was the reason that there was no retro-propulsion burn and the stage plowed straight ahead to such a great distance 300+ miles(?) rather than to either cancel forward velocity component or reverse horizontal component and do a partial RTLS, which would have had the ASDS / JRTIM in better weather? Obviously the decision to do so was made long before weather was known to be a factor and it wasn't possible to change things in the last few hours / days, but why originally was the decision made to do a long straight in arc to the recovery point? Not because of payload mass.?. Was it because they wanted to test a high speed re-entry? Was it because the L1 destination required more velocity?

cscott · « **Reply #2127 on:** 02/12/2015 01:09 pm »

Propellant considerations, yes.

JasonAW3 · « **Reply #2128 on:** 02/12/2015 01:24 pm »

Quote from: cscott on 02/12/2015 12:21 pm

The "success" of the water landing seems to prove that bad weather is no problem for the returning stage. They just need to nail the ASDS side.

For them to have landed that stage in the sea state that they were experiencing, they would have needed a platform similar in size and height to the SeaLaunch launch platform, or an off shore oil rig.

35 foot seas are nothing to laugh at. Even ocean liners tend to steer clear of those kind of storms.

mvpel · « **Reply #2129 on:** 02/12/2015 01:44 pm »

Quote from: JasonAW3 on 02/12/2015 01:24 pm

For them to have landed that stage in the sea state that they were experiencing, they would have needed a platform similar in size and height to the SeaLaunch launch platform, or an off shore oil rig.

Considering that this vessel costs $150 million a year to operate, it's probably not a terribly practical model to follow, even though it probably could support a Falcon 9 landing in 10-meter seas.

SBX-1 by mvpel, on Flickr

llanitedave · « **Reply #2130 on:** 02/12/2015 01:54 pm »

Quote from: kdhilliard on 02/12/2015 12:35 pm

Quote from: cscott on 02/12/2015 12:21 pm
The "success" of the water landing seems to prove that bad weather is no problem for the returning stage. They just need to nail the ASDS side.

But do we know what the lateral velocity of the stage was when it landed?

What do you mean, African stage, or European stage?

Zed_Noir · « **Reply #2131 on:** 02/12/2015 02:08 pm »

Quote from: mvpel on 02/12/2015 01:44 pm

Quote from: JasonAW3 on 02/12/2015 01:24 pm
For them to have landed that stage in the sea state that they were experiencing, they would have needed a platform similar in size and height to the SeaLaunch launch platform, or an off shore oil rig.

Considering that this vessel costs $150 million a year to operate, it's probably not a terribly practical model to follow, even though it probably could support a Falcon 9 landing in 10-meter seas.

SBX-1 by mvpel, on Flickr

Most of that $150M would be for the radar and supporting the radar operation. Not the platform's operating cost. Some cost numbers from an old oil production platform should be more relevant.

kdhilliard · « **Reply #2132 on:** 02/12/2015 02:15 pm »

Quote from: llanitedave on 02/12/2015 01:54 pm

Quote from: kdhilliard on 02/12/2015 12:35 pm
Quote from: cscott on 02/12/2015 12:21 pm
The "success" of the water landing seems to prove that bad weather is no problem for the returning stage. They just need to nail the ASDS side.
But do we know what the lateral velocity of the stage was when it landed?
What do you mean, African stage, or European stage?

A North American stage, you silly bunt! But seriously, landing on target, oriented vertically, and with near zero vertical velocity as you reach the deck is not enough if your lateral velocity sends you skidding off the deck or toppling over. I wasn't expecting Musk to include such info in his tweet, but I'm sure it was great interest to his engineers. This is a difficult control problem in high and gusty winds, and lacking more information we don't really know if a landing would have been successful had it not been for ASDS issues.

An additional issue is securing the stage to the ASDS after landing. There might be marginal conditions where the stage could land, but that it wouldn't be considered safe enough to send personnel on board to weld on the shoes.

The Amazing Catstronaut · « **Reply #2133 on:** 02/12/2015 02:34 pm »

Quote from: Zed_Noir on 02/12/2015 02:08 pm

Deducting the costs of the actual rigging equipment, of course, which are (probably?) fairly substantial.

I personally think/hypothesise/pull-an-opinion-out-of-my-behind the "upgrade" will be be a new-ish platform of such. It's awesome to see them getting straight down to the problem, though.

Edit: fixed derpy quotes ;3.

cscott · « **Reply #2134 on:** 02/12/2015 02:44 pm »

Quote from: Zed_Noir on 02/12/2015 02:08 pm

Quote from: mvpel on 02/12/2015 01:44 pm
Quote from: JasonAW3 on 02/12/2015 01:24 pm
For them to have landed that stage in the sea state that they were experiencing, they would have needed a platform similar in size and height to the SeaLaunch launch platform, or an off shore oil rig.

Considering that this vessel costs $150 million a year to operate, it's probably not a terribly practical model to follow, even though it probably could support a Falcon 9 landing in 10-meter seas.

SBX-1 by mvpel, on Flickr

Most of that $150M would be for the radar and supporting the radar operation. Not the platform's operating cost. Some cost numbers from an old oil production platform should be more relevant.

And FWIW, I was in Honolulu last week and that wonderful floating platform was surrounded by scaffolding and clearly not going *anywhere* anytime soon. So there are availability issues with platforms of this size, as well...

Ohsin · « **Reply #2135 on:** 02/12/2015 03:44 pm »

Go Quest on Vesselfinder about 20 km off inlet.

Kansan52 · « **Reply #2136 on:** 02/12/2015 03:54 pm »

Can they try another ASDS landing next flight or does everything go to hauling the two satellites?

kevinof · « **Reply #2137 on:** 02/12/2015 03:59 pm »

There are no legs on the next two flights.

Quote from: Kansan52 on 02/12/2015 03:54 pm

Can they try another ASDS landing next flight or does everything go to hauling the two satellites?

rpapo · « **Reply #2138 on:** 02/12/2015 04:04 pm »

Quote from: Ohsin on 02/12/2015 03:44 pm

Go Quest on Vesselfinder about 20 km off inlet.

That was sure quick! I wonder just how far ahead of time they got the message to return?

Kabloona · « **Reply #2139 on:** 02/12/2015 04:09 pm »

Quote from: rpapo on 02/12/2015 04:04 pm

Quote from: Ohsin on 02/12/2015 03:44 pm
Go Quest on Vesselfinder about 20 km off inlet.
That was sure quick! I wonder just how far ahead of time they got the message to return?

If they left just after splashdown last night, that's about 18 hours, which at 10 knots is around 200 statute miles of travel.

ELsbeth III probably doing only half that speed, so perhaps another ~18 hours before they hit port.