Author Topic: SpaceX Eastern Range Landing Facilities  (Read 226448 times)

Offline cscott

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Re: SpaceX Eastern Range Landing Facilities
« Reply #280 on: 04/07/2016 06:53 PM »
The even-simpler explanation is that there are three pads for FH stages, one big one for Dragon 2 landings, and one extra to ease logistics in case of a crowded schedule.

Offline sghill

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Re: SpaceX Eastern Range Landing Facilities
« Reply #281 on: 04/07/2016 08:03 PM »
For LC11 my best guess would be that it puts incoming rocket stages a wee bit to close to LC36 where BO is planning on building their launch facilities and where Moon Express also has facilities.

Might be an opportunity for CCAFB to establish a consolidated landing zone for both SpaceX and BO.

Pad 36, where BO will launch from, is actually two pad sites (A and B). One of which is already a landing pad, and was, until very recently, being used by Moon Express for landing testing.

The other pad will be the launch pad. And gift shop...

On a separate note.  All this talk about diverting to contingency pads, got me to thinking how long does the booster have during its descent to choose to divert to the contingency pad.  It can't be more than 1 second at most.

The only reason to use the diversion pad is because of wind gusts.  If it's an engine or control system problem, the booster is going to have to splash itself if it can, and if it can't, it's going to lawn dart wherever it was headed.

So what is the maximum height and time to impact where it could make a controlled divert decision.
« Last Edit: 04/07/2016 09:03 PM by sghill »
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Offline llanitedave

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Re: SpaceX Eastern Range Landing Facilities
« Reply #282 on: 04/08/2016 04:43 AM »
It's a bad day for the seal, but it is multiplied out by the infinitesimal probability of the seal being in that wrong place at that wrong time.  They just need the statistical probability of killing a seal to be well below <some number>, which is different from never killing a seal.
 


The seal's odds are much better than they would have been for an expendable launch, regardless.
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Offline CameronD

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Re: SpaceX Eastern Range Landing Facilities
« Reply #283 on: 04/08/2016 05:14 AM »
It's a bad day for the seal, but it is multiplied out by the infinitesimal probability of the seal being in that wrong place at that wrong time.  They just need the statistical probability of killing a seal to be well below <some number>, which is different from never killing a seal.
 

The seal's odds are much better than they would have been for an expendable launch, regardless.

How do you figure that?  The Falcon stage will be coming down belching fire over a wide perimeter.  A poor unfortunate little seal in the wrong spot would get a long, slow roasting before the metal coup de grace...

EDIT:  Whilst not wanting to proceed too far off-topic, FWIW, has anyone ever seen footage of an expended stage hitting the ocean?  What sort of splash are we taking about?
« Last Edit: 04/08/2016 05:29 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.

Online meekGee

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Re: SpaceX Eastern Range Landing Facilities
« Reply #284 on: 04/08/2016 06:28 AM »
It's a bad day for the seal, but it is multiplied out by the infinitesimal probability of the seal being in that wrong place at that wrong time.  They just need the statistical probability of killing a seal to be well below <some number>, which is different from never killing a seal.
 

The seal's odds are much better than they would have been for an expendable launch, regardless.

How do you figure that?  The Falcon stage will be coming down belching fire over a wide perimeter.  A poor unfortunate little seal in the wrong spot would get a long, slow roasting before the metal coup de grace...

EDIT:  Whilst not wanting to proceed too far off-topic, FWIW, has anyone ever seen footage of an expended stage hitting the ocean?  What sort of splash are we taking about?

Thus plenty of noisy time for the creature to dive, which would be their instinct... 

OTOH, an empty stage (or pieces thereof) coming down at terminal velocity?   No warning time. 

If I was a seal, I'd rather have the slow loud flamey thing.

Just sayin'.  Or a beach ball, those are good too.

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Offline rpapo

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Re: SpaceX Eastern Range Landing Facilities
« Reply #285 on: 04/08/2016 10:26 AM »
FWIW, has anyone ever seen footage of an expended stage hitting the ocean?  What sort of splash are we taking about?
There may be something out there in the archives, but if memory serves me the only film/video we have showing a first stage returning to earth are these:

(1) Various space shuttle SRB splashdowns.
(2) At least two shots of the Falcon 9 first stage "landing" on water (CASSIOPE, ORBCOMM).
(3) Two on-board videos of Falcon 9 landing on water (CRS-3, DISCOVR).
(4) Miscellaneous flight aborts where a rocket blew up right after launch, making the "return" of the stage quite visible.

Most of the time, the region where a first stage returns to earth (in pieces, usually) are marked off as hazard zone, so nobody goes there and therefore we don't get film of the event.
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Offline Garrett

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Re: SpaceX Eastern Range Landing Facilities
« Reply #286 on: 04/08/2016 10:54 AM »
On a separate note.  All this talk about diverting to contingency pads, got me to thinking how long does the booster have during its descent to choose to divert to the contingency pad.  It can't be more than 1 second at most.
My guess is that the booster will not do a last minute divert. Instead, during its freefall between boost back and the landing burn it will continuously be calculating which pad to land on. If all is nominal, then the center pad will be chosen, otherwise a contingency pad, and worst case an ocean landing.

I would presume that once the landing burn is started, the booster is commited to a specific pad (center or contigency).

Just my guess though.
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Offline MattMason

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Re: SpaceX Eastern Range Landing Facilities
« Reply #287 on: 04/08/2016 12:40 PM »
On a separate note.  All this talk about diverting to contingency pads, got me to thinking how long does the booster have during its descent to choose to divert to the contingency pad.  It can't be more than 1 second at most.
My guess is that the booster will not do a last minute divert. Instead, during its freefall between boost back and the landing burn it will continuously be calculating which pad to land on. If all is nominal, then the center pad will be chosen, otherwise a contingency pad, and worst case an ocean landing.

I would presume that once the landing burn is started, the booster is commited to a specific pad (center or contigency).

Just my guess though.

I'm certain that, based on prior discussions, the F9 booster is pre-programmed to one specific target and does not "pick" or change landing destinations. Landing is automatic and the booster hasn't the capacity to adjust targets on its own.
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Offline Kabloona

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Re: SpaceX Eastern Range Landing Facilities
« Reply #288 on: 04/08/2016 01:57 PM »
Quote
I'm certain that, based on prior discussions, the F9 booster is pre-programmed to one specific target and does not "pick" or change landing destinations. Landing is automatic and the booster hasn't the capacity to adjust targets on its own.

That does appear to be the case now for F9.

However, SpaceX's discussion of the "divert" option to different pads suggests that they anticipated a possible *future* capability for real-time retargeting, probably for FH where multiple boosters would be returning.

Whether they actually implement that capability for FH remains to be seen.
« Last Edit: 04/08/2016 02:21 PM by Kabloona »

Offline sghill

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Re: SpaceX Eastern Range Landing Facilities
« Reply #289 on: 04/08/2016 03:13 PM »
I'm certain that, based on prior discussions, the F9 booster is pre-programmed to one specific target and does not "pick" or change landing destinations. Landing is automatic and the booster hasn't the capacity to adjust targets on its own.

Then the divert pads are useless by definition. 

My original question was how high up (or how long until landing) can the decision be made for it to be worth anything.  I think Kabloona has it right.  They've got to develop the ability to think about the target for the divert pads to make any sense.

However, I think because of how ground winds are going to affect the final moments when a divert is going to happen, and the speed the booster returns before the hoverslam, the decision of which pad to land on happens less than a second before touchdown.  All of which makes separate pads (versus one huge pad) a little silly.

IMHO, the separate pads were intended all along to be separate simultaneous landing sites, and discussion of diversion pads is academic.  SpaceX will conduct a new EA when Falcon Heavy gets closer to flight and ask to use three (or 4) of the pads at once.

We've known since January 2015 when the FAA released its FONSI that the EIS was NOT REQUIRED, and that Falcon Heavy operations would necessitate changing it if it were required.  http://forum.nasaspaceflight.com/index.php?topic=36513.msg1408590#msg1408590

We also know from the attached FONSI just released in December 2015 (which we've not discussed before that I can recall) that the FAA and USAF has only studied a single core returning from either a F9 or FH, and that modifying the current approval situation will require additional environmental study (pages 2-3).

"Because the launch (or takeoff) of Falcon launch vehicles was analyzed in the 2007 and 2013 EAs, the scope of launch operations analyzed in the 2014 EA is limited to the return and landing of the Falcon 9 first stage, or a single core of the Falcon Heavy first stage, at LC-1. The EA assumes a normal launch mission of a Falcon vehicle from CCAFS with the successful separation of the second stage and payload, while the first stage begins its landing sequence.

As the Proposed Action would require Federal actions (as defined in 40 CFR § 1508.18) involving the USAF and FAA, the EA was prepared to satisfy the NEPA obligations of both agencies. The FAA’s Federal action in this matter pertains to its role in issuing licenses for the operation of commercial launch and reentry vehicles at launch sites. The USAF issued a FONSI on January 8, 2015, which stated the potential environmental impacts associated with the Proposed Action would not individually or cumulatively result in a significant impact on the quality of the human environment, and therefore, the preparation of an environmental impact statement (EIS) was not required. SpaceX is required to obtain a launch license from the FAA to conduct Falcon landings at CCAFS. SpaceX could request a new launch license to include takeoff and landing activities, or modify an existing launch license that has been issued to support Falcon 9 launches at CCAFS to include landing activities. Based on its independent review and consideration of the EA, the FAA issues this FONSI concurring with the analysis of impacts and findings in the EA and formally adopts the EA to support the issuance or modification of launch licenses for Falcon landings at LC-1, CCAFS. If changes to the Proposed Action fall outside the scope of the EA, additional environmental analysis will be required prior to the FAA issuing or modifying a license.

After reviewing and analyzing available data and information on existing conditions and potential impacts, including the EA, the FAA has determined issuance or modification of a launch license to conduct Falcon landings at CCAFS would not significantly affect the quality of the human environment within the meaning of NEPA. Therefore, the preparation of an EIS is not required, and the FAA is issuing this FONSI. The FAA made this determination in accordance with all applicable environmental laws and FAA regulations. The EA is incorporated by reference into this FONSI."
« Last Edit: 04/08/2016 06:05 PM by sghill »
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Offline MattMason

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Re: SpaceX Eastern Range Landing Facilities
« Reply #290 on: 04/08/2016 03:29 PM »
I'm certain that, based on prior discussions, the F9 booster is pre-programmed to one specific target and does not "pick" or change landing destinations. Landing is automatic and the booster hasn't the capacity to adjust targets on its own.

Then the divert pads are useless by definition. 

My original question was how high up (or how long until landing) can the decision be made for it to be worth anything.  I think Kabloona has it right.  They've got to develop the ability to think about the target for the divert pads to make any sense.

(snipped for thread brevity)

A bit too much jargon for my head to wrap around, but yes, I'd agree with you and Kabloona in it, lacking much else to go on. There's still the matter of how/if SpaceX sends updated GPS data to a returning booster. It seems logical (though I haven't verification) that boosters themselves don't have the capacity to alter their course data. And that change would have to be entered and verified from SpaceX to the booster before separation and boostback (if not before launch) or the calculations for needed fuel to accomplish the mission and have sufficient boostback fuel trajectory would get really messy, IMO.

I had problems projecting the correct trajectories for model rockets, so from here on it's clear I'm meddling in the affairs of rocket wizards here and will bow out for more wiser folk's input and more legitimate speculation.
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Offline cscott

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Re: SpaceX Eastern Range Landing Facilities
« Reply #291 on: 04/08/2016 03:52 PM »
I agree that the "divert" terminology was a fig leaf to get all five pads built while delaying EIS for multiple rocket return until (a) it was needed, and (b) they had some operations history to quantify the low environmental risk.

Offline rcoppola

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Re: SpaceX Eastern Range Landing Facilities
« Reply #292 on: 04/08/2016 04:38 PM »
I agree wrt the comments concerning Divert Pads.

Also, during yesterdays CRS-8 briefing, Hans made it seem fairly clear that FH boosters will always (or mostly) RTLS. In which case they'll need another Landing Pad whether at LZ-1 or close by as we all know. But...the range will also need to implement the Autonomous FTS as they can't track and deal with multiple incoming bogies, so to speak. But I'm curious how far apart they'll require these landing pads to be in relation to one another. I'd assume they'd require them to be as far apart as the established maximum distance debris would be scattered upon various impacts and/or last minute FTs, post divert profiles. In which case, I don't see any of those original conceptual divert pads being able to accommodate the second booster. imo.
« Last Edit: 04/08/2016 04:39 PM by rcoppola »
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Online meekGee

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Re: SpaceX Eastern Range Landing Facilities
« Reply #293 on: 04/08/2016 05:00 PM »
The way I read it, the center pad (being much larger and surrounded by a wide gravel strip) is actually the real "crash pad". 

1. After the third reentry burn, the stages is aimed just off shore.  If the stage fails during reentry (grid fin torn off, etc) then it will naturally splash, by default.
2. Using the grid fins, the stages moves the IIP inwards, and aims at the center pad.  If re-start fails, the stage will crash naturally there, by default.
3. Once the engine turns on successfully (about 30 seconds away), it diverts to the pre-assigned pad.  It might still crash, but it's a much smaller explosion (less fuel, less velocity)

EDIT:  fixed it, doh.  Reentry burn, not third burn.
« Last Edit: 04/08/2016 06:36 PM by meekGee »
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Offline rcoppola

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Re: SpaceX Eastern Range Landing Facilities
« Reply #294 on: 04/08/2016 05:14 PM »
Not sure that's how it does or should work. Once the landing burn is initiated, the stage turns towards the designated coordinates. if it doesn't start or detects some anomaly that will prevent it from making it, it splashes.
It doesn't need to aim or divert to a crash pad pre-landing burn.

If you look at that double exposure picture of the return profile, it would seem the stage diverts over land towards the pad after the landing burn as been initiated. Once you're committed, and over land for that short time, you're committed.
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Offline Doesitfloat

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Re: SpaceX Eastern Range Landing Facilities
« Reply #295 on: 04/08/2016 06:23 PM »
I notice that you have renamed the contingency pads on the EA report to "Divert pads."
IMO this limits the use to in-flight changes. They might have used the term contingency pads to cover more than just in flight redirect. Such as one of the pads is not available at Launch time.  They may rocket at one pad,  resurfacing another,  patching a hole and picking up pieces at another.  Might be why they want multiple contingency pads.
In this case the contingency pad would be targeted before launch and no divert necessary.  Of course it would also allow targeting of contingency pads for multiple FH boosters.

Edit: Picture
« Last Edit: 04/08/2016 06:33 PM by Doesitfloat »

Offline Kabloona

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Re: SpaceX Eastern Range Landing Facilities
« Reply #296 on: 04/08/2016 08:29 PM »
Quote
There's still the matter of how/if SpaceX sends updated GPS data to a returning booster.

This has been discussed elsewhere. The simplest method would probably be to have the coordinates of all pads pre-programmed in a look-up table in the flight computer. One of those is designated as the default coordinate set where the stage will attemot to land unless it receives a divert signal from the ground.

The divert signal would be a simple radio command from the ground telling the flight computer which "line" in the look-up table to select for the divert coordinates.

Offline mvpel

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Re: SpaceX Eastern Range Landing Facilities
« Reply #297 on: 04/17/2016 04:45 PM »
"Contingency" is defined as "dependence on... the fulfillment of a condition."

I submit that the "contingency" to which they're referring with these pads  has nothing to do with the flight path of a returning booster and it trying to decide where it's going to land, but on the condition  of the government approving the return of multiple boosters at the same time.


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« Last Edit: 04/17/2016 04:46 PM by mvpel »
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Re: SpaceX Eastern Range Landing Facilities
« Reply #298 on: 04/17/2016 05:22 PM »
"Contingency" is defined as "dependence on... the fulfillment of a condition."

I submit that the "contingency" to which they're referring with these pads  has nothing to do with the flight path of a returning booster and it trying to decide where it's going to land, but on the condition  of the government approving the return of multiple boosters at the same time.


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I think they may also be for if a pad is damaged or unavailable for some reason.  I guess technically multiple landings is a specific case of a pad not being available.
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Offline Hauerg

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Re: SpaceX Eastern Range Landing Facilities
« Reply #299 on: 04/17/2016 05:27 PM »
"Contingency" is defined as "dependence on... the fulfillment of a condition."

I submit that the "contingency" to which they're referring with these pads  has nothing to do with the flight path of a returning booster and it trying to decide where it's going to land, but on the condition  of the government approving the return of multiple boosters at the same time.


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I think they may also be for if a pad is damaged or unavailable for some reason.  I guess technically multiple landings is a specific case of a pad not being available.
You sound like a formula 1 designer interpreting the regulations.   :)

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