Falcon 9: JCSAT-14 (mission thread)

[anthdci]

I didn't get to see the launch, with the weather delay it meant I was on a Virgin Atlantic flight from Atlanta to Manchester when it when up  

 

Watched the webcast through though, and was wondering what happens to the second stage? Does it come back down and burn up with any remains hitting the ocean, or does it become space junk?

[flyingskippy]

The second stage will stay up for a while.  Eventually through atmospheric drag,  the stage will work it's way lower and lower until reentry. There it will burn up.  Could be years  down the road though. 

[Jim K Global Moderator]

I can not wait for them to send one of these first stages back up ... and re-land it. They may want to ramp up their timeline ... going to run out of room if they keep successfully landing them.  Aren't they suppose to relaunch the first stage from the previous mission sometime soon?

[anthdci]

  On 06/05/2016 at 21:11, flyingskippy said:

  Could be years  down the road though. 

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i suppose it's good that it will end up burnt up, but if spacex are ramping up launches there is going to be a lot of s2 floating around, wouldn't a tiny booster on the side that could de-orbit it quicker not be worth them looking at?

 

[Jim K Global Moderator]

Maybe Doc or Draggen can elaborate ... but I believe I read somewhere it takes (for GTO) around 2-6 months.  For LEO ... they usually produce a NOTAM because they'll deorbit them (because they still have fuel) so they'll come back down much sooner (hours/days?)

[BetaguyGZT]

  On 06/05/2016 at 21:18, anthdci said:

i suppose it's good that it will end up burnt up, but if spacex are ramping up launches there is going to be a lot of s2 floating around, wouldn't a tiny booster on the side that could de-orbit it quicker not be worth them looking at?

 

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My guess, and this is purely conjecture ... I'd be willing to put money on SpaceX already working on a way to safely de-orbit and land S2's like they are S1's. The trick with those, however, is that they're in a much better position to dictate when and where they come down at. Everything is easier with an S2 because they are so much lighter -- and everything is harder, for the same reasons. Less fuel capacity, they're aerodynamically less stable on their own relative to an S1. Even the engine itself isn't meant to be used in an atmosphere and would need re-working to function properly for landings.

 

 

And it's SpaceX -- they don't do parachutes if they can help it. So a rather curious idea comes to my own conciousness ...

 

 

Thoughts?  

[Jim K Global Moderator]

  On 06/05/2016 at 21:32, Unobscured Vision said:

My guess, and this is purely conjecture ... I'd be willing to put money on SpaceX already working on a way to safely de-orbit and land S2's like they are S1's. The trick with those, however, is that they're in a much better position to dictate when and where they come down at. Everything is easier with an S2 because they are so much lighter -- and everything is harder, for the same reasons. Less fuel capacity, they're aerodynamically less stable on their own relative to an S1. Even the engine itself isn't meant to be used in an atmosphere and would need re-working to function properly for landings.

 

 

And it's SpaceX -- they don't do parachutes if they can help it. So a rather curious idea comes to my own conciousness ...

 

 

Thoughts?  

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Sexy. Where do you think they would put them though on the S2?  Outside the body? Just a little math for the added weight/drag.

 

Also...you'd need some sort of heat shield for the S2.  Wonder where they would put it (assuming between payload and S2?).  Would be hard to keep it on a projectory to keep it from burning up.  If you have those above rockets on the outside ... then they might burn up.  Hmmm....space is hard.  Elon and crew will figure it out.

 

[BetaguyGZT]

Four pop-off panels.  The Super Draco's themselves could be mounted inside the S2, where they would need to be for center-of-weight purposes. We'll use those for the Landing.

 

The S2 Engine (Merlin-D) -- we'll use that to cancel (as much as possible) our orbital speed while we're uphill. This will eliminate the need to redesign it for atmospheric use (making the Accounting folks happy). The Super Draco's can be used to trim our speed so that we're not coming in hot or grossly off-target (and remember that we've got a perfectly functional RCS system too!). We do our Flip Maneuver using the RCS, set guidance to wherever we want to land, and tell the computer that we're in an S2 instead of an S1. Smaller-sized Landing Legs (but still up to the job), and we're in business.  

 

Changes SpaceX would have to make to the S2 are as follows:

 

- Add Super Dracos and mount them where and how needed so that the S2 is balanced properly

- Add some panels to cover the 'Dracos; preferably ones that do not get jettisoned off into space (retractable?) adding to the Space Junk problem

- Add a 5% fuel reserve to the S2 tanks to accommodate de-orbit burns (that cover all launch scenarios including GTO)

- Add 20% capacity to the RCS propellant system to accommodate maneuvering all the way down to landing

- Add Landing Legs and structural stiffening to the S2

- Add appropriate logic and control to the S2 to provide reentry and landing functions

- Add reentry hardware to the S2 (similar to the S1)

- Add aerodynamic guide fins to S2 (similar to the S1 but scaled down as needed)

 

It'll require a significant upgrade to the S2, but since they're bumping the platform up to 1.3 anyway, might as well do it. Anything that brings the company-cost-of-launch down (and brings the company business) ...  

[BetaguyGZT]

In thinking about this, the only real issue I really see with it (and yes, I know, I'm answering myself) is that the F9 is going to be top-heavy 30 seconds or so before staging. This one might need to be saved for Falcon Heavy ... 

[BetaguyGZT]

More conjecture about the S2 Reuse thing.

 

If they're doing upgrades to the S2, might as well wait until Raptor's ready. That's one's already on the board to fly as an S2 replacement; and that'll give the Engineering people time to sort out potential S2 Reuse.

 

We can't be the first ones to have thoughts about it.  

[anthdci]

  On 06/05/2016 at 22:21, Unobscured Vision said:

We can't be the first ones to have thoughts about it.  

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Of course we arent the first ones to think it! Space junk is a big thing at the moment, if spacex are landing and reusing the main bits then it makes they clients look much better to use them than use someone else who leaves numerous parts  in orbit

[flyingskippy]

I think there are a lot of reasons SpaceX put to the side S2 recovery.  

 

The velocity is higher so therefore so is heating during reentry.  Higher velocity means more fuel needed for a reentry burn. That in turn means less payload to orbit. A heat shield also cuts down on payload.  Adding any sort of weight whether it be super Dracos  or parachutes or anything cuts down the economics of the F9. 

 

F9 is in  this super sweet spot that is more than competitive compared to other launch service providers. While it would be really cool to see SpaceX recover a S2, I just don't see it being economical compared to the S1. 

[flyingskippy]

Here is some info on S2 tracking. 

 

https://www.reddit.com/r/spacex/comments/4cxe4j/april_1st_falcon_2nd_stage_orbit_update/?ref=search_posts

[BetaguyGZT]

  On 06/05/2016 at 22:46, anthdci said:

Of course we arent the first ones to think it! Space junk is a big thing at the moment, if spacex are landing and reusing the main bits then it makes they clients look much better to use them than use someone else who leaves numerous parts  in orbit

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No, I meant S2 Recovery and Reuse. I'm sure better minds than ours have already thought about it.

 

  On 07/05/2016 at 02:48, flyingskippy said:

I think there are a lot of reasons SpaceX put to the side S2 recovery.  

 

The velocity is higher so therefore so is heating during reentry.  Higher velocity means more fuel needed for a reentry burn. That in turn means less payload to orbit. A heat shield also cuts down on payload.  Adding any sort of weight whether it be super Dracos  or parachutes or anything cuts down the economics of the F9. 

 

F9 is in  this super sweet spot that is more than competitive compared to other launch service providers. While it would be really cool to see SpaceX recover a S2, I just don't see it being economical compared to the S1. 

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Well, if they do it on the premise of a de-orbit burn rather than a controlled re-entry like the S1 where the heat loads and such are far lower then something like a Space Shuttle or Apollo, or even Dragon experiences, then it wouldn't really need anything more than some extra metal at the bottom end of the S2 and the Engine area. At those speeds, the friction is substantial but nothing like the nastiness of the above. It's actually a controlled reentry; where everything else isn't.  

 

But yeah; I don't see it happening either. Not until the S2 gets a real upgrade and refit; slated for Raptor's debut, and that won't happen until after Falcon Heavy is launching.

[flyingskippy]

Believe me, I would love to see a S2 recovery. You don't know how many times I watched the F9R animation when it was first released. Amazed by its simplicity. 

 

I just don't see it happening with this current version because it isn't really economical recovering a stage with only one engine. The engineering required to get it to survive any sort of Reentry out weighs the cost of the stage itself. 

 

Maybe the raptor stage will be a different story. 

[DocM]

The lower orbit S2's are usually deorbited SW of Australia, but for GTO launches they're in an extremely elliptical Super-Synchronous orbit ~160-240 miles perigee by 45,000-90,000 miles apogee.  At each perigee pass the upper atmosphere causes drag which slows the stage down and lowers it. Eventually it'll be low & slow enough this "bite" will be sufficient to make it re-enter and burn up. Could be months, could be ayear or so. 

 

Are usable S2 won't be based on M1DVac but Raptor, because the future will belong to the methane architecture. Too many advantages to ignore, especially for military and BEO launches where the stage will have to coast for long periods. That long an exposure to cold causes RP-1 to gel and become useless. Methane laughs it off.

 

BOTE calcs,

 

Now ponder on what a mostly empty methane Falcon S2 stage needs to land vertically like S1. The Raptor stage needs to be 50-100% larger in capacity than a M1DVac stage to account for the lower bulk density of methane, extra propellants for the ∆V of DoD GSO payloads (direct insertion geostationary).

 

Now add vertical landing legs, SuperDraco thrusters, their prop & pressurization tanks etc. and it'd be much heavier - as much as 25-30% of disposable stage dry mass. That cuts deeply into payload mass.

 

To avoid vertical landings we embrace horizontal landings; shape the stage like a biconic capsule with a lightweight, disposable, skeletonized payload/fairing adapter. Like the early versions of Russia's Kliper capsule or Blue Origin's SV, it would re-enter on its side with an angle of attack to spread heat & physical loads, then pop a (light) paraglider and bare-bones skids to land. 

 

 

 

 

 

[Draggendrop Veteran]

Just to be a silly parrot and rehash the above comments....because I got bored.....

 

That is the one point that I appreciate about SpaceX, they do a good job of eventually bringing back higher elevation second stages. The low level LEO stages are routinely brought back down in a day or two, same for Roscosmos  and JAXA ISS missions. As mentioned above, higher ones, generally 2 to 6 months, a few near a year...but they come down by gaseous drag.

 

There is a curious spot also used very frequently, the "Spacecraft Cemetary", in the remote south Pacific...a lot of great "junk" dropped of there...

https://en.wikipedia.org/wiki/Spacecraft_cemetery

 

The real dilemma, if you will, is GEO spent payloads, generally 300+ km above orbital location. It takes 1500 m/s to down one as opposed to 11 m/s to push up, and the downpush is an unreasonable amount of fuel. So for now, they go up...and sadly, due to neglect or technical issues, not all are able to be pushed up. With a 1 degree orbital allotment, at that elevation, there is still lots of room, but it is a situation that will become a problem in the future.

 

Just for giggles, one payload in high "graveyard" will take 4000 years to come down....SNAP-10A

 

Many sites list graveyard payloads and their associated data and Spaceflight101 has a reentry section to give us a rundown of what and where, when one comes in, and an archive as well....

http://spaceflight101.com/re-entry/

 

Overall, It seems to me, that we do what we can, and an awareness is being brought to the forefront as of late, with better mitigation techniques.

It's that small stuff in LEO that causes headaches right now....

 

 

[BetaguyGZT]

All fine points, gentlemen.

 

I was looking at it purely from a PR and cost-savings standpoint for both the Company and the Customer. Certainly S2 Reuse is something SpaceX is already thinking about, and likely even working on. I'm sure we'll know when there's something to announce; and it's likely that it won't happen until Raptor.

[Draggendrop Veteran]

A while back, I was all for saving stage 2...but....not so much any more. I would rather see reuse of the fairing halves, those puppies are not cheap (composite materials). The second stage, as it is with the Mvac, it's need to be replaced with a higher performance unit, and lack of real high dollar goodies, tends to put this on the back burner and see how future upgrades to the second stage will pan out.

 

 

[DocM]

Returning a Raptor S2 would be on the critical path to returning the BFS, assuming it has an integrated S2/departure/return stage. And the USAF is paying part of the tab.

[bguy_1986]

Somebody said in a reddit maybe instead of bringing S2 down and re-using it, maybe they re-use it in space?  I doubt it can work as a fuel depot but maybe something to collect space junk?

[Draggendrop Veteran]

 

 

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Should be in soon...came direct and made good time...

[Draggendrop Veteran]

 

credit John Kraus

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Image from shore, approx 15 minutes ago...

 

edit....marine radio chatter has it coming in at 22:00 EDT, it is actually anchoring outside of port to take on crew, and will advise harbor master if wanting to port early...scheduled for 23:00 prior.

[Draggendrop Veteran]

 

 

 

 

 

[Draggendrop Veteran]

 

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