SpaceX Falcon 9 FT - ORBCOMM-2 - Dec. 21, 2015 (Return To Flight) DISCUSSION

[wolfpack]

They're not going to destroy it...

By "destroy" I mean invasive inspection methods. For example, I'm assuming a retro-burn will experience more base heating than just an ascent burn. And farther up the stage, impinging on mostly empty tanks. Perhaps you'd want to drill samples from the metal to see how it stood up to environment. Or look at cross-sections of plumbing or wiring in and around the engines and thrust structure.

These are guesses on my part, of course. Maybe it's not needed.

[wannamoonbase]

Or... it's as simple as realizing SES-9 will be delayed by what - 2 weeks? - and so there was a chance to use SLC-40 for the test and in addition get more practice with subcooled propellants. Basically both of the things I speculated about here http://forum.nasaspaceflight.com/index.php?topic=38149.msg1473858#msg1473858

True. But do we know why SES-9 has been delayed? It could be a problem they're working out with changes to the LC-40 GSE, which they'd rather do with the help of the flown core rather than a brand new one.

Especially when that brand new one could be the first one to be reflown later this year.

[terryy]

Found this picture on Instagram showing the first stage upright at SLC-40:

trypanosoma So awesome to see the @spacex #falcon9 1st stage sitting upright at SLC-40 today. Congratulations again to all involved in the launch and landing! Looking forward to watching the #jason3 #launch on the 17th!

https://www.instagram.com/p/BAgKlpqThVv/

[kirghizstan]

Can the first reflight party thread be called "There and Back Again"

[Ohsin]

Can the first reflight party thread be called "There and Back Again"

I think reusing old party thread would be more in spirit of things.

[georgegassaway]

By "destroy" I mean invasive inspection methods. For example, I'm assuming a retro-burn will experience more base heating than just an ascent burn. And farther up the stage, impinging on mostly empty tanks. Perhaps you'd want to drill samples from the metal to see how it stood up to environment. Or look at cross-sections of plumbing or wiring in and around the engines and thrust structure.

These are guesses on my part, of course. Maybe it's not needed.

Good points.

Actually, keeping F9-21 for a museum rather than refly it, does not necessarily mean that closer inspections of it would not be allowed to damage it to some extent.

Such as, cutting out some small samples for metallurgical testing, along the lines of what you said. 

Cutting some holes for access to wiring or other inaccessible components.  Even cutting off parts and re-welding them back on later.  Even to allow a person to fit "inside" certain areas, if need be.

Stuff that would totally ruin the booster for re-flight purposes. But as long as it could be reassembled and either patched over or even make a "feature" out of noting areas that were cut for thorough inspections, I could totally see that.  Not as ideal as superficially leaving it as it is, but understandable.

Indeed, for the sake of R&D, it makes way more sense to inspect it to the point that it may be damaged too much to refly it. 

So in a way, the "keep it" statement, the primary reason may be more due to it being unable to fly after some invasive and potentially damaging inspection methods.  While "oh by the way", when they are done thoroughly inspecting it, it can go to a museum.  And even at that.....there's no guarantees that if it does make it into a museum, that the 9 engines that flew on it will all be there (this assumes nothing goes badly during the static tests, and yes I know the too true famous Benny Hill joke).

There was some Apollo CM I saw in a museum, possibly even Apollo-11's  Columbia, that had core samples cut out of the heat shield. 

And last I saw Enterprise long ago (2008, when it was at Udvar-Hazy), it still had plastic wrap covering the LE area where some RCC panels had been removed for testing for the Columbia accident, to see whether a high-speed  Foam strike could indeed damage them.

Now if Musk decrees that F9-21's core not be visibly damaged at all by further inspections, then that's that. But otherwise, I think at least some degree of damage for the purpose of inspections would be on the table.  That's not the most sentimental thing, but Rocket Science (R&D) and a Space Launch Company's future  should be more important in this case.

- George Gassaway

[deruch]

Video of the booster on the pad taken 2016-01-14 ~3pm Eastern time (no static fire at time of video).

[Jdeshetler]

From this cool angle viewing with black line inserted as a centerline, the 1st stage seems to have shifted as much as 1.5 meter to the right at the last 2 meter without any issues!

[docmordrid]

Pressure induced gas "bubble" turned it into a hovercraft?

[Ben the Space Brit]

Speculation: Could SpaceX have the audacity to tru launching the OC-2 booster and go for another RTLS today? Absolutely not, right?

That's definitely a test flight I can see SpaceX doing in the fullness of time. Whether they would do it with this core depends on a lot of things, not least a successful static fire and full inspection of the hull integrity and internal structural integrity. It would be risking an invaluable source of engineering data unless they were very sure. That's the reason why I don't think that they're likely to just fire it into the sea.

Anyway, there isn't a nosecone on top of the core and its landing gear hasn't been replaced, so I doubt that they're planning on flying it again any time soon.

The NOTAM is probably at least in part just in case they have to let the core off the pad and use the range safety pack to self-destruct it due to an extreme contingency.

[hrissan]

From this cool angle viewing with black line as a centerline, the 1st stage seems to have shifted as much as 1.5 meter to the right at the last 2 meter without any issues!

IMHO If there is a wind, then the stable position before landing is "leaning" on the wind, but you cannot land this way, so during the last 1-2 vertical meters the bottom end quickly shifts so that the stage is vertical.

The whole landing solution (taking into account wind effects and quickly diminishing control authority of  grid fins) just amazes me every time I think about it.

[abaddon]

From this cool angle viewing with black line as a centerline, the 1st stage seems to have shifted as much as 1.5 meter to the right at the last 2 meter without any issues!

Ground effect, maybe.  I don't recall seeing anything like this with Grasshopper or F9R-Dev1, anyone else?  Of course Grasshopper was a lot heavier, and even F9R-Dev1 was likely loaded with more fuel than this core was...

[abaddon]

So, no official word yet on static fire from yesterday, whether it did happen, was successful, etc?

[Dante80]

It's in L2. Great time to be a member..C:

[x15_fan]

Curious to see ORB2 stage brought in vertical on crane at SLC-40. Does anyone know why they would do this rather than use the normal procedure via the HIF/TE? Is the SES stage in the HIF already blocking this ability?

https://www.instagram.com/p/BAfiYwJgmn4/

[Dante80]

Well...to use the TE you need a second stage on the rocket - I think. Doesn't the upper part of the TE latch on to that?

[x15_fan]

S1 from F9-21 is now vertical on SLC-40. It was placed there by a large crane, which is still attached as I write this. Rumor is there will be a static fire attempt Thursday.

Was S1 from F9-21 back inside the HIF or was it taken directly to the pad. 

The use of a crane would seem to indicate the SLC-40 transporter erector is gainfully employed with the SES-9 booster.

The holddowns are part of the TE.

I thought they could be separated? They've certainly done that at VFB (see image below), and I seem to recall an image of that at SLC-40 too - although I think that was pre-v1.1.

The TEL at SLC-40 is of the older design were they don't separate.

but they could use the one assigned for 39A?

Yes, sorry seems to have been discussed already here. Thanks

[Comga]

From this cool angle viewing with black line inserted as a centerline, the 1st stage seems to have shifted as much as 1.5 meter to the right at the last 2 meter without any issues!

That's a terrific gif but not a surprise.
Look at the clouds of dust behind the vehicle.  They are flowing to the right of the vehicle as seen from this angle.
As said, in the last few seconds, control authority diminishes.   As the control system finds zero velocity at zero altitude with the stage vertical to keep the pads level, the wind accelerates it to the right.  It seems to be doing a meter or so per second as it touches and comes quickly to a stop.

I think there is a whole thread dedicated to discussions about landing with crosswinds.  Obviously there are limits.

[Tuts36]

Per Elon's tweet re: engine 9 showing thrust fluctuations, is that the center engine?

[ugordan]

Per Elon's tweet re: engine 9 showing thrust fluctuations, is that the center engine?

Yes.

Edit: Hmmmm...

Maybe some debris ingestion. Engine data looks ok. Will borescope tonight. This is one of the outer engines.

https://twitter.com/elonmusk/status/688175650570547202

Then the User Guide is wrong...