SpaceX Falcon 9 - EchoStar 23 - March 16, 2017 - DISCUSSION

[Paul_G]

F9/EchoStar: The Falcon 9 rocket, horizontal on pad 39A, at 12:15pm EST; presumed hot fire test later today

Do we know whether the rocket was rolled back to the HIF, or did it stay on the pad overnight whilst what ever needed attention was attended to?

Paul

[M.E.T.]

Man, being a spaceflight fan is not a hobby for the impatient type of person, that's for sure. I do wonder if it will ever get to the type of routine, schedule based operation that the airline industry is characterized by.

I know Elon likes to equate the two industries when it comes to economies of scale and the like, but clearly we are still a long way from that technological maturity level.

[Barrie]

Is it possible that the issue causing the delay is some unforeseen consequence of the first stage being in an expendable configuration (ie no legs, grid fins, etc) ?

[intrepidpursuit]

Delayed again...and the launch date. Updated the article:

https://www.nasaspaceflight.com/2017/03/spacex-falcon-9-echostar-23-slc-40-return/

Key area of interest highlighted:

Due to the delays with the Static Fire test, SpaceX is now targeting a window that opens at 00:34 Eastern on March 14 and lasts for 2.5 hours. March 16 is the backup date. March 14 is currently the date for the Delta IV WGS-9 launch. ULA has yet to comment on the status of its launch schedule and this mission does not have a specified launch window at this time.

We've heard that the range has a 48 hour turn around time between launches. Since many range assets are shared between KSC and CCAFS, these rockets simply cannot launch on the same day. Right?

I'd heard that WGS was not range approved yet and we were assuming that it wouldn't be unless SpaceX launched on their primary date. Is that the case?

[Comga]

What time does the launch window open on the 12th?

According to Chris Bergin's article it opens at 1:34 AM EDT on the 14th.

[MKremer]

Is it possible that the issue causing the delay is some unforeseen consequence of the first stage being in an expendable configuration (ie no legs, grid fins, etc) ?

Doubtful. That would have been caught when first mating with the TEL.

I'm thinking it could be plumbing within the octoweb - either prop to the engines, or hydraulics. Those problems would be more likely to be found after it's erected on the pad and connected to the external feed/pressure fittings.

[Semmel]

I'm thinking it could be plumbing within the octoweb - either prop to the engines, or hydraulics. Those problems would be more likely to be found after it's erected on the pad and connected to the external feed/pressure fittings.

Stuff like that should have been caught in McGregor...

[Steven Pietrobon]

According to Chris Bergin's article it opens at 1:34 AM EDT on the 14th.

Oops. Someone needs to update the NSF calendar which still says the 12th!

http://forum.nasaspaceflight.com/index.php?action=calendar

[mheney]

Question - is this the first time that SpaceX has hit the beginning of the window on a static fire?

[The Roadie]

Question - is this the first time that SpaceX has hit the beginning of the window on a static fire?

After two days worth of scrubs, it's not really an accomplishment of note to hit it on the third day.

But in general, the public has no visibility into the T-0 target for static fires, so it's a difficult stat to keep.

[edkyle99]

Question - is this the first time that SpaceX has hit the beginning of the window on a static fire?

After two days worth of scrubs, it's not really an accomplishment of note to hit it on the third day.

But in general, the public has no visibility into the T-0 target for static fires, so it's a difficult stat to keep.

Wasn't it only one scrub followed by a day of delay?  This assumes that "scrub" means a halted countdown.

 - Ed Kyle

[FutureSpaceTourist]

Do we know what the upper level wind speed limit is for F9?

Updated forecast issued today attached, no change from yesterday's:

Weather 70% GO for Tues, thick cloud layer rule only possible violation.

80% GO on delay day, liftoff winds the only issue.

Edit: should have noted this from Tuesday's forecast

Maximum upper-level winds will be from the southwest at 140 knots at 40,000 feet.

[macpacheco]

Do we know what the upper level wind speed limit is for F9?

The issue isn't the wind intensity in itself, but rather the wind gradient, aka wind difference between consecutive layers.
That's called wind shear.

[Brovane]

They might have to exhaust all propellant on S1 for this mission. Any idea if they're aiming for better insertion (like SES-9) to make up for delays?

They could tried re-entry testing, IIRC they did it when flying F9 v1.1 on a GTO mission (with no landing reserves). Elon tweeted that the stage seemed to have survived a hot re-entry of ~127kPa.

I was wondering the same thing.  I guess we will have to wait until after the flight to find out what they achieve. 

[georgegassaway]

They might have to exhaust all propellant on S1 for this mission.

Since they want to cut weight to squeeze the most out of the booster, such as not flying with the legs, or the grid fins, and deleting all that is practical to delete (or never install), that it does not need after staging....

Perhaps delete (or not install) the RCS as well.  IIRC, it is needed for maneuvering the booster after staging, but not during or before staging. At the very least not load any Nitrogen for the RCS thrusters. If built with RCS hardware before choosing that specific booster to be an expendable, remove the RCS thrusters, Nitrogen tank, and whatever else associated with them unless too much trouble to be worth it  or not practical. 

Of course perhaps they don't need that much extra performance to justify deleting RCS hardware mass. Or possibly gather some additional re-entry data points, whatever might be valuable using RCS, without the grid fins to assist with aerodynamic stability so it didn't try to veer off a lot (I'm not expecting that is what they plan to do, just acknowledging a potential reason for RCS on this expendable flight.). 

[rsdavis9]

I haven't seen the numbers but maybe they left off the legs and grid fins not because of weight but because who wants to waste perfectly good hardware if they are not going to get it back.

[mvpel]

I hope they will be able to release some of the S1 video for this mission, it would be truly fascinating to see a destructive re-entry unfold from the rocket-cam view, or from inside the oxygen tank. It would probably be ITAR, but hopefully they can release at least a still or two.


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[ugordan]

This isn't the first hot/destructive reentry they've performed and they haven't released that footage so don't expect anything this time, either.

[Ben the Space Brit]

Time to projected t=0?

Currently 16 hours and 17 minutes until the window opens.

So, the vehicle (plus payload) is vertical on the pad and, further to the conversation quoted above, something occurs to me. Would the formal countdown have already begun or is there a looser time-line prior to a certain point before launch?

[AncientU]

This isn't the first hot/destructive reentry they've performed and they haven't released that footage so don't expect anything this time, either.

While on this topic, exactly what is that causes a returning stage to explode?  Lateral stresses due to tumbling, reentry heating reducing the strength of aluminum, BLEVE from hot skin flashing cryogens, ... ?