SpaceX Falcon 9 : X-37B OTV-5 : September 7, 2017 : DISCUSSION

[ZachS09]

I wonder if that instantaneous puff of condensation at 6:52 in addition to those more persistent vapor streaks at the base is the moment it crossed Mach 1.

I'm guessing that the "instantaneous puff of condensation" also means the incoming sonic boom just before the landing burn.

[Herb Schaltegger]

I'm guessing that the "instantaneous puff of condensation" also means the incoming sonic boom just before the landing burn.

Well, it means the stage is transonic. The boom is caused by the stage being supersonic, with an expanding shock cone (cones, in this case) emanating from points on the stage as it's descending.  The puff of condensation is cause by the stage going transonic in humid air. 

See below for a (not very readable) explanation. You'll get the gist, probably. You'd need a good 400-level college class in compressible fluid dynamics to follow the math.

https://en.wikipedia.org/wiki/Prandtl–Glauert_singularity

[AncientU]

This story says that SpaceX "was moving quickly to secure" the first stage. 
http://spacenews.com/cape-canaveral-facilities-prepare-for-hurricane-irma/
My guess is that means lifting it onto the work stand.  I don't see how they could do more. I could be wrong.

 - Ed Kyle

Motivation is a wonderful energy focusing mechanism...

[topopesto]

Is state to recover the fairing in this mission?

The Go Quest/Go Searcher support ships did not leave port, according to our ASDS tracking thread, and are currently tied up further inland than usual to ride out the storm.  So very unlikely there was any fairing recovery attempt, as I believe the Go * ships need to be over the horizon to collect fairing telemetry for even unsuccessful or "water landing" attempts.

Ok, thanks!

[kch]

I'm guessing that the "instantaneous puff of condensation" also means the incoming sonic boom just before the landing burn.

Well, it means the stage is transonic. The boom is caused by the stage being supersonic, with an expanding shock cone (cones, in this case) emanating from points on the stage as it's descending.  The puff of condensation is cause by the stage going transonic in humid air. 

See below for a (not very readable) explanation. You'll get the gist, probably. You'd need a good 400-level college class in compressible fluid dynamics to follow the math.

https://en.wikipedia.org/wiki/Prandtl–Glauert_singularity

Wiki (and other) addresses are often troublesome -- the last part gets left off the clickable link.  If you click the Insert Hyperlink button in the reply editor, then insert your address between the tags, it gets the whole address:

https://en.wikipedia.org/wiki/Prandtl–Glauert_singularity

[john smith 19]

Well, it means the stage is transonic. The boom is caused by the stage being supersonic, with an expanding shock cone (cones, in this case) emanating from points on the stage as it's descending.  The puff of condensation is cause by the stage going transonic in humid air. 

See below for a (not very readable) explanation. You'll get the gist, probably. You'd need a good 400-level college class in compressible fluid dynamics to follow the math.

https://en.wikipedia.org/wiki/Prandtl–Glauert_singularity

Amazing picture of the Hornet condensation cloud.

TBH when you've got a term that can lead to a division by 0 (as that equation can) you should realize "This is not physically real," but it kept the maths doable on a slide rule in the early years of the 20th Century, which is when I think it originates from (people forget that supersonic flow has been under study a lot longer than supersonic flight has been possible in an aircraft).   

Completely OT but it does suggest a basis for some kind of wacky dehumidification system. All you need do is collect the water before it has a chance to re vaporize.   

[Asteroza]

As an update, we're told the booster is off the LZ-1 pad via their expedited post landing processing which was initiated for the previous landing (CRS-12: The faster processing was a L2 note. Chris G asked Hans. Hans confirmed).

Great work by the LZ-1 team.

Is there a rough time period for how long expedited post landing processing takes to clear the landing pad?

[AncientU]

As an update, we're told the booster is off the LZ-1 pad via their expedited post landing processing which was initiated for the previous landing (CRS-12: The faster processing was a L2 note. Chris G asked Hans. Hans confirmed).

Great work by the LZ-1 team.

Is there a rough time period for how long expedited post landing processing takes to clear the landing pad?

It was tucked away two days after landing. 
Exact work hours would be informative if anyone here can share.

[FutureSpaceTourist]

DEIMOS IMAGING‏ @deimosimaging 6m6 minutes ago
Replying to @SpaceX

#DEIMOS2 caught Cape Canaveral's Landing Zone1 at around 15:58 UTC, September 7, less than 2hours after #Falcon9's first stage landed there!

https://twitter.com/deimosimaging/status/907255552153194496

[Rocket Science]

Three weeks after launch, the searching civilians at Seesat-L have yet to find OTV-5.  I wonder if it might be in a higher inclination orbit than expected.

 - Ed Kyle

Or a new "cloaking device"?

[Star One]

Three weeks after launch, the searching civilians at Seesat-L have yet to find OTV-5.  I wonder if it might be in a higher inclination orbit than expected.

 - Ed Kyle

Would it be possible for the F9 to have put it in an orbit like ORS-5 where there are no qualified amateur observers actually able to see it.

[Ben the Space Brit]

OTV5 has a Hall Effect engine. How much could they have used that to change the spacecraft's inclination and/or apogee in the time since launch? Enough to make it difficult to predict where the spacecraft would be?

[rsdavis9]

Three weeks after launch, the searching civilians at Seesat-L have yet to find OTV-5.  I wonder if it might be in a higher inclination orbit than expected.

 - Ed Kyle

Would it be possible for the F9 to have put it in an orbit like ORS-5 where there are no qualified amateur observers actually able to see it.

So is there a sun synchronous orbit that makes satellite viewing difficult?
I would assume if one half is in daylight that would help and if the dark half is over the pacific...

[Star One]

OTV5 has a Hall Effect engine. How much could they have used that to change the spacecraft's inclination and/or apogee in the time since launch? Enough to make it difficult to predict where the spacecraft would be?

That was OTV-4 that had this, there was no mention of such an engine on this one.

[Kansan52]

Three weeks after launch, the searching civilians at Seesat-L have yet to find OTV-5.  I wonder if it might be in a higher inclination orbit than expected.

 - Ed Kyle

Is this any longer than normal compared to other OTV missions?

[macpacheco]

My money is on the 2nd stage substantially changed the target inclination from the booster trajectory.
And X-37B has radar absorbing material, making it nearly impossible to detect it (helped by the sheer distance from the ground it flies at).
Its a secret space plane for a reason.

[hkultala]

My money is on the 2nd stage substantially changed the target inclination from the booster trajectory.
And X-37B has radar absorbing material, making it nearly impossible to detect it (helped by the sheer distance from the ground it flies at).
Its a secret space plane for a reason.

An basis for the claims about the radar-absorbing materials?

No reliable source seems to claim so.

[zubenelgenubi]

Three weeks after launch, the searching civilians at Seesat-L have yet to find OTV-5.  I wonder if it might be in a higher inclination orbit than expected.

 - Ed Kyle

Is this any longer than normal compared to other OTV missions?

<snip>
Looking back through the SeeSat-L archives:

OTV-1 launched April 22, 2010
1st usable observations made May 20, 2010
Ted Molczan wrote a great summary of the "discovery" process in this post:
http://www.satobs.org/seesat/May-2010/0190.html

OTV-2 launched March 5, 2011
1st observation March 9, 2011

OTV-3 launched December 11, 2012
1st observation 19 minutes after Centaur MECO

And, there have been times when the OTV has been "lost" for some time after an orbit change.

<snip>

ADD: OTV-4 launched May 20, 2015
1st observation May 25, 2015

[Tomness]

Three weeks after launch, the searching civilians at Seesat-L have yet to find OTV-5.  I wonder if it might be in a higher inclination orbit than expected.

 - Ed Kyle

I hope they don't find it... Silence is Golden and Secret can't stay a Secret if its known.... I think these Observations just allows other to find it quicker....

[macpacheco]

My money is on the 2nd stage substantially changed the target inclination from the booster trajectory.
And X-37B has radar absorbing material, making it nearly impossible to detect it (helped by the sheer distance from the ground it flies at).
Its a secret space plane for a reason.

An basis for the claims about the radar-absorbing materials?

No reliable source seems to claim so.

Any reliable sources would be under threat of jail time if they said anything. Stealth is nothing new. Not putting some stealth on a space plane would be incompetence in my view.