SpaceX F9 : CRS SpX-19 : December 5, 2019 - DISCUSSION

[CyndyC]

Space News...

Falcon 9 cargo mission for NASA demonstrated long-duration coast required by U.S. Air Force

LOS ANGELES  The upper stage of the SpaceX Falcon 9 mission to the International Space Station Dec. 5 successfully performed a six-hour coast and a deorbit burn, a test that had been requested by the U.S. Air Force to demonstrate the vehicle can deliver national security payloads directly to geosynchronous Earth orbit.

Something similar to the requirement above was also demonstrated earlier, on March 4, 2016 with the SES-9 launch. After a long delay following the CRS-7 anomaly in 2015, SpaceX compensated SES with a supersychronous injection. 

[gongora]

Space News...

Falcon 9 cargo mission for NASA demonstrated long-duration coast required by U.S. Air Force

LOS ANGELES  The upper stage of the SpaceX Falcon 9 mission to the International Space Station Dec. 5 successfully performed a six-hour coast and a deorbit burn, a test that had been requested by the U.S. Air Force to demonstrate the vehicle can deliver national security payloads directly to geosynchronous Earth orbit.

Something similar to the requirement above was also demonstrated earlier, on March 4, 2016 with the SES-9 launch. After a long delay following the CRS-7 anomaly in 2015, SpaceX compensated SES with a supersychronous injection.

Putting something in supersync GTO is not remotely similar to putting it directly in GEO.

[CyndyC]

Space News...

Falcon 9 cargo mission for NASA demonstrated long-duration coast required by U.S. Air Force

LOS ANGELES  The upper stage of the SpaceX Falcon 9 mission to the International Space Station Dec. 5 successfully performed a six-hour coast and a deorbit burn, a test that had been requested by the U.S. Air Force to demonstrate the vehicle can deliver national security payloads directly to geosynchronous Earth orbit.

Something similar to the requirement above was also demonstrated earlier, on March 4, 2016 with the SES-9 launch. After a long delay following the CRS-7 anomaly in 2015, SpaceX compensated SES with a supersychronous injection.

Putting something in supersync GTO is not remotely similar to putting it directly in GEO.

"Not remotely similar" is not a fair assessment, because supersync got the SES satellite to its final destination faster than previously planned, which is in essence what the Air Force wants to do with their national security satellites. However, I did find conflicting definitions for supersync on Stack Exchange, one saying the perigee is raised and the apogee is lowered, the latter cost offset by saving on inclination change, and as in the case of SES-9 as I remember it, the apogee was raised https://space.stackexchange.com/questions/13620/differences-between-launch-injection-and-transfer-orbits-for-geostationary-satel

[soltasto]

Supersync GTO from the second stage poimt of view is just a normal GTO mission where the only difference is that the second second stage burn lasts longr. The result is an higher that GEO altitude apogee and sometimes lower inclination.

There are no particular difficulties for this profile as the timing is almost identical to a normal GTO mission. A direct to GEO mission is much more complex and is not as trivial.

[FutureSpaceTourist]

Apple’s Tim Cook appreciating a CRS-19 launch photo:

https://twitter.com/johnkrausphotos/status/1204175292006359041

Thanks, @tim_cook! 🍎🤯🚀

Love the 'Sent from my iPhone' 😃

In response to:

https://twitter.com/johnkrausphotos/status/1202707507795386369

Today’s Falcon 9 launch of #CRS19 — Shot on an iPhone placed at Space Launch Complex 40! #ShotoniPhone

It’s amazing how far smartphone cameras have come 🚀🤯

[Norm38]

SpaceX retracts Falcon 9 booster’s landing legs a second time after speedy reuse..
By Eric Ralph Posted on July 29, 2019
https://www.teslarati.com/spacex-retracts-falcon-9-landings-legs-second-time/

Is this the 3rd time legs have been retracted?  (1056.1, 1056.2 and 1059.1)

[webdan]

Yes, very cool... reminds me when I used to write 3D software (long long time ago) using a home made version of Earth data (continents, islands, rivers, about 8000 data points), adding a random orbital inclination and letting it run for x hours.

The goal was to come back, pan around and try to figure out where I was.

Heading north north east over lake Chad at 1 minute in...

Space Videos

4K video of the #SpaceX #Dragon as it approached the ISS on 8th December. Mission CRS-19 was NASA's Cargo Resupply Mission to the space station.

This video was created using  thousands of individual photos taken by astronauts aboard the ISS then using software to interpolate missing frames, we have been able to recreate it in real-time.

The process isn't perfect and you may notice some artifacts but I think that on the whole it looks pretty cool!

Thanks for watching - why not support this channel and help us grow.
https://www.youtube.com/channel/UCakg...

[AndrewRG10]

Has anyone ever seen the Dragon following behind the ISS shortly before/after berthing? I noticed the ISS is flying overhead shortly after canadarm release and around 80 minutes after sunset. I curious to know if it's possible to see it and how long after departure I'd have to wait to see it.

[John Santos]

Has anyone ever seen the Dragon following behind the ISS shortly before/after berthing? I noticed the ISS is flying overhead shortly after canadarm release and around 80 minutes after sunset. I curious to know if it's possible to see it and how long after departure I'd have to wait to see it.

Go to https://www.heavens-above.com/PassSummary.aspx?satid=25544&lat=0&lng=0&loc=Unspecified&alt=0&tz=UCT, enter your location, and it will tell you when the ISS is visible.  Click on the pass in the table closest to the Dragon sep, and it will display a sky map showing the path of the ISS.  The ISS will be one of the brightest objects in the sky.  You might need binoculars to see the Dragon.

[AndrewRG10]

Has anyone ever seen the Dragon following behind the ISS shortly before/after berthing? I noticed the ISS is flying overhead shortly after canadarm release and around 80 minutes after sunset. I curious to know if it's possible to see it and how long after departure I'd have to wait to see it.

Go to https://www.heavens-above.com/PassSummary.aspx?satid=25544&lat=0&lng=0&loc=Unspecified&alt=0&tz=UCT, enter your location, and it will tell you when the ISS is visible.  Click on the pass in the table closest to the Dragon sep, and it will display a sky map showing the path of the ISS.  The ISS will be one of the brightest objects in the sky.  You might need binoculars to see the Dragon.

Yeh spotted ISS easily as usual, just Dragon was too close to the ISS. With the Binoculars I had I would've needed Dragon to be a good 1500m away from the ISS to tell the two apart. If only they departed 30 minutes earlier or so.

[Comga]

https://twitter.com/NASASpaceflight/status/1214491407685210112

This seems like another of those “out of an abundance of caution” investigations

When the solar panels are “glinting” they are reflecting light from the Sun, which subtends a half degree. Therefore, any particular portion of the solar panels that flexes by a quarter degree moves the “line of sight” the equivalent of the full angular diameter of the sun. That will make dramatic changes in brightness.
The Dracos do not fire perfectly smoothly. The solar panels are long, light, flexible, segmented structures. It would be very surprising if they DIDN’T shake with large multiples of that tiny angle. I would EXPECT the brightness of sunlight to vary dramatically and rapidly.
Dragon doesn’t need plume impingement to create this visible effect.
There are many people at NASA with the appropriate knowledge of the nature of scattered light (we affectionately call them “scatterbrains”) but they may never be asked if this is considered a propulsion problem. It’s like asking a surgeon what to do about a medical issue. They routinely recommend surgery. Plume modeling will be another “rabbit hole” that could result in delays and unnecessary modifications. Let’s hope that doesn’t happen.

[kenny008]

https://twitter.com/NASASpaceflight/status/1214491407685210112

This seems like another of those “out of an abundance of caution” investigations

When the solar panels are “glinting” they are reflecting light from the Sun, which subtends a half degree. Therefore, any particular portion of the solar panels that flexes by a quarter degree moves the “line of sight” the equivalent of the full angular diameter of the sun. That will make dramatic changes in brightness.
The Dracos do not fire perfectly smoothly. The solar panels are long, light, flexible, segmented structures. It would be very surprising if they DIDN’T shake with large multiples of that tiny angle. I would EXPECT the brightness of sunlight to vary dramatically and rapidly.
Dragon doesn’t need plume impingement to create this visible effect.
There are many people at NASA with the appropriate knowledge of the nature of scattered light (we affectionately call them “scatterbrains”) but they may never be asked if this is considered a propulsion problem. It’s like asking a surgeon what to do about a medical issue. They routinely recommend surgery. Plume modeling will be another “rabbit hole” that could result in delays and unnecessary modifications. Let’s hope that doesn’t happen.

I don't know if that's quite right.  He didn't say anything about glint.  He said the panels flexed "quite vigorously."  These guys have been up there a while and I'm sure they understand the difference between a mirror surface shaking slightly and changing a sunlit "glint," and the structure actually shaking vigorously.  It's good to take a look at compare the expected vs actual plume affects on the structure, as well as any possibly unexpected contamination due to the plume.  I guess "abundance of caution" might apply, but I think it's more just good analysis of the observations of a smart, professional observer's report.

And in case I'm misunderstanding your post, he wasn't talking about the Dragon's panels; he was talking about plume impingement on and movement of the Cygnus' panels.

[Comga]

(Snip)
And in case I'm misunderstanding your post, he wasn't talking about the Dragon's panels; he was talking about plume impingement on and movement of the Cygnus' panels.

Dang!
You appear to be correct
I did not listen and look sufficiently carefully.
On closer inspection that image looks more like overexposure to enhance the debris than glint, because the Dragon capsule is also very bright.
My mistake.

[SWGlassPit]

Noticed some pretty gnarly outgassing / contamination on the surfaces surrounding the GNC bay.  Inside of the CBM petals is getting pretty brown from outgassing as well.

[Herb Schaltegger]

Noticed some pretty gnarly outgassing / contamination on the surfaces surrounding the GNC bay. Inside of the CBM petals is getting pretty brown from outgassing as well.

Are you (and the ISS community) certain the discoloration is (1) real (e.g., not an artifact of lighting and color-balance); and (2) a result of outgassing (from which surfaces and materials?); surface contamination (e.g., propellant residues ); or oxidation from long-term orbital exposure to UV and atomic oxygen or other trace contaminants such as ammonia?

[SWGlassPit]

Noticed some pretty gnarly outgassing / contamination on the surfaces surrounding the GNC bay. Inside of the CBM petals is getting pretty brown from outgassing as well.

Are you (and the ISS community) certain the discoloration is (1) real (e.g., not an artifact of lighting and color-balance); and (2) a result of outgassing (from which surfaces and materials?); surface contamination (e.g., propellant residues ); or oxidation from long-term orbital exposure to UV and atomic oxygen or other trace contaminants such as ammonia?

On (1): yes, absolutely.  I've seen it personally on returned hardware, and this type of discoloration is visible in multiple other places that have known outgassing materials nearby.

On (2): It's a combination of things.  Contaminants outgas from all sorts of surfaces (silicone materials are notoriously bad for this, but a large number of polymeric materials spit out quite a bit of stuff).  When it's initially deposited, it's clear, but UV radiation causes discoloration.  This effect is visible on large portions of the Russian segment, and on the US segment, it's particularly bad on the edges of the airlock hatch thermal cover.

Here's a WIRED article from a year ago that talks pretty extensively about the problem.

[Herb Schaltegger]

On (1): yes, absolutely.  I've seen it personally on returned hardware, and this type of discoloration is visible in multiple other places that have known outgassing materials nearby.

On (2): It's a combination of things.  Contaminants outgas from all sorts of surfaces (silicone materials are notoriously bad for this, but a large number of polymeric materials spit out quite a bit of stuff).  When it's initially deposited, it's clear, but UV radiation causes discoloration.  This effect is visible on large portions of the Russian segment, and on the US segment, it's particularly bad on the edges of the airlock hatch thermal cover.

Here's a WIRED article from a year ago that talks pretty extensively about the problem.

Thanks for the link. It's been decades since my days as a baby engineer on Space Station Freedom. I'd like to see how much of what warned about (and were warned about by others) WRT to external contamination was warranted.

[zubenelgenubi]

Would it be accurate to say that this is some of the same general chemical process that produces tholins?
("organic" molecules, abiologically polymerized, then chemically altered by UV radiation)
(However, the polymers were produced by sapient carbon-based lifeforms.)