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

[Alexphysics]

What exactly is a "thermal demonstration"? Any educated guesses?

If you’re referring to the test to be performed with the upper stage, it’s demonstrating that the stage can maintain thermal control during an extended coast (e.g., not developing localized cold spots and fuel gelling, and not developing hot spots and increased oxidizer boil-off. Extended upper stage coasts are necessary for some mission profiles (specifically, direct GEO insertion missions for government payloads).

And this is different from what they had already demonstrated? Or just a continuation of the same?

Continuation. More data is always better

[LouScheffer]

Has there been a previous SpaceX launch for NASA that scrubbed due to landing conditions rather than launch conditions?

It used to be that landing conditions did not have any impact on launching.

No, this was also a problem in the Shuttle days.  If the weather at the possible trans-Atlantic abort sites was bad, they would scrub even if the weather was fine at the Cape.

[mjcrsmith]

Has there been a previous SpaceX launch for NASA that scrubbed due to landing conditions rather than launch conditions?

It used to be that landing conditions did not have any impact on launching.

No, this was also a problem in the Shuttle days.  If the weather at the possible trans-Atlantic abort sites was bad, they would scrub even if the weather was fine at the Cape.

I understand about the Shuttle.  But for the Falcon 9, my understanding was that for NASA payloads, getting the payload to orbit was the mission.  If SpaceX could land the booster, fine, that was on them, but the F9 launch would not be delayed for something would prevent the landing of the booster.  SpaceX would have to expend it.

To me, having NASA agree to delay due to the Landing of the booster is interesting. 

Cheers,
Roger

 

[matthewkantar]

There is still the upper level winds. We don't know what they would have done with good launch weather and bad landing weather do we?

[zubenelgenubi]

Has there been a previous SpaceX launch for NASA that scrubbed due to landing conditions rather than launch conditions?

It used to be that landing conditions did not have any impact on launching.

A flawed premise re: scrub: there were excessively high winds aloft at the launch site.

(Side question: was it high altitude wind speeds or wind shear?  Or both?)

The high winds and seas for first stage landing was (probably, no inside knowledge here) like the thief stabbing the already-dead Dagoth in Conan the Destroyer.



I do appreciate that he got his own victory fanfare.

[abaddon]

I understand about the Shuttle.  But for the Falcon 9, my understanding was that for NASA payloads, getting the payload to orbit was the mission.  If SpaceX could land the booster, fine, that was on them, but the F9 launch would not be delayed for something would prevent the landing of the booster.  SpaceX would have to expend it.

Your understanding was wrong.

[zubenelgenubi]

What exactly is a "thermal demonstration"? Any educated guesses?

If you’re referring to the test to be performed with the upper stage, it’s demonstrating that the stage can maintain thermal control during an extended coast (e.g., not developing localized cold spots and fuel gelling, and not developing hot spots and increased oxidizer boil-off. Extended upper stage coasts are necessary for some mission profiles (specifically, direct GEO insertion missions for government payloads).

And this is different from what they had already demonstrated? Or just a continuation of the same?

Continuation. More data is always better

See the upcoming AFSPC-44 launch thread.

[Wolfram66]

There is still the upper level winds. We don't know what they would have done with good launch weather and bad landing weather do we?

Posted on page 4 of the thread. Mid level shear and high winds aloft . Click java to Run 3-day movie at bottom

http://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=midshr&zoom=&time=

[Alexphysics]

Has there been a previous SpaceX launch for NASA that scrubbed due to landing conditions rather than launch conditions?

It used to be that landing conditions did not have any impact on launching.

No, this was also a problem in the Shuttle days.  If the weather at the possible trans-Atlantic abort sites was bad, they would scrub even if the weather was fine at the Cape.

I understand about the Shuttle.  But for the Falcon 9, my understanding was that for NASA payloads, getting the payload to orbit was the mission.  If SpaceX could land the booster, fine, that was on them, but the F9 launch would not be delayed for something would prevent the landing of the booster.  SpaceX would have to expend it.

To me, having NASA agree to delay due to the Landing of the booster is interesting. 

Cheers,
Roger

This is not completely new as a delay due to landing not being assured has already happened and the explanation back then from NASA was that they in fact prefer to delay this missions because these boosters can then be important for reuse on next CRS missions. Basically if it's lost, you can't reuse it on the next mission.

[AC in NC]

(Side question: was it high altitude wind speeds or wind shear?  Or both?)

AIUI after looking into launch criteria once:

The launch rule is "High Altitude Winds".  The word "speed" is not mentioned.  The Rule relates to "Shear Only" (although that obviously has speed as a component of the elsewhere mentioned algorithm).  Makes sort of "layman's sense" as winds only would certainly be far less than the high-altitude speed of the stage.

[haywoodfloyd]

ChrisG's wind speed tweet yesterday showed an approx. wind speed of 90 mph @ 12,000 M (or roughly 39,000 ft.). At that altitude the air is much thinner than at sea level, so what would be the effective wind speed at that altitude?

[Herb Schaltegger]

ChrisG's wind speed tweet yesterday showed an approx. wind speed of 90 mph @ 12,000 M (or roughly 39,000 ft.). At that altitude the air is much thinner than at sea level, so what would be the effective wind speed at that altitude?

Hit up good old Professor Google for the U.S. Standard Atmosphere models of atmospheric density versus altitude, then plug in the formula for q, dynamic pressure.

q=1/2*rho*v^2

My very rough estimate based on 32 years ago/rusty memory of fluid mechanics (and not even writing stuff down) puts dynamic pressure for those conditions at about 15 pounds/square foot. Doesn’t sound like much but in this case it’s a lateral load that the vehicle has to potentially steer against, spread out over the entire windward surface area of the rocket.

That’s in addition to the axial loads already carried by the structure of the rocket due to acceleration and dynamic pressure of moving lengthwise through the air.

[Herb Schaltegger]

https://twitter.com/trevormahlmann/status/1202244124734308355

Get your download fingers ready! Here’s my 289.5 megapixel panorama of a (rare) brand new #Falcon9 B1059.1 and Dragon resupply capsule headed to the @Space_Station today at 12:51pm ET! 🚀

This appears to be behind a paywall.  Or am I missing something? 

Works fine for me. It’s a link to a public tweet. The site link in the tweet takes you to the full-resolution image on the photographer’s site.

[Rondaz]

SpaceX Gears Up for Second CRS-19 Launch Attempt

Danielle Sempsrott Posted on December 5, 2019

SpaceX is preparing for the second launch attempt of its 19th Commercial Resupply Services (CRS-19) mission to the International Space Station today at 12:29 p.m. EST. The company’s Falcon 9 rocket and uncrewed Dragon spacecraft will lift off from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida. Join us here on the blog, as well as on NASA TV and the agency’s website, for live launch countdown coverage, beginning at 12 p.m. EST.

SpaceX made the decision to call off the first launch attempt yesterday due to upper-altitude winds and high winds at sea, creating dangerous conditions around the drone ship “Of Course I Still Love You,” which the rocket’s first stage will attempt landing on following its separation from the rest of the launch vehicle.

The Dragon spacecraft that will deliver critical supplies, equipment and material to the space station on this mission first flew to the orbiting laboratory in 2014 on CRS-4, and then again on CRS-11, making it the first spacecraft that SpaceX reused for resupply missions. Now preparing to fly for a third time, the material it will carry on CRS-19 will directly support dozens of research investigations taking place in space. To learn more about some of those research experiments

https://blogs.nasa.gov/spacex/2019/12/05/spacex-gears-up-for-second-crs-19-launch-attempt/

[garcianc]

https://twitter.com/trevormahlmann/status/1202244124734308355

Get your download fingers ready! Here’s my 289.5 megapixel panorama of a (rare) brand new #Falcon9 B1059.1 and Dragon resupply capsule headed to the @Space_Station today at 12:51pm ET! 🚀

This appears to be behind a paywall.  Or am I missing something? 

Works fine for me. It’s a link to a public tweet. The site link in the tweet takes you to the full-resolution image on the photographer’s site.

In my case, the link to the photographer's site asked be to become a Patron or to log in. I did not go any further, but I do understand if someone wants to limit repeated large downloads from their site, so the pause seemed reasonable.
I hope that helps.

[sferrin]

In my case, the link to the photographer's site asked be to become a Patron or to log in. I did not go any further, but I do understand if someone wants to limit repeated large downloads from their site, so the pause seemed reasonable.
I hope that helps.

Yep, that's what I ran into as well.  Was just wondering if I were missing a link to an open DL.

[2megs]

Throwing something into Trevor's tip jar definitely wasn't the worst thing I've ever done with $2, just saying.

[Chris Bergin]

Get on to the tube, boys and girls

[intelati]

My word. That looks like a dead center landing

[Kansan52]

Just before the video cut off, it appears that the camera on the second caught the Dragon on its separate course.