SpaceX Falcon 9 / Dragon 2 : SpX-DM2 : May 27, 2020 : DISCUSSION

[spacenut]

I assume both the launch and the booster landing site have to have good weather for a go launch on Wednesday.  From the weather predictions it seems like Saturday or Sunday would have better weather. 

[PreferToLurk]

I assume both the launch and the booster landing site have to have good weather for a go launch on Wednesday.  From the weather predictions it seems like Saturday or Sunday would have better weather.

Technically, it is just the launch site and the abort recovery zones that need good weather.  If somehow the launch site and abort recovery are green, and the booster recovery is red --  the mission will still launch.   This has been discussed up thread by people with much more knowledge of the situation than little old me.

NASA paid for a new booster, recovering that booster is completely secondary to everything else that might happen tomorrow.

[mclumber1]

I assume both the launch and the booster landing site have to have good weather for a go launch on Wednesday.  From the weather predictions it seems like Saturday or Sunday would have better weather.

If all abort areas are green, but the landing zone is not, the mission would still proceed because recovery of the booster isn't as important as the rest of this mission, I would assume.  But this would likely be a very rare occurrence, as the booster recovery area is pretty much in-line with all abort splashdown areas.  So if the weather is good for abort, it's also good for booster recovery.

[Nomadd]

 What are chilled water loops for?
https://twitter.com/SpaceflightNow/status/1265273856710922240

[Vettedrmr]

Avionics cooling?

[Herb Schaltegger]

What are chilled water loops for?
https://twitter.com/SpaceflightNow/status/1265273856710922240

Avionics cooling?

Yep, almost certainly avionics and/or cabin ECLSS heat exchangers. The only way to cool electronics in a closed environment is either forced air or cold-plates. And if you want the systems to work at all in a vacuum, cold-plates are the only way to cool them.

[FutureSpaceTourist]

https://twitter.com/sciguyspace/status/1265288946956881920

Interesting that NASA has set an August 30th target date for the first operational crew mission on Dragon. That is really soon, and suggests confidence in the performance of this vehicle. Obviously this test will have to go well.

[rdale]

Here's a buoy with webcam not too far from the booster recovery zone.

https://www.ndbc.noaa.gov/station_page.php?station=41004

[NX-0]

We have a Landing Bingo thread but no "guess the name" thread?

[eriblo]

We have a Landing Bingo thread but no "guess the name" thread?

Oh ye, of little faith.

[yg1968]

Lori Garver made some interesting tweets on the reasons that the NASA logo is on the Demo-1 Falcon 9 but isn't on the Falcon 9s for CRS missions:

https://twitter.com/Lori_Garver/status/1265329457671352322

Poor @SpaceX must have whiplash! @NASA wouldn’t approve ANY of our logos on the F9 during CRS. Ops & legal said it “wasn’t NASA’s rocket” & I got overruled. Small meatball was on the Dragon... looks like that has gotten biggger too! Yes, it was a challenging time! #timeschange

https://twitter.com/Lori_Garver/status/1265334718700158978

There were still a lot of “not invented here” bad feelings & if didn’t work, there was a hope by some that we would go back to the old way of doing business.  They wanted to distance @NASA & be ready to walk away. I argued it showed a lack of support - but I was only #2.

[NX-0]

Are the solar cells on the trunk generating useful electricity as it sits on the pad?

[sevenperforce]

Are the solar cells on the trunk generating useful electricity as it sits on the pad?

If the wiring was simple enough, sure. Parallel-wired meters spin backward as easily as they spin forward. But I strongly suspect there are a whole suite of interruptors and transformers and the like to prevent a ground power excursion from creating a surge on the vehicle.

Just speculation though.

[ZachS09]

Will F9 do a boostback burn during its descent to the drone ship?

[woods170]

Are the solar cells on the trunk generating useful electricity as it sits on the pad?

Are they generating electricity while it sits on the pad, in daylight? Yes.
Is that electricity useful while it sits on the pad? No.

Crew Dragon is supplied with electrical power by the ground support equipment right until very shortly before liftoff. From then, until activation of solar array power supply in orbit, the vehicle runs on battery power.

[FutureSpaceTourist]

https://twitter.com/sciguyspace/status/1265349608022200323

NASA and SpaceX will be playing chicken tomorrow afternoon with scattered showers and thunderstorms. Here are three radar forecasts for 4pm ET from the NAM, WRF, and HRRR models. None of these high-rese models are close to gospel, but provide a sense of the state of play.

[quasarquantum]

Will F9 do a boostback burn during its descent to the drone ship?

Only an entry burn, and then a landing burn. Boostback is only necessary when returning to launch site.

[Lars-J]

Will F9 do a boostback burn during its descent to the drone ship?

Only an entry burn, and then a landing burn. Boostback is only necessary when returning to launch site.

There are occasionally short "boostback burns" (more like aiming burns) after staging if the barge is not in the optimal place for the ballistic impact point. It depends on performance margin and/or placement of barge to to weather issues.

[zubenelgenubi]

It may be useful to remember that the day NASA waived weather requirements for the ill-fated Challenger mission was also the day that Reagan's State of the Union Address was to be given, no doubt including mention of schoolteacher Christa McAuliffe riding into space that morning.  As an ex-Washington lawyer, I can't help but to think some political pressure was applied to launch.  Hoping no repeat this Wednesday.

Perception or rumors swirling in early 1986 do not equal truth.

The text of the address, as President Reagan intended to deliver it on the evening of January 28, contained no mention of Christa McAullife on the scheduled launch of 51L. (He did intend to mention a young adult's, Richard Cavoli, experiment aboard the Shuttle on this launch.)

See John Logsdon, Ronald Reagan and the Space Frontier, p 283, 2018.

TL;DR = false

[ZachS09]

Will F9 do a boostback burn during its descent to the drone ship?

Only an entry burn, and then a landing burn. Boostback is only necessary when returning to launch site.

There are occasionally short "boostback burns" (more like aiming burns) after staging if the barge is not in the optimal place for the ballistic impact point. It depends on performance margin and/or placement of barge to to weather issues.

That’s what I meant by. I should’ve said “partial boostback”.

I asked that question because I saw that event on the Crew Dragon ascent artwork and looked back at the Iridium-NEXT F5 flight where B1041 did a single-engine boostback burn to land in a small zone in the Pacific a little bit over 500 km downrange.