SpaceX F9 : CRS SpX-18 : July 25, 2019 - DISCUSSION

[capoman]

Curious why the static fire is being postponed multiple times. Is it because of NASA's oversight reusing a booster?

[zubenelgenubi]

SF now NET Friday morning.

I take it that the launch can no longer occur on the 21st.

[Jarnis]

Curious why the static fire is being postponed multiple times. Is it because of NASA's oversight reusing a booster?

Almost certainly just some minor bugs with the hardware - either with the vehicle or the ground systems. Lots of things that can leak, get stuck etc...

[Paul Howard]

SpaceFlightNow says it's Monday, 22nd if they Static Fire today.

[AndyX]

SpaceFlightNow says it's Monday, 22nd if they Static Fire today.

Chris seems very cautious about that. So I'd wait for SpaceX to say what the launch date is.

[SMS]

https://twitter.com/SpaceflightNow/status/1152301288761286657

[Ken the Bin]

45th Weather Squadron: 60% 'Go' for Monday, 40% 'Go' for Wednesday.

[gongora]

45th Space Wing has just removed the weather forecast from their website. This usually means: no launch within the upcoming three days.

I still see it there:
https://www.patrick.af.mil/About-Us/Weather/

[ChrisC]

NASA webcast https://youtube.com/watch?v=CfRULatzLZQ

Interesting ... a separate, scheduled live webcast from NASA, SpaceX style.  I don't recall NASA ever doing this before.

[ZachS09]

NASA webcast https://youtube.com/watch?v=CfRULatzLZQ

Interesting ... a separate, scheduled live webcast from NASA, SpaceX style.  I don't recall NASA ever doing this before.

I thought they first did this during the DM-1 launch coverage.

[Alexphysics]

NASA webcast https://youtube.com/watch?v=CfRULatzLZQ

Interesting ... a separate, scheduled live webcast from NASA, SpaceX style.  I don't recall NASA ever doing this before.

They literally did this just the other day with the Soyuz MS-13 launch coverage.

[Solar_OPS]

Article about 3 ESA experiments to be delivered by CRS SpX-18:

http://www.esa.int/Our_Activities/Human_and_Robotic_Exploration/Research/SpaceX_to_deliver_Space_Station_science

[Lee Jay]

From the article:

"The change in color is designed to permit heat transfer from the LOX tank into the RP-1 tank, essentially taking some of the heat that isn’t needed in the LOX tank and transferring it to the RP-1 fuel tank where it is needed."

The LOX is colder than the RP1, thus the only way to move heat from the LOX to the RP1 is with a heat pump, correct?

I could see how the gray will absorb solar heat and thus heat the RP1, but I don't see how it could move heat from the LOX to the RP1.

[Semmel]

From the article:

"The change in color is designed to permit heat transfer from the LOX tank into the RP-1 tank, essentially taking some of the heat that isn’t needed in the LOX tank and transferring it to the RP-1 fuel tank where it is needed."

The LOX is colder than the RP1, thus the only way to move heat from the LOX to the RP1 is with a heat pump, correct?

I could see how the gray will absorb solar heat and thus heat the RP1, but I don't see how it could move heat from the LOX to the RP1.

Yes, the heat transfer is the other way around.

The LOX is colder than the RP1 and will suck out the heat from it over time. The gray color is supposed to absorb more sunlight and prevent the RP1 from getting too cold. This is mainly useful for longer coasts of S2. Since CRS 18 doesnt need a long S2 coast, I bet this is a proof of concept.
My hunch is, they run into RP1 temperature limits for some profitable reference orbits, like direct GSO insertion for FH payloads.

[Olaf]

https://oiir.hq.nasa.gov/asap/documents/NASA_ASAP_3rd_qtr_public_meeting_June_6_2019_FINAL_RevB_Signed_tagged.pdf

One EMU (#3003) did have a minor issue with a suit pressure sensor during EVA #52 and is being held in “ready spare” status until it is replaced by SN# 3009 which is manifested on the Space-X 18 cargo flight slated for July. Additionally, a spare Fan Pump Separator Unit will be delivered on SX-18.

[Rondaz]

SpaceX CRS-18: Launch Countdown Milestones for July 24 Liftoff

Anna Heiney Posted on July 24, 2019

The launch of SpaceX’s 18th commercial resupply services mission to the International Space Station for NASA is scheduled for 6:24 p.m. EDT with an instantaneous launch window. The SpaceX Falcon 9 rocket and Dragon spacecraft have been moved to the vertical launch position. Launch coverage will begin at 6 p.m. on NASA Television and the agency’s launch blog.

Meteorologists with the U.S. Air Force 45th Space Wing continue to predict a 30% chance of favorable weather for liftoff. The primary weather concerns are the cumulus cloud rule, lightning rule and attached anvil rule.

Packed with more than 5,000 pounds of research, crew supplies and hardware, the Dragon spacecraft will launch on a Falcon 9 rocket from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida.

Mission Timeline (all times approximate)
COUNTDOWN
– 00:38:00     SpaceX Launch Director verifies go for propellant load
– 00:35:00     RP-1 (rocket grade kerosene) loading begins
– 00:35:00     1st stage LOX (liquid oxygen) loading begins
– 00:16:00     2nd stage LOX loading begins
– 00:07:58     Dragon transitions to internal power
– 00:07:00     Falcon 9 begins pre-launch engine chill
– 00:01:00     Command flight computer to begin final prelaunch checks
– 00:01:00     Propellant tanks pressurize for flight
– 00:00:45     SpaceX Launch Director verifies go for launch
– 00:00:03     Engine controller commands engine ignition sequence to start
– 00:00:00     Falcon 9 liftoff

https://blogs.nasa.gov/kennedy/2019/07/24/spacex-crs-18-launch-countdown-milestones-for-july-24-liftoff/

[ejb749]

It looks to me like the cell over the cape right now is dissipating.

[jcm]

Which EMU unit will be up, which one will be down?

3003 will be returned.

But sill no word on the upward EMU s/n?

[Joseph Peterson]

So ceramic Starship tiles might be back.

[gongora]

Which EMU unit will be up, which one will be down?

3003 will be returned.

But sill no word on the upward EMU s/n?

https://oiir.hq.nasa.gov/asap/documents/NASA_ASAP_3rd_qtr_public_meeting_June_6_2019_FINAL_RevB_Signed_tagged.pdf

One EMU (#3003) did have a minor issue with a suit pressure sensor during EVA #52 and is being held in “ready spare” status until it is replaced by SN# 3009 which is manifested on the Space-X 18 cargo flight slated for July. Additionally, a spare Fan Pump Separator Unit will be delivered on SX-18.