Iridium-6/GRACE-FO Mission
Why Space Exploration Stack Exchange recommends it
Space Stack Exchange users cite it as primary-source evidence for what happened on this flight, such as the commentator's remarks, timestamps, altitudes and the solid oxygen vent seen on the second stage.
Recommended by 0 people across 0 different months, 2018 to 2021.
What it is
This is SpaceX's full live webcast of the Iridium-6/GRACE-FO Falcon 9 launch from Vandenberg on May 22, 2018. It follows the countdown, ascent, fairing separation, a lower-power second stage burn, and the deployment of the GRACE-FO satellites and five Iridium NEXT satellites. The commentary is delivered by SpaceX hosts during the live broadcast.
What people said
Cites user10509 · 2018-05 · Space Exploration Stack Exchange · on “Why is the first stage from the Falcon 9 SES-12 mission not recovered?”
[this video] At 4:13 minutes into the Iridium-6/GRACE-FO NASA Launch, the commentator mentions: The first stage is not going to be recovered, so there won't be any views from the drone ship downrange on this mission Why is the first stage for this mission not recovered?
Cites user12102 · 2018-05 · Space Exploration Stack Exchange · on “Why did this fairing separation happen at such a high altitude? (SpaceX Iridium-6/GRACE-FO)”
I noticed in the video [this video] of the recent Iridium-6/GRACE-FO launch that the fairing separation happened at an altitude of about 143 kilometers. This is significantly higher than any altitude I can remember. I first started watching this last year and noted the altitude for several launches here [LINK] . @awksp's excellent answer [LINK] explains the relative constancy of the altitude as likely originating from a standardized spec. The answer is thorough and worth reading, but here is a snippet from there: ...after the 3-sigma high theoretical free molecular heating for a flat plate normal to the free stream drops below 1135 W/m$^2$ (360 Btu/hr ft$^2$) based on the 1962 United States Stand
Cites Bob Jacobsen · 2018-05 · Space Exploration Stack Exchange · on “Is it normal for thrusters to "ice up"?”
Is it normal for thrusters to “ice up”? The thing circled in your photo is a LOX vent , not a thruster. The puffy white object is solid oxygen. Your question is directly answered at T+1.05:25 in the Iridium-6/GRACE-FO webcast [this video] : Currently you can see the camera on Stage 2, looking at the upper stage engine, that white object you see is solid oxygen, very fluffy, lighter than a snow ball. That is normal at this stage of the flight . [LINK]
Cites user10509 · 2018-05 · Space Exploration Stack Exchange · on “What are these circular structures around the rocket?”
[this video] of the Iridium-6/GRACE-FO NASA Launch (Falcon 9 SES-12). Edit 31 May: Too bad they have changed the content of the video (and still call it 'live'), so that you can no longer see the entire launch phase. You can still see that in this video [LINK] showing the entire launch. There's one ring visible at the top of the rocket after 1:30 minutes into the launch and it seems to emit light: [LINK] Shortly after 1:50 into the flight, you see 3 more 'rings' developing: [LINK] This is after going supersonic (1:11) and maximum dynamic pressure (1:24). They must be some sort of bow waves/shock waves. But: Why is there only one, later 4? Do they (especially the top one) really emit light?
Cites Bob Jacobsen · 2018-05 · Space Exploration Stack Exchange · on “What is this jet of material spraying out from Stage 2 during the SpaceX PAZ mission?”
The thing circled in the photo is a LOX vent. The puffy white snow-like stuff is solid oxygen. It was described at T+1.05:25 in the Iridium-6/GRACE-FO webcast [this video] .
Cites user12102 · 2018-05 · Space Exploration Stack Exchange · on “Efficiency and timing of the Iridium-6/GRACE-FO low-power burn and coast phase?”
In the video [this video] of the recent Iridium-6/GRACE-FO launch at about T+ 08:13 (curently at 24:12 in the video) the announcer says: Now in order to fly an efficient trajectory for both of the payloads, we’re actually now running the second stage engine at lower power. That means the burn will be longer. For folks who used to seeing us shut down the upper stage engine nine to nine and a half minutes in to flight, today we’ll actually be shutting down the engine just past T+10 minutes into flight. As planned for today, the longer burn at lower power obviously takes more time, but gives us a more efficient trajectory. GRACE-FO was deployed in a ~500 km circular orbit, which was done with a sing
Cites Bob Jacobsen · 2018-05 · Space Exploration Stack Exchange · on “Why rotate the Falcon 9 2nd stage after deployment?”
The thing circled in the photo is LOX vent. The puffy white object is solid oxygen. It was described at T+1.05:25 in the Iridium-6/GRACE-FO webcast [this video] . As such, it's not intended to rotate the spacecraft.
Cites Elden Crom · 2018-07 · Space Exploration Stack Exchange · on “Challenging the Kármán line from above”
For a starting point Falcon 9's Fairing is going 8700 kph [this video] (Mach 7.7 sea level) and it has no ablative shell. The returned fairings come back water logged but un-scorched [LINK] . The interesting point about this is that the booster was going 8650 kph, but suffers scorching inspite of the re-entry burn since it does not slow down in the wispy upper atmosphere and Block 5 has protective covers. SpaceX plans to recover the upper stage with a ballute [LINK] . Presumably without a re-entry burn. If this happens [LINK] then you will have a real answer to your question. I'm pretty sure the answer is yes if the craft is light enough and has enough drag/lift then yes it will survive re-entry,
Cites user12102 · 2021-04 · Space Exploration Stack Exchange · on “Is New Shepard an orbit-capable first stage? Could an (albeit small) 2nd stage with propulsion be put on top that could put a smallsat into orbit?”
@ChristopherJamesHuff ya that seems to be the crux of the question; comparing the first stage maximum horizontal velocity at say 100 km. It seems to be something like 2200 [this video] to 2400 [LINK] m/s at MECO for F9.