Starlink-21 Media Thread & Photographer Contest
It's that time again! As per usual, we like to keep things as tight as possible. If you have content you created to share (whether that be images of the launch, videos, GIFs, etc) or news articles about the flight, they go here.Photographer ContestWe are continuing the photographer contest, where you can submit your pictures related to this mission. That might be photos of the rocket on the pad, a shot of it launching or in flight, or pictures of the satellite overhead. We will put this thread into contest mode and announce the winner in a few days time.The winner will be allowed to post their picture directly on r/SpaceX and will get a special flair.Rules:You need to own the picture you are submitting1 picture per person (if you want to share more, mark the one you are entering with #Contest)If you have any feedback or ideas how to improve this contest, please send us a modmail!As usual, our standard media thread rules apply:All top level comments must consist of an image, video, GIF, tweet or article.If you're an amateur photographer, submit your content here. Professional photographers with subreddit accreditation can continue to submit to the front page; we also make exceptions for outstanding amateur content!Those in the aerospace industry (with subreddit accreditation) can likewise continue to post content on the front page.Mainstream media articles should be submitted here. Quality articles from dedicated spaceflight outlets may be submitted to the front page.Direct all questions to the live launch thread.Thanks!

Submitted March 14, 2021 at 03:39PM by ElongatedMuskrat
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Elon Musk: "SpaceX did 2X rest of world payload to orbit last year, probably 3X to 4X this year"
https://twitter.com/elonmusk/status/1371256869705109504

Submitted March 15, 2021 at 02:06AM by Exatrynzir
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Falcon 9's second stage among a field of stars as 60 more Starlink satellites launches to space yesterday
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Submitted March 15, 2021 at 03:04PM by johnkphotos
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Starship SN11 prepares to fly as SpaceX pushes for Orbital flight this summer
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Submitted March 15, 2021 at 04:19PM by AWildDragon
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SpaceX bid on launch of NASA cubesat mission
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Submitted March 16, 2021 at 01:48PM by Luna_8
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Apparent failure of Starlink-18 second stage after payload deployment
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Submitted March 16, 2021 at 09:49PM by pmgoldenretrievers
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Starship | SN10 | High-Altitude Flight Recap
https://www.youtube.com/watch?v=gA6ppby3JC8

Submitted March 17, 2021 at 01:36AM by ethan829
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B1058.6 and B1051.9, for the first time ever there are two boosters vertical in Port Canaveral
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Submitted March 17, 2021 at 04:56AM by Kyle_M_Photo
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An early SpaceX engineer crawled inside an imploding rocket on a jet in midair to save the company
Article
@EverythingScience @SpaceX

NASA has released 9 new renders of SpaceX's logistics module for the Gateway space station, under the name "Hero" (formerly "Dragon XL")
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Submitted March 17, 2021 at 10:00PM by stratohornet
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ℹ️ SN11 Update
🕐 Last Updated: 15:15 UTC - 18/03

🚀 Launch requires a good static fire first but the following TFRs, which could be possible launch windows, have been issued:
- Friday March 19th, 11:00 to 00:30 UTC (Unlikely)
- Saturday March 20th, 11:00 to 00:30 UTC
- Sunday March 21st, 11:00 to 00:30 UTC

🔥 Still no static fire in sight. No road closures scheduled yet. Launch can't occur before at least one more static fire.

Elon Musk: "SN11 almost ready to fly"

🔥Last static fire attempt info
✅ FAA Approval info

#SN11 @SpaceXChat

SpaceX engineer pleads guilty to selling insider trading tips on dark web
https://www.reuters.com/article/idUSKBN2BA2VM?il=0

@EverythingTechnology via Reddit

NASA, SpaceX Sign Joint Spaceflight Safety Agreement
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Submitted March 18, 2021 at 07:32PM by LcuBeatsWorking
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Elon: First Super Heavy Booster
https://twitter.com/elonmusk/status/1372688191803768840?s=09

Submitted March 19, 2021 at 12:19AM by cac2573
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<b>What is the optimal Starship flip? A trajectory optimization analysis.</b>
Hi everyone! It occurred to me last night that one of the tools I use in my robotics research (I am a PhD student in Mechanical Engineering right now) can be used to analyze/test the Starship landing maneuver. The method falls under a field of control theory called “optimal control theory” which is all about – as the name suggests – using a systematic method to optimize your controller or control signal according to some objective measure.I have been inspired to do this, in part because some internet arm-chair controls engineers in have suggested that issues with the landing maneuver are attributable to (and I am paraphrasing) SpaceX “haven’t tuned their PID parameters correctly yet,” or their trajectory is pitching over too far or something like that. I believe this is a bit of a Dunning-Kruger situation, and in my opinion, comes off a little offensive as it vastly underestimates the knowledge of SpaceX engineers. SpaceX have one of the most advanced aerospace controls and simulation research teams in the world. This analysis may help put into perspective one of the possible methods they use to plan a trajectory or do model-predictive-control (MPC).The MethodDirect collocation is a trajectory optimization method that breaks down the time in which you want to control something into discrete time points and solves a problem that minimizes an objective which is computed across the trajectory (for instance, minimize the total propellant expended for a rocket by integrating the mass burn at each time point in the trajectory, or minimize the total time it takes to complete the task).In specific, I am using a trapezoidal collocation method – as it is the easiest for me to code from scratch in a hurry. All of the code to solve this problem was written from scratch today. The problem I have specified is a bit more restricted and simplified than the actual landing problem.Here are some of the modeling choices I have made:Endpoint ConditionsI have started the problem at the approximate height (500 m) and vertical decent rate (90 m/s) of the Starship at the start of the SN10 landing burn according to some data from a video from FlightClub.io (<a href="https://twitter.com/flightclubio/status/1367556502047793154%5D">tweet</a>). I have started it at a pitch angle of 85 degrees. I have specified that it should land with zero velocity and zero pitch angle. I have allowed the total duration of the maneuver to be whatever it likes so the time interval is not fixed but allowed to be anything from 1 second to 60 seconds total.EngineI have simplified the model to include one centered engine, with a max thrust of 5 MN and a min throttle of 20% or 1 MN. The single engine must be on all the time from the start of the burn. In addition, I have allowed for an aggressive +/- 45 degrees of thrust vector control angle. The engine has no throttle or TVC lag. I have mounted the engine 20 m below the center of mass.Mass DistributionI am assuming Starship is a simple solid cylinder that is 9 m in diameter and 50 m tall weighing a total of 120 tons which is uniformly distributed. I do not include the changing propellant mass due to fuel burn. I do not include the fuel slosh etc.Aerodynamics (or lack thereof)I am ignoring air resistance to simplify things currently (I am an ME after all, not an AE). I realize that assuming the starship is a cylinder with round ends could probably give some decent analytical approximations to air resistance, but that opens a can of worms that I am not interested in eating at the moment. It goes without saying then, but I did not include the flaps in any way. In defense of this, they fold in almost immediately.The objectiveThe objective is to minimize the fuel required in the landing burn. I have simply implemented this as an objective to minimize the total thrust used throughout the maneuver under the assumption that thrust is proportional to mass flow…

[Elon Musk] Yes, Booster 1 is a production pathfinder, figuring out how to build & transport 70 meter tall stage. Booster 2 will fly.
https://twitter.com/elonmusk/status/1372695421487824903?s=21

Submitted March 19, 2021 at 11:36AM by tonybinky20
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"Looks like a new SpaceX support ship is in town. Shelia Bordelon has a crane on back and will possibly replace Ms. Tree and Ms. Chief for fairing recovery. Looks like they have begun testing/practicing because there is a fairing half on deck. #SpaceXFleet #SpaceX"
https://twitter.com/Kyle_M_Photo/status/1372661451878436865

Submitted March 19, 2021 at 05:21PM by Bunslow
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[Elon Musk] An orbital propellant depot optimized for cryogenic storage probably makes sense long-term
https://twitter.com/elonmusk/status/1373132222555848713?s=21

Submitted March 20, 2021 at 09:29AM by tonybinky20
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The current status of SpaceX's Starship & Superheavy prototypes. 21st March 2021 https://t.co/0RpzqVlzWb
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Submitted March 21, 2021 at 08:55AM by brendan290803
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