Elon: Starship 9m test tank made 7.5 bar at room temp! Small leak at a weld doubler. Will be repaired & retested at cryo.
https://twitter.com/elonmusk/status/1221938474233868288?s=21

Submitted January 28, 2020 at 12:30AM by Tommy099431
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<b>Stainless steel strength and why it matters to SpaceX</b>
There has been a lot of interest in Starship manufacturing in general and weld properties in particular so I thought a post to discuss the underlying material properties would be helpful for informed discussion.When SpaceX changed the Starship design from carbon fiber construction to stainless steel there were a lot of comments that "at least the joining process will be easy now as individual components can just be welded together". The most we can really say is that the process would be <em>easier</em> but not at all <em>easy</em>. The reason all comes down to material properties and how they change with temperature.Stainless steels are alloys of iron, nickel and chromium with additional trace elements to fine tune the properties of the alloy. Iron by itself is relatively weak at high temperatures and easy to oxidise/rust. Adding chromium and nickel improves the oxidisation resistance and also improves the high temperature strength. Some types of stainless steel have very poor low temperature (cryogenic) strength and others have very good low temperature strength depending on their crystalline structure.Metallic alloys have a crystalline structure that extends across a metal grain with each grain boundary joined to an adjacent grain with material that may differ from the bulk composition. A few specialised components such as jet engine turbine blades can be grown as a single crystal that is much stronger than a conventional metal but large components such as rocket tanks and components that must be joined by welds have millions of crystal grains.Stainless steel has two main crystalline structures - <a href="https://www.aksteel.com/our-products/stainless/martensitic-stainless-steels">martensitic</a> (400 series) which has a bcc (body centered cubic) crystalline form and <a href="https://www.aksteel.com/our-products/stainless/austenitic-stainless-steels">austenitic</a> (300 series) which has a fcc (face centered cubic) crystalline form. This <a href="https://image.slidesharecdn.com/lecture1-140211212924-phpapp02/95/lecture-11-metals-and-its-alloys-their-crystalline-structure-and-properties-8-638.jpg?cb=1392154267">slide</a> shows the difference in structures. There are also ferritic and duplex crystalline structures but they are not relevant here.<a href="https://www.bssa.org.uk/topics.php?article=41">Martensitic stainless steel is not suitable for cryogenic use</a> and therein hangs a tale. SpaceX used a non-aerospace supplier for the struts that held their COPVs inside the LOX tanks of the F9 rocket. The Heim (ball) joints used to provide a floating connection to the tanks to allow for thermal contraction of the struts were constructed of a martensitic stainless steel. SpaceX allowed for this by derating the strength of the struts but it turns out there is no safe lower bound for the strength of martensitic stainless at cryogenic temnperatures and a small percentage of struts would fail at loadings that would be reached in flight. Specifically in the flight of CRS-7.The solution of course was to change to a Heim joint constructed of austenitic stainless steel which actually gets stronger at low temperatures and remains sufficiently ductile to withstand shock loading. Hence began a love affair between Elon and austenitic stainless that would later bear fruit when the pitfalls of using carbon fiber composite for Starship became fully apparent.SpaceX have used 304 stainless plates for Starhopper and later changed to rolls of 301 stainless for Starship SN1. At some point they will change to a custom alloy they have dubbed 30x but it seems that has not happened yet.301 can be cold rolled to increase strength but there is an issue with the welded vertical joint in each ring. In the actual weld area and in the area each side of the weld the metal has been heated up to over 1000C so has become fully annealed and so has lost the extra strength gained with cold rolling. This…

SpaceX Boca Chica - Starship Test Tank 2 road trip to the Launch Site
https://youtu.be/DRP0k0Hiyxg

Submitted January 28, 2020 at 12:10AM by CProphet
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Elon: Liquid nitrogen cryogenic strength test underway ☃️
https://twitter.com/elonmusk/status/1222366667579117568?s=21

Submitted January 29, 2020 at 04:52AM by Tommy099431
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Starship test tank #2 was tested to destruction and made it to 8.5 bar
https://twitter.com/NASASpaceflight/status/1222367293197488129

Submitted January 29, 2020 at 05:11AM by Humble_Giveaway
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r/SpaceX Starlink-3 Media Thread [Videos, Images, GIFs, Articles go here!]
It's that time again, as per usual, we like to keep things as tight as possible, so if you have content you created to share, whether that be images of the launch, videos, GIF's, etc, they go here.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.

Submitted January 29, 2020 at 07:58AM by ElongatedMuskrat
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SpaceX Boca Chica - Starship Test Tank 2 Destructive Cryo Test (Video from BCG)
https://www.youtube.com/watch?v=2TDaMCMEc8Q

Submitted January 29, 2020 at 09:55AM by Russ_Dill
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r/SpaceX Starlink-3 Recovery Discussion & Updates Thread
Hello! I'm u/hitura-nobad, hosting my first booster recovery thread.Booster RecoverySpaceX deployed OCISLY, GO Quest and Hawk to carry out the booster recovery operation. B1051.3 successfully landed on Of Course I Still Love You.Fairing RecoveryGo Ms. Tree was able to catch on fairing half in her large net, while Go Ms. Chief missed it and the fairing made a soft water landing, and will be retrieved using a smaller net. Current Recovery Fleet StatusVesselRoleStatusHawkOCISLY TugboatWaiting at the LZGO QuestDroneship support shipWaiting at the LZGO Ms. ChiefFairing RecoveryAt the fairing landing zone (Fishing for a fairing)GO Ms. TreeFairing RecoveryAt the fairing landing zone (Caught a fairing) Estimated Arrival TimesVesselETAOCISLYTBDGO Ms. TreeTBDGO Ms. ChiefArrived Live UpdatesTimeUpdateJanuary 29th - 9:51 ESTMs. Tree caught a fairing half – our third successful catch!January 29th - 9:16 EST@SpaceX: Falcon 9’s first stage has landed on the Of Course I Still Love You droneship – our 49th successful landing of an orbital class booster! Links & ResourcesMarineTrafficRecovery Zone Map - Thanks to u/Raul74CzSpaceXFleet Updates on TwitterSpaceXFleet.com - SpaceXFleet Information!Jetty Park Webcam - Webcam looking at Port Canaveral entrance.

Submitted January 29, 2020 at 03:59PM by hitura-nobad
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Falcon 9 goes transonic on its way to orbit this morning during SpaceX’s fourth launch of 60 Starlink satellites.
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Submitted January 29, 2020 at 05:13PM by johnkphotos
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Starlink V1 L3 (#4) lifts off from SLC40
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Submitted January 29, 2020 at 07:35PM by spiel2001
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Dragon’s parachutes washed up on the Florida coast
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Submitted January 31, 2020 at 12:49AM by weeweebager
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Space Traffic Is Surging, And Critics Worry There Could Be A Crash
https://ift.tt/2GyDSbW

Submitted January 31, 2020 at 04:16PM by StrikitRich1
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Wait for it... Motorized tracking camera experiment at Starlink 3
https://youtu.be/f74ZCvdC9KU

Submitted February 01, 2020 at 12:09AM by learntimelapse
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r/SpaceX Discusses [February 2020, #65]
If you have a short question or spaceflight news...You may ask short, spaceflight-related questions and post news here, even if it is not about SpaceX. Be sure to check the FAQ and Wiki first to ensure you aren't submitting duplicate questions.If you have a long question...If your question is in-depth or an open-ended discussion, you can submit it to the subreddit as a post.If you'd like to discuss slightly relevant SpaceX content in greater detail...Please post to r/SpaceXLounge and create a thread there!This thread is not for...Questions answered in the FAQ. Browse there or use the search functionality first. Thanks!Non-spaceflight related questions or news.You can read and browse past Discussion threads in the Wiki.

Submitted February 01, 2020 at 01:40PM by ElongatedMuskrat
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<b>Starlink-4 Launch Campaign Thread</b>
<a href="https://pbs.twimg.com/media/D7TjU7DXkAAqtVZ.jpg"></a><a href="https://www.reddit.com/r/spacex/comments/ex0ilm/starlink3_launch_campaign_thread/#siteTable_t3_ex0ilm">JUMP TO COMMENTS</a>Starlink-4 (STARLINK V1.0-L4)OverviewStarlink-4 will launch the fourth batch of operational Starlink satellites into orbit aboard a Falcon 9 rocket. It will be the fifth Starlink mission overall. This launch is expected to be similar to the <a href="/r/spacex/wiki/launches#wiki_80_.2013_starlink-3_.28v1.0.29">previous Starlink launch</a> in late January, which saw 60 Starlink v1.0 satellites delivered to a single plane at a 290 km altitude. Following launch the satellites will utilize their onboard ion thrusters to raise their orbits to 350 km. In the following weeks the satellites will take turns moving to the operational 550 km altitude in three groups of 20, making use of precession rates to separate themselves into three planes. Due to the high mass of several dozen satellites, the booster will land on a drone ship at a similar downrange distance to a GTO launch.Liftoff currently scheduled for:Mid February TBDBackup dateTBDStatic fireTBDPayload60 Starlink version 1 satellites (expected)Payload mass60 * 260 kg = 15 600 kgDeployment orbitLow Earth Orbit, 290 km x 53° (expected)Operational orbitLow Earth Orbit, 550 km x 53°, 3 planesVehicleFalcon 9 v1.2 Block 5CoreunknownPast flights of this coreunknownFairing catch attemptlikelyLaunch site<a href="https://www.reddit.com/r/SpaceX/wiki/pads">SLC-40</a>, Cape Canaveral Air Force Station, FloridaLandingOCISLY: 32.54722 N, 75.92306 W (628 km downrange)Mission success criteriaSuccessful separation & deployment of the Starlink Satellites.Previous and Pending Starlink MissionsMissionDate (UTC)CorePadDeployment OrbitNotes<a href="https://twitter.com/StarlinkUpdates">Sat Update</a>1<a href="/r/spacex/wiki/launches#wiki_71_.2013_starlink_v0.9">Starlink v0.9</a>2019-05-241049.3SLC-40440km 53°60 test satellites with Ku band antennas<a href="https://twitter.com/StarlinkUpdates/status/1223537158339907585">Feb 1</a>2<a href="/r/spacex/wiki/launches#wiki_75_.2013_starlink-1_.28v1.0.29">Starlink-1</a>2019-11-111048.4SLC-40280km 53°60 version 1 satellites, v1.0 includes Ka band antennas<a href="https://twitter.com/StarlinkUpdates/status/1223537163930865664">Feb 1</a>3<a href="/r/spacex/wiki/launches#wiki_78_.2013_starlink-2_.28v1.0.29">Starlink-2</a>2020-01-071049.4SLC-40290km 53°60 version 1 satellites, 1 sat with experimental antireflective coating<a href="https://twitter.com/StarlinkUpdates/status/1223537169630924801">Feb 1</a>4<a href="/r/spacex/wiki/launches#wiki_80_.2013_starlink-3_.28v1.0.29">Starlink-3</a>2020-01-291051.3SLC-40290km 53°60 version 1 satellites<a href="https://twitter.com/StarlinkUpdates/status/1223537175402360833">Feb 1</a>5Starlink-4This MissionSLC-40290km 53°60 version 1 satellites expected-6<a href="/r/SpaceX/wiki/launches/manifest#wiki_upcoming_falcon_launches">Starlink-5</a>MarchLC-39A290km 53°60 version 1 satellites expected-7<a href="/r/SpaceX/wiki/launches/manifest#wiki_upcoming_falcon_launches">Starlink-6</a>MarchSLC-40 / LC-39A290km 53°60 version 1 satellites expected-Daily Starlink altitude updates on Twitter <a href="https://twitter.com/StarlinkUpdates">@StarlinkUpdates</a>Mission Numbering Explanation: Starlink-NHere on r/SpaceX, the number does not count Starlink v0.9.SpaceX does not name their Starlink missions publicly, although they do have an internal naming system which appears on publicly available launch hazard maps and Weather Squadron forecasts. That system follows the pattern <code>STARLINK VX-LY</code> where X and Y are version and launch numbers, respectively. Leading up to the first operational launch of Starlink, the mission name <code>Starlink-1</code> appeared on 45th Weather Squadron forecasts and we opted to use that naming scheme since future version numbers are uncertain and we didn't want to have missions…

Kimbal's blog documenting the early days of SpaceX! Was super interesting to read through after I found it.
https://ift.tt/37szbfD

Submitted February 02, 2020 at 06:56AM by hldndrsn
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SpaceX Update February 2020 (KSC Florida)
https://youtu.be/H-bzK9V0fd4

Submitted February 02, 2020 at 11:39AM by CProphet
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Video of B1051.3 (Starlink-3) returning to Port Canaveral on OCISLY, humans for scale
https://youtu.be/krJ2Emutjd4

Submitted February 02, 2020 at 04:43PM by learntimelapse
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Introducing the Starlink Deployment Update Bot
Hey everyone,I want to introduce my new Twitter bot to you:The Starlink Deployment Update BotWhat can it do?It is posting updated graphs of the Starlink satellite attitude for each launch once a day on twitter.How does it work?Part 1: The ScrapperIt uses wget to download https://www.celestrak.com/NORAD/elements/supplemental/starlink.txt three times a day, 1 hour after the update is released by SpaceX, and saves it onto my Server.Part 2: CalculatorThe next script loads the TLEs and calculates different orbit heights from them.Part 3: SeparatorThe following script splits the TLEs after the different missions and appends to the archive of previously calculated data points for the specific launch.Part 4: Generator/PlotterThe plotter uses Matplotlib to generated an updated graph from the given data and saves it as png.Part 5: PosterThe last script uploads the png to twitter and posts the thread once a day.Future ExpansionsPossibility to highlight specific satsLoading additional data from the r/SpaceX APIPlotting other interesting values than just orbital heightThanksu/thevehicledestroyer for helping to debug my TLE generation code making it more accurateDr. T.S. Kelso for providing me the exact times when SpaceX publishes new TLEs

Submitted February 02, 2020 at 06:21PM by hitura-nobad
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B1051.3's crush core compared to a normal landing
https://twitter.com/Kyle_M_Photo/status/1224125488219721729?s=19

Submitted February 03, 2020 at 08:58AM by Kyle_M_Photo
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GAO report about NASA Commercial Crew Program
https://ift.tt/2v4Hj7n

Submitted February 03, 2020 at 11:39PM by hainzgrimmer
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