SpaceX on Twitter: “Now targeting January 24 at 10:54 a.m. EST, 15:54 UTC, for launch of 60 Starlink satellites; team is continuing to monitor weather in the recovery area”
https://twitter.com/spacex/status/1219723537952296960?s=21

Submitted January 21, 2020 at 10:04PM by youfoundalec
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Elon Musk on Twitter: "Improved Accommodations" [Inside new Boca Chica tent]
https://twitter.com/elonmusk/status/1219858516619358208

Submitted January 22, 2020 at 04:29PM by rustybeancake
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SpaceX presses on with legal fight against U.S. Air Force over rocket contracts - SpaceNews.com
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Submitted January 23, 2020 at 08:22AM by jbmate
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Weather in the recovery area continues to be unfavorable so team is now targeting Monday, January 27 for launch of Starlink, pending Range availability
https://twitter.com/SpaceX/status/1220378488680697856?s=19

Submitted January 23, 2020 at 05:12PM by Aakarsh_K
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Nilesat partners with SpaceX to launch Nilesat-301 satellite in 2022
https://ift.tt/30KO2PU

Submitted January 23, 2020 at 06:57PM by ethan829
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SpaceX Demo-2 astronauts speak to the media after Crew Dragon's successful inflight abort test
https://www.youtube.com/watch?v=WJtMs1bb1f8

Submitted January 23, 2020 at 09:01PM by Helpful-Routine
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SpaceX releases preliminary results from Crew Dragon Abort
https://ift.tt/38GsHtL

Submitted January 24, 2020 at 06:21AM by MarsCent
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Header Tank test video (credit to SPadre)
https://youtu.be/WHvaU7sP99Q

Submitted January 24, 2020 at 07:41AM by OpelGT
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Starship Header Tank Pressurization Test [01/24/20] (Credit BocaChicaGal)
https://youtu.be/8z-VwbhiZOk

Submitted January 25, 2020 at 09:32AM by OpelGT
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2019 Report on NASA’s Top Management and Performance Challenges
https://ift.tt/2QxVKsZ

Submitted January 25, 2020 at 01:35PM by jorado
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Air Force test of an AC-130 connected to Starlink constellation successful
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Submitted January 25, 2020 at 05:09PM by TyrialFrost
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This is what it was like to track and film Crew Dragon with a telescope, equivalent to 5,000mm zoom lens
https://youtu.be/yeGaxUJNm6U

Submitted January 26, 2020 at 07:07AM by learntimelapse
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Starlink-3 Press Kit
https://ift.tt/2RrZRXX

Submitted January 26, 2020 at 05:44PM by hitura-nobad
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<b>r/SpaceX Starlink 3 Official Launch Discussion & Updates Thread</b>
<a href="/#%20MC%20//%20section%20intro"></a>Welcome to the <a href="/r/SpaceX">r/SpaceX</a> Starlink-3 Official Launch Discussion & Updates Thread!I'm <a href="/u/ModeHopper">u/ModeHopper</a>, your host for the Starlink-3 mission.MAKE SURE YOU CHECK WHEN THE SATELLITE TRAIN PASSES OVER YOU USING THE LINKS BELOWUseful Links for Starlink train viewing<a href="https://james.darpinian.com/satellites/?special=starlink-3">See A satellite Tonight</a> by <a href="/u/modeless">u/modeless</a><a href="https://www2.flightclub.io/pass-planner">FlightClub Pass planner</a> by <a href="/u/TheVehicleDestroyer">u/TheVehicleDestroyer</a><a href="https://www.heavens-above.com/">Heavens Above</a><a href="https://www.satflare.com/track.asp?q=StarLinkLaunch#TOP">Live tracking</a><a href="https://me.cmdr2.org/starlink">Pass Predictor and sat tracking</a> by <a href="/u/cmdr2">u/cmdr2</a><a href="https://www.n2yo.com/passes/?s=70000">n2yo.com</a>Starlink-3 (a.k.a. Starlink v1.0 Flight 3, Starlink Mission 4, etc.) will launch the third batch of Starlink version 1 satellites into orbit aboard a Falcon 9 rocket. It will be the fourth Starlink mission overall. This launch is expected to be similar to the <a href="https://www.reddit.com/r/spacex/wiki/launches#wiki_78_.2013_starlink-2_.28v1.0.29">previous Starlink launch</a> in early 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. This launch is of personal significance as I previously hosted the B1051 launch for the RADARSAT Constellation Mission.Mission DetailsLiftoff currently scheduled forJanuary 27, 14:49 UTC (9:49 AM local)Weather<a href="https://www.patrick.af.mil/Portals/14/Weather/L-1%20Forecast%2027%20Jan%20Launch.pdf?ver=2020-01-26-121601-767">50% GO (Thick cloud layer, disturbed weather).</a>Static fire<a href="https://twitter.com/SpaceX/status/1219338192169533440">Completed January 20th</a>Payload60 Starlink version 1 satellitesPayload mass60 * 260kg = 15,400kgDestination orbitLow Earth Orbit, 290km x 53°Operational orbitLow Earth Orbit, 550km x 53°, 3 planesLaunch vehicleFalcon 9 v1.2 Block 5Core<a href="https://www.reddit.com/r/spacex/wiki/cores#wiki_b1051">B1051</a>Flights of this core2 (Demo Mission 1, RADARSAT Constellation Mission)Fairing catch attemptExpected (both halves)Launch site<a href="https://www.reddit.com/r/SpaceX/wiki/pads">SLC-40</a>, Cape Canaveral Air Force Station, FloridaLanding attemptOCISLY: 32.54722 N, 75.92306 W (628 km downrange)Mission Success CriteriaSuccessful separation & deployment of the Starlink Satellites<a href="/#%20MC%20//%20section%20events"></a>TimelineTimeUpdate<a href="/#%20MC%20//%20row%200"></a> T-7d<a href="https://twitter.com/spaceflightnow/status/1219271152520105984">Falcon 9 vertical with payload</a><br><a href="/#%20MC%20//%20row%201"></a> T-9d<a href="https://twitter.com/spacexfleet/status/1218531908407177216">GO Quest underway</a><br><a href="/#%20MC%20//%20row%202"></a> T+10d<a href="https://twitter.com/julia_bergeron/status/1218023963533758464">OCISLY and Hawk underway</a><br><a href="/#%20MC%20//%20section%20viewing"></a><a href="/#%20MC%20//%20section%20stats"></a><a href="/#%20MC%20//%20section%20mission"></a><a href="/#%20MC%20//%20section%20landing"></a><a href="/#%20MC%20//%20section%20resources"></a><a href="/#%20MC%20//%20section%20participate"></a><a href="/#%20MC%20//%20section%20END"></a><a href="/#%20MC%20//%20let%20time%20=%201580136540000"></a> <a href="/#%20MC%20//%20let%20launch%20…

Starship payload vs transit time
It seems to me that going to Mars via Hohmann transfer is like moving your family to the other side of the earth via container ship. Theoretically possible and probably the cheapest but not the most pleasant or best use of human life. Usually people send their goods via container ship and themselves via planes.So I wondered how fast a Starship could transport say, 10 humans if that's all it was carrying? If we start with "no life-support" as a baseline and just use the weight of the humans (say 1 metric Tonne), then add life-support depending on the resultant numbers and converge to an optimal time/weight. (e.g. if it could be done in a day life-support requirements would be much less than if it took a week etc).I found this previous discussion https://www.reddit.com/r/spacex/comments/7595c3/bfr_payload_vs_transit_time_analysis/ but the analysis seems to break down at the scales I'm proposing.Has anyone else done these calculations? I'm going to try to do them myself but I'm not well equipped to know where to start.There is also the question of whether the Starship heat shielding would be up to the task of the increased speed of entry into the martian atmosphere.Thanks

Submitted January 27, 2020 at 04:30PM by crampies
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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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