Talk:Falcon 9 flight 20

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Falcon v1.2 Should be renamed v1.1 FF on the premise that the 1.2 designation is not confirmed. Avster2000NT (talk) 00:12, 13 October 2015 (UTC)

Delayed

Is it delayed? — Preceding unsigned comment added by 79.249.128.206 (talk) 10:02, 19 December 2015 (UTC)

Photo of landing?

Is there any prospect of having a photo of the landing itself that meets our free content licensing requirements? It's a historic moment in spaceflight, as the sudden reduction in launch cost completely changes the economics of space exploration. -- The Anome (talk) 14:33, 22 December 2015 (UTC)

Yes. SpaceX has made many available on it's Flickr page. NASA released a few. And many amatueurs have posted vids that may be compliant with Wiki license rulz. I see that some have been added to the article now. Plus, see a comment I left in the past hour in a new section below: Stabilized video. Cheers. N2e (talk) 00:11, 24 December 2015 (UTC)

Flight path of first stage?

Did it complete a (sub) orbit or was the stage braked and returned? If the latter, how achieved - aerodynamically or mostly or entirely with engine thrust? If the latter, what portion of the first stage fuel was required for this, including the extra fuel required for initial lift? — Preceding unsigned comment added by Dmoorenh (talk • contribs) 09:59, 23 December 2015 (UTC)

Dmoorenh—No, the booster never had even close to sufficient velocity to become orbital; it was always suborbital.

There were three engine burns to bring the first stage back (after the initial 2 minute 40 second burn of nine engines to loft the second stage).

• The first, the boostback burn (used three engines, nos. 1, 5 and 9), occurs outside the sensible atmosphere and does the most work. It has to brake the c. 5000 km/h downrange velocity (away from Cape Canaveral) and impart velocity back toward the Cape.
• The second is the re-entry burn, and occurs much closer to the Cape, as the booster begins to encounter the thicker parts of the atmosphere. It is used to a) control vehicle attitude as is the vehicle is buffeted by the hypersonic to supersonic to subsonic transition; to b) reduce velocity so it will neither overheat nor break up as it encounters the thicker atmosphere in the hypersonic/supersonic/transonic buffet/subsonic transitions; and 3) provide additional steering (fine tuning) of the descent trajectory that was initially set by the boostback burn. (there is more detail (and links) on these transitions in the SpaceX reusable launch system development program article.)
• The third extra burn (only one engine) is the landing burn. This is what is most visible in most of the videos you can see on the internet (although some captured the higher altitude re-entry burn as well). This one takes the vehicle from it's subsonic terminal velocity, and brakes it for the hoverslam landing (zero velocity at zero altitude even though the throttled thrust on the single engine exceeds the very low weight of the rocket (with so little propellant remaining) at this time in the flight.

Hope that is helpful to you. Cheers. N2e (talk) 00:08, 24 December 2015 (UTC)

Here's the PopMech writeup of the first stage flight, and comparison with Blue Origin [1]

• http://pop.h-cdn.co/assets/15/52/1450888612-bevsx.jpg
• http://i.imgur.com/ATkpdAX.png
• https://i.imgur.com/D9BdO86.png

-- 70.51.44.60 (talk) 08:48, 28 December 2015 (UTC)

Stabilized video of the landing burn on F9 Flt 20

Here is a stabilized video of the third of three burns related to bringing the booster back (the landing burn) on Falcon 9 Flight 20, 22 Dec 2015 (UTC), as it lands at Landing Zone 1. This is from a NASA source video, and was stabilized (in post-processing) by someone on YouTube named Jay DeShetler. Link is here.

Maybe someone with YouTube savvyness can ask DeShetler if they would be willing to upload the video to WikiMedia with an appropriate share and share-alike Wiki-friendly license so it could be used on wiki. Cheers. N2e (talk) 23:53, 23 December 2015 (UTC)

Booster max altitude

What is the highest altitude reached by the Falcon first stage booster before descending back to Earth? Video shows stage separation at about 76 km, but booster continued to ascend on parabolic trajectory before descending back to KSC.--Arado (talk) 09:36, 24 December 2015 (UTC)

Post-landing news conference with Elon Musk

Here is a recording (link here) of the post-launch and post-landing teleconference with the press that Elon Musk gave. The audio has quite a bit of wind noise on the microphone; but you can hear everything the reporters heard. That YouTube audio was posted yesterday, 23 Dec 2015.

Today, someone has helpfully posted a full transcript of the recording. (link here). If you use any of this as a primary source to details about the launch, flight, landing, future plans, etc., you should recognize this is a primary source, and while okay to use for verifiability purposes in some cases, is not considered as good a source for Wikipedia as a secondary source, something written on by a reliable source (like a newspaper, or one of the space media journalists). Cheers. N2e (talk) 10:28, 24 December 2015 (UTC)

Nothing on why this is important?

There is nothing in this article that explains why this is important or notable. Seems to be related to reducing the cost of space flights? That should be explained here. T-bonham (talk) 22:33, 24 December 2015 (UTC)

Agreed. And the article should be improved in that way. Feel free to help out. Some of what is important is articulated in other articles and could, perhaps, be briefly summarized (with citations) in this article to cover the missing importance prose that you mention. N2e (talk) 12:57, 28 December 2015 (UTC)

A paragraph on the significance of the landing has been added to the introduction. Doublesuited (talk) 07:59, 31 December 2015 (UTC)

I think the importance rating on this article is incorrect, it shouldn't be "Low" since it marks a historic rocket landing for spaceflight. -- 70.51.44.60 (talk) 06:22, 27 December 2015 (UTC)

To your specific concern, 70.51.44.60, I have reassessed the article for the Spaceflight and Rocketry WikiProjects. N2e (talk) 12:57, 28 December 2015 (UTC)

Safety?

I see nothing about the risks to residents in the surrounding area from a landing, risks that are inherent in such a procedure. Thousands of people live in that part of Florida. — Preceding unsigned comment added by 108.249.146.8 (talk) 13:46, 26 December 2015 (UTC)

Welcome. If you find some sourced information, feel free to add it, along with a citation. After all, on Wikipedia, anyone can edit. I believe that the USAF/FAA or some regulatory agency did an Environmental Assessment of the returning first stages before giving approval to this test attempt at a landing; that document includes analysis of sound, sonic boom effects, etc. Cheers. N2e (talk) 14:57, 26 December 2015 (UTC)

Impact on the culture

Why was this section cut [2]? The tone is appropriate, the fancy words are in quotes. --Ysangkok (talk) 15:31, 1 January 2016 (UTC)

I agree, Ysangkok. I think it should be changed back, just clearly attributing the analysis to the publication or editor/writer who made the observations, in order to maintain neutral POV. N2e (talk) 22:44, 4 January 2016 (UTC)

Toned it down while keeping some excitement from The Atlantic. — JFG ^talk 18:13, 13 March 2018 (UTC)

This is F9-21

Should be moved. Nergaal (talk) 10:58, 13 March 2018 (UTC)

It's not. — JFG ^talk 18:03, 13 March 2018 (UTC)

Does SpaceX keep an internal log of their flight numbers? Nergaal (talk) 20:50, 13 March 2018 (UTC)

No idea. But all journalistic sources have referred to this mission as the 20th Falcon 9 flight, and we have a full list that matches the count. What makes you think it would be flight 21? — JFG ^talk 20:59, 13 March 2018 (UTC)

This log seems to assign flight numbering in non-chronological order, presumably from a "contract assignment" order. It's unclear to me how that specific log is kept, but it counts Atmos-6 as F-29. Nergaal (talk) 10:46, 14 March 2018 (UTC)

OK thanks. Looks like the order of flights when first scheduled, e.g. Zuma was scheduled for October 2017 then repeatedly delayed. It may be an internal SpaceX numbering scheme, or something else cooked up by the source author. As for Wikipedia, we should stick to a chronological order of launches, as we do on all rocket launch histories. — JFG ^talk 12:52, 14 March 2018 (UTC)

The site seems to have very extensive logs on space launches, so I wouldn't be surprised if this numbering scheme is legit from an original SpaceX internal count, which probably didn't really last past the Atmos-6 due to PR reasons. Nergaal (talk) 16:43, 14 March 2018 (UTC)