Talk:SpaceX reusable launch system development program

Disagreement between Intro and History

The first paragraph of the Introduction states that "the project's long-term objectives include returning a launch vehicle first stage to the launch site in minutes and to return a second stage to the launch pad" - this is at odds with the last paragraph of the History section which states that "by late 2014, SpaceX suspended or abandoned the plan to recover and reuse the Falcon 9 second stage". — Preceding unsigned comment added by JHarvey418 (talk • contribs) 18:19, 14 August 2015 (UTC)

Good observation. We should probably clean up the text. But I think the contradiction dissapears when one recalls that this SpaceX technology development program is not specific to just the Falcon 9 launch vehicle. The company has decided not to pursue Falcon 9 second-stage reuse; they absolutely have a long-term goal of second-stage reuse also as a part of this tech dev program. It would appear, based on company statements to date, that the second-stage reuse will get additional development effort when the MCT launch vehicle development get's underway with more than the skeleton crew of current design resources. Cheers. N2e (talk) 19:20, 14 August 2015 (UTC)

Since this discussion in August, I've added some prose to endeavor to explicate the distinction: aiming for both stages long term, but the near-term Falcon 9 focus is only on the first stage. See what you think. N2e (talk) 05:38, 25 December 2015 (UTC)

Maintenance + unmanned

High maintenance costs ruined the economics of the reusable Space Shuttle. But that was presumably at least partly due to the Shuttle having to be extra safe to carry people, so that Falcon 9 may perhaps avoid similar problems if its payloads stay unmanned. Are there no reliable sources discussing these matters, or if there are, shouldn't they appear in the article? (The Space Shuttle's problems meant that I assumed Falcon 9 was just hype until I worked out the above arguments, but if those arguments are correct I shouldn't have had to try to work them out for myself, and neither should our other readers).Tlhslobus (talk) 13:27, 23 December 2015 (UTC)

As I understand it, many parts of the Space Shuttle had to be stripped down and rebuilt with every flight. I believe SpaceX's aim is to be able to just refuel and relaunch, in the same way as an aircraft can be refueled and relaunched. Presumably they intend to use telemetry and non-destructive inspection techniques to avoid the need for a full maintenance inspection every time. SpaceX certainly intend to make the Falcon man-rated. -- The Anome (talk) 13:40, 23 December 2015 (UTC)

Thanks. But the article currently has no mention at all of any of that in the Economic Issues and Technical Feasibility sections, which is where sceptical-but-open-to-persuasion readers like me are going to head, and not much of it elsewhere either, in the sense that it's perhaps implicit in Elon Musk's stated wishes, but an owner's wish list is not a very informative discussion of an issue. Indeed apart from wishful talk about hoping to colonize Mars (which we've been hearing for 50 years, despite the discovery of serious problems with solar flares, and cosmic rays, and the lack of any serious 'Artificial gravity' research programme on any of the various space stations), the article gives the impression that the serious plans are currently only for reusable rocket stages 1 and 2, which for a manned rocket is the equivalent of re-using the rockets but throwing away the manned bits, at least leaving the impression that any manned flight will be much less reusable than the Space Shuttle. Tlhslobus (talk) 14:19, 23 December 2015 (UTC)

If you're talking about Earth-bound missions, I believe that SpaceX intends to make all three components reusable: the first stage and second stage boosters, and the Dragon capsule, all landing vertically on their own rocket thrust. In the case of the Dragon, the landing rockets are also planned to serve as the attitude thrusters and launch escape mechanism. I can't find a reference for this at the moment, but they released a video last year (with a backing track by Muse, IIRC) showing an animation of how the whole process is intended to work. We really need to have this covered in more detail in the article. Mars I don't know about. -- The Anome (talk) 14:36, 23 December 2015 (UTC)

You are correct, in the long term, but not for the nearer term, with the Falcon 9/Falcon Heavy. Both are addressed in the article prose, but perhaps could be made more clear.

1. In the lede it says "The project's long-term objectives include returning a launch vehicle first stage to the launch site in minutes and to return a second stage to the launch pad following orbital realignment with the launch site and atmospheric reentry in up to 24 hours. SpaceX long term goal is that both stages of their orbital launch vehicle will be designed to allow reuse a few hours after return.[1]". (emphasis added)
2. In the History section, it says: "By late 2014, SpaceX suspended or abandoned the plan to recover and reuse the Falcon 9 second stage;[33] the additional mass of the required heat shield, landing gear, and low-powered landing engines would incur too great a performance penalty."

So, using all extant sources we have, SpaceX is still aiming for this, but in their MCT launch vehicle and in the Mars Colonial Transporter; not with the Falcon 9 nor Falcon Heavy. (however, with the new USAF contract to SpaceX earlier this month for SpaceX to develop an "upper stage" Raptor-like methane-fueled full-flow-staged-combustion prototype engine for the F9 and FH (see the article lede of Raptor (rocket engine) for a source), there is some speculation that a newer/newish second stage design for F9/FH might be able to be reusable, like Musk originally wanted, rather than like SpaceX decided to drop development resources from in late 2014, as shown in the quotation above. SpaceX, however, has neither confirmed nor denied any interest in even making a stage that would ever fly with the new USAF-1/3-paid-for prototype engine, nor publically said anything about making such a hypothetical stage reusable, contra the earlier late 2014 plans. YMMV.) Cheers. N2e (talk) 23:36, 19 January 2016 (UTC)

Thanks for the great info, The Anome. I wonder can that video be used as an acceptable RS, if it can be found? Also, do you by any chance know whether they say anything anywhere about returning to the Moon (or is it all just about Mars, with its far greater and possibly insuperable problems for the human body)?

Think I have seen a Elon Musk interview where on being asked this question he likened it to if you build an aircraft capable of crossing the Atlantic then are there going to be other people flying across the English Channel? That of course doesn't indicate that SpaceX have moon plans and may tend to indicate either they don't or they don't want to disclose any plans they have. Impression was he thinks it is inconceivable we would do Mars and not also have someone else doing something on the moon. crandles (talk) 17:12, 23 December 2015 (UTC)

He used boats rather than planes. See [1] crandles (talk) 23:22, 23 December 2015 (UTC)

First stage velocity at separation

It is probably time to revisit the article info on separation speeds before booster flyback. New, specific, info is available on the first two actual flights of the Falcon 9 full thrust version of the rocket is now available: Falcon 9 Flight 20 in Dec 2015 and Falcon 9 Flight 22, slated for launch later today. This source ( Klotz, Irene (2016-02-23). "Satellite operator SES says interested in used SpaceX rocket". Reuters. Retrieved 2016-02-24.) provides clear info on the Falcon 9 part of the question:

the rocket launching this week will be flying almost twice as fast as the one used in December - between 4,971- to 5,592 mph ( 8,000- to 9,000 kph), compared to 3,107 mph (5,000 kph) - by the time it separates from the second-stage motor, SpaceX said.

FWIW, the info on these velocities that is currently in the first paragraph of this article, is based on orginal forward-looking design information from several years ago in 2012 (and there was lengthy Talk page discussion getting to that...):

If the technology is used on a reusable Falcon 9 rocket, the first-stage separation would occur at a velocity of approximately 2.0 km/s (6,500 km/h; 4,100 mph; Mach 6) rather than the 3.4 km/s (11,000 km/h; 7,000 mph; Mach 10) for an expendable Falcon 9, to provide the residual fuel necessary for the deceleration and turnaround maneuver and the controlled descent and landing.

So the article will definitely need an update, and I don't have time to do it just now. N2e (talk) 12:57, 24 February 2016 (UTC)

Flight 22 landing: Significance of extra push - consequently phrasing looks wrong

@N2e: There was an agreement that an extra push would be given to reduce time to reach final orbit. This came from second stage being run until depletion of fuel rather than shutting down when a target orbit was reached. This has very little, if any, effect on amount of fuel left in first stage. I don't mind this piece of information being given - Not quite sure where I would move it to. Seems well covered in Falcon_9_Flight_22 and not sure it needs to be here as well. However, I do object to phrasing that indicates that because of the extra push there is little fuel left to land the first stage. Far, far, more important is that the payload was heavy for being lifted to GTO. Unless you have or there is a reference indicating such importance, such a level of importance should not be implied by the article. So the phrasing should reflect this. If other editors want to insist on including mention of the extra push fine but for accuracy don't phrase to indicate this is primary reason for little fuel being left to land first stage. Can we please change the phrasing or remove it? crandles (talk) 14:12, 9 April 2016 (UTC)

I get your two points. I don't have time to relook a the sources just now, but in the long news conference by the SES executive Halliwell I recall him mentioning the extra push, and impact on the probability that SpaceX successfully landing the first stage would go down. It seemed to me, as I heard that and other sources, that given SpaceX's loss of flight 19, and subsequent 6 or so month delay to the return-to-flight, it pushed SES back a bunch, and thus reduced SES near-term revenue statements (SES were going public on that in securities regulation announcements), and since SES is a really good (though not exclusive) SpaceX customer, SpaceX decided to "take one for the customer" and burn harder/longer, and reduce landing probability of the experimental controlled-descent first stage. No problem; all good business. But the push or extra burn or whatever was mentioned by Halliwell, and picked up by space media who covered that. So I think the extra push should not be left out of the article. On your second point, I have not seen sources that clarify how much of the extra push was first stage vs. second stage. Given the extra push was talked about, and sourced, it is not at all clear that just because the second stage did a "burn to (safe) depletion" rather than a "burn to target orbit", then that would mean the first stage didn't give some extra push also, and thus use up some of the propellant that would have been part of its return and landing prop margin; SpaceX clearly decided to do a special 3-engine landing burn on flight 22, never before even tested, in order to have a (small probability) shot at bringing the thing in and landing it. N2e (talk) 18:55, 9 April 2016 (UTC)

I fully agree with crandles on this edit which improves the reader's understanding that mass and speed are the key factors in setting practical limits to booster recovery. Here we had a rocket which couldn't reduce its re-entry velocity as much as would be feasible on a LEO Dragon launch, for example. That being said, I would assume that the negotiated supersynchronous trajectory had an impact on the first stage as well as the second stage, taking both of them to their limits? However we are surely going down the sweet and sour path of WP:OR... This case was undoubtedly a great way to push the envelope on what these Falcons can withstand! — JFG ^talk 07:26, 10 April 2016 (UTC)

Looking again at the ref http://spaceflightnow.com/2016/02/24/falcon-9-rocket-to-give-ses-9-telecom-satellite-an-extra-boost/] "Halliwell said SES’s contract with SpaceX called for the rocket to deploy SES 9 into a “sub-synchronous” transfer orbit with an apogee around 16,155 miles (26,000 kilometers) in altitude. ... The change in the Falcon 9’s launch profile will put SES 9 into an initial orbit with an apogee approximately 24,419 miles (39,300 kilometers) above Earth." 26000km to 39300km is quite a difference that doesn't seem likely to come from just a couple of extra seconds burn from the second stage. This makes it seem to have a more significant effect than I was thinking when reading the change was just a slightly longer burn on the second stage. Would still suggest payload weight "heavier than the Falcon 9 rocket’s advertised lift capacity to geosynchronous transfer orbit" is likely a major effect but without reference we shouldn't indicate which is more important. Can we find a wording that suggests both are factors without indicating one is more important than the other? Perhaps I will have a go at adding a little more. Hope bit added serves. crandles (talk) 11:05, 10 April 2016 (UTC)

Sure, give it a go. That was why I suggested we beat it around on the Talk page for a bit. Just was a shame to lose that aspect of the extra energy added for movement of the trajectory to a higher energy orbit, and one that was beyond what the contract called for. N2e (talk) 02:23, 12 April 2016 (UTC)

Source

This video of Musk news conference following the second successful landing of a booster (first one was Dec 2015, on land), and the first one on a droneship, explains a bit about the test philosophy, and why do it on an active orbital mission rather than as most government-funded missions to date where the test flight itself would be a single planned dedicated mission. Musk Discusses CRS-8 Successes with Media, 8 April 2016, at 19:20-21:50. Would be a good source to potentially improve the article. N2e (talk) 02:44, 16 April 2016 (UTC)

Fairing

SpaceX is working on fairing reusability. I may add a mention of that. --Pmsyyz (talk) 16:23, 6 March 2017 (UTC)

And they achieved a recovery on the 30 March 2017 launch. It is now mentioned in the article, and sourced. N2e (talk) 04:55, 1 April 2017 (UTC)

Deeper and more analytical secondary sources

Now that it's been over a day since the successful launch and flight of a "flight-proven" booster stage, the deeper and more serious pieces of space media journalism are being posted.

• this one has a good bit of sourced info on costs, flight rates, etc. https://www.spaceintelreport.com/spacexs-reusability-effort-faces-one-more-big-challenge.
• https://www.nasaspaceflight.com/2017/03/spacex-historic-falcon-9-re-flight-ses-10/ N2e (talk) 05:48, 1 April 2017 (UTC)