# Continuing discussion of SpaceX launches \[edited title\] **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [December 22, 2015, 12:37am UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048 "2015-12-22T00:37:01Z")\ **Posts on this page:** 20\ **Page:** 6
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [January 21, 2016, 5:56am UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/101 "2016-01-21T05:56:49Z")
> [@Magiver](#): > > I thoroughly get the point about launching over civilian areas even if they’re remote. But I’m talking about land out west where NOBODY lives. They’ll be finding crashed planes out there until the end of time. The way US space programs operate, the area must be _completely_ evacuated - not even a few scattered ranchers, hikers, ships, etc. [White Sands Missile Range](https://en.wikipedia.org/wiki/White_Sands_Missile_Range) is the largest area in continental US that can be evacuated for a missile or rocket launch. This is where NASA launches sounding rockets (suborbital research rockets) - I’ve worked on several launches there myself. Every launch involves closing the White Sands National Monument and a few roads, to make sure there is **nobody** within the possible landing area. But even here, the size of the range limits the altitude and downrange (horizontal distance) that the rockets are allowed to fly. The Falcon-9 1st stage flight path will definitely violate this flight envelope. ---
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [January 21, 2016, 5:20pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/102 "2016-01-21T17:20:13Z")
> [@Magiver](#): > > Nice links to the Chinese launch sites. > > I thoroughly get the point about launching over civilian areas even if they’re remote. But I’m talking about land out west where NOBODY lives. They’ll be finding crashed planes out there until the end of time. > > As for sea landings I think it would be much cheaper to focus on locking down the rocket than stabilizing the platform. In an era of robotic systems I would think it easier to seek out and latch on to the rocket then to try to control the pitch of the sea. I guess I didn’t directly answer your question. E.g., how much area has to be uninhabited? To do that, you can look at hazard maps for each launch – these are off-limit areas published by the FAA for each launch, compiled into handy maps by a guy on Reddit. This is the [map for the CRS-7 launch](https://www.google.com/maps/d/u/0/viewer?mid=zXmjsQgIEPtk.kSyT9f2SlzlM), showing the liftoff hazard area in yellow, the first stage splashdown area in red (in case of no landing attempt) and the landing area and barge in blue. The landing barge in this case was 220 miles NE. For other launches, the landing barge or midpoint of the splashdown hazard area has been 400 miles ENE, 120 miles NE, 500 miles E, and 170 miles S. Future launches will launch with different headings (though most will be similar) and the Falcon Heavy will need to land much further down range. So let’s say we want to put a launch site out west. It needs to have the lowest possible latitude, good weather and accessibility. To simplify matters let’s assume that this site will only be used for launches almost due east, since that’s how most heavy heavy to geosynchronous orbit and beyond are launched. Conservatively you’d need a strip of completely uninhabited land 400+ miles long and 50+ miles wide. Even in the remotest parts of Arizona, New Mexico, and Texas I don’t think there’s anywhere like that. Far less conservatively you’d want (say) 50miles downrange to be completely uninhabited, flight paths that don’t pass over any towns or major highways, and a number of uninhabited landing zones 400 miles to the east. Physically possible? Sure. Politically feasible? I’ll let you convince the people of West Texas that they should relocate, or evacuate for every launch. And then, after the inevitable launch failure that rains debris near a small farming town, destroying fields and a few buildings, you can convince Congress that launches should be allowed to continue. And figure out how to economically insure each launch to cover property damage liability, deal with the rain of civil lawsuits, injunctions against future launches… 😛 ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [January 22, 2016, 12:16am UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/103 "2016-01-22T00:16:26Z")
If the concept of “Cheap and easy access to Space” is to be realized, the rules about overflights will need to be drastically altered. Every once in a while, an airplane falls down and makes a mess. Yet we allow them to overfly large cities, even during the takeoff and landing phases, which are the highest risk parts of a flight. Hell, I remember when the jockeys at Wright-Patt would create sonic booms which broke people’s windows (yes, I am ancient). When the massive fireballs of failed launches become a remote memory, “SpacePorts” will become quite common. One, Spaceport America (301 S. Foch St., Truth or Consequences, NM 87901) thought it had a winner with Virgin Galactic. They are now looking for more [del]suckers with more money than brains[/del] investors with Vision. ---
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [February 23, 2016, 10:56pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/104 "2016-02-23T22:56:41Z")
Bump for the next launch: Tomorrow, Feb 24th, SpaceX will be launching the SES-9 communications satellite. Launch window is between 6:45 PM and 8:15 PM EST, with a ~60% chance of favorable weather. SpaceX will live stream this launch [here](https://spacex.com/webcast). For this launch, there will be another barge landing attempt. However, SpaceX will be launching its payload into a higher orbit than originally intended, to help the satellite owner get their satellite into position faster (helping make up for the ~7 month delay following last year’s launch failure…) This means the landing will be a lot further down range, 600 km east of Florida, and there will be very little margin for error during the landing burns. Nobody seems confident about a successful landing. (I’ll keep bumping this thread for each launch as long as there’s interest.) ---
**Author:** ![2gigch1](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/2gigch1/32/3313_2.png) [@2gigch1](https://boards.straightdope.com/u/2gigch1)\ **Post date:** [February 23, 2016, 11:14pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/105 "2016-02-23T23:14:49Z")
Thanks for the bump and please do. I have been subscribing to a YouTube weekly space interest broadcast called TMRO (Tomorrow). Every Saturday they put on an hour long TV program from their apartment discussing the topics of interest to the space community. Worth a watch, and some of their other offerings like Space Pod (a weekly short informational video) [TMRO YouTube Site](https://www.youtube.com/user/TMRO) ---
**Author:** ![cardinal\_fang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal_fang/32/15316_2.png) [@cardinal\_fang](https://boards.straightdope.com/u/cardinal_fang)\ **Post date:** [February 25, 2016, 10:50pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/106 "2016-02-25T22:50:00Z")
Bump and FYI to note that the launch was delayed to today, and is scheduled for 5:47 CST (when this post is about an hour old). Weather is 80% favourable at this time. [Link](http://www.spacex.com/webcast). ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [February 25, 2016, 11:10pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/107 "2016-02-25T23:10:22Z")
Thanks, Fang. ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [February 25, 2016, 11:30pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/108 "2016-02-25T23:30:08Z")
Any cable channels carrying this? ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [February 25, 2016, 11:36pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/109 "2016-02-25T23:36:32Z")
It’s not a NASA flight, so it’s not on NASA TV unfortunately. I’m not aware of any other channels that stream this kind of stuff. ---
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [February 25, 2016, 11:41pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/110 "2016-02-25T23:41:26Z")
If anyone wants even more info, there’s a nifty live visualization of a (simulated) trajectory here: > **[Flight Club](https://flightclub.io/world.php?watch=1&code=SES9)** > > Flight Club is the rocket launch simulator and orbital trajectory visualiser for all things space! ---
**Author:** ![Pork\_Rind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pork_rind/32/111_2.png) [@Pork\_Rind](https://boards.straightdope.com/u/Pork_Rind)\ **Post date:** [February 25, 2016, 11:44pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/111 "2016-02-25T23:44:21Z")
I was gonna say you can watch it streaming on [spacex.com](http://spacex.com) but it looks like they’ve scrubbed for the evening. Something came up as an issue at T-1:41 ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [February 25, 2016, 11:45pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/112 "2016-02-25T23:45:50Z")
I thought it was just me. I lost the feed at :41 ---
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [February 25, 2016, 11:47pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/113 "2016-02-25T23:47:58Z")
Mmmyup. They seem to be having trouble with super-chilled liquid oxygen. In another launch with higher margins that might be OK, but for this launch I saw a calculation that showed how a very slight reduction in performance in the Falcon 9 would ultimately end up with the payload reaching its final orbit several days or weeks later. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [February 25, 2016, 11:49pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/114 "2016-02-25T23:49:16Z")
Sounded like problems with the liquid oxygen subcooling again. This is a new thing with the F9 “Full Thrust”, and this particular flight is very performance-sensitive (it’s right at the limits of the rocket) so they need every last kelvin of cooling they can achieve. I suspect they didn’t get quite the cooling level they wanted. The previous FT rocket was not so performance sensitive and they probably didn’t care if they didn’t quite hit their target. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [February 25, 2016, 11:52pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/115 "2016-02-25T23:52:08Z")
\ The SES-9 satellite carries an ion engine which puts it in its final orbit, but like all electric thrusters it’s very slow. SpaceX made a somewhat last minute flight profile change to give them a few hundred m/s of extra delta-V, cutting their final positioning time substantially, but this obviously demands higher performance from the rocket. ---
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [February 25, 2016, 11:54pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/116 "2016-02-25T23:54:16Z")
It’s also (comparatively) trivial to fill a tank full of liquid oxygen when it’s right at its boiling point. There will be constant boil-off, but that can be easily replaced with more liquid oxygen. Super-chilling requires some kind of active chilling and recirculating in the rocket, or (what SpaceX seems to be doing) loading the oxygen immediately before the launch so it doesn’t have time to warm up. ---
**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\ **Post date:** [February 27, 2016, 5:26pm UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/117 "2016-02-27T17:26:14Z")
Just for kicks, there are two landing barges. The Pacific one is named _Just Read The Instructions_, and the Atlantic one (which I’ve seen docked at Port Canaveral) is named _Of Course I Still Love You_. ---
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [February 29, 2016, 12:04am UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/118 "2016-02-29T00:04:57Z")
Another slightly tardy last-minute bump: Today is the next launch attempt. The first countdown was cancelled at 6:45 when a boat entered the exclusion zone by the launch site. They’re now trying to determine whether they can clear the water and make another attempt tonight before the launch window ends around 8:20. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [February 29, 2016, 12:33am UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/119 "2016-02-29T00:33:29Z")
Well, that was… interesting. Launch aborted after main engine ignition. I guess something didn’t go quite right with the engine ignition sequence? ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [February 29, 2016, 12:54am UTC](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048/120 "2016-02-29T00:54:35Z")
> [@lazybratsche](#): > > Super-chilling requires some kind of active chilling and recirculating in the rocket, or (what SpaceX seems to be doing) loading the oxygen immediately before the launch so it doesn’t have time to warm up. Supercooling (producing “densified” LO[SUB]x[/SUB]) requires rapid loading in the supercooled condition; there is no practical way to cool the oxidizer once loaded into the vehicle, as it would require some kind of heavy heat exchanger with circulating liquid nitrogen that would have to be carried along into launch. LO[SUB]x[/SUB] densification has been considered for launch vehicles before, especially for single-stage-to-orbit (SSTO) vehicles that are extremely mass sensitive such as the X-33, but from a logistical and launch availability standpoint it is extremely challenging for a number of reasons; not only because it requires rapid loading, but also because the heating and stratification that occurs during the loading sequence can cause loss of densification. The supercooled LO[SUB]x[/SUB] will vent at a higher rate resulting in oxygen impingement on potentially sensitive components on the vehicle which has to be accounted for, including redistribution the amplified heat transfer from even moderate ground winds (which was one of the major contributors to the failure of the STS-51-L starboard booster). In other words, LO[SUB]x[/SUB] densification is an expensive and complex way to eke out a small amount of additional impulse for a given propellant volume. The added complexity and cost is contrary to realizing lower cost and higher launch availability, so SpaceX is presumably betting on being able to make the loading process expedient and reliable but in practice they are running into the same problems that have prevented existing launch vehicle providers from adopting densified propellants. Stranger [Previous page](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048.md?page=5) [Next page](https://boards.straightdope.com/t/continuing-discussion-of-spacex-launches-edited-title/741048.md?page=7)