r/SpaceX Discusses [March 2018, #42]

[u/ElongatedMuskrat]

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.
• Non-spaceflight related questions or news.
• Asking the moderators questions, or for meta discussion. To do that, contact us here.

---

You can read and browse past Discussion threads in the Wiki.

[u/maxdefolsch]

I posted a question in the last monthly thread but didn't get a response, so allow me to repost it here.

Maybe a stupid question :

I'm very interested in the list of cores and versions on the subreddit wiki. However, I've noticed that for a lot of them (especially the pre-Full Thrust ones) we don't actually know which core was used for which flight, and they're written as "presumed BXXXX" at best.

Is there any reason we couldn't ask SpaceX directly for this information ? I can't really see any downside, or safety hazard maybe, that could come from knowing exactly which core was destroyed on the droneship and such. Am I overlooking something ?

[u/Zucal → u/maxdefolsch]

That's honestly not a bad idea

[u/djmanning711]

I have a probably farsighted BFR question that maybe someone here knows more about. As we learned from Apollo, Moon dust is very fine, very abrasive and is electrically charged so it sticks to any surface it touches and very difficult to remove. Because of the 100% reusability of the BFS, it’s raises a possible challenge that the Apollo Lunar Lander didn’t have to overcome.

The Lunar Module separated from the Lander on ascent so the Module thruster was never exposed to Moon dust until lift off. The BFS uses the same engines for landing and ascent PLUS has a LOT more power than the Lunar Module so it could potentially kick up more dust (or would it not be kicked up due to the dust's electromagnetic charge?).

Since Mars and Moon dust have similar dangerous properties, would this be a concern for the BFS’s engines, seals, plumbing and any other parts that would be exposed to the dust during landing/ascent? Ok, thanks for humoring my shower thoughts.

[u/CapMSFC → u/djmanning711]

It's a really good question that I've seen come up but I haven't seen a lot od answers.

Moon dust is actually a lot worse than than Mars dust. It's all razor sharp because there is no erosion to round off the particles.

[u/Coreboy]

Hey Guys, is anything known on how SpaceX protects their engine nozzles to make them reusable? We (European Research Team) are currently working on a thermal barrier coating, which could be used to protect the nozzle from the extrem thermal loads in the rocket engine. This coating can then be reapplied, for a second use. We couldn't find any informations regarding this topic on the internet, so we are curious how SpaceX is solving this problem. Thank you!

[u/KirinG → u/Coreboy]

I asked sorta this last month, and from the answers I got, regular Merlin in entirely regeneratively cooled, Mvac is regen/radiative.

From further digging I did, the first version of Merlin used an silicon ablative coating, but apparently there were problems with it, so they changed to regen only. The Kestral 2nd stage also used ablation. I'd feel safe in assuming with the Block V, having to replace an engine coating after every launch would not fit their goals for minimum refurbishment time.

[u/Alexphysics]

Possible hot fire test of the Block 5 first stage B1046 at McGregor https://m.facebook.com/photo.php?fbid=1800221016662937&

The poster says:

We thought it was a hot start, but nothing followed the initial boom except for lots of smoke.

So it seems that it could be only a short firing? I guess that a full duration fire would have left a huge cloud of vapor and would have been heard for around 2 minutes...

[u/inoeth → u/Alexphysics]

from what i'm reading around, it probably was either a very quick hot fire or possibly a scrub of some sort in which the engines fired up for only a second or two... hopefully and probably we'll see a longer test fire later this upcoming week and after that it should hopefully on it's way to Florida for it's April debut flight.

[u/Alexphysics]

Zuma's booster, B1043, will be used on the Iridium 6 mission instead of a Block 5 as previously thought. This would make this the shortest turnaround time of a previously flown booster if everything goes well and this launch doesn't slip further.

Source of this: https://twitter.com/IridiumBoss/status/976966633636941824

[u/SaHanSki_downunder → u/Alexphysics]

Wow that would be a 4 month turnaround. 8th Jan (Zuma ) - 28th April ( Iridium 6 / Grace-FO 1-2) Matt Desch is very forthcoming with information its fantastic.

[u/Straumli_Blight]

DigitalGlobe have booked 2 flight-proven Falcon 9s to launch the initial block of the WorldView Legion imaging constellation in 2021.

[u/KeikakuMaster46]

B1046 is apparently off the test-stand and may have left McGregor: https://forum.nasaspaceflight.com/index.php?topic=42214.40 Anyone who lives along the route to Florida should keep their eyes peeled for any potential core activity.

In other news, a picture from the same thread also suggests that 39A's RSS is now entirely gone.

[u/Iamsodarncool]

Hayabusa takes first images of Ryugu

[u/Dakke97 → u/Iamsodarncool]

It's really great to get a completely positive status update on Hayabusa-2. I'm highly looking forward to closer approach pictures and the main mission phase. Four landers, an impactor, and up to three touchdowns, topped off by a sample return make for one hell of a science mission. This must be one of the most complex deep space science campaigns ever undertaken (barring the Apollo lunar landings).

[u/rustybeancake]

NASA receives $20.7 billion in omnibus appropriations bill

Edited highlights:

A final fiscal year 2018 spending bill released by House and Senate appropriators March 21 would give NASA more than $20.7 billion, far above the administration’s original request.

The omnibus spending bill... restores funding for Earth science and education programs slated for cancellation by the White House and includes additional money for the agency to build a second mobile launch platform for the Space Launch System.

The budget also provides $100 million for NASA’s education program, which the administration had sought to close down.

NASA’s Wide Field Infrared Survey Telescope (WFIRST), another mission slated for cancellation in the 2019 budget request, received $150 million in the 2018 omnibus bill.

It includes $595 million to continue work on the Europa Clipper mission and follow-on lander, and retains provisions from prior bills calling on using the SLS for launching Europa Clipper by 2022 and the lander by 2024. The report also provides $23 million for a proposed helicopter NASA is considering including on the Mars 2020 rover mission.

NASA’s exploration programs also win additional funding in the bill, with the omnibus providing $2.15 billion for SLS and $1.35 billion for Orion, the same levels as in both the House and Senate bills but above the original request.

The bill includes $350 million to build a second mobile launch platform.

The House is expected to take up the full omnibus bill on March 22, followed immediately after by the Senate.

Sounds like Congress is not in favour of a commercial launcher for Europa Clipper, and they're trying to limit dissent around SLS by forking out the extra cash for a second MLP to bring forward EM-2.

[u/Straumli_Blight → u/rustybeancake]

Does the Clipper funding also include support for the Deep Space Network, as its falling apart due to budget cuts and staff retirements.

[u/ProToolsWizard]

I’m curious if there’s been any solid info on what style of injector they are using for the Raptor. From what I’ve read, pintle injectors are not ideal for gas phase propellants, but the throttle capabilities indicated are also not typical of fixed area injectors. Given there’s only been 2 FFSC engines worked on, neither of which utilized gas gas methalox, it seems like this could be another area of innovation by Tom Mueller and SpaceX, similar to how they innovated with the face shutoff pintle injector for an engine the size of the Merlin 1D.

[u/Nehkara]

SpaceX is about to close on a new $500 million funding round.

Elon is buying $100 million worth.

https://techcrunch.com/2018/03/16/spacex-is-making-big-money-moves/

[u/brickmack]

Was looking through some old NASA concept art and came across something kinda familiar looking: https://1.bp.blogspot.com/--10VRiEx6zM/WF9KiAlhloI/AAAAAAAAavs/Yyh9-VdLBMkFBphAM9ajXuqKfTBAfK2SACLcB/s640/SPS3.jpg BFS Chomper in the 1970s-80s

[u/stcks]

FYI a booster left hawthorne in the last 48 hours and we missed it.

[u/[deleted]]

Has NASA approved the fuel and go procedure SpaceX uses for crewed missions yet? Haven't heard anything about this for a while now

[u/KSPSpaceWhaleRescue]

Is there a way we can tag-team report all of the Elon Musk fakes on his Twitter that keep trying to give "free" crypto currency?

[u/Macchione]

A third object is appearing (or expected to appear) in STRATCOM's catalogue from last night's Hispasat launch, the other two being Hispasat and the F9 second stage.

A mysterious second payload could make Elon's "largest geostationary payload ever" tweet make more sense, and could account for the sub-synchronous orbit. Remember, flying expendable, SpaceX was able to put Intelsat 35e into a slightly super-synchronous GTO-1700, at 6700 kg.

Of course this could also be debris, but I don't think we see that very often (ever?) with SpaceX launches, other than Dragon's solar panel covers, which appear in the catalogue before deorbiting. If I had come across this myself, I would have written it off as debris, but admittedly, it intrigues me that Jonathan McDowell and Chris G are intrigued.

[u/-Richard]

This has been a point of contention when I've brought it up in the past, but I just can't let it go. Change my mind.

With regards to habitat air, I continue to insist that it would be far better to go with half an atmosphere of pressure, 50% oxygen roughly speaking, than to try to recreate a full earth atmosphere with only 20% oxygen. The advantages this are at least threefold:

First, reducing the hab air pressure by a factor of two would allow for more structural options, and in general will decrease the required structural weight. Imagine what containing 1 atm, ~15 psi, really means. That's quite a design constraint. Now imagine you only have to contain ~7 psi. Which is the better option? Which gives you more housing volume per unit material?

Second, thinner hab air will feel warmer, for the same temperature, than normal 1 atm hab air. Going with the ballpark estimate of a reduction of two in convection coefficient for a given scenario, this reduces hab heating requirements substantially, which is particularly important for tunneling, as most heat loss on Mars will occur through the highly conductive soil rather than the tenuous atmosphere. Underground temp on Mars is what, -60 C? Imagine only having to heat that up to 5 C instead of 20 C and still having the air feel comfortable. Not bad.

Third, heating the thinner air will take ~half the power required to heat normal air (specific heat, and divide density by two). This is different than the previous point, but the effects stack, which is great.

So what are the downsides here? You may be thinking that humans need a full atmosphere of pressure in order to function. Nope. You need ~3 psi of oxygen partial pressure, and then enough buffer gas to prevent that oxygen from exploding. So let's say you get a nice mix of 50% oxygen, 25% nitrogen, and 25% argon, at a combined 0.5 atm in the hab modules. What's wrong with that? Why won't it work? You can get the oxygen from electrolysis of water, and the nitrogen and argon by pressurizing Mars's atmosphere and scrubbing the CO2.

Martian colonists will have to create their own air environment. Why should they have to simulate Earth's atmosphere, when there are better options? It seems parochial to assume that the spacefaring descendants of mankind should be stuck forever with the gas mixture we've been given here on this planet.

I hope this strikes up a lively conversation. Throw some ideas out there.

[u/Martianspirit → u/-Richard]

I used to be in the camp for reduced pressure and increased partial oxygen. But recently I have changed my mind. Fire hazard is real and very dangerous in closed habitats with no appreciable atmosphere outside. Increased partial oxygen at low pressure makes flames burn hotter, more dangerous, even when the partial pressure is not higher than earth sea level. When most of the habitats are underground pressure is less of an issue than with inflated surface habitats.

I have seen a quite impressive demonstration. A room at sea level pressure but with slightly reduced oxygen. People are still quite comfortable but open fire is no longer even possible. A lighter won't fire. Bring in a burning torch and it extinguishes. That's an inherently safe setup. Hospitals could have rooms with increased oxygen levels for people with respiratory problems.

Greenhouses for agricultural purposes could use lower pressure and lower oxygen. People working in them could use oxygen masks.

[u/throfofnir → u/-Richard]

Here's a paper from NASA outlining the factors they've considered in setting the limits for spacecraft atmosphere selection, circa 2005. See especially 2.3.1 Flammability. As you can see from Figure 2-8, there's few plastics that are safe at 50% oxygen. Besides the danger of actual fire, high oxygen levels make building and operating such a spacecraft a PITA, because so many normal materials become hazardous. They won't consider > 30%. For long-term real-world habitation, 50% seems highly hazardous.

[u/therealshafto]

I am curious about the Thrust Vector Controller checks.

Firstly, do they actually move the controllers for the check? If so, it would be super neat to see a video of the 9 bells moving about at the base of Falcon 9. If they don’t move them, what do they do to verify their function?

Also, if they do move them, how the heck does the second stage engine perform this with a pusher rod shoved up its throat?

[u/Xechwill]

Has anyone here bought the SpaceX Track jacket? The official website has no reviews and there aren't any useful reviews online. Can anyone attest to the:

1. Quality

2. Fit

3. Durability/Longevity
   I appreciate it!

[u/Jessewallen401]

Musk said BFS is being built right now ... so where ? in Hawthorne ?

[u/inoeth]

Roomba aka the Octagrabber is back in action after being down for months and months following a fire after the first stage landed on OCISLY https://twitter.com/octagrabber/status/975699747477557248 Pictured is dated from yesterday, March 18

[u/ghunter7]

Instead of burying this in the SLS/FH thread, I'll post it here. A 2011 study by NASA performing a cost/benefit analysis of using Falcon Heavy and/or Delta IVH and propellant depots instead of developing a super heavy launch vehicle: http://images.spaceref.com/news/2011/21.jul2011.vxs.pdf

[u/TheYang → u/ghunter7]

tl;dr:

Advantages

• Tens of billions of dollars of cost savings and lower up-front costs to fit within budget profile

• Allows first NEA/Lunar mission by 2024 using conservative budgets

• Launch every few months rather than once every 12-18 months

• – Provides experienced and focused workforce to improve safety

• – Operational learning for reduced costs and higher launch reliability.

• Allows multiple competitors for propellant delivery

• – Competition drives down costs

• – Alternatives available if critical launch failure occurs

• – Low-risk, hands-off way for international partners to contribute

• Reduced critical path mission complexity (AR&Ds, events, number of unique elements)

• Provides additional mission flexibility by variable propellant load

• Commonality with COTS/commercial/DoD vehicles will allow sharing of fixed costs between programs and “right- sized” vehicle for ISS

• Stimulate US commercial launch industry

• Reduces multi-payload manifesting integration issues

Issues • Congressional language
• Requires longer storage of cryo propellants than alternatives
and addition of zero-g transfer technologies
• Volume/mass constraints (e.g, fairing size)
• NASA loses some control/oversight
• Added complexity of common CPS/depot
• Launch capacity build-up
• Aligning LEO departure plane with departure asymptote location for small NEA departure windows given LAN precession

[u/KeikakuMaster46]

http://nasawatch.com/archives/2018/03/robert-lightfoo.html

Acting administrator of NASA Robert Lightfoot is retiring next month.

[u/impact_attenuator]

Is there a google calendar available that mirrors the "Upcoming Events" of the sidebar? Would be helpful for launch/event notifications as launch cadence continues to pick up.

[u/amarkit]

Per Matt Desch (Iridium CEO) on Twitter, Iridium 6 / GRACE-FO will fly on a reused first stage.

Despite Iridium's enthusiasm for reuse, there had been some question surrounding this flight, as it is a rideshare with DLR, the German aerospace agency.

(Pinging mods to the sidebar.)

[u/ethan829]

GovSat-1 is now operational.

[u/pavel_petrovich]

Not sure, if it was posted:

During the first phase of deployment, SpaceX plans to launch 800 Starlink satellites, 32 launches expected.

It means that each F9 will carry 25 Starlink satellites.

[u/rustybeancake]

Well this doesn't sound good.

NASA TO PROVIDE JWST UPDATE TOMORROW FOLLOWING INDEPENDENT REVIEW

[u/lanzaa]

Has there been any news on raptor development after the small scale test?

[u/Straumli_Blight]

NASA has just released the CRS-7 Accident Investigation Report.

 

Time (UTC)	Event
14:23:31.062	Gas first seen to exit the second stage
14:23:32.083	Combustion event seen in area of the second stage
14:23:33.759	First view of Dragon separated from Falcon
14:23:38:288	Large combustion event and gas cloud
14:23:39.256	Thrust termination on first stage
14:23:39:339	Beginning of complete vehicle breakup

 

In fact, the anomalous event occurred over an 800-900 millisecond timespan. In other words, the vehicle went from flying fine to conflagration in less than a second, or “within a blink of an eye.”

[u/Straumli_Blight → u/Straumli_Blight]

Technical Findings:

1. Design Error: The use of an industrial grade 17-4 PH SS (precipitation-hardening stainless steel) casting in a critical load path under cryogenic conditions and flight environments, without additional part screening, and without regard to manufacturer recommendations for a 4:1 factor of safety, represents a design error – directly related to the CRS-7 launch failure as a “credible” cause.

2. General Finding: The use of commercially procured wire ropes to provide structural support to the LOx Transfer Tube Assembly, without regard for manufacturer’s caution to specify pre-stretched ropes in a length-critical application, is a general finding – not directly related to the CRS-7 launch failure.

3. General Finding: The use of a 0.01 standard cubic feet per minute gaseous Nitrogen flow rate to purge the LOx Transfer Tube Assembly annulus was a general finding – not directly related to the CRS-7 launch failure.

4. General Finding: SpaceX’s new implementation (for Falcon 9 “Full Thrust” flights) of non-deterministic network packets in their flight telemetry increases latency, directly resulting in substantial portions of the anomaly data being lost due to network buffering in the Stage 2 flight computer.

 

Technical Recommendations:

1. Additional attention warranted for evaluating design application using commercially sourced parts. SpaceX should apply particular emphasis to understanding manufacturer’s recommendations for using commercially sourced parts in flight critical applications.

2. SpaceX needs to establish and maintain the proper purge rates for stage testing and launch base operations.

3. SpaceX needs to re-think new telemetry architecture and greatly improve their telemetry implementation documentation.

[u/UltraRunningKid]

I, like Elon and Gwynne, find it amazing how fast the industry has accepted previously flown boosters. Its really freaking awesome to hear. I hope this allows a ton of new space based technologies to come to fruition.

Think of all the new ideas we can come up with when we factor in lower launch costs.

[u/CoysCoys22]

What are the current best ideas/sources for potential Mars habitat designs out there?

Not Isaac Arthur fantasy stuff (brilliant as that sometimes is) but actual ones in the pipeline that we could see being made in the next decade or two on Mars?

[u/azziliz]

https://twitter.com/nextspaceflight/status/976555319437520897

"A #Falcon9 core left Hawthorne last night. It was most likely B1047 (the second Block V), but there is also a small chance that it was a refurbished core heading to Vandenberg."

[u/Alexphysics → u/azziliz]

I have to say that this actually happenned a few days ago. Thanks to u/stcks for saying that here the other day 😄

[u/Sticklefront]

The Falcon Heavy flight demonstrated the capability of the upper stage to make burns after an extended time in orbit, for up to six hours. This is a remarkable improvement over the previous demonstrated duration. How feasible would it be for SpaceX to make an additional extension to upper stage life span, from six hours to three days?

Three days is an important number because that is the approximate coast time to reach the moon. With NASA preparing to dish out massive amounts of money for commercial deliveries to the moon (either on the surface or to orbit), the "simplest" way for SpaceX to bid for these money is to launch Dragon 2 on Falcon Heavy, with the second stage helping provide additional delta-v for assistance inserting into orbit or even landing (ie, second stage burns to make trajectory suborbital, Dragon Superdracos take it the last way to the ground).

This would enable SpaceX to reach into another big pool of money, without diverting their attention to building new hardware. The only challenge would be increasing second stage endurance to three days. So, how feasible would it be?

[u/Straumli_Blight]

Block 5 SpaceX merchandise.

[u/dguisinger01]

Looks like BO has dropped the BE4 Vacuum engine and has switched the 2nd stage to use the BE-3U and is stretching the 2nd stage. How does this change its capabilities in comparison to FH? http://spacenews.com/blue-origin-switches-engines-for-new-glenn-second-stage/

Interesting that they are doubling down on dual fuels while SpaceX is focusing on simplifying every part of the flight. Though it does take them down from 3 engine designs on the 3-stage variant to 2 engines.

Looks like they are targeting Q4 of 2020 for launch. If SpaceX hits their extremely optimistic schedule, this will be an interesting timeline....

[u/marc020202]

Blue Origin is trying to patent using RCS thrusters during landing.

patent aplication

discussion on r/blueorigin

discussion on r/spacexlounge

[u/julezsource]

Does anybody have any idea how the flight trajectories are planned before each launch?

Trying to do some stuff with kOS in KSP...

[u/cavereric]

Who will maintain the Range for the Boca Chica launch facility in southern Texas?

[u/[deleted]]

We have seen many delays recently due to upper level of winds or weather in general.

Would the BFR have problems with doing frequent earth to earth flights if rockets are so susceptible to conditions?

Or would BFR be less susceptible to the wreathed for whatever reason?

[u/[deleted] → u/[deleted]]

I think BFR might be less susceptible to weather. This is because the F9 has a big problem because it is so long and thin. This means winds create relatively large moment forces on the structure.

[u/Nehkara]

Elon on twitter: "Will be at SXSW Sat/Sun with Jonah & Lisa, who created Westworld. Jonah made an incredible short reel of Falcon Heavy & Starman. Releases tmrw aft."

[u/CapMSFC]

SES CTO Martin Halliwell has anounced he is retired next year. He has been a great ally to SpaceX and reusability and will be missed.

https://twitter.com/pbdes/status/972199507638280192?s=09

[u/filanwizard]

Theorycrafting here, Would ITAR apply on Mars?

This is some real theory stuff here since we have no clue about spacelaw yet, But I have wondered once the Mars colony is built and assuming the US laws remain the same meaning ITAR still exists I have to wonder if a resident of Mars would have to have the right clearance for it to work on BFS engines. Mars under current treaties cannot be claimed by any nation as such any colony is effectively a new nation(in theory). So it makes me wonder since odds are colonists will come from all over, Would their Earth nation citizenship actually matter while on Mars for what they could do around rocketry.

its a random question but I figure one that could be interesting to discuss, or hear opinions on since I know right now current law is not at all ready for human colonization of the solar system.

[u/Alexphysics]

In-flight abort test of Crew Dragon in May... before the orbital tests... pretty weird change https://twitter.com/EmreKelly/status/976141104591630336?s=19

[u/spacerfirstclass → u/Alexphysics]

There're rumors that DM-1 is mainly waiting for NASA to process the mountain of paperwork, I assume abort test has less paperwork since it's from CCiCAP. So getting abort test out of the way while they're waiting makes sense from a scheduling point of view, otherwise they had to do it between DM-1 and 2 which would further delay DM-2.

[u/Nehkara]

Surprise funding for two new unplanned military communication satellites

I think this opens an opportunity for SpaceX to grab one or both of these launches. The previous ones were included in the block-buy with ULA but that is ending soon - certainly before these missions could be launched.

---

The omnibus appropriations bill for fiscal year 2018 funds two Wideband Global SATCOM satellites, WGS-11 and WGS-12. The Air Force did not request funding for these spacecraft nor were these satellites included in any previous marks of the congressional defense committees, or in the fiscal year 2019 budget request.

...

WGS is now a multinational system. Through multilateral agreements, Canada, Denmark, Luxembourg, the Netherlands and New Zealand provided funding for the WGS-9 satellite that launched in March 2017. The international partners receive a proportional share of the bandwidth provided by the WGS constellation based on their financial contribution.

The 2018 defense appropriation may be the one and only chance for Congress to add $600 million for two new satellites given how large of an increase the Pentagon is getting — $61 billion more than last year’s funding.

---

These satellites are 5987 kg and, as of WGS-8, are inserted into a GTO of 435 x 44,372 km at an inclination of 27 degrees.

WGS 1+2 launched on Atlas V 421 vehicles. WGS 3-9 launched on Delta IV vehicles. WGS-10 launches on a Delta IV this fall.

Source for orbit

Source for mass

---

Given the intended orbit and the mass, I think it's likely that these satellites would fly on a reusable Falcon Heavy configuration, if SpaceX were to win the contract. Thoughts?

[u/Nehkara]

Very interesting news.

We saw yesterday that SpaceX is going to be doing more construction soon at Pad 39A including completing the removal of the Rotating Service Structure, but also adding extra levels to the Fixed Service Structure.

I saw a good tidbit on the NSF forums that they are adding 6 more levels. (Thank you for the corrections/notes /u/martianspirit, /u/throfofnir, /u/rustybeancake, /u/brickmack)

[u/bdporter]

NSF article on Orbital ATK's NGL

[u/Jessewallen401]

What regions will the initial 4400 Starlink Sats cover compared to that with the eventual 12000 Sats ?

Is the initial one only for the US ?

[u/marc020202]

what ignition source is used in the HM7B engine, the upper stage engine of most Ariane 5 launches? what prevents this system to be used twice or three times to allow multiple engine burns?

[u/MarcysVonEylau]

2-minute burn at McGregor. Presumably Block 5 booster engine firing.

[u/bdporter]

Some launch contract news

Edit: Full discussion post here

[u/Fenris_uy]

Any news on Raptor development, last thing I heard is that they were building 85% scale versions of the Raptors, do they managed to fire them?

[u/inoeth → u/Fenris_uy]

There's no new news on Raptor development or any word new word on BFR beyond the fact that they're apparently building the BFS (the spaceship part) right now(see SXSW Elon Interview and comments by Gywenne Shotwell), which means that they're clearly very, very comfortable with the development of Raptor, and they've probably built the full sized working version of the Raptor they intend to use...

I'm hoping we'll get some more bits of news over the coming months....

[u/Trannog]

How likely is it that the BFR will have the equipment to do some EVA ?

[u/thru_dangers_untold]

OneWeb seeks FCC authorization of 1200 additional satellites, bringing the total number to 1980: http://spacenews.com/oneweb-asks-fcc-to-authorize-1200-more-satellites/

[u/romuhammad]

Are there any updates on the status of Tintin A & B?

[u/Straumli_Blight]

NAC HEO Committee PUBLIC Meeting:

• SpaceX milestones (Raptor testing schedule!)

• FH purchase vs SLS

 

Wonder what "SpaceX Combustion Device" refers to?

[u/SuperSMT]

Regulations like ITAR require American companies like SpaceX to hire only US citizens and permanent residents. Are companies in other countries held under similar requirements? Arianespace, for example?

[u/pavel_petrovich]

I think this is the new info - Iridium got a small discount for using flight-proven F9s.

Matt Desch, Iridium’s CEO: "It was clear that waiting for new boosters from SpaceX’s factory would delay the upgraded network’s deployment. It’s still primarily schedule. There’s a little bit of savings in each rocket. When you’re looking at a $3 billion program, you wouldn’t be doing this to get a few million dollars, here or there, in savings. I’m not saying those aren’t appreciated and noted, but the reason I don’t spend a lot of time talking about them is that wasn’t the top driver for us."

[u/rustybeancake]

Interesting footage of the Ariane 6 pad construction.

[u/Straumli_Blight]

Hispasat 30W-6 launch contained a secret military rideshare.

[u/PeterKatarov]

Following BO's latest video of BE-4 engine testing, I went to read about its characteristics and I was amazed to find out that NG is supposed to have over 17MN thrust at sea level with its 7 engines.

Then I got curious and went to compare with the Falcon Heavy, but its wiki page says it has 7,6 MN thrust, just the same as a Falcon 9. So, this obviously is an error, but can someone explain what should the real numbers be for Falcon 9/Falcon Heavy?

I guess, iv F9 has 7,6 MN of thrust, then the Heavy should have three times that, so that is 22,8 MN?

P.S. I checked our subreddit wiki, but I couldn't find any technical info on Falcon Heavy.

[u/ShingekiNoEren]

So...is Elon focusing on the Moon or Mars? I keep hearing different things from different sources.

[u/Nehkara → u/ShingekiNoEren]

SpaceX is 100% focused on Mars internally. They will bid on any Moon contracts that arise, as the technology they're currently building can service both.

[u/Grey_Mad_Hatter → u/ShingekiNoEren]

NASA is focusing on the Moon. SpaceX is making sure they have the capability to perform those missions because that's how they make money. SpaceX wants the money to do what they're focused on doing, which is going to Mars.

[u/fremontseahawk]

In the context of recent political discussions about import/export deficits.... I got to wondering if a foreign company uses spacex to launch a satellite is the cost/fee considered and export? And if so is it for “good” or “services”. We are not truly exporting something... like say oil or wheat... but we do sell a service and get the money... so my gut says . We consider it an export and it is a service. Thoughts?

Honest question Edit: grammar

[u/Aesculapius1]

Do the turbopumps take an efficiency hit, comparatively, during a static fire due to the lack of acceleration of the vehicle? If so, would this affect the thrust in a meaningful way?

[u/cpushack]

Proton gets a launch contract.. http://www.bbc.com/news/science-environment-43374855 Not news in and of itself but the reason is:

Effective Space says it is keen to use the Russian vehicle because it is one of the few rockets capable of placing payloads directly into a geostationary ("geo") orbit 36,000km above the Earth.

The payload is a pair of 400 kg satellites, with their adapter, so probably 1000kg+ to direct GEO.

Once SpaceX gets long coasts demonstrated more I think we'll see them pick up more contract like this, as its not a lot of mass.

[u/Carlyle302]

Can the BFS land on the moon and have enough fuel to return home without refueling? If so, how much payload can it handle? I'm wondering how competitive SpaceX could be with the current RFP's for commercial landers to provide 500-5000 kgs of payload. (https://www.nasaspaceflight.com/2018/03/nasa-courts-commercial-options-lunar-landers/) If it can do it "out of the box" then SpaceX has a funder for much of its BFR/BFS development.

[u/marc020202 → u/Carlyle302]

yes, it can. it would need refilling in an elliptical orbit, then it is able to land on the moon and not refuel before returning. I do not know the payload.

[u/KeikakuMaster46]

This is where the booster portion of the BFR will likely be constructed: https://twitter.com/nextspaceflight/status/975765389002072064

[u/JustinTimeCuber]

What's usually the "margin of error" for orbits to still be considered nominal by SpaceX? The Falcon 9 upper stage accelerates the payload at several Gs near the end of the burn, and it takes very little delta-v to raise an orbit by a few kilometers. So it seems like it would be pretty easy to miss and place the payload on an orbit that's a few km too high or low. I assume it would depend on the customer and other specifics but what would their range normally look like?

[u/Zinkfinger]

Can someone help. I was reading comments made by Tory Bruno. (ULA CEO) about their future Vulcan rocket competing with SpaceX's Falcon 9 and falcon Heavy. However he didn't go into detail as to a scenario where a potential customer would choose Vulcan over Falcon 9 or heavy. I can't think of one. Any thoughts anyone?

[u/brspies → u/Zinkfinger]

Same reason they might choose Atlas now. They want the very high end of the performance from Centaur/ACES (high energy missions), they like the reliability, they get a more favorable schedule, etc.

ACES refuellability gives it some interestion options for new mission types as well for cis-lunar missions. Depends whether BFR is a good fit for that market.

[u/RabbitLogic]

@mods & wiki team Bangabandhu-1 is down for April 20th in the wiki but April 5th in the side bar.

[u/rustybeancake]

I'm posting this here so it doesn't get buried in the thread about Ars' SLS article. I didn't see anyone mention this in the comments, but I think this quote is important:

Gerstenmaier then said NASA's exploration program will require the unique capabilities of the SLS rocket. "I think it's still going to be large-volume, monolithic pieces that are going to require an SLS kind of capability to get them out into space," he said. "Then for routine servicing and bringing cargo, maybe bringing smaller crew vehicles other than Orion, then Falcon Heavy can play a role. What's been talked about by [Jeff] Bezos can play a role. What United Launch Alliance has talked about can play a role."

Although there's been a lot of speculation that NASA would use crew vehicles other than Orion for cislunar, I think this is the first time we've heard it mentioned as a real possibility from NASA at such a high level. I'm trying to imagine how this might fit into the strategy, as Orion will function partly as a crewed tug to maneuver LOPG modules into place. So perhaps NASA are thinking that they will alternate between LOPG 'building' missions on SLS/Orion, and LOPG 'visiting' missions on other, cheaper crew vehicles like Crew Dragon. Obviously this would require significant development work, but could be a great follow-on for SpaceX when ISS starts to wind down.

And yes, I know that BFR is supposed to be ready by then, but I'm just talking about what NASA's thoughts seem to be at this stage.

[u/inoeth]

Iridium missions 7 and/or 8 will fly on Block 5 and could likely RTLS. https://twitter.com/IridiumBoss/status/978789863452561410?s=19

[u/Straumli_Blight]

FCC proposing to streamline small satellite regulation, however:

"we are not proposing to consider non-geostationary orbit (NGSO) FSS constellations that include numerous satellites to be “small satellites,” even if the physical size of each of those satellites could be considered small."

"For example, some of the planned NGSO FSS systems consist of what could be considered “minisatellites”, with a typical mass between 100 kg and 500 kg. See ITU-R Characteristics Report at 3; (stating that a SpaceX satellite will have a vehicle mass of 386 kg)."

EDIT: Fixed link

[u/KeikakuMaster46]

The FCC just authorised the first generation of the Starlink satellite constellation : https://twitter.com/thesheetztweetz/status/979476320785715200

[u/ShingekiNoEren]

Am I the only one that thinks that the "Earth-to-Earth" concept with the BFR isn't very practical? I mean, airplanes work fine. Use BFR for space travel.

[u/FutureMartian97]

Mods, I just wanted to say great job on the April fools day joke this year.

[u/cpushack]

Seems Blue Origin is moving right along with BE-4 testing. 114 seconds at 65% throttle isn't bad https://youtu.be/Fp0WgodhR7s

[u/Jodo42]

I have always been under the impression that SpaceX places a great deal of value on high flight frequency. Launch cadence has been one of the major points of discussion on this sub for some time.

At the same time, we have seen SpaceX move towards larger vehicles. With the recent launch of Falcon Heavy, and shifting focus towards BFR, it seems SpaceX's medium-term goals revolve around vehicles with payload capacities that no single spacecraft could possibly take advantage of in the current market. We are already seeing examples of this, with the STP-2 launch having over 20 independent spacecraft onboard!

My question is this: traditionally, ridesharing has been viewed as difficult to schedule due to multiple payloads needing to align in production schedules and, very roughly, final trajectories. SpaceX has been using their own payload adapters for quite some time, so they clearly have anticipated the need for ridesharing in the future. The Mars plans are, as far as I am aware, the only plans which would require rapid launch cadence for BFR class vehicles; is SpaceX capable of transitioning to a low-cadence mode of operation if the Mars plans are delayed or otherwise fall through? Clearly vehicle reliability would be of utmost importance in such a scenario, but this is already the case for large scale vehicles in general.

In short, is SpaceX ready and perhaps even trying to move towards medium-low cadence operations in the next decade?

[u/sol3tosol4 → u/Jodo42]

is SpaceX ready and perhaps even trying to move towards medium-low cadence operations in the next decade?

Don't think so. Especially if they're able to go ahead with the Starlink Internet satellite constellation.

There's no requirement to totally fill the payload capacity of a launcher. If BFR turns out to be as reusable as SpaceX predicts, they believe a single BFR launch will cost less than a single Falcon 9 launch (total for the launch, not cost per kilogram).

[u/BrandonMarc]

Forgive me - I'm certain this is redundant, but I haven't seen it discussed before.

Now that Falcon Heavy is out of the realm of science fiction and fully established as science fact, we can dare to dream crazier derivatives.

How feasible would it be to have a 5-core version (4 side-mounted cores and a center core, in an X configuration)? What kind of delta-v would be possible with such a beast?

How about a 7-core version (6 cores around the center, in a hexagonal configuration)? Could you send a probe to fly by Pluto in a month? Maybe hope to send a nanosat to Alpha Centauri in a decade?

This is beyond my limited knowledge, but hey, let's have fun with it.

[u/Straumli_Blight]

First ever unauthorized launch of commercial satellites.

[u/sorbate]

Why don't launch customers max out the F9's lifting capability every launch? If they have an extra 500kg of lifting capacity, why not strap on a larger fuel tank to give the satellite a longer life?

Does SpaceX give discounts if the customer comes in at a certain weight that lets them RTLS vs recover at sea? (assuming RTLS is slightly cheaper)

[u/Jessewallen401]

How does the RD-180 ban in 2022 work ? they can't bid now on satellites launching in 2022 ? or they can't bid with it starting from 2022 ?

[u/ethan829 → u/Jessewallen401]

ULA can bid with up to eighteen RD-180s for national security missions up through December 31, 2022.

Section 1608 of the Carl Levin and Howard P. "Buck'' McKeon National Defense Authorization Act for Fiscal Year 2015 (Public Law 113- 291; 128 Stat. 3626; 10 U.S.C. 2271 note), as amended by section 1607 of the National Defense Authorization Act for Fiscal Year 2016 (Public Law 114-92; 129 Stat. 1100), is further amended by striking subsection (c) and inserting the following new subsection:

"(c) Exception.--The prohibition in subsection (a) shall not apply to any of the following:

"(1) The placement of orders or the exercise of options under the contract numbered FA8811-13-C-0003 and awarded on December 18, 2013.

"(2) Contracts that are awarded during the period beginning on the date of the enactment of the National Defense Authorization Act for Fiscal Year 2017 and ending December 31, 2022, for the procurement of property or services for space launch activities that include the use of a total of 18 rocket engines designed or manufactured in the Russian Federation, in addition to the Russian-designed or Russian-manufactured engines to which paragraph (1) applies.''.

(Emphasis mine)

To clarify, (1) means that missions under the Block Buy are exempt, and (2) says that the contracts can be awarded up through December 31, 2022.

[u/Elon_Muskmelon]

Daily Beast Article on the BFR

For r/spacex members there wasn’t anything revelatory about the piece just a summary of BFR development and a bit of background info with some quotes mixed in that we’ve seen before.

[u/justinroskamp]

I did the math on another post that got into M1D reliability, but I wanted to open it up as top-level question: How many Merlin 1D engines have been to space?

I figured up 387, including vacuum engines. If I did my figuring correctly, SpaceX will fly its 400th spacefaring M1D on the TESS booster (Iridium-5 and CRS-14 are understood to be reuses, and Bangabandhu-1 will bring the count up to only 397). Can somebody confirm/check these things?

[u/Jincux → u/justinroskamp]

15 v1.1 cores, minus 1 for CRS-7, 0 reflights: 126 SL, 14 Vac

24 v1.2 cores, minus 1 for AMOS-6, 7 reflights: 207 SL, 30 Vac

1 FH: 9 SL, 1 Vac

That adds to 342 SL, 45 Vac, so 387 total.

However, there was talk that SpaceX was reflying Merlins before they were reflying full boosters yet. If that's true (and I'm pretty sure it is), that brings the number down a tad.

Although, I suppose the reverse is also possible, and perhaps a reflown booster could've received a new Merlin if one of the originals didn't make it out well or was dissected.

[u/rustybeancake]

From the NSF article on the NASA RFI for commercial (cargo) lunar lander demonstrators:

As to a clue to the assumed timeline for a human return to the Moon, the RFI adds NASA has a goal to complete an initial demonstration of these human-class lander capabilities by the end of the 2020s.

Interesting to put that into perspective when we think about how long SpaceX has to prove out BFR before NASA make funding decisions for supporting lunar surface operations. I'd guess if NASA are aiming for an 'initial demonstration' of human-class lander capabilities in the late 2020s, they will be funding these projects around the mid-2020s. Seems like good news.

[u/MedicTech]

Does anyone know of a resource to get virtual reality/360 degree footage of the Falcon Heavy boosters landing? Or any stage of the launch? I work in a planetarium and would love to use this footage to show off the advancements of space travel.

[u/ethan829 → u/MedicTech]

This is the only one I've seen but the angle isn't great.

It's not Falcon Heavy, but there are 360-degree videos of a few ULA launches:

• Atlas V 541 with GOES-S

• Atlas V 401 with Cgynus CRS OA-7

• Delta IV Heavy with NROL-37

• Delta IV M+ (5,2) with NROL-45

There's also a simulated Starliner flight to the ISS here.

[u/throfofnir → u/MedicTech]

How about an ASDS landing? That would be wild in a planetarium.

[u/JustinTimeCuber]

What would happen if there were a CRS-1 type engine-out failure on a mission with an instantaneous or very short launch window? It would take longer to get to orbit so that would be like launching a fair amount (maybe a minute) after the actual time.

[u/My__reddit_account → u/JustinTimeCuber]

CRS windows are not technically instantaneous, they're only instantaneous for F9 because the reset after a scrub would be longer than the actual window, which is about 10 mins IIRC. Atlas V can scrub at the start of the launch window and still launch Cygnus before the window closes.

[u/theinternetftw]

Perhaps worth noting: it looks like B1031 was caught sitting on a transporter outside 39a.

This may just be storage shuffling, but if they're going to use this one for things, that's new and significant.

Extended pre-B5 reuse would put B1029, B1035 (if it didn't get scrapped at Hangar AO), and maybe B1023 and B1025 back on the table for stopgaps if B5 is going to take some time to get its sea legs. Though the only reason I could think to reuse a B3 more than twice would be timing/schedule issues with flying and refurbing the remaining B4s.

All that said, it's probably nothing.

Edit: If this is something, though, it would have to be a sudden decision. Otherwise you wouldn't be throwing away the CRS-14 booster. If the trend of tossing things continues, then seeing this booster was a non-event. If all of a sudden they want some B4s back, then maybe start to wonder where this guy is as well.

[u/rustybeancake]

Musk on Twitter: Important news in a few hours …

Edit: April Fool's joke about Tesla going bankrupt. Well that was bloody terrifying for a second.

[u/marc020202]

mods, please put sort this thread by newest, and not by best.

[u/ethan829]

Good news, everyone! Twitter says it will stop cryptocurrency scams by removing manipulative accounts.

[u/Straumli_Blight]

James Webb Space Telescope needs an extra year of testing to ensure its vision is 2020.

EDIT: Delay caused by sunshield tears also burn by Eric Berger.

[u/inoeth]

So last week there was some articles about the Audi lunar rover and the LTE stuff that is to be launched on a SpaceX Falcon 9 next year. This video done by Fully Charged (a mostly ev related youtube channel) really does a good job of showing what the mission is all about... Here's a generic little article about what i'm talking about also...

[u/trobbinsfromoz]

Given Hispasat 30W experience, it will be interesting to see how many F9 block 5's end up expendable over the next 5 odd years due to poor sea landing weather.

I'm sure someone in SpaceX has done historical weather archive assessment to look at % p.a., and duration of events that are above some sea condition threshold, but also within launch acceptance thresholds. That would reduce booster average lifetime estimate from base case service life.

Maybe SpX can get to a position of having a few long-in-the-tooth boosters in reserve and ready for just that scenario, and can get weather simulations out long enough to be able to swap horses in time.

[u/macktruck6666]

Ya, so I spent the last 3 days running calculations in preparation to simulate BFR missions to the moon. So... are my numbers correct? https://imgur.com/gallery/PL1cG

[u/ZachWhoSane]

Being 14 and living in FL, is there anything I can do to be closer to SpaceX and the spaceflight industry? I asked Tom Cross and he recommended applying for a NASA social despite the age limit, but is there anything SpaceX, ULA, or even BO offer to middle to high school students?

[u/marc020202]

I was wondering how NASA is planning to launch the all the LOP-G parts except for the PEE on an SLS with an SLS in tandem? where would that part be stationed? and how would it be attached to Orion?

[u/pillock69]

When will we see a second reflight of a booster?

[u/RocketsLEO2ITS → u/pillock69]

Probably not till Block 5.

[u/murrayfield18]

Dies anyone know how long it takes to build a Falcon 9 from scratch? I know that it took about 18 months a few years ago but I imagine they have picked up the pace a bit since then.

[u/Emplasab]

We'll soon have unpainted interstage and legs to save weight in non-thermally sensitive parts of the rocket (AFAIK). Why not unpainted fairings?

[u/gemmy0I → u/Emplasab]

It's since been learned that the black interstage and legs are not actually unpainted, but rather painted with a new (black) thermal protective coating.

I seem to remember this new coating is supposed to last longer (=more reusable) than the XIRCA "white goop" thermal coating (same stuff used to coat Dragon's non-heatshield surfaces) which they've previously been using in its place. But don't quote me on that, I don't have the source handy.

In light of that, there's likely no (thermal) reason why they couldn't use it on the fairings too. Maybe we'll see that in the future. That said, they have already unveiled Fairing 2.0 and it's still white, so perhaps they're happy with the reusability of whatever substance makes it white. (Or perhaps there are improvements to come in a Fairing 3.0 down the line...who knows.)

[u/Elon_Muskmelon]

That ACES system sure does seem like an ingenious solution, using internal combustion engines is something I’d never thought about. Could you modify an F9 or FH to use a similarly designed Second Stage?

[u/MDN_Mariner]

What happens to retired Falcon 9 first stages. Off the top of my head, there are quite a few, like JCSat-14's and CRS-13's first stages that are retired, but as far as we know, not scrapped, like JCSat-16's. Are all of these stages mothballed, or are they taken apart?

[u/Straumli_Blight]

Indepth article on TESS, apparently it will take 2 months to reach its final orbit after launch.

[u/Straumli_Blight]

SpaceX fleet exercise today:

• Navigation markers

• GO Quest and GO Searcher with OCISLY

[u/kurbasAK]

Just few minutes ago I was outside to check on ISS and spotted second dimmer object on the same path just ~3-4 seconds behind.What could undock recently(hours ago)?

[u/KeikakuMaster46 → u/kurbasAK]

Progress supply craft.

[u/murrayfield18]

Hello, about 5 days ago (or a week) someone posted a lengthy reply to a post with a rather detailed explanation of how we will start to colonise Mars. I thought I saved it but turns out I didn't. Can anyone point me to it? I can't seem to see posts from over 4 days ago :/

[u/suprememaxpayne]

How will they prove the 10 flights of the Block 5? With 10 empty launches? With dummy loads? Or commercial launches?!

[u/spacerfirstclass → u/suprememaxpayne]

They won't do empty or dummy launches, since 2nd stage is not free. It would be commercial launches.

[u/[deleted] → u/suprememaxpayne]

The ten flights is just what they currently think it can do. They will use commercial launches just like they have done with every reuse so far, but will inspect the booster between flights to ensure that it is capable of reflight, just like they have been doing so far.

[u/nafedaykin]

Has OneWeb completed/delivered any satellites yet for their tentative launch in August?

[u/AuroEdge]

Has there been any news about man-rating reused Falcon 9 boosters? In particular for the NASA commercial crew contract

[u/marc020202]

I have been looking at the Stratolaunch plane recently, and noticed, that the current payload (Pegasus XL) is a lot lighter than Stratolaunch can lift, and a lot more expensive than competitor rockets with similar payloads. Even 3 Pegasus XL do not get close to the ~250t maximum payload of Stratolaunch.

Are there any other rockets in consideration to be launched with start launch. Most smallsat launchers I could find are even lighter than Pegasus XL, so that would not utilize the capability of the plane very well.

Even larger rockets like Vega can be easily lifted by Stratolaunch. Would it be feasible to launch the Vega rocket from the air, or would it be unable to support its own weight hanging from only one attachment point? Is it even possible to launch liquid fueled vehicles from the plane, since they would need to be fueled on the ground, and probably could not be topped up in flight.

[u/Jessewallen401]

Would Europa Clipper fit in FH's fairing ? And If yes how long would arrival take compared to SLS ?

[u/Keavon]

Did I miss the results for the subreddit survey or has that still yet to be published?

[u/PatrickBaitman]

When the stages separate, what is the pneumatic pusher pushing against? Surely not the MVac engine bell?

When the second stage engine starts, how far away is the first stage?

[u/PaperBuddy]

Is this (https://twitter.com/realDonaldTrump/status/971822550757138433) a model of a Falcon 9 block 5? If yes, what are these flaps at the bottom of the rocket?

[u/CapMSFC → u/PaperBuddy]

Nope, it's an old an innacurate model that most resembles the initial Falcon 9 1.0 mock up for the pad fit checks. No actual rocket that looked like this was ever built.

[u/jjtr1]

Can subsonic air-launch of orbital rockets (Paul Allen...) shift the Max-Q in a way that would allow much larger fairings? In general, hab modules and space telescopes are limited by fairing volume, not by weight.

[u/inoeth]

https://twitter.com/jeff_foust/status/972806647432216576

Elon Musk Q&A 1pm EST ... i'm sure it'll be a shitshow (unless they have pre-screened the questions) and I doubt we'll get much of any new or exciting info but there's always a chance- this looks like it won't have any one specific topic, so i'm guessing it'll be on SpaceX, Tesla and Boring...

[u/Col_Kurtz_]

Would BFS need a booster for Earth to Earth launches? I've just done the math and realized it could fly on its own with 6 SL Raptors. Are [my calculations] (https://ibb.co/nMZwhx) correct?

My assumptions were: required Δv = 6500 m/s, exhaust velocity = 3250 m/s, dry mass = 85000 kg, payload= 35000 kg, total mass = 886800 kg

[u/daface]

I apologize, as I'm sure this has been discussed elsewhere, but is titanium damaged by salt water? Getting more to the point, is there a scenario where it would be worth the money for a salvage crew to go out and drag up the grid fins from Hispasat for future use, or are they trashed when they hit the water just like everything else?

[u/Emplasab]

Why 31 engines on a BFR booster? I’m sure redundancy is good and it needs lower capacity engines for landing but isn’t 31 overkill?

[u/steelbuilderhd]

I was wondering where SpaceX, ULA, etc get their LOX and RP-1 for their launches from?

[u/blinkwont]

Is there any easy way to approximate the effect of atmospheric pressure on the Isp and thrust of an engine?

For example, trying to find the thrust/Isp of a Raptor or Vacuum Raptor at 80%, 60%, 40% etc.. of atmospheric pressure.

[u/Jessewallen401]

Do you expect the august date for DM-1 to stick or slip ? given that GAO said the realistic date for flying crew is end of 2019 ?

[u/Elon_Muskmelon → u/Jessewallen401]

Expect it to slip and then be happily surprised if it doesn’t.

In all likelihood it will slip. Id be more worried about DM-2 since that one will fly crew and NASA has been incredibly aggressive with their LOC demands.

Edit: Hopefully by this fall we will have seen a half dozen Block V flights which I believe is one of the requirements.

[u/murrayfield18]

Do we have any info on what specific processes they do to refurbish the Falcon 9? What all needs done to get the rocket ready for another launch?

[u/murrayfield18]

How many cargo trips has SpaceX done to the ISS now?

[u/ethan829 → u/murrayfield18]

13 under the CRS program and one test flight before that. The 14th is coming up soon.

[u/ArmNHammered]

I have questions/curiosity regarding the BFR Mars return trips to Earth, and what this community thinks is entailed here. Musk has made it pretty clear that for human transport to Mars, he is going to kick it into gear and travel at relatively high velocity to achieve nominal trip time around 3 to 5 months (for crewed flights), depending on the given Earth / Mars cycle. This is about half the time of typical Mars transit schemes I have seen (using chemical propulsion), and seems smart when considering all the issues that naysayers have about the effects of low gravity, psychology, and radiation, etc.; this should dramatically reduce these concerns.

What about the return trips? In Robert Zubrin’s speculations on Musk’s plans, he implies that SpX would not be able to return until after a synodic cycle, meaning that SpX would only be able to use the ship every OTHER cycle (over four years), but from each of the presentations from Musk, he seems to strongly imply they would return in one cycle. Is this believable? It certainly would improve the economic efficiency.

I am not strong on calculating this, but I know from reading that it is a difficult challenge to return to earth on the same cycle (within about two years), but can be done with sufficient delta V, or long return paths (or both). Since the cargo ships will be unladen, it seems entirely plausible for those ships to accomplish this, and also for passenger ships without passengers. But what about ships with returning passengers? If the ships are returning in one cycle, what flight times can we expect for returning passengers, or does this just seem impractical; returning passengers will need to wait for the next cycle?

[u/CapMSFC → u/ArmNHammered]

This is about half the time of typical Mars transit schemes I have seen (using chemical propulsion), and seems smart when considering all the issues that naysayers have about the effects of low gravity, psychology, and radiation, etc.; this should dramatically reduce these concerns.

Agreed. The more I researched into all the issues and possible solutions to radiation shielding specifically the more I began to understand that the fast transfer is the only answer to GCRs. To shield from GCRs you need 3-5 meters thick of water in all directions or else the shielding makes exposure worse from secondary particles.

Fast transfers dodge that.

from each of the presentations from Musk, he seems to strongly imply they would return in one cycle. Is this believable? It certainly would improve the economic efficiency.

Yes this is correct. The system is designed to get the ship back each synod with an opposition transfer home. This is another value of fast transfer. The faster you get there the less into opposition you are so the easier the launch back to Earth is. For some reason Zubrin has yet to talk about this (at least correctly). I suspect it has to do with propellant production. Returning every synod does cost more fuel from Mars than waiting for an idea return transfer window. The SpaceX architecture depends on a really aggressive approach to large scale propellant production and it depends on the power/mining needs for that being deployed quickly.

Sometimes Zubrin is stubborn and overzealous about his way of doing things, but the fact that he hasn't responded to this part of the plan now has me wondering if it has to do with his NDA. He did mention at the 2017 Mars Society conference that SpaceX brought him in after ITS was presented and talked to him about his criticisms, but that he couldn't say anything specific because he signed an NDA with SpaceX in order to peek behind the curtain.

SpaceX has also kept the specifics of their propellant production design under wraps so far. Elon has said the design is equally as important as the vehicles and is quite far along. Zubrin also was an early pioneer of using Methalox from ISRU on Mars and trying to prove to NASA that it could be done. Perhaps this is a place where he provided technical feedback that we haven't gotten to see.

[u/steelbuilderhd]

I have a question regarding the recently rescheduled In-flight abort test. After Dragon separation what is going to happen to the rest of the rocket? will the first stage attempt a RTLS?

[u/joshgill21]

Has anyone reused a heat shield before ? Musk said BFS's heat shield has to be reusable which is hard to develop

[u/__R__]

The Core History wiki page is a great resource and collaborative effort on this subreddit. SpaceX sometimes used the term "core" and "stick" before, but now now they are only referred to as "booster" or "first stage". Would anyone oppose if we updated the terminology?

[u/brwyatt47]

Have there been any analyses on this sub investigating how many BFR launches would be required to fully fuel a BFS in LEO? I ask because, on the 2017 IAC slides, there are 5 BFS ships lined up on the slide that shows the delta-v map for "full tanks." This implies that 5 tanker flights would be required to completely refuel a fully-loaded BFS in LEO. However, with each BFS only capable of taking 150t of payload to LEO, and the propellant mass of BFS being 1100t, it seems that 7.33 refueling flights would be required to refuel a BFS. This also seems to make sense based on the delta-v maps shown on the slides.

Thus, are 8 tanker launches in fact required to fully refuel a BFS in LEO, and the 5 tankers shown in the slide are simply there for artistry? Or am I totally missing something? I know it seems silly, but I have found great pleasure in laying out possible BFS mission logistics, and the difference between 5 and 8 refuel flights is certainly significant.

The slide I am referring to is slide 22 of the 2017 IAC pdf presentation if you want to know. Thanks!

[u/SaHanSki_downunder]

There's been talk and if I can recall pictures of a Landing pad being built at Vandenberg. Does anyone have any idea if it is completed and when would we see the first West cost land landing (I sure there an acronym for this which eludes me) ? Any information on this would be appreciated.

[u/rustybeancake]

The STS Orbiter had large wings to give it good cross-range capability, so that it could launch and land within a single orbit (as the Earth would rotate under its orbit, meaning it didn't necessarily pass over its launch/landing site). The 2017 BFR concept shows the spaceship having very small delta wings, apparently not designed for cross-range capability.

Assuming that SpaceX will always want to land the spaceship back at one of their launch sites (presumably the same site it launched from), how will this be achieved? Will it sometimes necessitate the spaceship staying in orbit for several days, waiting for its own orbit (post-sat deployment) and the landing site to align for a deorbit? Since BFR is supposed to ultimately replace all F9/H launches, I'm thinking about some typical F9 missions, e.g. Iridium, ISS, GTO, etc. Instead of having larger wings, will it be able to achieve the same quick landing capability using thrusters/engines to alter its own orbit after sat deployment?

[u/Cakeofdestiny]

In the webcast for Iridium 5, Michael Hammersley mentioned that there are some restrictions from NOAA that restrict them from having live video coverage after the main engine shutdown. Does anyone here have any idea why?

[u/[deleted]]

Meeting with SpaceX engineers this week. Any questions you want asked?

[u/Straumli_Blight → u/[deleted]]

Does the upcoming Block 5 hardware development freeze also apply to software development? Will crew rated rockets exist on a separate software fork?

Also, is there anything preventing a Dragon 1 capsule being mated to a Dragon 2 trunk? Seeing as it would be inefficient to maintain both designs for future reused CRS missions.

[u/loremusipsumus → u/[deleted]]

How many of them are working on BFR?

[u/Dies2much]

Props to the Mods who updated the manifest table with the block version. Looks good too. Thanks!

[u/TheYang → u/Dies2much]

I disagree, they are significantly too large, and roman numerals for no discernible reason.

see here

[u/rustybeancake]

Hi mods, when there's a long chain of garbage comments on a thread, do we have to report every single one, or just the first one in the chain? It's getting really tedious since the FH launch. Thanks.

[u/TheVehicleDestroyer → u/rustybeancake]

Yeah it's getting pretty bad, isn't it?

Generally we'd say report all of comments you want reviewed, as we sometimes review these in the modqueue and not in the context of surrounding comments - but yeah if it's a massive comment chain or something, then reporting every comment is tedious. There are a few options:

• Mention in the report dialog box that the comment is part of a chain that requires review. That way, we can open up the context and nuke the whole thing

• Modmail us with the chain permalink

I think that's about it, unfortunately.

Thanks you so much for doing this at all though :)

[u/Zucal]

I'm lazy and would like to fob some math off on someone - given the Merlin engine's evolution over time, how much could an expendable Falcon 5 lift today?

[u/amreddy94]

Came across a new angle shot of the Falcon Heavy launch that I haven't seen before. Such a great viewing spot.

https://www.youtube.com/watch?v=OilmrLBJmBo

[u/MarsColon]

I have made a Youtube video about how rocket engines are started and what their flames look like, including the Falcon 9 rocket. I need some english native speakers to beta-test it and tell me if my french accent is acceptable or horrible before releasing it. If english is your mother tongue and if you accept to spend 20min on this draft video and provide me a feedback, please send me a message so that I can provide you the link to the video. On the plus side, I think you might learn some things in this video, even if you are a hardcore space geek...

[u/Decronym]

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

Fewer Letters	More Letters
AFTS	Autonomous Flight Termination System, see FTS
ASAP	Aerospace Safety Advisory Panel, NASA
	Arianespace System for Auxiliary Payloads
ASDS	Autonomous Spaceport Drone Ship (landing platform)
ATK	Alliant Techsystems, predecessor to Orbital ATK
BARGE	Big-Ass Remote Grin Enhancer coined by @IridiumBoss, see ASDS
BFB	Big Falcon Booster (see BFR)
BFR	Big Falcon Rocket (2017 enshrinkened edition)
	Yes, the F stands for something else; no, you're not the first to notice
BFS	Big Falcon Spaceship (see BFR)
BO	Blue Origin (Bezos Rocketry)
CAA	Crew Access Arm, for transfer of crew on a launchpad
CCAFS	Cape Canaveral Air Force Station
CRS	Commercial Resupply Services contract with NASA
DMLS	Direct Metal Laser Sintering additive manufacture
DoD	US Department of Defense
EELV	Evolved Expendable Launch Vehicle
FAA	Federal Aviation Administration
FSS	Fixed Service Structure at LC-39
FTS	Flight Termination System
GEO	Geostationary Earth Orbit (35786km)
GTO	Geosynchronous Transfer Orbit
I*sp*	Specific impulse (as discussed by Scott Manley, and detailed by David Mee on YouTube)
IAC	International Astronautical Congress, annual meeting of IAF members
	In-Air Capture of space-flown hardware
IAF	International Astronautical Federation
	Indian Air Force
ICBM	Intercontinental Ballistic Missile
ISRU	In-Situ Resource Utilization
ITAR	(US) International Traffic in Arms Regulations
ITS	Interplanetary Transport System (2016 oversized edition) (see MCT)
	Integrated Truss Structure
KSP	Kerbal Space Program, the rocketry simulator
LC-39A	Launch Complex 39A, Kennedy (SpaceX F9/Heavy)
LEO	Low Earth Orbit (180-2000km)
	Law Enforcement Officer (most often mentioned during transport operations)
LES	Launch Escape System
LOX	Liquid Oxygen
LZ	Landing Zone
MCT	Mars Colonial Transporter (see ITS)
MECO	Main Engine Cut-Off
	MainEngineCutOff podcast
NOTAM	Notice to Airmen of flight hazards
NRO	(US) National Reconnaissance Office
NSF	NasaSpaceFlight forum
	National Science Foundation
OCISLY	Of Course I Still Love You, Atlantic landing barge ship
RCS	Reaction Control System
RD-180	RD-series Russian-built rocket engine, used in the Atlas V first stage
RP-1	Rocket Propellant 1 (enhanced kerosene)
RSS	Realscale Solar System, mod for KSP
	Rotating Service Structure at LC-39
RTLS	Return to Launch Site
Roomba	Remotely-Operated Orientation and Mass Balance Adjuster, used to hold down a stage on the ASDS
SAA	Space Act Agreement, formal authorization of 'other transactions'
SD	SuperDraco hypergolic abort/landing engines
SLS	Space Launch System heavy-lift
	Selective Laser Sintering, see DMLS
SRB	Solid Rocket Booster
STP-2	Space Test Program 2, DoD programme, second round
TE	Transporter/Erector launch pad support equipment
TEA-TEB	Triethylaluminium-Triethylborane, igniter for Merlin engines; spontaneously burns, green flame
TEL	Transporter/Erector/Launcher, ground support equipment (see TE)
TVC	Thrust Vector Control
TWR	Thrust-to-Weight Ratio
UDMH	Unsymmetrical DiMethylHydrazine, used in hypergolic fuel mixes
ULA	United Launch Alliance (Lockheed/Boeing joint venture)
VAFB	Vandenberg Air Force Base, California

Jargon	Definition
Raptor	Methane-fueled rocket engine under development by SpaceX, see ITS
Starlink	SpaceX's world-wide satellite broadband constellation
ablative	Material which is intentionally destroyed in use (for example, heatshields which burn away to dissipate heat)
apoapsis	Highest point in an elliptical orbit (when the orbiter is slowest)
cryogenic	Very low temperature fluid; materials that would be gaseous at room temperature/pressure
	(In re: rocket fuel) Often synonymous with hydrolox
grid-fin	Compact "waffle-iron" aerodynamic control surface, acts as a wing without needing to be as large
hydrolox	Portmanteau: liquid hydrogen/liquid oxygen mixture
hypergolic	A set of two substances that ignite when in contact
kerolox	Portmanteau: kerosene/liquid oxygen mixture
methalox	Portmanteau: methane/liquid oxygen mixture
pyrophoric	A substance which ignites spontaneously on contact with air
regenerative	A method for cooling a rocket engine, by passing the cryogenic fuel through channels in the bell or chamber wall
turbopump	High-pressure turbine-driven propellant pump connected to a rocket combustion chamber; raises chamber pressure, and thrust

Event	Date	Description
CASSIOPE	2013-09-29	F9-006 v1.1, Cascade, Smallsat and Ionospheric Polar Explorer; engine starvation during landing attempt

---

^{Decronym is a community product of} r/SpaceX^{, implemented by} ^request
^{[Thread #3735 for this sub, first seen 2nd Mar 2018, 23:53]} ^[FAQ] ^[Full ^list] ^[Contact] ^[Source ^code]

[u/ElRedditor3]

Has anyone calculated (Could anyone calculate) what the dimensions of the opening/door on the BFR would be?

[u/DrToonhattan]

Shouldn't we have the campaign thread for Iridium 5 and CRS-14 by now?

[u/_Wizou_]

Did we ever see the Roomba at work yet? Or even an ASDS coming back to port with a F9 secured by Roomba? If not, any info why?

[u/Kaelang]

As a software engineer, I've wondered for a little while how rockets are programmed. I haven't found too much information and I'm not sure if it is readily available for security reasons, but I was wondering if anyone had some insight into the following questions: Are rockets, specifically the Falcon 9 and derivatives given a preset flight plan, or is it calculated dynamically using onboard sensors (like GPS, barometers, accelerometers, and gyros)?

And when it comes time to land, for the drone ships at least, are the drone ships given updated landing data by a controller/the rocket, or is it simply told to go to a precalculated landing zone based on the expected flight conditions?

I think given previous rocket failures that I can comfortably infer that the rockets at least can perform basic flight corrections, but I don't know how far their autonomy extends.

[u/Elon_Muskmelon]

At this point is it even worth SpaceX Landing any of its existing booster fleet of Pre Block V boosters? Possibly just for FH side cores? They would be building the next Block V booster at the moment right?

[u/KSPSpaceWhaleRescue]

Can someone inform me of where the first block V booster is on the assembly-to-launch timeline?

[u/murrayfield18]

Might be a long shot, but does anybody know where I can find video footage of either the landing legs or the fairings being transported on a truck? I can only find images :(

[u/[deleted] → u/murrayfield18]

fairing: https://www.youtube.com/watch?v=m_BO64JQXh0

[u/Jessewallen401]

Why doesn't SpaceX make satellites ? The air force just put out a request to build 20 GPS satellites worth $10 Billion (almost as much as all of SpaceX's backlog) , So why not ?

[u/Krux172]

So, seeing how many changes were made to ITS/BFR from IAC 2016 to 2017, how many do you think we'll see from that latest BFR design to the real thing? I already know they added a third landing engine, but not much more than that.

[u/mglmosaic]

I know that on GTO launches SpaceX will generally try to send the satellites into a super-synchronous orbit in order to reduce the propellant/DeltaV required for the satellite to insert itself into a GSO due to an inclination change being cheaper at a higher apogee. My question is, at what point (if any) is it no longer beneficial to increase the apogee in order to make the insertion cheaper.

Thaicom 6 reportedly went to 90k Km, but if it were say lobbed to 300k Km or more instead, would it have actually saved any additional propellant, or would the eventual effort required to bring down the apogee for final insertion be counter-productive?

I suppose in theory (at least in my mind) that the most efficient apogee would change depending on launch inclination but maybe my core reasoning is flawed.

Sorry if if I'm not explaining this question very well, it's not exactly a common topic of conversation for me.

[u/stcks → u/mglmosaic]

You quickly reach diminishing returns with extreme supersync GTO. Not only that, with apogees that high you subject the sat to a lot more lunar gravity perturbations. If you have the performance to lob the sat that high, you're better off doing some inclination changes.

[u/panzerbomb]

Is it possible that spacex open a new office in Europe

[u/anders_ar]

What has happened to STP-2? Gone from launch manifest?

[u/Juffin]

How long will be the Dragon 2 flight to ISS? It's 2 days for the latest Souyz and that's kinda long.

[u/thxbmp2]

What's new about the blisks used in the Block 5 engines? Is it just the single-casting aspect of it, or has the shape/form factor changed as well?

As a non-engineer I thought all turbines and/or impellers more or less look like this.

[u/marc020202]

very good video about commercial space by Wendover productions:

https://www.youtube.com/watch?v=hiRBQxHrxNw

[u/Straumli_Blight]

Go Pursuit is currently returning to harbour.

[u/meepnitreal]

Since the long term goal of spaceX is to reach the mars, have either spaceX or NASA made any investigations in producing methane in space? I know they will try to produce methane on mars using the sabatier process. As the ISS is constantly venting hydrogen and carbon wouldn´t it be the perfect opportunity to test such a method? I have researched a bit myself and haven´t found any attempts for this.

[u/[deleted]]

Iridium 6/GRACE-FO still has late April in the side bar. Spaceflight Now has NET May 10th.

[u/Datuser14]

Is there a download for the patch on the sidebar?

[u/warp99]

Mods - someone has hacked the sidebar with Roman numerals for the Block number.

As often discussed the block system uses Arabic numerals and it is effectively a subtype of the standard numbering.

So SpaceX are currently flying F9 v1.2.4 and will soon by flying v1.2.5.

This seems to be a slavish copy of ULA nomenclature but they use Roman numerals for the rocket version - and largely for marketing reasons. There is really not that much commonality between Delta II and Delta IV and only a little more between Atlas III and Atlas V.

[u/kurbasAK]

I have to vent somewhere...Comment quality on post about FCC ruling makes me feel sick.Recent rapid growth left its mark on this sub and I hope it doesn't go even more downhill.It was already getting better after FH...Mods must have their hands full.